Merging upstream version 1.68.2+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

26 files changed, 1625 insertions, 743 deletions

diff --git a/compiler/rustc_mir_build/Cargo.toml b/compiler/rustc_mir_build/Cargo.toml
index 2baa3bfcb..4ad3343d3 100644
--- a/compiler/rustc_mir_build/Cargo.toml
+++ b/compiler/rustc_mir_build/Cargo.toml
@@ -17,6 +17,7 @@ rustc_index = { path = "../rustc_index" }
 rustc_errors = { path = "../rustc_errors" }
 rustc_hir = { path = "../rustc_hir" }
 rustc_infer = { path = "../rustc_infer" }
+rustc_macros = { path = "../rustc_macros" }
 rustc_serialize = { path = "../rustc_serialize" }
 rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
diff --git a/compiler/rustc_mir_build/src/build/block.rs b/compiler/rustc_mir_build/src/build/block.rs
index 49d7136a2..2643d33ce 100644
--- a/compiler/rustc_mir_build/src/build/block.rs
+++ b/compiler/rustc_mir_build/src/build/block.rs
@@ -231,7 +231,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                                         remainder_span,
                                         pattern,
                                         None,
-                                        Some((None, initializer_span)),
+                                        Some((Some(&destination), initializer_span)),
                                     );
                                     this.visit_primary_bindings(
                                         pattern,
@@ -373,7 +373,9 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             // the case of `!`, no return value is required, as the block will never return.
             // Opaque types of empty bodies also need this unit assignment, in order to infer that their
             // type is actually unit. Otherwise there will be no defining use found in the MIR.
-            if destination_ty.is_unit() || matches!(destination_ty.kind(), ty::Opaque(..)) {
+            if destination_ty.is_unit()
+                || matches!(destination_ty.kind(), ty::Alias(ty::Opaque, ..))
+            {
                 // We only want to assign an implicit `()` as the return value of the block if the
                 // block does not diverge. (Otherwise, we may try to assign a unit to a `!`-type.)
                 this.cfg.push_assign_unit(block, source_info, destination, this.tcx);
diff --git a/compiler/rustc_mir_build/src/build/custom/mod.rs b/compiler/rustc_mir_build/src/build/custom/mod.rs
index eb021f477..33fdc1901 100644
--- a/compiler/rustc_mir_build/src/build/custom/mod.rs
+++ b/compiler/rustc_mir_build/src/build/custom/mod.rs
@@ -20,11 +20,12 @@
 use rustc_ast::Attribute;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_hir::def_id::DefId;
+use rustc_hir::HirId;
 use rustc_index::vec::IndexVec;
 use rustc_middle::{
     mir::*,
     thir::*,
-    ty::{Ty, TyCtxt},
+    ty::{ParamEnv, Ty, TyCtxt},
 };
 use rustc_span::Span;
 
@@ -33,6 +34,7 @@ mod parse;
 pub(super) fn build_custom_mir<'tcx>(
     tcx: TyCtxt<'tcx>,
     did: DefId,
+    hir_id: HirId,
     thir: &Thir<'tcx>,
     expr: ExprId,
     params: &IndexVec<ParamId, Param<'tcx>>,
@@ -67,12 +69,16 @@ pub(super) fn build_custom_mir<'tcx>(
         parent_scope: None,
         inlined: None,
         inlined_parent_scope: None,
-        local_data: ClearCrossCrate::Clear,
+        local_data: ClearCrossCrate::Set(SourceScopeLocalData {
+            lint_root: hir_id,
+            safety: Safety::Safe,
+        }),
     });
     body.injection_phase = Some(parse_attribute(attr));
 
     let mut pctxt = ParseCtxt {
         tcx,
+        param_env: tcx.param_env(did),
         thir,
         source_scope: OUTERMOST_SOURCE_SCOPE,
         body: &mut body,
@@ -80,10 +86,10 @@ pub(super) fn build_custom_mir<'tcx>(
         block_map: FxHashMap::default(),
     };
 
-    let res = (|| {
+    let res: PResult<_> = try {
         pctxt.parse_args(&params)?;
-        pctxt.parse_body(expr)
-    })();
+        pctxt.parse_body(expr)?;
+    };
     if let Err(err) = res {
         tcx.sess.diagnostic().span_fatal(
             err.span,
@@ -127,6 +133,7 @@ fn parse_attribute(attr: &Attribute) -> MirPhase {
 
 struct ParseCtxt<'tcx, 'body> {
     tcx: TyCtxt<'tcx>,
+    param_env: ParamEnv<'tcx>,
     thir: &'body Thir<'tcx>,
     source_scope: SourceScope,
 
diff --git a/compiler/rustc_mir_build/src/build/custom/parse/instruction.rs b/compiler/rustc_mir_build/src/build/custom/parse/instruction.rs
index 03206af33..0bca02589 100644
--- a/compiler/rustc_mir_build/src/build/custom/parse/instruction.rs
+++ b/compiler/rustc_mir_build/src/build/custom/parse/instruction.rs
@@ -1,16 +1,33 @@
 use rustc_middle::mir::interpret::{ConstValue, Scalar};
+use rustc_middle::mir::tcx::PlaceTy;
 use rustc_middle::{mir::*, thir::*, ty};
+use rustc_span::Span;
+use rustc_target::abi::VariantIdx;
+
+use crate::build::custom::ParseError;
+use crate::build::expr::as_constant::as_constant_inner;
 
 use super::{parse_by_kind, PResult, ParseCtxt};
 
 impl<'tcx, 'body> ParseCtxt<'tcx, 'body> {
     pub fn parse_statement(&self, expr_id: ExprId) -> PResult<StatementKind<'tcx>> {
         parse_by_kind!(self, expr_id, _, "statement",
+            @call("mir_storage_live", args) => {
+                Ok(StatementKind::StorageLive(self.parse_local(args[0])?))
+            },
+            @call("mir_storage_dead", args) => {
+                Ok(StatementKind::StorageDead(self.parse_local(args[0])?))
+            },
             @call("mir_retag", args) => {
                 Ok(StatementKind::Retag(RetagKind::Default, Box::new(self.parse_place(args[0])?)))
             },
-            @call("mir_retag_raw", args) => {
-                Ok(StatementKind::Retag(RetagKind::Raw, Box::new(self.parse_place(args[0])?)))
+            @call("mir_set_discriminant", args) => {
+                let place = self.parse_place(args[0])?;
+                let var = self.parse_integer_literal(args[1])? as u32;
+                Ok(StatementKind::SetDiscriminant {
+                    place: Box::new(place),
+                    variant_index: VariantIdx::from_u32(var),
+                })
             },
             ExprKind::Assign { lhs, rhs } => {
                 let lhs = self.parse_place(*lhs)?;
@@ -21,18 +38,109 @@ impl<'tcx, 'body> ParseCtxt<'tcx, 'body> {
     }
 
     pub fn parse_terminator(&self, expr_id: ExprId) -> PResult<TerminatorKind<'tcx>> {
-        parse_by_kind!(self, expr_id, _, "terminator",
+        parse_by_kind!(self, expr_id, expr, "terminator",
             @call("mir_return", _args) => {
                 Ok(TerminatorKind::Return)
             },
             @call("mir_goto", args) => {
                 Ok(TerminatorKind::Goto { target: self.parse_block(args[0])? } )
             },
+            @call("mir_unreachable", _args) => {
+                Ok(TerminatorKind::Unreachable)
+            },
+            @call("mir_drop", args) => {
+                Ok(TerminatorKind::Drop {
+                    place: self.parse_place(args[0])?,
+                    target: self.parse_block(args[1])?,
+                    unwind: None,
+                })
+            },
+            @call("mir_drop_and_replace", args) => {
+                Ok(TerminatorKind::DropAndReplace {
+                    place: self.parse_place(args[0])?,
+                    value: self.parse_operand(args[1])?,
+                    target: self.parse_block(args[2])?,
+                    unwind: None,
+                })
+            },
+            @call("mir_call", args) => {
+                let destination = self.parse_place(args[0])?;
+                let target = self.parse_block(args[1])?;
+                self.parse_call(args[2], destination, target)
+            },
+            ExprKind::Match { scrutinee, arms } => {
+                let discr = self.parse_operand(*scrutinee)?;
+                self.parse_match(arms, expr.span).map(|t| TerminatorKind::SwitchInt { discr, targets: t })
+            },
+        )
+    }
+
+    fn parse_match(&self, arms: &[ArmId], span: Span) -> PResult<SwitchTargets> {
+        let Some((otherwise, rest)) = arms.split_last() else {
+            return Err(ParseError {
+                span,
+                item_description: "no arms".to_string(),
+                expected: "at least one arm".to_string(),
+            })
+        };
+
+        let otherwise = &self.thir[*otherwise];
+        let PatKind::Wild = otherwise.pattern.kind else {
+            return Err(ParseError {
+                span: otherwise.span,
+                item_description: format!("{:?}", otherwise.pattern.kind),
+                expected: "wildcard pattern".to_string(),
+            })
+        };
+        let otherwise = self.parse_block(otherwise.body)?;
+
+        let mut values = Vec::new();
+        let mut targets = Vec::new();
+        for arm in rest {
+            let arm = &self.thir[*arm];
+            let PatKind::Constant { value } = arm.pattern.kind else {
+                return Err(ParseError {
+                    span: arm.pattern.span,
+                    item_description: format!("{:?}", arm.pattern.kind),
+                    expected: "constant pattern".to_string(),
+                })
+            };
+            values.push(value.eval_bits(self.tcx, self.param_env, arm.pattern.ty));
+            targets.push(self.parse_block(arm.body)?);
+        }
+
+        Ok(SwitchTargets::new(values.into_iter().zip(targets), otherwise))
+    }
+
+    fn parse_call(
+        &self,
+        expr_id: ExprId,
+        destination: Place<'tcx>,
+        target: BasicBlock,
+    ) -> PResult<TerminatorKind<'tcx>> {
+        parse_by_kind!(self, expr_id, _, "function call",
+            ExprKind::Call { fun, args, from_hir_call, fn_span, .. } => {
+                let fun = self.parse_operand(*fun)?;
+                let args = args
+                    .iter()
+                    .map(|arg| self.parse_operand(*arg))
+                    .collect::<PResult<Vec<_>>>()?;
+                Ok(TerminatorKind::Call {
+                    func: fun,
+                    args,
+                    destination,
+                    target: Some(target),
+                    cleanup: None,
+                    from_hir_call: *from_hir_call,
+                    fn_span: *fn_span,
+                })
+            },
         )
     }
 
     fn parse_rvalue(&self, expr_id: ExprId) -> PResult<Rvalue<'tcx>> {
         parse_by_kind!(self, expr_id, _, "rvalue",
+            @call("mir_discriminant", args) => self.parse_place(args[0]).map(Rvalue::Discriminant),
             ExprKind::Borrow { borrow_kind, arg } => Ok(
                 Rvalue::Ref(self.tcx.lifetimes.re_erased, *borrow_kind, self.parse_place(*arg)?)
             ),
@@ -55,7 +163,7 @@ impl<'tcx, 'body> ParseCtxt<'tcx, 'body> {
             | ExprKind::ConstParam { .. }
             | ExprKind::ConstBlock { .. } => {
                 Ok(Operand::Constant(Box::new(
-                    crate::build::expr::as_constant::as_constant_inner(expr, |_| None, self.tcx)
+                    as_constant_inner(expr, |_| None, self.tcx)
                 )))
             },
             _ => self.parse_place(expr_id).map(Operand::Copy),
@@ -63,12 +171,42 @@ impl<'tcx, 'body> ParseCtxt<'tcx, 'body> {
     }
 
     fn parse_place(&self, expr_id: ExprId) -> PResult<Place<'tcx>> {
-        parse_by_kind!(self, expr_id, _, "place",
-            ExprKind::Deref { arg } => Ok(
-                self.parse_place(*arg)?.project_deeper(&[PlaceElem::Deref], self.tcx)
-            ),
-            _ => self.parse_local(expr_id).map(Place::from),
-        )
+        self.parse_place_inner(expr_id).map(|(x, _)| x)
+    }
+
+    fn parse_place_inner(&self, expr_id: ExprId) -> PResult<(Place<'tcx>, PlaceTy<'tcx>)> {
+        let (parent, proj) = parse_by_kind!(self, expr_id, expr, "place",
+            @call("mir_field", args) => {
+                let (parent, ty) = self.parse_place_inner(args[0])?;
+                let field = Field::from_u32(self.parse_integer_literal(args[1])? as u32);
+                let field_ty = ty.field_ty(self.tcx, field);
+                let proj = PlaceElem::Field(field, field_ty);
+                let place = parent.project_deeper(&[proj], self.tcx);
+                return Ok((place, PlaceTy::from_ty(field_ty)));
+            },
+            @call("mir_variant", args) => {
+                (args[0], PlaceElem::Downcast(
+                    None,
+                    VariantIdx::from_u32(self.parse_integer_literal(args[1])? as u32)
+                ))
+            },
+            ExprKind::Deref { arg } => {
+                parse_by_kind!(self, *arg, _, "does not matter",
+                    @call("mir_make_place", args) => return self.parse_place_inner(args[0]),
+                    _ => (*arg, PlaceElem::Deref),
+                )
+            },
+            ExprKind::Index { lhs, index } => (*lhs, PlaceElem::Index(self.parse_local(*index)?)),
+            ExprKind::Field { lhs, name: field, .. } => (*lhs, PlaceElem::Field(*field, expr.ty)),
+            _ => {
+                let place = self.parse_local(expr_id).map(Place::from)?;
+                return Ok((place, PlaceTy::from_ty(expr.ty)))
+            },
+        );
+        let (parent, ty) = self.parse_place_inner(parent)?;
+        let place = parent.project_deeper(&[proj], self.tcx);
+        let ty = ty.projection_ty(self.tcx, proj);
+        Ok((place, ty))
     }
 
     fn parse_local(&self, expr_id: ExprId) -> PResult<Local> {
@@ -102,4 +240,16 @@ impl<'tcx, 'body> ParseCtxt<'tcx, 'body> {
             },
         )
     }
+
+    fn parse_integer_literal(&self, expr_id: ExprId) -> PResult<u128> {
+        parse_by_kind!(self, expr_id, expr, "constant",
+            ExprKind::Literal { .. }
+            | ExprKind::NamedConst { .. }
+            | ExprKind::NonHirLiteral { .. }
+            | ExprKind::ConstBlock { .. } => Ok({
+                let value = as_constant_inner(expr, |_| None, self.tcx);
+                value.literal.eval_bits(self.tcx, self.param_env, value.ty())
+            }),
+        )
+    }
 }
diff --git a/compiler/rustc_mir_build/src/build/expr/as_constant.rs b/compiler/rustc_mir_build/src/build/expr/as_constant.rs
index 717c62315..1d96893c7 100644
--- a/compiler/rustc_mir_build/src/build/expr/as_constant.rs
+++ b/compiler/rustc_mir_build/src/build/expr/as_constant.rs
@@ -66,14 +66,14 @@ pub fn as_constant_inner<'tcx>(
 
             let literal = ConstantKind::Val(ConstValue::Scalar(Scalar::Int(lit)), ty);
 
-            Constant { span, user_ty: user_ty, literal }
+            Constant { span, user_ty, literal }
         }
         ExprKind::ZstLiteral { ref user_ty } => {
             let user_ty = user_ty.as_ref().map(push_cuta).flatten();
 
             let literal = ConstantKind::Val(ConstValue::ZeroSized, ty);
 
-            Constant { span, user_ty: user_ty, literal }
+            Constant { span, user_ty, literal }
         }
         ExprKind::NamedConst { def_id, substs, ref user_ty } => {
             let user_ty = user_ty.as_ref().map(push_cuta).flatten();
@@ -135,14 +135,14 @@ pub(crate) fn lit_to_mir_constant<'tcx>(
             let allocation = tcx.intern_const_alloc(allocation);
             ConstValue::Slice { data: allocation, start: 0, end: s.len() }
         }
-        (ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _))
+        (ast::LitKind::ByteStr(data, _), ty::Ref(_, inner_ty, _))
             if matches!(inner_ty.kind(), ty::Slice(_)) =>
         {
             let allocation = Allocation::from_bytes_byte_aligned_immutable(data as &[u8]);
             let allocation = tcx.intern_const_alloc(allocation);
             ConstValue::Slice { data: allocation, start: 0, end: data.len() }
         }
-        (ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _)) if inner_ty.is_array() => {
+        (ast::LitKind::ByteStr(data, _), ty::Ref(_, inner_ty, _)) if inner_ty.is_array() => {
             let id = tcx.allocate_bytes(data);
             ConstValue::Scalar(Scalar::from_pointer(id.into(), &tcx))
         }
diff --git a/compiler/rustc_mir_build/src/build/expr/as_operand.rs b/compiler/rustc_mir_build/src/build/expr/as_operand.rs
index c8610af70..c621efb3b 100644
--- a/compiler/rustc_mir_build/src/build/expr/as_operand.rs
+++ b/compiler/rustc_mir_build/src/build/expr/as_operand.rs
@@ -27,7 +27,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
     /// suitable also to be passed as function arguments.
     ///
     /// The operand returned from this function will *not be valid* after an ExprKind::Scope is
-    /// passed, so please do *not* return it from functions to avoid bad miscompiles.  Returns an
+    /// passed, so please do *not* return it from functions to avoid bad miscompiles. Returns an
     /// operand suitable for use as a call argument. This is almost always equivalent to
     /// `as_operand`, except for the particular case of passing values of (potentially) unsized
     /// types "by value" (see details below).
@@ -72,7 +72,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
     /// will actually provide a pointer to the interior of the box, and not move the `dyn Debug`
     /// value to the stack.
     ///
-    /// See #68034 for more details.
+    /// See #68304 for more details.
     pub(crate) fn as_local_call_operand(
         &mut self,
         block: BasicBlock,
diff --git a/compiler/rustc_mir_build/src/build/expr/as_place.rs b/compiler/rustc_mir_build/src/build/expr/as_place.rs
index edd527286..e22fa6365 100644
--- a/compiler/rustc_mir_build/src/build/expr/as_place.rs
+++ b/compiler/rustc_mir_build/src/build/expr/as_place.rs
@@ -81,8 +81,8 @@ pub(in crate::build) struct PlaceBuilder<'tcx> {
 /// ProjectionElems `Downcast`, `ConstantIndex`, `Index`, or `Subslice` because those will never be
 /// part of a path that is captured by a closure. We stop applying projections once we see the first
 /// projection that isn't captured by a closure.
-fn convert_to_hir_projections_and_truncate_for_capture<'tcx>(
-    mir_projections: &[PlaceElem<'tcx>],
+fn convert_to_hir_projections_and_truncate_for_capture(
+    mir_projections: &[PlaceElem<'_>],
 ) -> Vec<HirProjectionKind> {
     let mut hir_projections = Vec::new();
     let mut variant = None;
diff --git a/compiler/rustc_mir_build/src/build/expr/as_rvalue.rs b/compiler/rustc_mir_build/src/build/expr/as_rvalue.rs
index 0814793f2..c7b3eb44d 100644
--- a/compiler/rustc_mir_build/src/build/expr/as_rvalue.rs
+++ b/compiler/rustc_mir_build/src/build/expr/as_rvalue.rs
@@ -142,7 +142,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 let exchange_malloc = Operand::function_handle(
                     tcx,
                     tcx.require_lang_item(LangItem::ExchangeMalloc, Some(expr_span)),
-                    ty::List::empty(),
+                    [],
                     expr_span,
                 );
                 let storage = this.temp(tcx.mk_mut_ptr(tcx.types.u8), expr_span);
diff --git a/compiler/rustc_mir_build/src/build/expr/into.rs b/compiler/rustc_mir_build/src/build/expr/into.rs
index 218a26e62..38b1fa91d 100644
--- a/compiler/rustc_mir_build/src/build/expr/into.rs
+++ b/compiler/rustc_mir_build/src/build/expr/into.rs
@@ -183,7 +183,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     LogicalOp::And => (else_block, shortcircuit_block),
                     LogicalOp::Or => (shortcircuit_block, else_block),
                 };
-                let term = TerminatorKind::if_(this.tcx, lhs, blocks.0, blocks.1);
+                let term = TerminatorKind::if_(lhs, blocks.0, blocks.1);
                 this.cfg.terminate(block, source_info, term);
 
                 this.cfg.push_assign_constant(
diff --git a/compiler/rustc_mir_build/src/build/expr/stmt.rs b/compiler/rustc_mir_build/src/build/expr/stmt.rs
index 00dbcaeb0..780836851 100644
--- a/compiler/rustc_mir_build/src/build/expr/stmt.rs
+++ b/compiler/rustc_mir_build/src/build/expr/stmt.rs
@@ -6,10 +6,8 @@ use rustc_middle::thir::*;
 
 impl<'a, 'tcx> Builder<'a, 'tcx> {
     /// Builds a block of MIR statements to evaluate the THIR `expr`.
-    /// If the original expression was an AST statement,
-    /// (e.g., `some().code(&here());`) then `opt_stmt_span` is the
-    /// span of that statement (including its semicolon, if any).
-    /// The scope is used if a statement temporary must be dropped.
+    ///
+    /// The `statement_scope` is used if a statement temporary must be dropped.
     pub(crate) fn stmt_expr(
         &mut self,
         mut block: BasicBlock,
@@ -59,7 +57,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 // question raised here -- should we "freeze" the
                 // value of the lhs here?  I'm inclined to think not,
                 // since it seems closer to the semantics of the
-                // overloaded version, which takes `&mut self`.  This
+                // overloaded version, which takes `&mut self`. This
                 // only affects weird things like `x += {x += 1; x}`
                 // -- is that equal to `x + (x + 1)` or `2*(x+1)`?
 
@@ -115,7 +113,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 //
                 // it is usually better to focus on `the_value` rather
                 // than the entirety of block(s) surrounding it.
-                let adjusted_span = (|| {
+                let adjusted_span =
                     if let ExprKind::Block { block } = expr.kind
                         && let Some(tail_ex) = this.thir[block].expr
                     {
@@ -137,10 +135,10 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                             tail_result_is_ignored: true,
                             span: expr.span,
                         });
-                        return Some(expr.span);
-                    }
-                    None
-                })();
+                        Some(expr.span)
+                    } else {
+                        None
+                    };
 
                 let temp =
                     unpack!(block = this.as_temp(block, statement_scope, expr, Mutability::Not));
diff --git a/compiler/rustc_mir_build/src/build/matches/mod.rs b/compiler/rustc_mir_build/src/build/matches/mod.rs
index 691cbee2c..0961ce11e 100644
--- a/compiler/rustc_mir_build/src/build/matches/mod.rs
+++ b/compiler/rustc_mir_build/src/build/matches/mod.rs
@@ -30,7 +30,6 @@ mod test;
 mod util;
 
 use std::borrow::Borrow;
-use std::convert::TryFrom;
 use std::mem;
 
 impl<'a, 'tcx> Builder<'a, 'tcx> {
@@ -95,7 +94,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
                 let then_block = this.cfg.start_new_block();
                 let else_block = this.cfg.start_new_block();
-                let term = TerminatorKind::if_(this.tcx, operand, then_block, else_block);
+                let term = TerminatorKind::if_(operand, then_block, else_block);
 
                 let source_info = this.source_info(expr_span);
                 this.cfg.terminate(block, source_info, term);
@@ -1871,7 +1870,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         // ```
         // let place = Foo::new();
         // match place { foo if inspect(foo)
-        //     => feed(foo), ...  }
+        //     => feed(foo), ... }
         // ```
         //
         // will be treated as if it were really something like:
@@ -1886,7 +1885,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         // ```
         // let place = Foo::new();
         // match place { ref mut foo if inspect(foo)
-        //     => feed(foo), ...  }
+        //     => feed(foo), ... }
         // ```
         //
         // will be treated as if it were really something like:
@@ -2211,7 +2210,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             BindingMode::ByValue => ty::BindingMode::BindByValue(mutability),
             BindingMode::ByRef(_) => ty::BindingMode::BindByReference(mutability),
         };
-        let local = LocalDecl::<'tcx> {
+        let local = LocalDecl {
             mutability,
             ty: var_ty,
             user_ty: if user_ty.is_empty() { None } else { Some(Box::new(user_ty)) },
diff --git a/compiler/rustc_mir_build/src/build/matches/test.rs b/compiler/rustc_mir_build/src/build/matches/test.rs
index 58513bde2..ad7a568a2 100644
--- a/compiler/rustc_mir_build/src/build/matches/test.rs
+++ b/compiler/rustc_mir_build/src/build/matches/test.rs
@@ -203,7 +203,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     self.source_info(match_start_span),
                     TerminatorKind::SwitchInt {
                         discr: Operand::Move(discr),
-                        switch_ty: discr_ty,
                         targets: switch_targets,
                     },
                 );
@@ -221,7 +220,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                         0 => (second_bb, first_bb),
                         v => span_bug!(test.span, "expected boolean value but got {:?}", v),
                     };
-                    TerminatorKind::if_(self.tcx, Operand::Copy(place), true_bb, false_bb)
+                    TerminatorKind::if_(Operand::Copy(place), true_bb, false_bb)
                 } else {
                     // The switch may be inexhaustive so we have a catch all block
                     debug_assert_eq!(options.len() + 1, target_blocks.len());
@@ -232,7 +231,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     );
                     TerminatorKind::SwitchInt {
                         discr: Operand::Copy(place),
-                        switch_ty,
                         targets: switch_targets,
                     }
                 };
@@ -378,7 +376,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         self.cfg.terminate(
             block,
             source_info,
-            TerminatorKind::if_(self.tcx, Operand::Move(result), success_block, fail_block),
+            TerminatorKind::if_(Operand::Move(result), success_block, fail_block),
         );
     }
 
@@ -458,7 +456,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     span: source_info.span,
 
                     // FIXME(#54571): This constant comes from user input (a
-                    // constant in a pattern).  Are there forms where users can add
+                    // constant in a pattern). Are there forms where users can add
                     // type annotations here?  For example, an associated constant?
                     // Need to experiment.
                     user_ty: None,
@@ -482,7 +480,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         self.cfg.terminate(
             eq_block,
             source_info,
-            TerminatorKind::if_(self.tcx, Operand::Move(eq_result), success_block, fail_block),
+            TerminatorKind::if_(Operand::Move(eq_result), success_block, fail_block),
         );
     }
 
@@ -506,7 +504,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
     /// This is used by the overall `match_candidates` algorithm to structure
     /// the match as a whole. See `match_candidates` for more details.
     ///
-    /// FIXME(#29623). In some cases, we have some tricky choices to make.  for
+    /// FIXME(#29623). In some cases, we have some tricky choices to make. for
     /// example, if we are testing that `x == 22`, but the candidate is `x @
     /// 13..55`, what should we do? In the event that the test is true, we know
     /// that the candidate applies, but in the event of false, we don't know
@@ -553,16 +551,15 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             //
             // FIXME(#29623) we could use PatKind::Range to rule
             // things out here, in some cases.
-            (
-                &TestKind::SwitchInt { switch_ty: _, ref options },
-                &PatKind::Constant { ref value },
-            ) if is_switch_ty(match_pair.pattern.ty) => {
+            (TestKind::SwitchInt { switch_ty: _, options }, PatKind::Constant { value })
+                if is_switch_ty(match_pair.pattern.ty) =>
+            {
                 let index = options.get_index_of(value).unwrap();
                 self.candidate_without_match_pair(match_pair_index, candidate);
                 Some(index)
             }
 
-            (&TestKind::SwitchInt { switch_ty: _, ref options }, &PatKind::Range(ref range)) => {
+            (TestKind::SwitchInt { switch_ty: _, options }, PatKind::Range(range)) => {
                 let not_contained =
                     self.values_not_contained_in_range(&*range, options).unwrap_or(false);
 
@@ -580,7 +577,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
             (
                 &TestKind::Len { len: test_len, op: BinOp::Eq },
-                &PatKind::Slice { ref prefix, ref slice, ref suffix },
+                PatKind::Slice { prefix, slice, suffix },
             ) => {
                 let pat_len = (prefix.len() + suffix.len()) as u64;
                 match (test_len.cmp(&pat_len), slice) {
@@ -617,7 +614,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
             (
                 &TestKind::Len { len: test_len, op: BinOp::Ge },
-                &PatKind::Slice { ref prefix, ref slice, ref suffix },
+                PatKind::Slice { prefix, slice, suffix },
             ) => {
                 // the test is `$actual_len >= test_len`
                 let pat_len = (prefix.len() + suffix.len()) as u64;
@@ -653,7 +650,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 }
             }
 
-            (&TestKind::Range(ref test), &PatKind::Range(ref pat)) => {
+            (TestKind::Range(test), PatKind::Range(pat)) => {
                 use std::cmp::Ordering::*;
 
                 if test == pat {
@@ -680,7 +677,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 no_overlap
             }
 
-            (&TestKind::Range(ref range), &PatKind::Constant { value }) => {
+            (TestKind::Range(range), &PatKind::Constant { value }) => {
                 if let Some(false) = self.const_range_contains(&*range, value) {
                     // `value` is not contained in the testing range,
                     // so `value` can be matched only if this test fails.
@@ -840,8 +837,6 @@ fn trait_method<'tcx>(
     method_name: Symbol,
     substs: impl IntoIterator<Item = impl Into<GenericArg<'tcx>>>,
 ) -> ConstantKind<'tcx> {
-    let substs = tcx.mk_substs(substs.into_iter().map(Into::into));
-
     // The unhygienic comparison here is acceptable because this is only
     // used on known traits.
     let item = tcx
diff --git a/compiler/rustc_mir_build/src/build/matches/util.rs b/compiler/rustc_mir_build/src/build/matches/util.rs
index bd435f9ab..cbd494862 100644
--- a/compiler/rustc_mir_build/src/build/matches/util.rs
+++ b/compiler/rustc_mir_build/src/build/matches/util.rs
@@ -7,7 +7,6 @@ use rustc_middle::thir::*;
 use rustc_middle::ty;
 use rustc_middle::ty::TypeVisitable;
 use smallvec::SmallVec;
-use std::convert::TryInto;
 
 impl<'a, 'tcx> Builder<'a, 'tcx> {
     pub(crate) fn field_match_pairs<'pat>(
diff --git a/compiler/rustc_mir_build/src/build/mod.rs b/compiler/rustc_mir_build/src/build/mod.rs
index 007f3b55e..9daf68a15 100644
--- a/compiler/rustc_mir_build/src/build/mod.rs
+++ b/compiler/rustc_mir_build/src/build/mod.rs
@@ -28,10 +28,10 @@ use rustc_target::spec::abi::Abi;
 
 use super::lints;
 
-pub(crate) fn mir_built<'tcx>(
-    tcx: TyCtxt<'tcx>,
+pub(crate) fn mir_built(
+    tcx: TyCtxt<'_>,
     def: ty::WithOptConstParam<LocalDefId>,
-) -> &'tcx rustc_data_structures::steal::Steal<Body<'tcx>> {
+) -> &rustc_data_structures::steal::Steal<Body<'_>> {
     if let Some(def) = def.try_upgrade(tcx) {
         return tcx.mir_built(def);
     }
@@ -372,7 +372,7 @@ struct CFG<'tcx> {
 }
 
 rustc_index::newtype_index! {
-    struct ScopeId { .. }
+    struct ScopeId {}
 }
 
 #[derive(Debug)]
@@ -487,6 +487,7 @@ fn construct_fn<'tcx>(
         return custom::build_custom_mir(
             tcx,
             fn_def.did.to_def_id(),
+            fn_id,
             thir,
             expr,
             arguments,
@@ -624,12 +625,12 @@ fn construct_const<'a, 'tcx>(
 ///
 /// This is required because we may still want to run MIR passes on an item
 /// with type errors, but normal MIR construction can't handle that in general.
-fn construct_error<'tcx>(
-    tcx: TyCtxt<'tcx>,
+fn construct_error(
+    tcx: TyCtxt<'_>,
     def: LocalDefId,
     body_owner_kind: hir::BodyOwnerKind,
     err: ErrorGuaranteed,
-) -> Body<'tcx> {
+) -> Body<'_> {
     let span = tcx.def_span(def);
     let hir_id = tcx.hir().local_def_id_to_hir_id(def);
     let generator_kind = tcx.generator_kind(def);
diff --git a/compiler/rustc_mir_build/src/build/scope.rs b/compiler/rustc_mir_build/src/build/scope.rs
index 33f49ffda..591b41633 100644
--- a/compiler/rustc_mir_build/src/build/scope.rs
+++ b/compiler/rustc_mir_build/src/build/scope.rs
@@ -53,7 +53,7 @@ loop {
 ```
 
 When processing the `let x`, we will add one drop to the scope for
-`x`.  The break will then insert a drop for `x`. When we process `let
+`x`. The break will then insert a drop for `x`. When we process `let
 y`, we will add another drop (in fact, to a subscope, but let's ignore
 that for now); any later drops would also drop `y`.
 
@@ -185,7 +185,7 @@ pub(crate) enum BreakableTarget {
 }
 
 rustc_index::newtype_index! {
-    struct DropIdx { .. }
+    struct DropIdx {}
 }
 
 const ROOT_NODE: DropIdx = DropIdx::from_u32(0);
@@ -757,7 +757,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             if self.tcx.sess.opts.unstable_opts.maximal_hir_to_mir_coverage {
                 // Some consumers of rustc need to map MIR locations back to HIR nodes. Currently the
                 // the only part of rustc that tracks MIR -> HIR is the `SourceScopeLocalData::lint_root`
-                // field that tracks lint levels for MIR locations.  Normally the number of source scopes
+                // field that tracks lint levels for MIR locations. Normally the number of source scopes
                 // is limited to the set of nodes with lint annotations. The -Zmaximal-hir-to-mir-coverage
                 // flag changes this behavior to maximize the number of source scopes, increasing the
                 // granularity of the MIR->HIR mapping.
diff --git a/compiler/rustc_mir_build/src/check_unsafety.rs b/compiler/rustc_mir_build/src/check_unsafety.rs
index fb1ea9ed3..03a7f2d70 100644
--- a/compiler/rustc_mir_build/src/check_unsafety.rs
+++ b/compiler/rustc_mir_build/src/check_unsafety.rs
@@ -1,10 +1,11 @@
 use crate::build::ExprCategory;
+use crate::errors::*;
 use rustc_middle::thir::visit::{self, Visitor};
 
-use rustc_errors::struct_span_err;
 use rustc_hir as hir;
 use rustc_middle::mir::BorrowKind;
 use rustc_middle::thir::*;
+use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_middle::ty::{self, ParamEnv, Ty, TyCtxt};
 use rustc_session::lint::builtin::{UNSAFE_OP_IN_UNSAFE_FN, UNUSED_UNSAFE};
 use rustc_session::lint::Level;
@@ -12,7 +13,6 @@ use rustc_span::def_id::{DefId, LocalDefId};
 use rustc_span::symbol::Symbol;
 use rustc_span::Span;
 
-use std::borrow::Cow;
 use std::ops::Bound;
 
 struct UnsafetyVisitor<'a, 'tcx> {
@@ -46,7 +46,9 @@ impl<'tcx> UnsafetyVisitor<'_, 'tcx> {
             self.warn_unused_unsafe(
                 hir_id,
                 block_span,
-                Some((self.tcx.sess.source_map().guess_head_span(enclosing_span), "block")),
+                Some(UnusedUnsafeEnclosing::Block {
+                    span: self.tcx.sess.source_map().guess_head_span(enclosing_span),
+                }),
             );
             f(self);
         } else {
@@ -60,7 +62,9 @@ impl<'tcx> UnsafetyVisitor<'_, 'tcx> {
                     hir_id,
                     span,
                     if self.unsafe_op_in_unsafe_fn_allowed() {
-                        self.body_unsafety.unsafe_fn_sig_span().map(|span| (span, "fn"))
+                        self.body_unsafety
+                            .unsafe_fn_sig_span()
+                            .map(|span| UnusedUnsafeEnclosing::Function { span })
                     } else {
                         None
                     },
@@ -83,30 +87,11 @@ impl<'tcx> UnsafetyVisitor<'_, 'tcx> {
             }
             SafetyContext::UnsafeFn if unsafe_op_in_unsafe_fn_allowed => {}
             SafetyContext::UnsafeFn => {
-                let (description, note) = kind.description_and_note(self.tcx);
                 // unsafe_op_in_unsafe_fn is disallowed
-                self.tcx.struct_span_lint_hir(
-                    UNSAFE_OP_IN_UNSAFE_FN,
-                    self.hir_context,
-                    span,
-                    format!("{} is unsafe and requires unsafe block (error E0133)", description,),
-                    |lint| lint.span_label(span, kind.simple_description()).note(note),
-                )
+                kind.emit_unsafe_op_in_unsafe_fn_lint(self.tcx, self.hir_context, span);
             }
             SafetyContext::Safe => {
-                let (description, note) = kind.description_and_note(self.tcx);
-                let fn_sugg = if unsafe_op_in_unsafe_fn_allowed { " function or" } else { "" };
-                struct_span_err!(
-                    self.tcx.sess,
-                    span,
-                    E0133,
-                    "{} is unsafe and requires unsafe{} block",
-                    description,
-                    fn_sugg,
-                )
-                .span_label(span, kind.simple_description())
-                .note(note)
-                .emit();
+                kind.emit_requires_unsafe_err(self.tcx, span, unsafe_op_in_unsafe_fn_allowed);
             }
         }
     }
@@ -115,23 +100,33 @@ impl<'tcx> UnsafetyVisitor<'_, 'tcx> {
         &self,
         hir_id: hir::HirId,
         block_span: Span,
-        enclosing_unsafe: Option<(Span, &'static str)>,
+        enclosing_unsafe: Option<UnusedUnsafeEnclosing>,
     ) {
         let block_span = self.tcx.sess.source_map().guess_head_span(block_span);
-        let msg = "unnecessary `unsafe` block";
-        self.tcx.struct_span_lint_hir(UNUSED_UNSAFE, hir_id, block_span, msg, |lint| {
-            lint.span_label(block_span, msg);
-            if let Some((span, kind)) = enclosing_unsafe {
-                lint.span_label(span, format!("because it's nested under this `unsafe` {}", kind));
-            }
-            lint
-        });
+        self.tcx.emit_spanned_lint(
+            UNUSED_UNSAFE,
+            hir_id,
+            block_span,
+            UnusedUnsafe { span: block_span, enclosing: enclosing_unsafe },
+        );
     }
 
     /// Whether the `unsafe_op_in_unsafe_fn` lint is `allow`ed at the current HIR node.
     fn unsafe_op_in_unsafe_fn_allowed(&self) -> bool {
         self.tcx.lint_level_at_node(UNSAFE_OP_IN_UNSAFE_FN, self.hir_context).0 == Level::Allow
     }
+
+    /// Handle closures/generators/inline-consts, which is unsafecked with their parent body.
+    fn visit_inner_body(&mut self, def: ty::WithOptConstParam<LocalDefId>) {
+        if let Ok((inner_thir, expr)) = self.tcx.thir_body(def) {
+            let inner_thir = &inner_thir.borrow();
+            let hir_context = self.tcx.hir().local_def_id_to_hir_id(def.did);
+            let mut inner_visitor = UnsafetyVisitor { thir: inner_thir, hir_context, ..*self };
+            inner_visitor.visit_expr(&inner_thir[expr]);
+            // Unsafe blocks can be used in the inner body, make sure to take it into account
+            self.safety_context = inner_visitor.safety_context;
+        }
+    }
 }
 
 // Searches for accesses to layout constrained fields.
@@ -408,16 +403,11 @@ impl<'a, 'tcx> Visitor<'a, 'tcx> for UnsafetyVisitor<'a, 'tcx> {
                 } else {
                     ty::WithOptConstParam::unknown(closure_id)
                 };
-                let (closure_thir, expr) = self.tcx.thir_body(closure_def).unwrap_or_else(|_| {
-                    (self.tcx.alloc_steal_thir(Thir::new()), ExprId::from_u32(0))
-                });
-                let closure_thir = &closure_thir.borrow();
-                let hir_context = self.tcx.hir().local_def_id_to_hir_id(closure_id);
-                let mut closure_visitor =
-                    UnsafetyVisitor { thir: closure_thir, hir_context, ..*self };
-                closure_visitor.visit_expr(&closure_thir[expr]);
-                // Unsafe blocks can be used in closures, make sure to take it into account
-                self.safety_context = closure_visitor.safety_context;
+                self.visit_inner_body(closure_def);
+            }
+            ExprKind::ConstBlock { did, substs: _ } => {
+                let def_id = did.expect_local();
+                self.visit_inner_body(ty::WithOptConstParam::unknown(def_id));
             }
             ExprKind::Field { lhs, .. } => {
                 let lhs = &self.thir[lhs];
@@ -529,94 +519,201 @@ enum UnsafeOpKind {
 use UnsafeOpKind::*;
 
 impl UnsafeOpKind {
-    pub fn simple_description(&self) -> &'static str {
-        match self {
-            CallToUnsafeFunction(..) => "call to unsafe function",
-            UseOfInlineAssembly => "use of inline assembly",
-            InitializingTypeWith => "initializing type with `rustc_layout_scalar_valid_range` attr",
-            UseOfMutableStatic => "use of mutable static",
-            UseOfExternStatic => "use of extern static",
-            DerefOfRawPointer => "dereference of raw pointer",
-            AccessToUnionField => "access to union field",
-            MutationOfLayoutConstrainedField => "mutation of layout constrained field",
-            BorrowOfLayoutConstrainedField => {
-                "borrow of layout constrained field with interior mutability"
-            }
-            CallToFunctionWith(..) => "call to function with `#[target_feature]`",
-        }
-    }
-
-    pub fn description_and_note(&self, tcx: TyCtxt<'_>) -> (Cow<'static, str>, &'static str) {
+    pub fn emit_unsafe_op_in_unsafe_fn_lint(
+        &self,
+        tcx: TyCtxt<'_>,
+        hir_id: hir::HirId,
+        span: Span,
+    ) {
+        // FIXME: ideally we would want to trim the def paths, but this is not
+        // feasible with the current lint emission API (see issue #106126).
         match self {
-            CallToUnsafeFunction(did) => (
-                if let Some(did) = did {
-                    Cow::from(format!("call to unsafe function `{}`", tcx.def_path_str(*did)))
-                } else {
-                    Cow::Borrowed(self.simple_description())
+            CallToUnsafeFunction(Some(did)) => tcx.emit_spanned_lint(
+                UNSAFE_OP_IN_UNSAFE_FN,
+                hir_id,
+                span,
+                UnsafeOpInUnsafeFnCallToUnsafeFunctionRequiresUnsafe {
+                    span,
+                    function: &with_no_trimmed_paths!(tcx.def_path_str(*did)),
                 },
-                "consult the function's documentation for information on how to avoid undefined \
-                 behavior",
             ),
-            UseOfInlineAssembly => (
-                Cow::Borrowed(self.simple_description()),
-                "inline assembly is entirely unchecked and can cause undefined behavior",
+            CallToUnsafeFunction(None) => tcx.emit_spanned_lint(
+                UNSAFE_OP_IN_UNSAFE_FN,
+                hir_id,
+                span,
+                UnsafeOpInUnsafeFnCallToUnsafeFunctionRequiresUnsafeNameless { span },
             ),
-            InitializingTypeWith => (
-                Cow::Borrowed(self.simple_description()),
-                "initializing a layout restricted type's field with a value outside the valid \
-                 range is undefined behavior",
+            UseOfInlineAssembly => tcx.emit_spanned_lint(
+                UNSAFE_OP_IN_UNSAFE_FN,
+                hir_id,
+                span,
+                UnsafeOpInUnsafeFnUseOfInlineAssemblyRequiresUnsafe { span },
             ),
-            UseOfMutableStatic => (
-                Cow::Borrowed(self.simple_description()),
-                "mutable statics can be mutated by multiple threads: aliasing violations or data \
-                 races will cause undefined behavior",
+            InitializingTypeWith => tcx.emit_spanned_lint(
+                UNSAFE_OP_IN_UNSAFE_FN,
+                hir_id,
+                span,
+                UnsafeOpInUnsafeFnInitializingTypeWithRequiresUnsafe { span },
             ),
-            UseOfExternStatic => (
-                Cow::Borrowed(self.simple_description()),
-                "extern statics are not controlled by the Rust type system: invalid data, \
-                 aliasing violations or data races will cause undefined behavior",
+            UseOfMutableStatic => tcx.emit_spanned_lint(
+                UNSAFE_OP_IN_UNSAFE_FN,
+                hir_id,
+                span,
+                UnsafeOpInUnsafeFnUseOfMutableStaticRequiresUnsafe { span },
             ),
-            DerefOfRawPointer => (
-                Cow::Borrowed(self.simple_description()),
-                "raw pointers may be null, dangling or unaligned; they can violate aliasing rules \
-                 and cause data races: all of these are undefined behavior",
+            UseOfExternStatic => tcx.emit_spanned_lint(
+                UNSAFE_OP_IN_UNSAFE_FN,
+                hir_id,
+                span,
+                UnsafeOpInUnsafeFnUseOfExternStaticRequiresUnsafe { span },
             ),
-            AccessToUnionField => (
-                Cow::Borrowed(self.simple_description()),
-                "the field may not be properly initialized: using uninitialized data will cause \
-                 undefined behavior",
+            DerefOfRawPointer => tcx.emit_spanned_lint(
+                UNSAFE_OP_IN_UNSAFE_FN,
+                hir_id,
+                span,
+                UnsafeOpInUnsafeFnDerefOfRawPointerRequiresUnsafe { span },
+            ),
+            AccessToUnionField => tcx.emit_spanned_lint(
+                UNSAFE_OP_IN_UNSAFE_FN,
+                hir_id,
+                span,
+                UnsafeOpInUnsafeFnAccessToUnionFieldRequiresUnsafe { span },
             ),
-            MutationOfLayoutConstrainedField => (
-                Cow::Borrowed(self.simple_description()),
-                "mutating layout constrained fields cannot statically be checked for valid values",
+            MutationOfLayoutConstrainedField => tcx.emit_spanned_lint(
+                UNSAFE_OP_IN_UNSAFE_FN,
+                hir_id,
+                span,
+                UnsafeOpInUnsafeFnMutationOfLayoutConstrainedFieldRequiresUnsafe { span },
             ),
-            BorrowOfLayoutConstrainedField => (
-                Cow::Borrowed(self.simple_description()),
-                "references to fields of layout constrained fields lose the constraints. Coupled \
-                 with interior mutability, the field can be changed to invalid values",
+            BorrowOfLayoutConstrainedField => tcx.emit_spanned_lint(
+                UNSAFE_OP_IN_UNSAFE_FN,
+                hir_id,
+                span,
+                UnsafeOpInUnsafeFnBorrowOfLayoutConstrainedFieldRequiresUnsafe { span },
             ),
-            CallToFunctionWith(did) => (
-                Cow::from(format!(
-                    "call to function `{}` with `#[target_feature]`",
-                    tcx.def_path_str(*did)
-                )),
-                "can only be called if the required target features are available",
+            CallToFunctionWith(did) => tcx.emit_spanned_lint(
+                UNSAFE_OP_IN_UNSAFE_FN,
+                hir_id,
+                span,
+                UnsafeOpInUnsafeFnCallToFunctionWithRequiresUnsafe {
+                    span,
+                    function: &with_no_trimmed_paths!(tcx.def_path_str(*did)),
+                },
             ),
         }
     }
+
+    pub fn emit_requires_unsafe_err(
+        &self,
+        tcx: TyCtxt<'_>,
+        span: Span,
+        unsafe_op_in_unsafe_fn_allowed: bool,
+    ) {
+        match self {
+            CallToUnsafeFunction(Some(did)) if unsafe_op_in_unsafe_fn_allowed => {
+                tcx.sess.emit_err(CallToUnsafeFunctionRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+                    span,
+                    function: &tcx.def_path_str(*did),
+                });
+            }
+            CallToUnsafeFunction(Some(did)) => {
+                tcx.sess.emit_err(CallToUnsafeFunctionRequiresUnsafe {
+                    span,
+                    function: &tcx.def_path_str(*did),
+                });
+            }
+            CallToUnsafeFunction(None) if unsafe_op_in_unsafe_fn_allowed => {
+                tcx.sess.emit_err(
+                    CallToUnsafeFunctionRequiresUnsafeNamelessUnsafeOpInUnsafeFnAllowed { span },
+                );
+            }
+            CallToUnsafeFunction(None) => {
+                tcx.sess.emit_err(CallToUnsafeFunctionRequiresUnsafeNameless { span });
+            }
+            UseOfInlineAssembly if unsafe_op_in_unsafe_fn_allowed => {
+                tcx.sess
+                    .emit_err(UseOfInlineAssemblyRequiresUnsafeUnsafeOpInUnsafeFnAllowed { span });
+            }
+            UseOfInlineAssembly => {
+                tcx.sess.emit_err(UseOfInlineAssemblyRequiresUnsafe { span });
+            }
+            InitializingTypeWith if unsafe_op_in_unsafe_fn_allowed => {
+                tcx.sess
+                    .emit_err(InitializingTypeWithRequiresUnsafeUnsafeOpInUnsafeFnAllowed { span });
+            }
+            InitializingTypeWith => {
+                tcx.sess.emit_err(InitializingTypeWithRequiresUnsafe { span });
+            }
+            UseOfMutableStatic if unsafe_op_in_unsafe_fn_allowed => {
+                tcx.sess
+                    .emit_err(UseOfMutableStaticRequiresUnsafeUnsafeOpInUnsafeFnAllowed { span });
+            }
+            UseOfMutableStatic => {
+                tcx.sess.emit_err(UseOfMutableStaticRequiresUnsafe { span });
+            }
+            UseOfExternStatic if unsafe_op_in_unsafe_fn_allowed => {
+                tcx.sess
+                    .emit_err(UseOfExternStaticRequiresUnsafeUnsafeOpInUnsafeFnAllowed { span });
+            }
+            UseOfExternStatic => {
+                tcx.sess.emit_err(UseOfExternStaticRequiresUnsafe { span });
+            }
+            DerefOfRawPointer if unsafe_op_in_unsafe_fn_allowed => {
+                tcx.sess
+                    .emit_err(DerefOfRawPointerRequiresUnsafeUnsafeOpInUnsafeFnAllowed { span });
+            }
+            DerefOfRawPointer => {
+                tcx.sess.emit_err(DerefOfRawPointerRequiresUnsafe { span });
+            }
+            AccessToUnionField if unsafe_op_in_unsafe_fn_allowed => {
+                tcx.sess
+                    .emit_err(AccessToUnionFieldRequiresUnsafeUnsafeOpInUnsafeFnAllowed { span });
+            }
+            AccessToUnionField => {
+                tcx.sess.emit_err(AccessToUnionFieldRequiresUnsafe { span });
+            }
+            MutationOfLayoutConstrainedField if unsafe_op_in_unsafe_fn_allowed => {
+                tcx.sess.emit_err(
+                    MutationOfLayoutConstrainedFieldRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+                        span,
+                    },
+                );
+            }
+            MutationOfLayoutConstrainedField => {
+                tcx.sess.emit_err(MutationOfLayoutConstrainedFieldRequiresUnsafe { span });
+            }
+            BorrowOfLayoutConstrainedField if unsafe_op_in_unsafe_fn_allowed => {
+                tcx.sess.emit_err(
+                    BorrowOfLayoutConstrainedFieldRequiresUnsafeUnsafeOpInUnsafeFnAllowed { span },
+                );
+            }
+            BorrowOfLayoutConstrainedField => {
+                tcx.sess.emit_err(BorrowOfLayoutConstrainedFieldRequiresUnsafe { span });
+            }
+            CallToFunctionWith(did) if unsafe_op_in_unsafe_fn_allowed => {
+                tcx.sess.emit_err(CallToFunctionWithRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+                    span,
+                    function: &tcx.def_path_str(*did),
+                });
+            }
+            CallToFunctionWith(did) => {
+                tcx.sess.emit_err(CallToFunctionWithRequiresUnsafe {
+                    span,
+                    function: &tcx.def_path_str(*did),
+                });
+            }
+        }
+    }
 }
 
-pub fn check_unsafety<'tcx>(tcx: TyCtxt<'tcx>, def: ty::WithOptConstParam<LocalDefId>) {
+pub fn check_unsafety(tcx: TyCtxt<'_>, def: ty::WithOptConstParam<LocalDefId>) {
     // THIR unsafeck is gated under `-Z thir-unsafeck`
     if !tcx.sess.opts.unstable_opts.thir_unsafeck {
         return;
     }
 
-    // Closures are handled by their owner, if it has a body
-    if tcx.is_closure(def.did.to_def_id()) {
-        let hir = tcx.hir();
-        let owner = hir.enclosing_body_owner(hir.local_def_id_to_hir_id(def.did));
-        tcx.ensure().thir_check_unsafety(owner);
+    // Closures and inline consts are handled by their owner, if it has a body
+    if tcx.is_typeck_child(def.did.to_def_id()) {
         return;
     }
 
@@ -655,7 +752,7 @@ pub fn check_unsafety<'tcx>(tcx: TyCtxt<'tcx>, def: ty::WithOptConstParam<LocalD
     visitor.visit_expr(&thir[expr]);
 }
 
-pub(crate) fn thir_check_unsafety<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) {
+pub(crate) fn thir_check_unsafety(tcx: TyCtxt<'_>, def_id: LocalDefId) {
     if let Some(def) = ty::WithOptConstParam::try_lookup(def_id, tcx) {
         tcx.thir_check_unsafety_for_const_arg(def)
     } else {
@@ -663,8 +760,8 @@ pub(crate) fn thir_check_unsafety<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) {
     }
 }
 
-pub(crate) fn thir_check_unsafety_for_const_arg<'tcx>(
-    tcx: TyCtxt<'tcx>,
+pub(crate) fn thir_check_unsafety_for_const_arg(
+    tcx: TyCtxt<'_>,
     (did, param_did): (LocalDefId, DefId),
 ) {
     check_unsafety(tcx, ty::WithOptConstParam { did, const_param_did: Some(param_did) })
diff --git a/compiler/rustc_mir_build/src/errors.rs b/compiler/rustc_mir_build/src/errors.rs
new file mode 100644
index 000000000..7f81aef1c
--- /dev/null
+++ b/compiler/rustc_mir_build/src/errors.rs
@@ -0,0 +1,865 @@
+use crate::thir::pattern::deconstruct_pat::DeconstructedPat;
+use crate::thir::pattern::MatchCheckCtxt;
+use rustc_errors::Handler;
+use rustc_errors::{
+    error_code, AddToDiagnostic, Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed,
+    IntoDiagnostic, MultiSpan, SubdiagnosticMessage,
+};
+use rustc_hir::def::Res;
+use rustc_macros::{Diagnostic, LintDiagnostic, Subdiagnostic};
+use rustc_middle::thir::Pat;
+use rustc_middle::ty::{self, Ty};
+use rustc_span::{symbol::Ident, Span};
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unconditional_recursion)]
+#[help]
+pub struct UnconditionalRecursion {
+    #[label]
+    pub span: Span,
+    #[label(mir_build_unconditional_recursion_call_site_label)]
+    pub call_sites: Vec<Span>,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_call_to_unsafe_fn_requires_unsafe)]
+#[note]
+pub struct UnsafeOpInUnsafeFnCallToUnsafeFunctionRequiresUnsafe<'a> {
+    #[label]
+    pub span: Span,
+    pub function: &'a str,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_call_to_unsafe_fn_requires_unsafe_nameless)]
+#[note]
+pub struct UnsafeOpInUnsafeFnCallToUnsafeFunctionRequiresUnsafeNameless {
+    #[label]
+    pub span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_inline_assembly_requires_unsafe)]
+#[note]
+pub struct UnsafeOpInUnsafeFnUseOfInlineAssemblyRequiresUnsafe {
+    #[label]
+    pub span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_initializing_type_with_requires_unsafe)]
+#[note]
+pub struct UnsafeOpInUnsafeFnInitializingTypeWithRequiresUnsafe {
+    #[label]
+    pub span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_mutable_static_requires_unsafe)]
+#[note]
+pub struct UnsafeOpInUnsafeFnUseOfMutableStaticRequiresUnsafe {
+    #[label]
+    pub span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_extern_static_requires_unsafe)]
+#[note]
+pub struct UnsafeOpInUnsafeFnUseOfExternStaticRequiresUnsafe {
+    #[label]
+    pub span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_deref_raw_pointer_requires_unsafe)]
+#[note]
+pub struct UnsafeOpInUnsafeFnDerefOfRawPointerRequiresUnsafe {
+    #[label]
+    pub span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_union_field_requires_unsafe)]
+#[note]
+pub struct UnsafeOpInUnsafeFnAccessToUnionFieldRequiresUnsafe {
+    #[label]
+    pub span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_mutation_of_layout_constrained_field_requires_unsafe)]
+#[note]
+pub struct UnsafeOpInUnsafeFnMutationOfLayoutConstrainedFieldRequiresUnsafe {
+    #[label]
+    pub span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_borrow_of_layout_constrained_field_requires_unsafe)]
+pub struct UnsafeOpInUnsafeFnBorrowOfLayoutConstrainedFieldRequiresUnsafe {
+    #[label]
+    pub span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unsafe_op_in_unsafe_fn_call_to_fn_with_requires_unsafe)]
+#[note]
+pub struct UnsafeOpInUnsafeFnCallToFunctionWithRequiresUnsafe<'a> {
+    #[label]
+    pub span: Span,
+    pub function: &'a str,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_call_to_unsafe_fn_requires_unsafe, code = "E0133")]
+#[note]
+pub struct CallToUnsafeFunctionRequiresUnsafe<'a> {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+    pub function: &'a str,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_call_to_unsafe_fn_requires_unsafe_nameless, code = "E0133")]
+#[note]
+pub struct CallToUnsafeFunctionRequiresUnsafeNameless {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_call_to_unsafe_fn_requires_unsafe_unsafe_op_in_unsafe_fn_allowed, code = "E0133")]
+#[note]
+pub struct CallToUnsafeFunctionRequiresUnsafeUnsafeOpInUnsafeFnAllowed<'a> {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+    pub function: &'a str,
+}
+
+#[derive(Diagnostic)]
+#[diag(
+    mir_build_call_to_unsafe_fn_requires_unsafe_nameless_unsafe_op_in_unsafe_fn_allowed,
+    code = "E0133"
+)]
+#[note]
+pub struct CallToUnsafeFunctionRequiresUnsafeNamelessUnsafeOpInUnsafeFnAllowed {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_inline_assembly_requires_unsafe, code = "E0133")]
+#[note]
+pub struct UseOfInlineAssemblyRequiresUnsafe {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_inline_assembly_requires_unsafe_unsafe_op_in_unsafe_fn_allowed, code = "E0133")]
+#[note]
+pub struct UseOfInlineAssemblyRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_initializing_type_with_requires_unsafe, code = "E0133")]
+#[note]
+pub struct InitializingTypeWithRequiresUnsafe {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(
+    mir_build_initializing_type_with_requires_unsafe_unsafe_op_in_unsafe_fn_allowed,
+    code = "E0133"
+)]
+#[note]
+pub struct InitializingTypeWithRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_mutable_static_requires_unsafe, code = "E0133")]
+#[note]
+pub struct UseOfMutableStaticRequiresUnsafe {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_mutable_static_requires_unsafe_unsafe_op_in_unsafe_fn_allowed, code = "E0133")]
+#[note]
+pub struct UseOfMutableStaticRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_extern_static_requires_unsafe, code = "E0133")]
+#[note]
+pub struct UseOfExternStaticRequiresUnsafe {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_extern_static_requires_unsafe_unsafe_op_in_unsafe_fn_allowed, code = "E0133")]
+#[note]
+pub struct UseOfExternStaticRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_deref_raw_pointer_requires_unsafe, code = "E0133")]
+#[note]
+pub struct DerefOfRawPointerRequiresUnsafe {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_deref_raw_pointer_requires_unsafe_unsafe_op_in_unsafe_fn_allowed, code = "E0133")]
+#[note]
+pub struct DerefOfRawPointerRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_union_field_requires_unsafe, code = "E0133")]
+#[note]
+pub struct AccessToUnionFieldRequiresUnsafe {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_union_field_requires_unsafe_unsafe_op_in_unsafe_fn_allowed, code = "E0133")]
+#[note]
+pub struct AccessToUnionFieldRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_mutation_of_layout_constrained_field_requires_unsafe, code = "E0133")]
+#[note]
+pub struct MutationOfLayoutConstrainedFieldRequiresUnsafe {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(
+    mir_build_mutation_of_layout_constrained_field_requires_unsafe_unsafe_op_in_unsafe_fn_allowed,
+    code = "E0133"
+)]
+#[note]
+pub struct MutationOfLayoutConstrainedFieldRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_borrow_of_layout_constrained_field_requires_unsafe, code = "E0133")]
+#[note]
+pub struct BorrowOfLayoutConstrainedFieldRequiresUnsafe {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(
+    mir_build_borrow_of_layout_constrained_field_requires_unsafe_unsafe_op_in_unsafe_fn_allowed,
+    code = "E0133"
+)]
+#[note]
+pub struct BorrowOfLayoutConstrainedFieldRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_call_to_fn_with_requires_unsafe, code = "E0133")]
+#[note]
+pub struct CallToFunctionWithRequiresUnsafe<'a> {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+    pub function: &'a str,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_call_to_fn_with_requires_unsafe_unsafe_op_in_unsafe_fn_allowed, code = "E0133")]
+#[note]
+pub struct CallToFunctionWithRequiresUnsafeUnsafeOpInUnsafeFnAllowed<'a> {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+    pub function: &'a str,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unused_unsafe)]
+pub struct UnusedUnsafe {
+    #[label]
+    pub span: Span,
+    #[subdiagnostic]
+    pub enclosing: Option<UnusedUnsafeEnclosing>,
+}
+
+#[derive(Subdiagnostic)]
+pub enum UnusedUnsafeEnclosing {
+    #[label(mir_build_unused_unsafe_enclosing_block_label)]
+    Block {
+        #[primary_span]
+        span: Span,
+    },
+    #[label(mir_build_unused_unsafe_enclosing_fn_label)]
+    Function {
+        #[primary_span]
+        span: Span,
+    },
+}
+
+pub(crate) struct NonExhaustivePatternsTypeNotEmpty<'p, 'tcx, 'm> {
+    pub cx: &'m MatchCheckCtxt<'p, 'tcx>,
+    pub expr_span: Span,
+    pub span: Span,
+    pub ty: Ty<'tcx>,
+}
+
+impl<'a> IntoDiagnostic<'a> for NonExhaustivePatternsTypeNotEmpty<'_, '_, '_> {
+    fn into_diagnostic(self, handler: &'a Handler) -> DiagnosticBuilder<'_, ErrorGuaranteed> {
+        let mut diag = handler.struct_span_err_with_code(
+            self.span,
+            rustc_errors::fluent::mir_build_non_exhaustive_patterns_type_not_empty,
+            error_code!(E0004),
+        );
+
+        let peeled_ty = self.ty.peel_refs();
+        diag.set_arg("ty", self.ty);
+        diag.set_arg("peeled_ty", peeled_ty);
+
+        if let ty::Adt(def, _) = peeled_ty.kind() {
+            let def_span = self
+                .cx
+                .tcx
+                .hir()
+                .get_if_local(def.did())
+                .and_then(|node| node.ident())
+                .map(|ident| ident.span)
+                .unwrap_or_else(|| self.cx.tcx.def_span(def.did()));
+
+            // workaround to make test pass
+            let mut span: MultiSpan = def_span.into();
+            span.push_span_label(def_span, "");
+
+            diag.span_note(span, rustc_errors::fluent::def_note);
+        }
+
+        let is_variant_list_non_exhaustive = match self.ty.kind() {
+            ty::Adt(def, _) if def.is_variant_list_non_exhaustive() && !def.did().is_local() => {
+                true
+            }
+            _ => false,
+        };
+
+        if is_variant_list_non_exhaustive {
+            diag.note(rustc_errors::fluent::non_exhaustive_type_note);
+        } else {
+            diag.note(rustc_errors::fluent::type_note);
+        }
+
+        if let ty::Ref(_, sub_ty, _) = self.ty.kind() {
+            if !sub_ty.is_inhabited_from(self.cx.tcx, self.cx.module, self.cx.param_env) {
+                diag.note(rustc_errors::fluent::reference_note);
+            }
+        }
+
+        let mut suggestion = None;
+        let sm = self.cx.tcx.sess.source_map();
+        if self.span.eq_ctxt(self.expr_span) {
+            // Get the span for the empty match body `{}`.
+            let (indentation, more) = if let Some(snippet) = sm.indentation_before(self.span) {
+                (format!("\n{}", snippet), "    ")
+            } else {
+                (" ".to_string(), "")
+            };
+            suggestion = Some((
+                self.span.shrink_to_hi().with_hi(self.expr_span.hi()),
+                format!(
+                    " {{{indentation}{more}_ => todo!(),{indentation}}}",
+                    indentation = indentation,
+                    more = more,
+                ),
+            ));
+        }
+
+        if let Some((span, sugg)) = suggestion {
+            diag.span_suggestion_verbose(
+                span,
+                rustc_errors::fluent::suggestion,
+                sugg,
+                Applicability::HasPlaceholders,
+            );
+        } else {
+            diag.help(rustc_errors::fluent::help);
+        }
+
+        diag
+    }
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_static_in_pattern, code = "E0158")]
+pub struct StaticInPattern {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_assoc_const_in_pattern, code = "E0158")]
+pub struct AssocConstInPattern {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_const_param_in_pattern, code = "E0158")]
+pub struct ConstParamInPattern {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_non_const_path, code = "E0080")]
+pub struct NonConstPath {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_unreachable_pattern)]
+pub struct UnreachablePattern {
+    #[label]
+    pub span: Option<Span>,
+    #[label(catchall_label)]
+    pub catchall: Option<Span>,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_const_pattern_depends_on_generic_parameter)]
+pub struct ConstPatternDependsOnGenericParameter {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_could_not_eval_const_pattern)]
+pub struct CouldNotEvalConstPattern {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_lower_range_bound_must_be_less_than_or_equal_to_upper, code = "E0030")]
+pub struct LowerRangeBoundMustBeLessThanOrEqualToUpper {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+    #[note(teach_note)]
+    pub teach: Option<()>,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_literal_in_range_out_of_bounds)]
+pub struct LiteralOutOfRange<'tcx> {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+    pub ty: Ty<'tcx>,
+    pub max: u128,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_lower_range_bound_must_be_less_than_upper, code = "E0579")]
+pub struct LowerRangeBoundMustBeLessThanUpper {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_leading_irrefutable_let_patterns)]
+#[note]
+#[help]
+pub struct LeadingIrrefutableLetPatterns {
+    pub count: usize,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_trailing_irrefutable_let_patterns)]
+#[note]
+#[help]
+pub struct TrailingIrrefutableLetPatterns {
+    pub count: usize,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_bindings_with_variant_name, code = "E0170")]
+pub struct BindingsWithVariantName {
+    #[suggestion(code = "{ty_path}::{ident}", applicability = "machine-applicable")]
+    pub suggestion: Option<Span>,
+    pub ty_path: String,
+    pub ident: Ident,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_irrefutable_let_patterns_generic_let)]
+#[note]
+#[help]
+pub struct IrrefutableLetPatternsGenericLet {
+    pub count: usize,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_irrefutable_let_patterns_if_let)]
+#[note]
+#[help]
+pub struct IrrefutableLetPatternsIfLet {
+    pub count: usize,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_irrefutable_let_patterns_if_let_guard)]
+#[note]
+#[help]
+pub struct IrrefutableLetPatternsIfLetGuard {
+    pub count: usize,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_irrefutable_let_patterns_let_else)]
+#[note]
+#[help]
+pub struct IrrefutableLetPatternsLetElse {
+    pub count: usize,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_irrefutable_let_patterns_while_let)]
+#[note]
+#[help]
+pub struct IrrefutableLetPatternsWhileLet {
+    pub count: usize,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_borrow_of_moved_value)]
+pub struct BorrowOfMovedValue<'tcx> {
+    #[primary_span]
+    pub span: Span,
+    #[label]
+    #[label(occurs_because_label)]
+    pub binding_span: Span,
+    #[label(value_borrowed_label)]
+    pub conflicts_ref: Vec<Span>,
+    pub name: Ident,
+    pub ty: Ty<'tcx>,
+    #[suggestion(code = "ref ", applicability = "machine-applicable")]
+    pub suggest_borrowing: Option<Span>,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_multiple_mut_borrows)]
+pub struct MultipleMutBorrows {
+    #[primary_span]
+    pub span: Span,
+    #[label]
+    pub binding_span: Span,
+    #[subdiagnostic]
+    pub occurences: Vec<MultipleMutBorrowOccurence>,
+    pub name: Ident,
+}
+
+#[derive(Subdiagnostic)]
+pub enum MultipleMutBorrowOccurence {
+    #[label(mutable_borrow)]
+    Mutable {
+        #[primary_span]
+        span: Span,
+        name_mut: Ident,
+    },
+    #[label(immutable_borrow)]
+    Immutable {
+        #[primary_span]
+        span: Span,
+        name_immut: Ident,
+    },
+    #[label(moved)]
+    Moved {
+        #[primary_span]
+        span: Span,
+        name_moved: Ident,
+    },
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_union_pattern)]
+pub struct UnionPattern {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_type_not_structural)]
+pub struct TypeNotStructural<'tcx> {
+    #[primary_span]
+    pub span: Span,
+    pub non_sm_ty: Ty<'tcx>,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_invalid_pattern)]
+pub struct InvalidPattern<'tcx> {
+    #[primary_span]
+    pub span: Span,
+    pub non_sm_ty: Ty<'tcx>,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_unsized_pattern)]
+pub struct UnsizedPattern<'tcx> {
+    #[primary_span]
+    pub span: Span,
+    pub non_sm_ty: Ty<'tcx>,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_float_pattern)]
+pub struct FloatPattern;
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_pointer_pattern)]
+pub struct PointerPattern;
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_indirect_structural_match)]
+pub struct IndirectStructuralMatch<'tcx> {
+    pub non_sm_ty: Ty<'tcx>,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_nontrivial_structural_match)]
+pub struct NontrivialStructuralMatch<'tcx> {
+    pub non_sm_ty: Ty<'tcx>,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_overlapping_range_endpoints)]
+#[note]
+pub struct OverlappingRangeEndpoints<'tcx> {
+    #[label(range)]
+    pub range: Span,
+    #[subdiagnostic]
+    pub overlap: Vec<Overlap<'tcx>>,
+}
+
+pub struct Overlap<'tcx> {
+    pub span: Span,
+    pub range: Pat<'tcx>,
+}
+
+impl<'tcx> AddToDiagnostic for Overlap<'tcx> {
+    fn add_to_diagnostic_with<F>(self, diag: &mut Diagnostic, _: F)
+    where
+        F: Fn(&mut Diagnostic, SubdiagnosticMessage) -> SubdiagnosticMessage,
+    {
+        let Overlap { span, range } = self;
+
+        // FIXME(mejrs) unfortunately `#[derive(LintDiagnostic)]`
+        // does not support `#[subdiagnostic(eager)]`...
+        let message = format!("this range overlaps on `{range}`...");
+        diag.span_label(span, message);
+    }
+}
+
+#[derive(LintDiagnostic)]
+#[diag(mir_build_non_exhaustive_omitted_pattern)]
+#[help]
+#[note]
+pub(crate) struct NonExhaustiveOmittedPattern<'tcx> {
+    pub scrut_ty: Ty<'tcx>,
+    #[subdiagnostic]
+    pub uncovered: Uncovered<'tcx>,
+}
+
+#[derive(Subdiagnostic)]
+#[label(mir_build_uncovered)]
+pub(crate) struct Uncovered<'tcx> {
+    #[primary_span]
+    span: Span,
+    count: usize,
+    witness_1: Pat<'tcx>,
+    witness_2: Pat<'tcx>,
+    witness_3: Pat<'tcx>,
+    remainder: usize,
+}
+
+impl<'tcx> Uncovered<'tcx> {
+    pub fn new<'p>(
+        span: Span,
+        cx: &MatchCheckCtxt<'p, 'tcx>,
+        witnesses: Vec<DeconstructedPat<'p, 'tcx>>,
+    ) -> Self {
+        let witness_1 = witnesses.get(0).unwrap().to_pat(cx);
+        Self {
+            span,
+            count: witnesses.len(),
+            // Substitute dummy values if witnesses is smaller than 3. These will never be read.
+            witness_2: witnesses.get(1).map(|w| w.to_pat(cx)).unwrap_or_else(|| witness_1.clone()),
+            witness_3: witnesses.get(2).map(|w| w.to_pat(cx)).unwrap_or_else(|| witness_1.clone()),
+            witness_1,
+            remainder: witnesses.len().saturating_sub(3),
+        }
+    }
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_pattern_not_covered, code = "E0005")]
+pub(crate) struct PatternNotCovered<'s, 'tcx> {
+    #[primary_span]
+    pub span: Span,
+    pub origin: &'s str,
+    #[subdiagnostic]
+    pub uncovered: Uncovered<'tcx>,
+    #[subdiagnostic]
+    pub inform: Option<Inform>,
+    #[subdiagnostic]
+    pub interpreted_as_const: Option<InterpretedAsConst>,
+    #[subdiagnostic]
+    pub adt_defined_here: Option<AdtDefinedHere<'tcx>>,
+    #[note(pattern_ty)]
+    pub _p: (),
+    pub pattern_ty: Ty<'tcx>,
+    #[subdiagnostic]
+    pub let_suggestion: Option<SuggestLet>,
+    #[subdiagnostic]
+    pub misc_suggestion: Option<MiscPatternSuggestion>,
+    #[subdiagnostic]
+    pub res_defined_here: Option<ResDefinedHere>,
+}
+
+#[derive(Subdiagnostic)]
+#[note(mir_build_inform_irrefutable)]
+#[note(mir_build_more_information)]
+pub struct Inform;
+
+pub struct AdtDefinedHere<'tcx> {
+    pub adt_def_span: Span,
+    pub ty: Ty<'tcx>,
+    pub variants: Vec<Variant>,
+}
+
+pub struct Variant {
+    pub span: Span,
+}
+
+impl<'tcx> AddToDiagnostic for AdtDefinedHere<'tcx> {
+    fn add_to_diagnostic_with<F>(self, diag: &mut Diagnostic, _: F)
+    where
+        F: Fn(&mut Diagnostic, SubdiagnosticMessage) -> SubdiagnosticMessage,
+    {
+        diag.set_arg("ty", self.ty);
+        let mut spans = MultiSpan::from(self.adt_def_span);
+
+        for Variant { span } in self.variants {
+            spans.push_span_label(span, rustc_errors::fluent::mir_build_variant_defined_here);
+        }
+
+        diag.span_note(spans, rustc_errors::fluent::mir_build_adt_defined_here);
+    }
+}
+
+#[derive(Subdiagnostic)]
+#[label(mir_build_res_defined_here)]
+pub struct ResDefinedHere {
+    #[primary_span]
+    pub def_span: Span,
+    pub res: Res,
+}
+
+#[derive(Subdiagnostic)]
+#[suggestion(
+    mir_build_interpreted_as_const,
+    code = "{variable}_var",
+    applicability = "maybe-incorrect"
+)]
+#[label(mir_build_confused)]
+pub struct InterpretedAsConst {
+    #[primary_span]
+    pub span: Span,
+    pub article: &'static str,
+    pub variable: String,
+    pub res: Res,
+}
+
+#[derive(Subdiagnostic)]
+pub enum SuggestLet {
+    #[multipart_suggestion(mir_build_suggest_if_let, applicability = "has-placeholders")]
+    If {
+        #[suggestion_part(code = "if ")]
+        start_span: Span,
+        #[suggestion_part(code = " {{ todo!() }}")]
+        semi_span: Span,
+        count: usize,
+    },
+    #[suggestion(
+        mir_build_suggest_let_else,
+        code = " else {{ todo!() }}",
+        applicability = "has-placeholders"
+    )]
+    Else {
+        #[primary_span]
+        end_span: Span,
+        count: usize,
+    },
+}
+
+#[derive(Subdiagnostic)]
+pub enum MiscPatternSuggestion {
+    #[suggestion(
+        mir_build_suggest_attempted_int_lit,
+        code = "_",
+        applicability = "maybe-incorrect"
+    )]
+    AttemptedIntegerLiteral {
+        #[primary_span]
+        start_span: Span,
+    },
+}
diff --git a/compiler/rustc_mir_build/src/lib.rs b/compiler/rustc_mir_build/src/lib.rs
index 879752945..a428180a4 100644
--- a/compiler/rustc_mir_build/src/lib.rs
+++ b/compiler/rustc_mir_build/src/lib.rs
@@ -5,11 +5,11 @@
 #![feature(assert_matches)]
 #![feature(associated_type_bounds)]
 #![feature(box_patterns)]
-#![feature(control_flow_enum)]
 #![feature(if_let_guard)]
 #![feature(let_chains)]
 #![feature(min_specialization)]
 #![feature(once_cell)]
+#![feature(try_blocks)]
 #![recursion_limit = "256"]
 
 #[macro_use]
@@ -19,6 +19,7 @@ extern crate rustc_middle;
 
 mod build;
 mod check_unsafety;
+mod errors;
 mod lints;
 pub mod thir;
 
diff --git a/compiler/rustc_mir_build/src/lints.rs b/compiler/rustc_mir_build/src/lints.rs
index b21f30efc..f67f24b43 100644
--- a/compiler/rustc_mir_build/src/lints.rs
+++ b/compiler/rustc_mir_build/src/lints.rs
@@ -1,3 +1,4 @@
+use crate::errors::UnconditionalRecursion;
 use rustc_data_structures::graph::iterate::{
     NodeStatus, TriColorDepthFirstSearch, TriColorVisitor,
 };
@@ -36,19 +37,11 @@ pub(crate) fn check<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'tcx>) {
 
         let sp = tcx.def_span(def_id);
         let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
-        tcx.struct_span_lint_hir(
+        tcx.emit_spanned_lint(
             UNCONDITIONAL_RECURSION,
             hir_id,
             sp,
-            "function cannot return without recursing",
-            |lint| {
-                lint.span_label(sp, "cannot return without recursing");
-                // offer some help to the programmer.
-                for call_span in vis.reachable_recursive_calls {
-                    lint.span_label(call_span, "recursive call site");
-                }
-                lint.help("a `loop` may express intention better if this is on purpose")
-            },
+            UnconditionalRecursion { span: sp, call_sites: vis.reachable_recursive_calls },
         );
     }
 }
@@ -67,7 +60,7 @@ impl<'mir, 'tcx> Search<'mir, 'tcx> {
     /// Returns `true` if `func` refers to the function we are searching in.
     fn is_recursive_call(&self, func: &Operand<'tcx>, args: &[Operand<'tcx>]) -> bool {
         let Search { tcx, body, trait_substs, .. } = *self;
-        // Resolving function type to a specific instance that is being called is expensive.  To
+        // Resolving function type to a specific instance that is being called is expensive. To
         // avoid the cost we check the number of arguments first, which is sufficient to reject
         // most of calls as non-recursive.
         if args.len() != body.arg_count {
@@ -125,7 +118,7 @@ impl<'mir, 'tcx> TriColorVisitor<BasicBlocks<'tcx>> for Search<'mir, 'tcx> {
             // A diverging InlineAsm is treated as non-recursing
             TerminatorKind::InlineAsm { destination, .. } => {
                 if destination.is_some() {
-                    ControlFlow::CONTINUE
+                    ControlFlow::Continue(())
                 } else {
                     ControlFlow::Break(NonRecursive)
                 }
@@ -139,7 +132,7 @@ impl<'mir, 'tcx> TriColorVisitor<BasicBlocks<'tcx>> for Search<'mir, 'tcx> {
             | TerminatorKind::FalseEdge { .. }
             | TerminatorKind::FalseUnwind { .. }
             | TerminatorKind::Goto { .. }
-            | TerminatorKind::SwitchInt { .. } => ControlFlow::CONTINUE,
+            | TerminatorKind::SwitchInt { .. } => ControlFlow::Continue(()),
         }
     }
 
@@ -152,7 +145,7 @@ impl<'mir, 'tcx> TriColorVisitor<BasicBlocks<'tcx>> for Search<'mir, 'tcx> {
             }
         }
 
-        ControlFlow::CONTINUE
+        ControlFlow::Continue(())
     }
 
     fn ignore_edge(&mut self, bb: BasicBlock, target: BasicBlock) -> bool {
diff --git a/compiler/rustc_mir_build/src/thir/constant.rs b/compiler/rustc_mir_build/src/thir/constant.rs
index a9ed945d4..57ae6a365 100644
--- a/compiler/rustc_mir_build/src/thir/constant.rs
+++ b/compiler/rustc_mir_build/src/thir/constant.rs
@@ -33,13 +33,13 @@ pub(crate) fn lit_to_const<'tcx>(
             let str_bytes = s.as_str().as_bytes();
             ty::ValTree::from_raw_bytes(tcx, str_bytes)
         }
-        (ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _))
+        (ast::LitKind::ByteStr(data, _), ty::Ref(_, inner_ty, _))
             if matches!(inner_ty.kind(), ty::Slice(_)) =>
         {
             let bytes = data as &[u8];
             ty::ValTree::from_raw_bytes(tcx, bytes)
         }
-        (ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _)) if inner_ty.is_array() => {
+        (ast::LitKind::ByteStr(data, _), ty::Ref(_, inner_ty, _)) if inner_ty.is_array() => {
             let bytes = data as &[u8];
             ty::ValTree::from_raw_bytes(tcx, bytes)
         }
diff --git a/compiler/rustc_mir_build/src/thir/cx/mod.rs b/compiler/rustc_mir_build/src/thir/cx/mod.rs
index b5c4b7b13..a355e1bda 100644
--- a/compiler/rustc_mir_build/src/thir/cx/mod.rs
+++ b/compiler/rustc_mir_build/src/thir/cx/mod.rs
@@ -18,10 +18,10 @@ use rustc_middle::thir::*;
 use rustc_middle::ty::{self, RvalueScopes, TyCtxt};
 use rustc_span::Span;
 
-pub(crate) fn thir_body<'tcx>(
-    tcx: TyCtxt<'tcx>,
+pub(crate) fn thir_body(
+    tcx: TyCtxt<'_>,
     owner_def: ty::WithOptConstParam<LocalDefId>,
-) -> Result<(&'tcx Steal<Thir<'tcx>>, ExprId), ErrorGuaranteed> {
+) -> Result<(&Steal<Thir<'_>>, ExprId), ErrorGuaranteed> {
     let hir = tcx.hir();
     let body = hir.body(hir.body_owned_by(owner_def.did));
     let mut cx = Cx::new(tcx, owner_def);
@@ -52,10 +52,7 @@ pub(crate) fn thir_body<'tcx>(
     Ok((tcx.alloc_steal_thir(cx.thir), expr))
 }
 
-pub(crate) fn thir_tree<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    owner_def: ty::WithOptConstParam<LocalDefId>,
-) -> String {
+pub(crate) fn thir_tree(tcx: TyCtxt<'_>, owner_def: ty::WithOptConstParam<LocalDefId>) -> String {
     match thir_body(tcx, owner_def) {
         Ok((thir, _)) => format!("{:#?}", thir.steal()),
         Err(_) => "error".into(),
diff --git a/compiler/rustc_mir_build/src/thir/pattern/check_match.rs b/compiler/rustc_mir_build/src/thir/pattern/check_match.rs
index e369dba55..34e637f59 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/check_match.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/check_match.rs
@@ -4,18 +4,22 @@ use super::usefulness::{
 };
 use super::{PatCtxt, PatternError};
 
+use crate::errors::*;
+
+use hir::{ExprKind, PatKind};
 use rustc_arena::TypedArena;
-use rustc_ast::Mutability;
+use rustc_ast::{LitKind, Mutability};
 use rustc_errors::{
-    error_code, pluralize, struct_span_err, Applicability, DelayDm, Diagnostic, DiagnosticBuilder,
-    ErrorGuaranteed, MultiSpan,
+    struct_span_err, Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed, MultiSpan,
 };
 use rustc_hir as hir;
 use rustc_hir::def::*;
 use rustc_hir::def_id::DefId;
 use rustc_hir::intravisit::{self, Visitor};
 use rustc_hir::{HirId, Pat};
+use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_middle::ty::{self, AdtDef, Ty, TyCtxt};
+
 use rustc_session::lint::builtin::{
     BINDINGS_WITH_VARIANT_NAME, IRREFUTABLE_LET_PATTERNS, UNREACHABLE_PATTERNS,
 };
@@ -107,28 +111,20 @@ impl PatCtxt<'_, '_> {
         for error in &self.errors {
             match *error {
                 PatternError::StaticInPattern(span) => {
-                    self.span_e0158(span, "statics cannot be referenced in patterns")
+                    self.tcx.sess.emit_err(StaticInPattern { span });
                 }
                 PatternError::AssocConstInPattern(span) => {
-                    self.span_e0158(span, "associated consts cannot be referenced in patterns")
+                    self.tcx.sess.emit_err(AssocConstInPattern { span });
                 }
                 PatternError::ConstParamInPattern(span) => {
-                    self.span_e0158(span, "const parameters cannot be referenced in patterns")
+                    self.tcx.sess.emit_err(ConstParamInPattern { span });
                 }
                 PatternError::NonConstPath(span) => {
-                    rustc_middle::mir::interpret::struct_error(
-                        self.tcx.at(span),
-                        "runtime values cannot be referenced in patterns",
-                    )
-                    .emit();
+                    self.tcx.sess.emit_err(NonConstPath { span });
                 }
             }
         }
     }
-
-    fn span_e0158(&self, span: Span, text: &str) {
-        struct_span_err!(self.tcx.sess, span, E0158, "{}", text).emit();
-    }
 }
 
 impl<'p, 'tcx> MatchVisitor<'_, 'p, 'tcx> {
@@ -251,14 +247,14 @@ impl<'p, 'tcx> MatchVisitor<'_, 'p, 'tcx> {
 
     fn check_let_chain(&mut self, cx: &mut MatchCheckCtxt<'p, 'tcx>, pat_id: HirId) -> bool {
         let hir = self.tcx.hir();
-        let parent = hir.get_parent_node(pat_id);
+        let parent = hir.parent_id(pat_id);
 
         // First, figure out if the given pattern is part of a let chain,
         // and if so, obtain the top node of the chain.
         let mut top = parent;
         let mut part_of_chain = false;
         loop {
-            let new_top = hir.get_parent_node(top);
+            let new_top = hir.parent_id(top);
             if let hir::Node::Expr(
                 hir::Expr {
                     kind: hir::ExprKind::Binary(Spanned { node: hir::BinOpKind::And, .. }, lhs, rhs),
@@ -345,29 +341,6 @@ impl<'p, 'tcx> MatchVisitor<'_, 'p, 'tcx> {
             );
             return true;
         }
-        let lint_affix = |affix: &[Option<(Span, bool)>], kind, suggestion| {
-            let span_start = affix[0].unwrap().0;
-            let span_end = affix.last().unwrap().unwrap().0;
-            let span = span_start.to(span_end);
-            let cnt = affix.len();
-            let s = pluralize!(cnt);
-            cx.tcx.struct_span_lint_hir(
-                IRREFUTABLE_LET_PATTERNS,
-                top,
-                span,
-                format!("{kind} irrefutable pattern{s} in let chain"),
-                |lint| {
-                    lint.note(format!(
-                        "{these} pattern{s} will always match",
-                        these = pluralize!("this", cnt),
-                    ))
-                    .help(format!(
-                        "consider moving {} {suggestion}",
-                        if cnt > 1 { "them" } else { "it" }
-                    ))
-                },
-            );
-        };
         if let Some(until) = chain_refutabilities.iter().position(|r| !matches!(*r, Some((_, false)))) && until > 0 {
             // The chain has a non-zero prefix of irrefutable `let` statements.
 
@@ -381,13 +354,21 @@ impl<'p, 'tcx> MatchVisitor<'_, 'p, 'tcx> {
             if !matches!(let_source, LetSource::WhileLet | LetSource::IfLetGuard) {
                 // Emit the lint
                 let prefix = &chain_refutabilities[..until];
-                lint_affix(prefix, "leading", "outside of the construct");
+                let span_start = prefix[0].unwrap().0;
+                let span_end = prefix.last().unwrap().unwrap().0;
+                let span = span_start.to(span_end);
+                let count = prefix.len();
+                cx.tcx.emit_spanned_lint(IRREFUTABLE_LET_PATTERNS, top, span, LeadingIrrefutableLetPatterns { count });
             }
         }
         if let Some(from) = chain_refutabilities.iter().rposition(|r| !matches!(*r, Some((_, false)))) && from != (chain_refutabilities.len() - 1) {
             // The chain has a non-empty suffix of irrefutable `let` statements
             let suffix = &chain_refutabilities[from + 1..];
-            lint_affix(suffix, "trailing", "into the body");
+            let span_start = suffix[0].unwrap().0;
+            let span_end = suffix.last().unwrap().unwrap().0;
+            let span = span_start.to(span_end);
+            let count = suffix.len();
+            cx.tcx.emit_spanned_lint(IRREFUTABLE_LET_PATTERNS, top, span, TrailingIrrefutableLetPatterns { count });
         }
         true
     }
@@ -397,8 +378,8 @@ impl<'p, 'tcx> MatchVisitor<'_, 'p, 'tcx> {
 
         let pattern = self.lower_pattern(&mut cx, pat, &mut false);
         let pattern_ty = pattern.ty();
-        let arms = vec![MatchArm { pat: pattern, hir_id: pat.hir_id, has_guard: false }];
-        let report = compute_match_usefulness(&cx, &arms, pat.hir_id, pattern_ty);
+        let arm = MatchArm { pat: pattern, hir_id: pat.hir_id, has_guard: false };
+        let report = compute_match_usefulness(&cx, &[arm], pat.hir_id, pattern_ty);
 
         // Note: we ignore whether the pattern is unreachable (i.e. whether the type is empty). We
         // only care about exhaustiveness here.
@@ -409,145 +390,84 @@ impl<'p, 'tcx> MatchVisitor<'_, 'p, 'tcx> {
             return;
         }
 
-        let joined_patterns = joined_uncovered_patterns(&cx, &witnesses);
-
-        let mut bindings = vec![];
-
-        let mut err = struct_span_err!(
-            self.tcx.sess,
-            pat.span,
-            E0005,
-            "refutable pattern in {}: {} not covered",
-            origin,
-            joined_patterns
-        );
-        let suggest_if_let = match &pat.kind {
-            hir::PatKind::Path(hir::QPath::Resolved(None, path))
-                if path.segments.len() == 1 && path.segments[0].args.is_none() =>
+        let (inform, interpreted_as_const, res_defined_here,let_suggestion, misc_suggestion) =
+            if let hir::PatKind::Path(hir::QPath::Resolved(
+                None,
+                hir::Path {
+                    segments: &[hir::PathSegment { args: None, res, ident, .. }],
+                    ..
+                },
+            )) = &pat.kind
             {
-                const_not_var(&mut err, cx.tcx, pat, path);
-                false
-            }
-            _ => {
-                pat.walk(&mut |pat: &hir::Pat<'_>| {
-                    match pat.kind {
-                        hir::PatKind::Binding(_, _, ident, _) => {
-                            bindings.push(ident);
+                (
+                    None,
+                    Some(InterpretedAsConst {
+                        span: pat.span,
+                        article: res.article(),
+                        variable: ident.to_string().to_lowercase(),
+                        res,
+                    }),
+                    try {
+                        ResDefinedHere {
+                            def_span: cx.tcx.hir().res_span(res)?,
+                            res,
                         }
-                        _ => {}
+                    },
+                    None,
+                    None,
+                )
+            } else if let Some(span) = sp && self.tcx.sess.source_map().is_span_accessible(span) {
+                let mut bindings = vec![];
+                pat.walk_always(&mut |pat: &hir::Pat<'_>| {
+                    if let hir::PatKind::Binding(_, _, ident, _) = pat.kind {
+                        bindings.push(ident);
                     }
-                    true
                 });
-
-                err.span_label(pat.span, pattern_not_covered_label(&witnesses, &joined_patterns));
-                true
-            }
-        };
-
-        if let (Some(span), true) = (sp, suggest_if_let) {
-            err.note(
-                "`let` bindings require an \"irrefutable pattern\", like a `struct` or \
-                 an `enum` with only one variant",
-            );
-            if self.tcx.sess.source_map().is_span_accessible(span) {
                 let semi_span = span.shrink_to_hi().with_lo(span.hi() - BytePos(1));
                 let start_span = span.shrink_to_lo();
                 let end_span = semi_span.shrink_to_lo();
-                err.multipart_suggestion(
-                    &format!(
-                        "you might want to use `if let` to ignore the variant{} that {} matched",
-                        pluralize!(witnesses.len()),
-                        match witnesses.len() {
-                            1 => "isn't",
-                            _ => "aren't",
-                        },
-                    ),
-                    vec![
-                        match &bindings[..] {
-                            [] => (start_span, "if ".to_string()),
-                            [binding] => (start_span, format!("let {} = if ", binding)),
-                            bindings => (
-                                start_span,
-                                format!(
-                                    "let ({}) = if ",
-                                    bindings
-                                        .iter()
-                                        .map(|ident| ident.to_string())
-                                        .collect::<Vec<_>>()
-                                        .join(", ")
-                                ),
-                            ),
-                        },
-                        match &bindings[..] {
-                            [] => (semi_span, " { todo!() }".to_string()),
-                            [binding] => {
-                                (end_span, format!(" {{ {} }} else {{ todo!() }}", binding))
-                            }
-                            bindings => (
-                                end_span,
-                                format!(
-                                    " {{ ({}) }} else {{ todo!() }}",
-                                    bindings
-                                        .iter()
-                                        .map(|ident| ident.to_string())
-                                        .collect::<Vec<_>>()
-                                        .join(", ")
-                                ),
-                            ),
-                        },
-                    ],
-                    Applicability::HasPlaceholders,
-                );
-                if !bindings.is_empty() {
-                    err.span_suggestion_verbose(
-                        semi_span.shrink_to_lo(),
-                        &format!(
-                            "alternatively, you might want to use \
-                             let else to handle the variant{} that {} matched",
-                            pluralize!(witnesses.len()),
-                            match witnesses.len() {
-                                1 => "isn't",
-                                _ => "aren't",
-                            },
-                        ),
-                        " else { todo!() }",
-                        Applicability::HasPlaceholders,
-                    );
-                }
-            }
-            err.note(
-                "for more information, visit \
-                 https://doc.rust-lang.org/book/ch18-02-refutability.html",
-            );
-        }
-
-        adt_defined_here(&cx, &mut err, pattern_ty, &witnesses);
-        err.note(&format!("the matched value is of type `{}`", pattern_ty));
-        err.emit();
-    }
-}
+                let count = witnesses.len();
+
+                // If the pattern to match is an integer literal:
+                let int_suggestion = if
+                    let PatKind::Lit(expr) = &pat.kind
+                    && bindings.is_empty()
+                    && let ExprKind::Lit(Spanned { node: LitKind::Int(_, _), span }) = expr.kind {
+                    // Then give a suggestion, the user might've meant to create a binding instead.
+                    Some(MiscPatternSuggestion::AttemptedIntegerLiteral { start_span: span.shrink_to_lo() })
+                } else { None };
+
+                let let_suggestion = if bindings.is_empty() {SuggestLet::If{start_span, semi_span, count}} else{ SuggestLet::Else{end_span, count }};
+                (sp.map(|_|Inform), None, None, Some(let_suggestion), int_suggestion)
+            } else{
+                (sp.map(|_|Inform), None, None,  None, None)
+            };
 
-/// A path pattern was interpreted as a constant, not a new variable.
-/// This caused an irrefutable match failure in e.g. `let`.
-fn const_not_var(err: &mut Diagnostic, tcx: TyCtxt<'_>, pat: &Pat<'_>, path: &hir::Path<'_>) {
-    let descr = path.res.descr();
-    err.span_label(
-        pat.span,
-        format!("interpreted as {} {} pattern, not a new variable", path.res.article(), descr,),
-    );
+        let adt_defined_here = try {
+            let ty = pattern_ty.peel_refs();
+            let ty::Adt(def, _) = ty.kind() else { None? };
+            let adt_def_span = cx.tcx.hir().get_if_local(def.did())?.ident()?.span;
+            let mut variants = vec![];
 
-    err.span_suggestion(
-        pat.span,
-        "introduce a variable instead",
-        format!("{}_var", path.segments[0].ident).to_lowercase(),
-        // Cannot use `MachineApplicable` as it's not really *always* correct
-        // because there may be such an identifier in scope or the user maybe
-        // really wanted to match against the constant. This is quite unlikely however.
-        Applicability::MaybeIncorrect,
-    );
+            for span in maybe_point_at_variant(&cx, *def, witnesses.iter().take(5)) {
+                variants.push(Variant { span });
+            }
+            AdtDefinedHere { adt_def_span, ty, variants }
+        };
 
-    if let Some(span) = tcx.hir().res_span(path.res) {
-        err.span_label(span, format!("{} defined here", descr));
+        self.tcx.sess.emit_err(PatternNotCovered {
+            span: pat.span,
+            origin,
+            uncovered: Uncovered::new(pat.span, &cx, witnesses),
+            inform,
+            interpreted_as_const,
+            _p: (),
+            pattern_ty,
+            let_suggestion,
+            misc_suggestion,
+            res_defined_here,
+            adt_defined_here,
+        });
     }
 }
 
@@ -568,32 +488,22 @@ fn check_for_bindings_named_same_as_variants(
             })
         {
             let variant_count = edef.variants().len();
-            cx.tcx.struct_span_lint_hir(
+            let ty_path = with_no_trimmed_paths!({
+                cx.tcx.def_path_str(edef.did())
+            });
+            cx.tcx.emit_spanned_lint(
                 BINDINGS_WITH_VARIANT_NAME,
                 p.hir_id,
                 p.span,
-                DelayDm(|| format!(
-                    "pattern binding `{}` is named the same as one \
-                        of the variants of the type `{}`",
-                    ident, cx.tcx.def_path_str(edef.did())
-                )),
-                |lint| {
-                    let ty_path = cx.tcx.def_path_str(edef.did());
-                    lint.code(error_code!(E0170));
-
+                BindingsWithVariantName {
                     // If this is an irrefutable pattern, and there's > 1 variant,
                     // then we can't actually match on this. Applying the below
                     // suggestion would produce code that breaks on `check_irrefutable`.
-                    if rf == Refutable || variant_count == 1 {
-                        lint.span_suggestion(
-                            p.span,
-                            "to match on the variant, qualify the path",
-                            format!("{}::{}", ty_path, ident),
-                            Applicability::MachineApplicable,
-                        );
-                    }
-
-                    lint
+                    suggestion: if rf == Refutable || variant_count == 1 {
+                        Some(p.span)
+                    } else { None },
+                    ty_path,
+                    ident,
                 },
             )
         }
@@ -611,14 +521,12 @@ fn pat_is_catchall(pat: &DeconstructedPat<'_, '_>) -> bool {
 }
 
 fn unreachable_pattern(tcx: TyCtxt<'_>, span: Span, id: HirId, catchall: Option<Span>) {
-    tcx.struct_span_lint_hir(UNREACHABLE_PATTERNS, id, span, "unreachable pattern", |lint| {
-        if let Some(catchall) = catchall {
-            // We had a catchall pattern, hint at that.
-            lint.span_label(span, "unreachable pattern");
-            lint.span_label(catchall, "matches any value");
-        }
-        lint
-    });
+    tcx.emit_spanned_lint(
+        UNREACHABLE_PATTERNS,
+        id,
+        span,
+        UnreachablePattern { span: if catchall.is_some() { Some(span) } else { None }, catchall },
+    );
 }
 
 fn irrefutable_let_pattern(tcx: TyCtxt<'_>, id: HirId, span: Span) {
@@ -634,67 +542,18 @@ fn irrefutable_let_patterns(
     span: Span,
 ) {
     macro_rules! emit_diag {
-        (
-            $lint:expr,
-            $source_name:expr,
-            $note_sufix:expr,
-            $help_sufix:expr
-        ) => {{
-            let s = pluralize!(count);
-            let these = pluralize!("this", count);
-            tcx.struct_span_lint_hir(
-                IRREFUTABLE_LET_PATTERNS,
-                id,
-                span,
-                format!("irrefutable {} pattern{s}", $source_name),
-                |lint| {
-                    lint.note(&format!(
-                        "{these} pattern{s} will always match, so the {}",
-                        $note_sufix
-                    ))
-                    .help(concat!("consider ", $help_sufix))
-                },
-            )
+        ($lint:tt) => {{
+            tcx.emit_spanned_lint(IRREFUTABLE_LET_PATTERNS, id, span, $lint { count });
         }};
     }
 
     match source {
-        LetSource::GenericLet => {
-            emit_diag!(lint, "`let`", "`let` is useless", "removing `let`");
-        }
-        LetSource::IfLet => {
-            emit_diag!(
-                lint,
-                "`if let`",
-                "`if let` is useless",
-                "replacing the `if let` with a `let`"
-            );
-        }
-        LetSource::IfLetGuard => {
-            emit_diag!(
-                lint,
-                "`if let` guard",
-                "guard is useless",
-                "removing the guard and adding a `let` inside the match arm"
-            );
-        }
-        LetSource::LetElse => {
-            emit_diag!(
-                lint,
-                "`let...else`",
-                "`else` clause is useless",
-                "removing the `else` clause"
-            );
-        }
-        LetSource::WhileLet => {
-            emit_diag!(
-                lint,
-                "`while let`",
-                "loop will never exit",
-                "instead using a `loop { ... }` with a `let` inside it"
-            );
-        }
-    };
+        LetSource::GenericLet => emit_diag!(IrrefutableLetPatternsGenericLet),
+        LetSource::IfLet => emit_diag!(IrrefutableLetPatternsIfLet),
+        LetSource::IfLetGuard => emit_diag!(IrrefutableLetPatternsIfLetGuard),
+        LetSource::LetElse => emit_diag!(IrrefutableLetPatternsLetElse),
+        LetSource::WhileLet => emit_diag!(IrrefutableLetPatternsWhileLet),
+    }
 }
 
 fn is_let_irrefutable<'p, 'tcx>(
@@ -760,15 +619,17 @@ fn non_exhaustive_match<'p, 'tcx>(
     // informative.
     let mut err;
     let pattern;
-    let mut patterns_len = 0;
+    let patterns_len;
     if is_empty_match && !non_empty_enum {
-        err = create_e0004(
-            cx.tcx.sess,
-            sp,
-            format!("non-exhaustive patterns: type `{}` is non-empty", scrut_ty),
-        );
-        pattern = "_".to_string();
+        cx.tcx.sess.emit_err(NonExhaustivePatternsTypeNotEmpty {
+            cx,
+            expr_span,
+            span: sp,
+            ty: scrut_ty,
+        });
+        return;
     } else {
+        // FIXME: migration of this diagnostic will require list support
         let joined_patterns = joined_uncovered_patterns(cx, &witnesses);
         err = create_e0004(
             cx.tcx.sess,
@@ -1039,24 +900,17 @@ fn check_borrow_conflicts_in_at_patterns(cx: &MatchVisitor<'_, '_, '_>, pat: &Pa
                 }
             });
             if !conflicts_ref.is_empty() {
-                let occurs_because = format!(
-                    "move occurs because `{}` has type `{}` which does not implement the `Copy` trait",
+                sess.emit_err(BorrowOfMovedValue {
+                    span: pat.span,
+                    binding_span,
+                    conflicts_ref,
                     name,
-                    typeck_results.node_type(pat.hir_id),
-                );
-                let mut err = sess.struct_span_err(pat.span, "borrow of moved value");
-                err.span_label(binding_span, format!("value moved into `{}` here", name))
-                    .span_label(binding_span, occurs_because)
-                    .span_labels(conflicts_ref, "value borrowed here after move");
-                if pat.span.contains(binding_span) {
-                    err.span_suggestion_verbose(
-                        binding_span.shrink_to_lo(),
-                        "borrow this binding in the pattern to avoid moving the value",
-                        "ref ".to_string(),
-                        Applicability::MachineApplicable,
-                    );
-                }
-                err.emit();
+                    ty: typeck_results.node_type(pat.hir_id),
+                    suggest_borrowing: pat
+                        .span
+                        .contains(binding_span)
+                        .then(|| binding_span.shrink_to_lo()),
+                });
             }
             return;
         }
@@ -1086,19 +940,18 @@ fn check_borrow_conflicts_in_at_patterns(cx: &MatchVisitor<'_, '_, '_>, pat: &Pa
     // Report errors if any.
     if !conflicts_mut_mut.is_empty() {
         // Report mutability conflicts for e.g. `ref mut x @ Some(ref mut y)`.
-        let mut err = sess
-            .struct_span_err(pat.span, "cannot borrow value as mutable more than once at a time");
-        err.span_label(binding_span, format!("first mutable borrow, by `{}`, occurs here", name));
-        for (span, name) in conflicts_mut_mut {
-            err.span_label(span, format!("another mutable borrow, by `{}`, occurs here", name));
+        let mut occurences = vec![];
+
+        for (span, name_mut) in conflicts_mut_mut {
+            occurences.push(MultipleMutBorrowOccurence::Mutable { span, name_mut });
         }
-        for (span, name) in conflicts_mut_ref {
-            err.span_label(span, format!("also borrowed as immutable, by `{}`, here", name));
+        for (span, name_immut) in conflicts_mut_ref {
+            occurences.push(MultipleMutBorrowOccurence::Immutable { span, name_immut });
         }
-        for (span, name) in conflicts_move {
-            err.span_label(span, format!("also moved into `{}` here", name));
+        for (span, name_moved) in conflicts_move {
+            occurences.push(MultipleMutBorrowOccurence::Moved { span, name_moved });
         }
-        err.emit();
+        sess.emit_err(MultipleMutBorrows { span: pat.span, binding_span, occurences, name });
     } else if !conflicts_mut_ref.is_empty() {
         // Report mutability conflicts for e.g. `ref x @ Some(ref mut y)` or the converse.
         let (primary, also) = match mut_outer {
@@ -1140,7 +993,7 @@ pub enum LetSource {
 fn let_source(tcx: TyCtxt<'_>, pat_id: HirId) -> LetSource {
     let hir = tcx.hir();
 
-    let parent = hir.get_parent_node(pat_id);
+    let parent = hir.parent_id(pat_id);
     let_source_parent(tcx, parent, Some(pat_id))
 }
 
@@ -1159,7 +1012,7 @@ fn let_source_parent(tcx: TyCtxt<'_>, parent: HirId, pat_id: Option<HirId>) -> L
         _ => {}
     }
 
-    let parent_parent = hir.get_parent_node(parent);
+    let parent_parent = hir.parent_id(parent);
     let parent_parent_node = hir.get(parent_parent);
     match parent_parent_node {
         hir::Node::Stmt(hir::Stmt { kind: hir::StmtKind::Local(_), .. }) => {
@@ -1171,8 +1024,8 @@ fn let_source_parent(tcx: TyCtxt<'_>, parent: HirId, pat_id: Option<HirId>) -> L
         _ => {}
     }
 
-    let parent_parent_parent = hir.get_parent_node(parent_parent);
-    let parent_parent_parent_parent = hir.get_parent_node(parent_parent_parent);
+    let parent_parent_parent = hir.parent_id(parent_parent);
+    let parent_parent_parent_parent = hir.parent_id(parent_parent_parent);
     let parent_parent_parent_parent_node = hir.get(parent_parent_parent_parent);
 
     if let hir::Node::Expr(hir::Expr {
diff --git a/compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs b/compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs
index a21f6cd39..7f3519945 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs
@@ -1,11 +1,9 @@
-use rustc_errors::DelayDm;
 use rustc_hir as hir;
 use rustc_index::vec::Idx;
 use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
 use rustc_middle::mir::{self, Field};
 use rustc_middle::thir::{FieldPat, Pat, PatKind};
-use rustc_middle::ty::print::with_no_trimmed_paths;
-use rustc_middle::ty::{self, AdtDef, Ty, TyCtxt};
+use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_session::lint;
 use rustc_span::Span;
 use rustc_trait_selection::traits::predicate_for_trait_def;
@@ -15,6 +13,10 @@ use rustc_trait_selection::traits::{self, ObligationCause, PredicateObligation};
 use std::cell::Cell;
 
 use super::PatCtxt;
+use crate::errors::{
+    FloatPattern, IndirectStructuralMatch, InvalidPattern, NontrivialStructuralMatch,
+    PointerPattern, TypeNotStructural, UnionPattern, UnsizedPattern,
+};
 
 impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
     /// Converts an evaluated constant to a pattern (if possible).
@@ -70,7 +72,7 @@ mod fallback_to_const_ref {
     /// hoops to get a reference to the value.
     pub(super) struct FallbackToConstRef(());
 
-    pub(super) fn fallback_to_const_ref<'tcx>(c2p: &super::ConstToPat<'tcx>) -> FallbackToConstRef {
+    pub(super) fn fallback_to_const_ref(c2p: &super::ConstToPat<'_>) -> FallbackToConstRef {
         assert!(c2p.behind_reference.get());
         FallbackToConstRef(())
     }
@@ -105,47 +107,6 @@ impl<'tcx> ConstToPat<'tcx> {
         self.infcx.tcx
     }
 
-    fn adt_derive_msg(&self, adt_def: AdtDef<'tcx>) -> String {
-        let path = self.tcx().def_path_str(adt_def.did());
-        format!(
-            "to use a constant of type `{}` in a pattern, \
-            `{}` must be annotated with `#[derive(PartialEq, Eq)]`",
-            path, path,
-        )
-    }
-
-    fn search_for_structural_match_violation(&self, ty: Ty<'tcx>) -> Option<String> {
-        traits::search_for_structural_match_violation(self.span, self.tcx(), ty).map(|non_sm_ty| {
-            with_no_trimmed_paths!(match non_sm_ty.kind() {
-                ty::Adt(adt, _) => self.adt_derive_msg(*adt),
-                ty::Dynamic(..) => {
-                    "trait objects cannot be used in patterns".to_string()
-                }
-                ty::Opaque(..) => {
-                    "opaque types cannot be used in patterns".to_string()
-                }
-                ty::Closure(..) => {
-                    "closures cannot be used in patterns".to_string()
-                }
-                ty::Generator(..) | ty::GeneratorWitness(..) => {
-                    "generators cannot be used in patterns".to_string()
-                }
-                ty::Float(..) => {
-                    "floating-point numbers cannot be used in patterns".to_string()
-                }
-                ty::FnPtr(..) => {
-                    "function pointers cannot be used in patterns".to_string()
-                }
-                ty::RawPtr(..) => {
-                    "raw pointers cannot be used in patterns".to_string()
-                }
-                _ => {
-                    bug!("use of a value of `{non_sm_ty}` inside a pattern")
-                }
-            })
-        })
-    }
-
     fn type_marked_structural(&self, ty: Ty<'tcx>) -> bool {
         ty.is_structural_eq_shallow(self.infcx.tcx)
     }
@@ -176,7 +137,8 @@ impl<'tcx> ConstToPat<'tcx> {
             // If we were able to successfully convert the const to some pat,
             // double-check that all types in the const implement `Structural`.
 
-            let structural = self.search_for_structural_match_violation(cv.ty());
+            let structural =
+                traits::search_for_structural_match_violation(self.span, self.tcx(), cv.ty());
             debug!(
                 "search_for_structural_match_violation cv.ty: {:?} returned: {:?}",
                 cv.ty(),
@@ -194,17 +156,18 @@ impl<'tcx> ConstToPat<'tcx> {
                 return inlined_const_as_pat;
             }
 
-            if let Some(msg) = structural {
+            if let Some(non_sm_ty) = structural {
                 if !self.type_may_have_partial_eq_impl(cv.ty()) {
-                    // span_fatal avoids ICE from resolution of non-existent method (rare case).
-                    self.tcx().sess.span_fatal(self.span, &msg);
+                    // fatal avoids ICE from resolution of non-existent method (rare case).
+                    self.tcx()
+                        .sess
+                        .emit_fatal(TypeNotStructural { span: self.span, non_sm_ty: non_sm_ty });
                 } else if mir_structural_match_violation && !self.saw_const_match_lint.get() {
-                    self.tcx().struct_span_lint_hir(
+                    self.tcx().emit_spanned_lint(
                         lint::builtin::INDIRECT_STRUCTURAL_MATCH,
                         self.id,
                         self.span,
-                        msg,
-                        |lint| lint,
+                        IndirectStructuralMatch { non_sm_ty },
                     );
                 } else {
                     debug!(
@@ -278,12 +241,11 @@ impl<'tcx> ConstToPat<'tcx> {
         let kind = match cv.ty().kind() {
             ty::Float(_) => {
                 if self.include_lint_checks {
-                    tcx.struct_span_lint_hir(
+                    tcx.emit_spanned_lint(
                         lint::builtin::ILLEGAL_FLOATING_POINT_LITERAL_PATTERN,
                         id,
                         span,
-                        "floating-point types cannot be used in patterns",
-                        |lint| lint,
+                        FloatPattern,
                     );
                 }
                 PatKind::Constant { value: cv }
@@ -291,29 +253,22 @@ impl<'tcx> ConstToPat<'tcx> {
             ty::Adt(adt_def, _) if adt_def.is_union() => {
                 // Matching on union fields is unsafe, we can't hide it in constants
                 self.saw_const_match_error.set(true);
-                let msg = "cannot use unions in constant patterns";
-                if self.include_lint_checks {
-                    tcx.sess.span_err(span, msg);
-                } else {
-                    tcx.sess.delay_span_bug(span, msg);
-                }
+                let err = UnionPattern { span };
+                tcx.sess.create_err(err).emit_unless(!self.include_lint_checks);
                 PatKind::Wild
             }
             ty::Adt(..)
                 if !self.type_may_have_partial_eq_impl(cv.ty())
                     // FIXME(#73448): Find a way to bring const qualification into parity with
                     // `search_for_structural_match_violation` and then remove this condition.
-                    && self.search_for_structural_match_violation(cv.ty()).is_some() =>
+
+                    // Obtain the actual type that isn't annotated. If we just looked at `cv.ty` we
+                    // could get `Option<NonStructEq>`, even though `Option` is annotated with derive.
+                    && let Some(non_sm_ty) = traits::search_for_structural_match_violation(span, tcx, cv.ty()) =>
             {
-                // Obtain the actual type that isn't annotated. If we just looked at `cv.ty` we
-                // could get `Option<NonStructEq>`, even though `Option` is annotated with derive.
-                let msg = self.search_for_structural_match_violation(cv.ty()).unwrap();
                 self.saw_const_match_error.set(true);
-                if self.include_lint_checks {
-                    tcx.sess.span_err(self.span, &msg);
-                } else {
-                    tcx.sess.delay_span_bug(self.span, &msg);
-                }
+                let err = TypeNotStructural { span, non_sm_ty };
+                tcx.sess.create_err(err).emit_unless(!self.include_lint_checks);
                 PatKind::Wild
             }
             // If the type is not structurally comparable, just emit the constant directly,
@@ -331,19 +286,11 @@ impl<'tcx> ConstToPat<'tcx> {
                     && !self.saw_const_match_lint.get()
                 {
                     self.saw_const_match_lint.set(true);
-                    tcx.struct_span_lint_hir(
+                    tcx.emit_spanned_lint(
                         lint::builtin::INDIRECT_STRUCTURAL_MATCH,
                         id,
                         span,
-                        DelayDm(|| {
-                            format!(
-                                "to use a constant of type `{}` in a pattern, \
-                                 `{}` must be annotated with `#[derive(PartialEq, Eq)]`",
-                                cv.ty(),
-                                cv.ty(),
-                            )
-                        }),
-                        |lint| lint,
+                        IndirectStructuralMatch { non_sm_ty: cv.ty() },
                     );
                 }
                 // Since we are behind a reference, we can just bubble the error up so we get a
@@ -357,18 +304,9 @@ impl<'tcx> ConstToPat<'tcx> {
                     adt_def,
                     cv.ty()
                 );
-                let path = tcx.def_path_str(adt_def.did());
-                let msg = format!(
-                    "to use a constant of type `{}` in a pattern, \
-                     `{}` must be annotated with `#[derive(PartialEq, Eq)]`",
-                    path, path,
-                );
                 self.saw_const_match_error.set(true);
-                if self.include_lint_checks {
-                    tcx.sess.span_err(span, &msg);
-                } else {
-                    tcx.sess.delay_span_bug(span, &msg);
-                }
+                let err = TypeNotStructural { span, non_sm_ty: cv.ty() };
+                tcx.sess.create_err(err).emit_unless(!self.include_lint_checks);
                 PatKind::Wild
             }
             ty::Adt(adt_def, substs) if adt_def.is_enum() => {
@@ -401,12 +339,8 @@ impl<'tcx> ConstToPat<'tcx> {
                 // These are not allowed and will error elsewhere anyway.
                 ty::Dynamic(..) => {
                     self.saw_const_match_error.set(true);
-                    let msg = format!("`{}` cannot be used in patterns", cv.ty());
-                    if self.include_lint_checks {
-                        tcx.sess.span_err(span, &msg);
-                    } else {
-                        tcx.sess.delay_span_bug(span, &msg);
-                    }
+                    let err = InvalidPattern { span, non_sm_ty: cv.ty() };
+                    tcx.sess.create_err(err).emit_unless(!self.include_lint_checks);
                     PatKind::Wild
                 }
                 // `&str` is represented as `ConstValue::Slice`, let's keep using this
@@ -471,32 +405,26 @@ impl<'tcx> ConstToPat<'tcx> {
                 // this pattern to a `PartialEq::eq` comparison and `PartialEq::eq` takes a
                 // reference. This makes the rest of the matching logic simpler as it doesn't have
                 // to figure out how to get a reference again.
-                ty::Adt(adt_def, _) if !self.type_marked_structural(*pointee_ty) => {
+                ty::Adt(_, _) if !self.type_marked_structural(*pointee_ty) => {
                     if self.behind_reference.get() {
                         if self.include_lint_checks
                             && !self.saw_const_match_error.get()
                             && !self.saw_const_match_lint.get()
                         {
-                            self.saw_const_match_lint.set(true);
-                            let msg = self.adt_derive_msg(adt_def);
-                            self.tcx().struct_span_lint_hir(
+                           self.saw_const_match_lint.set(true);
+                           tcx.emit_spanned_lint(
                                 lint::builtin::INDIRECT_STRUCTURAL_MATCH,
                                 self.id,
-                                self.span,
-                                msg,
-                                |lint| lint,
+                                span,
+                                IndirectStructuralMatch { non_sm_ty: *pointee_ty },
                             );
                         }
                         PatKind::Constant { value: cv }
                     } else {
                         if !self.saw_const_match_error.get() {
                             self.saw_const_match_error.set(true);
-                            let msg = self.adt_derive_msg(adt_def);
-                            if self.include_lint_checks {
-                                tcx.sess.span_err(span, &msg);
-                            } else {
-                                tcx.sess.delay_span_bug(span, &msg);
-                            }
+                            let err = TypeNotStructural { span, non_sm_ty: *pointee_ty };
+                            tcx.sess.create_err(err).emit_unless(!self.include_lint_checks);
                         }
                         PatKind::Wild
                     }
@@ -508,12 +436,10 @@ impl<'tcx> ConstToPat<'tcx> {
                     if !pointee_ty.is_sized(tcx, param_env) {
                         // `tcx.deref_mir_constant()` below will ICE with an unsized type
                         // (except slices, which are handled in a separate arm above).
-                        let msg = format!("cannot use unsized non-slice type `{}` in constant patterns", pointee_ty);
-                        if self.include_lint_checks {
-                            tcx.sess.span_err(span, &msg);
-                        } else {
-                            tcx.sess.delay_span_bug(span, &msg);
-                        }
+
+                        let err = UnsizedPattern { span, non_sm_ty: *pointee_ty };
+                        tcx.sess.create_err(err).emit_unless(!self.include_lint_checks);
+
                         PatKind::Wild
                     } else {
                         let old = self.behind_reference.replace(true);
@@ -545,27 +471,19 @@ impl<'tcx> ConstToPat<'tcx> {
                     && !self.saw_const_match_lint.get()
                 {
                     self.saw_const_match_lint.set(true);
-                    let msg = "function pointers and unsized pointers in patterns behave \
-                        unpredictably and should not be relied upon. \
-                        See https://github.com/rust-lang/rust/issues/70861 for details.";
-                    tcx.struct_span_lint_hir(
+                    tcx.emit_spanned_lint(
                         lint::builtin::POINTER_STRUCTURAL_MATCH,
                         id,
                         span,
-                        msg,
-                        |lint| lint,
+                        PointerPattern
                     );
                 }
                 PatKind::Constant { value: cv }
             }
             _ => {
                 self.saw_const_match_error.set(true);
-                let msg = format!("`{}` cannot be used in patterns", cv.ty());
-                if self.include_lint_checks {
-                    tcx.sess.span_err(span, &msg);
-                } else {
-                    tcx.sess.delay_span_bug(span, &msg);
-                }
+                let err = InvalidPattern { span, non_sm_ty: cv.ty() };
+                    tcx.sess.create_err(err).emit_unless(!self.include_lint_checks);
                 PatKind::Wild
             }
         };
@@ -576,21 +494,17 @@ impl<'tcx> ConstToPat<'tcx> {
             && mir_structural_match_violation
             // FIXME(#73448): Find a way to bring const qualification into parity with
             // `search_for_structural_match_violation` and then remove this condition.
-            && self.search_for_structural_match_violation(cv.ty()).is_some()
-        {
-            self.saw_const_match_lint.set(true);
+
             // Obtain the actual type that isn't annotated. If we just looked at `cv.ty` we
             // could get `Option<NonStructEq>`, even though `Option` is annotated with derive.
-            let msg = self.search_for_structural_match_violation(cv.ty()).unwrap().replace(
-                "in a pattern,",
-                "in a pattern, the constant's initializer must be trivial or",
-            );
-            tcx.struct_span_lint_hir(
+            && let Some(non_sm_ty) = traits::search_for_structural_match_violation(span, tcx, cv.ty())
+        {
+            self.saw_const_match_lint.set(true);
+            tcx.emit_spanned_lint(
                 lint::builtin::NONTRIVIAL_STRUCTURAL_MATCH,
                 id,
                 span,
-                msg,
-                |lint| lint,
+                NontrivialStructuralMatch {non_sm_ty}
             );
         }
 
diff --git a/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs b/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs
index d60e8722c..aba5429da 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs
@@ -45,7 +45,7 @@
 use std::cell::Cell;
 use std::cmp::{self, max, min, Ordering};
 use std::fmt;
-use std::iter::{once, IntoIterator};
+use std::iter::once;
 use std::ops::RangeInclusive;
 
 use smallvec::{smallvec, SmallVec};
@@ -67,6 +67,7 @@ use self::SliceKind::*;
 
 use super::compare_const_vals;
 use super::usefulness::{MatchCheckCtxt, PatCtxt};
+use crate::errors::{Overlap, OverlappingRangeEndpoints};
 
 /// Recursively expand this pattern into its subpatterns. Only useful for or-patterns.
 fn expand_or_pat<'p, 'tcx>(pat: &'p Pat<'tcx>) -> Vec<&'p Pat<'tcx>> {
@@ -96,7 +97,7 @@ fn expand_or_pat<'p, 'tcx>(pat: &'p Pat<'tcx>) -> Vec<&'p Pat<'tcx>> {
 /// `IntRange` is never used to encode an empty range or a "range" that wraps
 /// around the (offset) space: i.e., `range.lo <= range.hi`.
 #[derive(Clone, PartialEq, Eq)]
-pub(super) struct IntRange {
+pub(crate) struct IntRange {
     range: RangeInclusive<u128>,
     /// Keeps the bias used for encoding the range. It depends on the type of the range and
     /// possibly the pointer size of the current architecture. The algorithm ensures we never
@@ -140,27 +141,22 @@ impl IntRange {
     ) -> Option<IntRange> {
         let ty = value.ty();
         if let Some((target_size, bias)) = Self::integral_size_and_signed_bias(tcx, ty) {
-            let val = (|| {
-                match value {
-                    mir::ConstantKind::Val(ConstValue::Scalar(scalar), _) => {
-                        // For this specific pattern we can skip a lot of effort and go
-                        // straight to the result, after doing a bit of checking. (We
-                        // could remove this branch and just fall through, which
-                        // is more general but much slower.)
-                        return scalar.to_bits_or_ptr_internal(target_size).unwrap().left();
-                    }
-                    mir::ConstantKind::Ty(c) => match c.kind() {
-                        ty::ConstKind::Value(_) => bug!(
-                            "encountered ConstValue in mir::ConstantKind::Ty, whereas this is expected to be in ConstantKind::Val"
-                        ),
-                        _ => {}
-                    },
-                    _ => {}
+            let val = if let mir::ConstantKind::Val(ConstValue::Scalar(scalar), _) = value {
+                // For this specific pattern we can skip a lot of effort and go
+                // straight to the result, after doing a bit of checking. (We
+                // could remove this branch and just fall through, which
+                // is more general but much slower.)
+                scalar.to_bits_or_ptr_internal(target_size).unwrap().left()?
+            } else {
+                if let mir::ConstantKind::Ty(c) = value
+                    && let ty::ConstKind::Value(_) = c.kind()
+                {
+                    bug!("encountered ConstValue in mir::ConstantKind::Ty, whereas this is expected to be in ConstantKind::Val");
                 }
 
                 // This is a more general form of the previous case.
-                value.try_eval_bits(tcx, param_env, ty)
-            })()?;
+                value.try_eval_bits(tcx, param_env, ty)?
+            };
             let val = val ^ bias;
             Some(IntRange { range: val..=val, bias })
         } else {
@@ -284,32 +280,21 @@ impl IntRange {
             return;
         }
 
-        let overlaps: Vec<_> = pats
+        let overlap: Vec<_> = pats
             .filter_map(|pat| Some((pat.ctor().as_int_range()?, pat.span())))
             .filter(|(range, _)| self.suspicious_intersection(range))
-            .map(|(range, span)| (self.intersection(&range).unwrap(), span))
+            .map(|(range, span)| Overlap {
+                range: self.intersection(&range).unwrap().to_pat(pcx.cx.tcx, pcx.ty),
+                span,
+            })
             .collect();
 
-        if !overlaps.is_empty() {
-            pcx.cx.tcx.struct_span_lint_hir(
+        if !overlap.is_empty() {
+            pcx.cx.tcx.emit_spanned_lint(
                 lint::builtin::OVERLAPPING_RANGE_ENDPOINTS,
                 hir_id,
                 pcx.span,
-                "multiple patterns overlap on their endpoints",
-                |lint| {
-                    for (int_range, span) in overlaps {
-                        lint.span_label(
-                            span,
-                            &format!(
-                                "this range overlaps on `{}`...",
-                                int_range.to_pat(pcx.cx.tcx, pcx.ty)
-                            ),
-                        );
-                    }
-                    lint.span_label(pcx.span, "... with this range");
-                    lint.note("you likely meant to write mutually exclusive ranges");
-                    lint
-                },
+                OverlappingRangeEndpoints { overlap, range: pcx.span },
             );
         }
     }
@@ -404,7 +389,7 @@ impl SplitIntRange {
     }
 
     /// Iterate over the contained ranges.
-    fn iter<'a>(&'a self) -> impl Iterator<Item = IntRange> + Captures<'a> {
+    fn iter(&self) -> impl Iterator<Item = IntRange> + Captures<'_> {
         use IntBorder::*;
 
         let self_range = Self::to_borders(self.range.clone());
@@ -612,7 +597,7 @@ impl SplitVarLenSlice {
     }
 
     /// Iterate over the partition of this slice.
-    fn iter<'a>(&'a self) -> impl Iterator<Item = Slice> + Captures<'a> {
+    fn iter(&self) -> impl Iterator<Item = Slice> + Captures<'_> {
         let smaller_lengths = match self.array_len {
             // The only admissible fixed-length slice is one of the array size. Whether `max_slice`
             // is fixed-length or variable-length, it will be the only relevant slice to output
diff --git a/compiler/rustc_mir_build/src/thir/pattern/mod.rs b/compiler/rustc_mir_build/src/thir/pattern/mod.rs
index 48a231a6c..3a6ef87c9 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/mod.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/mod.rs
@@ -2,14 +2,16 @@
 
 mod check_match;
 mod const_to_pat;
-mod deconstruct_pat;
+pub(crate) mod deconstruct_pat;
 mod usefulness;
 
 pub(crate) use self::check_match::check_match;
+pub(crate) use self::usefulness::MatchCheckCtxt;
 
+use crate::errors::*;
 use crate::thir::util::UserAnnotatedTyHelpers;
 
-use rustc_errors::struct_span_err;
+use rustc_errors::error_code;
 use rustc_hir as hir;
 use rustc_hir::def::{CtorOf, DefKind, Res};
 use rustc_hir::pat_util::EnumerateAndAdjustIterator;
@@ -127,10 +129,20 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
         hi: mir::ConstantKind<'tcx>,
         end: RangeEnd,
         span: Span,
+        lo_expr: Option<&hir::Expr<'tcx>>,
+        hi_expr: Option<&hir::Expr<'tcx>>,
     ) -> PatKind<'tcx> {
         assert_eq!(lo.ty(), ty);
         assert_eq!(hi.ty(), ty);
         let cmp = compare_const_vals(self.tcx, lo, hi, self.param_env);
+        let max = || {
+            self.tcx
+                .layout_of(self.param_env.with_reveal_all_normalized(self.tcx).and(ty))
+                .ok()
+                .unwrap()
+                .size
+                .unsigned_int_max()
+        };
         match (end, cmp) {
             // `x..y` where `x < y`.
             // Non-empty because the range includes at least `x`.
@@ -139,13 +151,27 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
             }
             // `x..y` where `x >= y`. The range is empty => error.
             (RangeEnd::Excluded, _) => {
-                struct_span_err!(
-                    self.tcx.sess,
-                    span,
-                    E0579,
-                    "lower range bound must be less than upper"
-                )
-                .emit();
+                let mut lower_overflow = false;
+                let mut higher_overflow = false;
+                if let Some(hir::Expr { kind: hir::ExprKind::Lit(lit), .. }) = lo_expr
+                    && let rustc_ast::ast::LitKind::Int(val, _) = lit.node
+                {
+                    if lo.eval_bits(self.tcx, self.param_env, ty) != val {
+                        lower_overflow = true;
+                        self.tcx.sess.emit_err(LiteralOutOfRange { span: lit.span, ty, max: max() });
+                    }
+                }
+                if let Some(hir::Expr { kind: hir::ExprKind::Lit(lit), .. }) = hi_expr
+                    && let rustc_ast::ast::LitKind::Int(val, _) = lit.node
+                {
+                    if hi.eval_bits(self.tcx, self.param_env, ty) != val {
+                        higher_overflow = true;
+                        self.tcx.sess.emit_err(LiteralOutOfRange { span: lit.span, ty, max: max() });
+                    }
+                }
+                if !lower_overflow && !higher_overflow {
+                    self.tcx.sess.emit_err(LowerRangeBoundMustBeLessThanUpper { span });
+                }
                 PatKind::Wild
             }
             // `x..=y` where `x == y`.
@@ -156,23 +182,34 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
             }
             // `x..=y` where `x > y` hence the range is empty => error.
             (RangeEnd::Included, _) => {
-                let mut err = struct_span_err!(
-                    self.tcx.sess,
-                    span,
-                    E0030,
-                    "lower range bound must be less than or equal to upper"
-                );
-                err.span_label(span, "lower bound larger than upper bound");
-                if self.tcx.sess.teach(&err.get_code().unwrap()) {
-                    err.note(
-                        "When matching against a range, the compiler \
-                              verifies that the range is non-empty. Range \
-                              patterns include both end-points, so this is \
-                              equivalent to requiring the start of the range \
-                              to be less than or equal to the end of the range.",
-                    );
+                let mut lower_overflow = false;
+                let mut higher_overflow = false;
+                if let Some(hir::Expr { kind: hir::ExprKind::Lit(lit), .. }) = lo_expr
+                    && let rustc_ast::ast::LitKind::Int(val, _) = lit.node
+                {
+                    if lo.eval_bits(self.tcx, self.param_env, ty) != val {
+                        lower_overflow = true;
+                        self.tcx.sess.emit_err(LiteralOutOfRange { span: lit.span, ty, max: max() });
+                    }
+                }
+                if let Some(hir::Expr { kind: hir::ExprKind::Lit(lit), .. }) = hi_expr
+                    && let rustc_ast::ast::LitKind::Int(val, _) = lit.node
+                {
+                    if hi.eval_bits(self.tcx, self.param_env, ty) != val {
+                        higher_overflow = true;
+                        self.tcx.sess.emit_err(LiteralOutOfRange { span: lit.span, ty, max: max() });
+                    }
+                }
+                if !lower_overflow && !higher_overflow {
+                    self.tcx.sess.emit_err(LowerRangeBoundMustBeLessThanOrEqualToUpper {
+                        span,
+                        teach: if self.tcx.sess.teach(&error_code!(E0030)) {
+                            Some(())
+                        } else {
+                            None
+                        },
+                    });
                 }
-                err.emit();
                 PatKind::Wild
             }
         }
@@ -218,7 +255,9 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
 
                 let (lp, hp) = (lo.as_ref().map(|(x, _)| x), hi.as_ref().map(|(x, _)| x));
                 let mut kind = match self.normalize_range_pattern_ends(ty, lp, hp) {
-                    Some((lc, hc)) => self.lower_pattern_range(ty, lc, hc, end, lo_span),
+                    Some((lc, hc)) => {
+                        self.lower_pattern_range(ty, lc, hc, end, lo_span, lo_expr, hi_expr)
+                    }
                     None => {
                         let msg = &format!(
                             "found bad range pattern `{:?}` outside of error recovery",
@@ -501,7 +540,7 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
             }
 
             Err(_) => {
-                self.tcx.sess.span_err(span, "could not evaluate constant pattern");
+                self.tcx.sess.emit_err(CouldNotEvalConstPattern { span });
                 return pat_from_kind(PatKind::Wild);
             }
         };
@@ -548,11 +587,11 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
             Err(ErrorHandled::TooGeneric) => {
                 // While `Reported | Linted` cases will have diagnostics emitted already
                 // it is not true for TooGeneric case, so we need to give user more information.
-                self.tcx.sess.span_err(span, "constant pattern depends on a generic parameter");
+                self.tcx.sess.emit_err(ConstPatternDependsOnGenericParameter { span });
                 pat_from_kind(PatKind::Wild)
             }
             Err(_) => {
-                self.tcx.sess.span_err(span, "could not evaluate constant pattern");
+                self.tcx.sess.emit_err(CouldNotEvalConstPattern { span });
                 pat_from_kind(PatKind::Wild)
             }
         }
@@ -584,7 +623,7 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
             mir::ConstantKind::Val(_, _) => self.const_to_pat(value, id, span, false).kind,
             mir::ConstantKind::Unevaluated(..) => {
                 // If we land here it means the const can't be evaluated because it's `TooGeneric`.
-                self.tcx.sess.span_err(span, "constant pattern depends on a generic parameter");
+                self.tcx.sess.emit_err(ConstPatternDependsOnGenericParameter { span });
                 return PatKind::Wild;
             }
         }
diff --git a/compiler/rustc_mir_build/src/thir/pattern/usefulness.rs b/compiler/rustc_mir_build/src/thir/pattern/usefulness.rs
index 3e370a053..be66d0d47 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/usefulness.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/usefulness.rs
@@ -291,9 +291,8 @@
 
 use self::ArmType::*;
 use self::Usefulness::*;
-
-use super::check_match::{joined_uncovered_patterns, pattern_not_covered_label};
 use super::deconstruct_pat::{Constructor, DeconstructedPat, Fields, SplitWildcard};
+use crate::errors::{NonExhaustiveOmittedPattern, Uncovered};
 
 use rustc_data_structures::captures::Captures;
 
@@ -743,31 +742,6 @@ impl<'p, 'tcx> Witness<'p, 'tcx> {
     }
 }
 
-/// Report that a match of a `non_exhaustive` enum marked with `non_exhaustive_omitted_patterns`
-/// is not exhaustive enough.
-///
-/// NB: The partner lint for structs lives in `compiler/rustc_hir_analysis/src/check/pat.rs`.
-fn lint_non_exhaustive_omitted_patterns<'p, 'tcx>(
-    cx: &MatchCheckCtxt<'p, 'tcx>,
-    scrut_ty: Ty<'tcx>,
-    sp: Span,
-    hir_id: HirId,
-    witnesses: Vec<DeconstructedPat<'p, 'tcx>>,
-) {
-    cx.tcx.struct_span_lint_hir(NON_EXHAUSTIVE_OMITTED_PATTERNS, hir_id, sp, "some variants are not matched explicitly", |lint| {
-        let joined_patterns = joined_uncovered_patterns(cx, &witnesses);
-        lint.span_label(sp, pattern_not_covered_label(&witnesses, &joined_patterns));
-        lint.help(
-            "ensure that all variants are matched explicitly by adding the suggested match arms",
-        );
-        lint.note(&format!(
-            "the matched value is of type `{}` and the `non_exhaustive_omitted_patterns` attribute was found",
-            scrut_ty,
-        ));
-        lint
-    });
-}
-
 /// Algorithm from <http://moscova.inria.fr/~maranget/papers/warn/index.html>.
 /// The algorithm from the paper has been modified to correctly handle empty
 /// types. The changes are:
@@ -845,7 +819,7 @@ fn is_useful<'p, 'tcx>(
 
         // Opaque types can't get destructured/split, but the patterns can
         // actually hint at hidden types, so we use the patterns' types instead.
-        if let ty::Opaque(..) = ty.kind() {
+        if let ty::Alias(ty::Opaque, ..) = ty.kind() {
             if let Some(row) = rows.first() {
                 ty = row.head().ty();
             }
@@ -913,7 +887,19 @@ fn is_useful<'p, 'tcx>(
                         .collect::<Vec<_>>()
                 };
 
-                lint_non_exhaustive_omitted_patterns(pcx.cx, pcx.ty, pcx.span, hir_id, patterns);
+                // Report that a match of a `non_exhaustive` enum marked with `non_exhaustive_omitted_patterns`
+                // is not exhaustive enough.
+                //
+                // NB: The partner lint for structs lives in `compiler/rustc_hir_analysis/src/check/pat.rs`.
+                cx.tcx.emit_spanned_lint(
+                    NON_EXHAUSTIVE_OMITTED_PATTERNS,
+                    hir_id,
+                    pcx.span,
+                    NonExhaustiveOmittedPattern {
+                        scrut_ty: pcx.ty,
+                        uncovered: Uncovered::new(pcx.span, pcx.cx, patterns),
+                    },
+                );
             }
 
             ret.extend(usefulness);