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-rw-r--r--compiler/rustc_typeck/src/check/demand.rs1442
1 files changed, 1442 insertions, 0 deletions
diff --git a/compiler/rustc_typeck/src/check/demand.rs b/compiler/rustc_typeck/src/check/demand.rs
new file mode 100644
index 000000000..4de48dc5b
--- /dev/null
+++ b/compiler/rustc_typeck/src/check/demand.rs
@@ -0,0 +1,1442 @@
+use crate::check::FnCtxt;
+use rustc_infer::infer::InferOk;
+use rustc_middle::middle::stability::EvalResult;
+use rustc_trait_selection::infer::InferCtxtExt as _;
+use rustc_trait_selection::traits::ObligationCause;
+
+use rustc_ast::util::parser::PREC_POSTFIX;
+use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed};
+use rustc_hir as hir;
+use rustc_hir::lang_items::LangItem;
+use rustc_hir::{is_range_literal, Node};
+use rustc_middle::lint::in_external_macro;
+use rustc_middle::ty::adjustment::AllowTwoPhase;
+use rustc_middle::ty::error::{ExpectedFound, TypeError};
+use rustc_middle::ty::print::with_no_trimmed_paths;
+use rustc_middle::ty::{self, Article, AssocItem, Ty, TypeAndMut};
+use rustc_span::symbol::{sym, Symbol};
+use rustc_span::{BytePos, Span};
+
+use super::method::probe;
+
+use std::iter;
+
+impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
+ pub fn emit_coerce_suggestions(
+ &self,
+ err: &mut Diagnostic,
+ expr: &hir::Expr<'tcx>,
+ expr_ty: Ty<'tcx>,
+ expected: Ty<'tcx>,
+ expected_ty_expr: Option<&'tcx hir::Expr<'tcx>>,
+ error: Option<TypeError<'tcx>>,
+ ) {
+ self.annotate_expected_due_to_let_ty(err, expr, error);
+ self.suggest_deref_ref_or_into(err, expr, expected, expr_ty, expected_ty_expr);
+ self.suggest_compatible_variants(err, expr, expected, expr_ty);
+ self.suggest_non_zero_new_unwrap(err, expr, expected, expr_ty);
+ if self.suggest_calling_boxed_future_when_appropriate(err, expr, expected, expr_ty) {
+ return;
+ }
+ self.suggest_no_capture_closure(err, expected, expr_ty);
+ self.suggest_boxing_when_appropriate(err, expr, expected, expr_ty);
+ self.suggest_missing_parentheses(err, expr);
+ self.suggest_block_to_brackets_peeling_refs(err, expr, expr_ty, expected);
+ self.note_type_is_not_clone(err, expected, expr_ty, expr);
+ self.note_need_for_fn_pointer(err, expected, expr_ty);
+ self.note_internal_mutation_in_method(err, expr, expected, expr_ty);
+ self.report_closure_inferred_return_type(err, expected);
+ }
+
+ // Requires that the two types unify, and prints an error message if
+ // they don't.
+ pub fn demand_suptype(&self, sp: Span, expected: Ty<'tcx>, actual: Ty<'tcx>) {
+ if let Some(mut e) = self.demand_suptype_diag(sp, expected, actual) {
+ e.emit();
+ }
+ }
+
+ pub fn demand_suptype_diag(
+ &self,
+ sp: Span,
+ expected: Ty<'tcx>,
+ actual: Ty<'tcx>,
+ ) -> Option<DiagnosticBuilder<'tcx, ErrorGuaranteed>> {
+ self.demand_suptype_with_origin(&self.misc(sp), expected, actual)
+ }
+
+ #[instrument(skip(self), level = "debug")]
+ pub fn demand_suptype_with_origin(
+ &self,
+ cause: &ObligationCause<'tcx>,
+ expected: Ty<'tcx>,
+ actual: Ty<'tcx>,
+ ) -> Option<DiagnosticBuilder<'tcx, ErrorGuaranteed>> {
+ match self.at(cause, self.param_env).sup(expected, actual) {
+ Ok(InferOk { obligations, value: () }) => {
+ self.register_predicates(obligations);
+ None
+ }
+ Err(e) => Some(self.report_mismatched_types(&cause, expected, actual, e)),
+ }
+ }
+
+ pub fn demand_eqtype(&self, sp: Span, expected: Ty<'tcx>, actual: Ty<'tcx>) {
+ if let Some(mut err) = self.demand_eqtype_diag(sp, expected, actual) {
+ err.emit();
+ }
+ }
+
+ pub fn demand_eqtype_diag(
+ &self,
+ sp: Span,
+ expected: Ty<'tcx>,
+ actual: Ty<'tcx>,
+ ) -> Option<DiagnosticBuilder<'tcx, ErrorGuaranteed>> {
+ self.demand_eqtype_with_origin(&self.misc(sp), expected, actual)
+ }
+
+ pub fn demand_eqtype_with_origin(
+ &self,
+ cause: &ObligationCause<'tcx>,
+ expected: Ty<'tcx>,
+ actual: Ty<'tcx>,
+ ) -> Option<DiagnosticBuilder<'tcx, ErrorGuaranteed>> {
+ match self.at(cause, self.param_env).eq(expected, actual) {
+ Ok(InferOk { obligations, value: () }) => {
+ self.register_predicates(obligations);
+ None
+ }
+ Err(e) => Some(self.report_mismatched_types(cause, expected, actual, e)),
+ }
+ }
+
+ pub fn demand_coerce(
+ &self,
+ expr: &hir::Expr<'tcx>,
+ checked_ty: Ty<'tcx>,
+ expected: Ty<'tcx>,
+ expected_ty_expr: Option<&'tcx hir::Expr<'tcx>>,
+ allow_two_phase: AllowTwoPhase,
+ ) -> Ty<'tcx> {
+ let (ty, err) =
+ self.demand_coerce_diag(expr, checked_ty, expected, expected_ty_expr, allow_two_phase);
+ if let Some(mut err) = err {
+ err.emit();
+ }
+ ty
+ }
+
+ /// Checks that the type of `expr` can be coerced to `expected`.
+ ///
+ /// N.B., this code relies on `self.diverges` to be accurate. In particular, assignments to `!`
+ /// will be permitted if the diverges flag is currently "always".
+ #[tracing::instrument(level = "debug", skip(self, expr, expected_ty_expr, allow_two_phase))]
+ pub fn demand_coerce_diag(
+ &self,
+ expr: &hir::Expr<'tcx>,
+ checked_ty: Ty<'tcx>,
+ expected: Ty<'tcx>,
+ expected_ty_expr: Option<&'tcx hir::Expr<'tcx>>,
+ allow_two_phase: AllowTwoPhase,
+ ) -> (Ty<'tcx>, Option<DiagnosticBuilder<'tcx, ErrorGuaranteed>>) {
+ let expected = self.resolve_vars_with_obligations(expected);
+
+ let e = match self.try_coerce(expr, checked_ty, expected, allow_two_phase, None) {
+ Ok(ty) => return (ty, None),
+ Err(e) => e,
+ };
+
+ self.set_tainted_by_errors();
+ let expr = expr.peel_drop_temps();
+ let cause = self.misc(expr.span);
+ let expr_ty = self.resolve_vars_with_obligations(checked_ty);
+ let mut err = self.report_mismatched_types(&cause, expected, expr_ty, e.clone());
+
+ let is_insufficiently_polymorphic =
+ matches!(e, TypeError::RegionsInsufficientlyPolymorphic(..));
+
+ // FIXME(#73154): For now, we do leak check when coercing function
+ // pointers in typeck, instead of only during borrowck. This can lead
+ // to these `RegionsInsufficientlyPolymorphic` errors that aren't helpful.
+ if !is_insufficiently_polymorphic {
+ self.emit_coerce_suggestions(
+ &mut err,
+ expr,
+ expr_ty,
+ expected,
+ expected_ty_expr,
+ Some(e),
+ );
+ }
+
+ (expected, Some(err))
+ }
+
+ fn annotate_expected_due_to_let_ty(
+ &self,
+ err: &mut Diagnostic,
+ expr: &hir::Expr<'_>,
+ error: Option<TypeError<'_>>,
+ ) {
+ let parent = self.tcx.hir().get_parent_node(expr.hir_id);
+ match (self.tcx.hir().find(parent), error) {
+ (Some(hir::Node::Local(hir::Local { ty: Some(ty), init: Some(init), .. })), _)
+ if init.hir_id == expr.hir_id =>
+ {
+ // Point at `let` assignment type.
+ err.span_label(ty.span, "expected due to this");
+ }
+ (
+ Some(hir::Node::Expr(hir::Expr {
+ kind: hir::ExprKind::Assign(lhs, rhs, _), ..
+ })),
+ Some(TypeError::Sorts(ExpectedFound { expected, .. })),
+ ) if rhs.hir_id == expr.hir_id && !expected.is_closure() => {
+ // We ignore closures explicitly because we already point at them elsewhere.
+ // Point at the assigned-to binding.
+ let mut primary_span = lhs.span;
+ let mut secondary_span = lhs.span;
+ let mut post_message = "";
+ match lhs.kind {
+ hir::ExprKind::Path(hir::QPath::Resolved(
+ None,
+ hir::Path {
+ res:
+ hir::def::Res::Def(
+ hir::def::DefKind::Static(_) | hir::def::DefKind::Const,
+ def_id,
+ ),
+ ..
+ },
+ )) => {
+ if let Some(hir::Node::Item(hir::Item {
+ ident,
+ kind: hir::ItemKind::Static(ty, ..) | hir::ItemKind::Const(ty, ..),
+ ..
+ })) = self.tcx.hir().get_if_local(*def_id)
+ {
+ primary_span = ty.span;
+ secondary_span = ident.span;
+ post_message = " type";
+ }
+ }
+ hir::ExprKind::Path(hir::QPath::Resolved(
+ None,
+ hir::Path { res: hir::def::Res::Local(hir_id), .. },
+ )) => {
+ if let Some(hir::Node::Pat(pat)) = self.tcx.hir().find(*hir_id) {
+ let parent = self.tcx.hir().get_parent_node(pat.hir_id);
+ primary_span = pat.span;
+ secondary_span = pat.span;
+ match self.tcx.hir().find(parent) {
+ Some(hir::Node::Local(hir::Local { ty: Some(ty), .. })) => {
+ primary_span = ty.span;
+ post_message = " type";
+ }
+ Some(hir::Node::Local(hir::Local { init: Some(init), .. })) => {
+ primary_span = init.span;
+ post_message = " value";
+ }
+ Some(hir::Node::Param(hir::Param { ty_span, .. })) => {
+ primary_span = *ty_span;
+ post_message = " parameter type";
+ }
+ _ => {}
+ }
+ }
+ }
+ _ => {}
+ }
+
+ if primary_span != secondary_span
+ && self
+ .tcx
+ .sess
+ .source_map()
+ .is_multiline(secondary_span.shrink_to_hi().until(primary_span))
+ {
+ // We are pointing at the binding's type or initializer value, but it's pattern
+ // is in a different line, so we point at both.
+ err.span_label(secondary_span, "expected due to the type of this binding");
+ err.span_label(primary_span, &format!("expected due to this{post_message}"));
+ } else if post_message == "" {
+ // We are pointing at either the assignment lhs or the binding def pattern.
+ err.span_label(primary_span, "expected due to the type of this binding");
+ } else {
+ // We are pointing at the binding's type or initializer value.
+ err.span_label(primary_span, &format!("expected due to this{post_message}"));
+ }
+
+ if !lhs.is_syntactic_place_expr() {
+ // We already emitted E0070 "invalid left-hand side of assignment", so we
+ // silence this.
+ err.downgrade_to_delayed_bug();
+ }
+ }
+ _ => {}
+ }
+ }
+
+ /// If the expected type is an enum (Issue #55250) with any variants whose
+ /// sole field is of the found type, suggest such variants. (Issue #42764)
+ fn suggest_compatible_variants(
+ &self,
+ err: &mut Diagnostic,
+ expr: &hir::Expr<'_>,
+ expected: Ty<'tcx>,
+ expr_ty: Ty<'tcx>,
+ ) {
+ if let ty::Adt(expected_adt, substs) = expected.kind() {
+ if let hir::ExprKind::Field(base, ident) = expr.kind {
+ let base_ty = self.typeck_results.borrow().expr_ty(base);
+ if self.can_eq(self.param_env, base_ty, expected).is_ok()
+ && let Some(base_span) = base.span.find_ancestor_inside(expr.span)
+ {
+ err.span_suggestion_verbose(
+ expr.span.with_lo(base_span.hi()),
+ format!("consider removing the tuple struct field `{ident}`"),
+ "",
+ Applicability::MaybeIncorrect,
+ );
+ return
+ }
+ }
+
+ // If the expression is of type () and it's the return expression of a block,
+ // we suggest adding a separate return expression instead.
+ // (To avoid things like suggesting `Ok(while .. { .. })`.)
+ if expr_ty.is_unit() {
+ let mut id = expr.hir_id;
+ let mut parent;
+
+ // Unroll desugaring, to make sure this works for `for` loops etc.
+ loop {
+ parent = self.tcx.hir().get_parent_node(id);
+ if let Some(parent_span) = self.tcx.hir().opt_span(parent) {
+ if parent_span.find_ancestor_inside(expr.span).is_some() {
+ // The parent node is part of the same span, so is the result of the
+ // same expansion/desugaring and not the 'real' parent node.
+ id = parent;
+ continue;
+ }
+ }
+ break;
+ }
+
+ if let Some(hir::Node::Block(&hir::Block {
+ span: block_span, expr: Some(e), ..
+ })) = self.tcx.hir().find(parent)
+ {
+ if e.hir_id == id {
+ if let Some(span) = expr.span.find_ancestor_inside(block_span) {
+ let return_suggestions = if self
+ .tcx
+ .is_diagnostic_item(sym::Result, expected_adt.did())
+ {
+ vec!["Ok(())"]
+ } else if self.tcx.is_diagnostic_item(sym::Option, expected_adt.did()) {
+ vec!["None", "Some(())"]
+ } else {
+ return;
+ };
+ if let Some(indent) =
+ self.tcx.sess.source_map().indentation_before(span.shrink_to_lo())
+ {
+ // Add a semicolon, except after `}`.
+ let semicolon =
+ match self.tcx.sess.source_map().span_to_snippet(span) {
+ Ok(s) if s.ends_with('}') => "",
+ _ => ";",
+ };
+ err.span_suggestions(
+ span.shrink_to_hi(),
+ "try adding an expression at the end of the block",
+ return_suggestions
+ .into_iter()
+ .map(|r| format!("{semicolon}\n{indent}{r}")),
+ Applicability::MaybeIncorrect,
+ );
+ }
+ return;
+ }
+ }
+ }
+ }
+
+ let compatible_variants: Vec<(String, _, _, Option<String>)> = expected_adt
+ .variants()
+ .iter()
+ .filter(|variant| {
+ variant.fields.len() == 1
+ })
+ .filter_map(|variant| {
+ let sole_field = &variant.fields[0];
+
+ let field_is_local = sole_field.did.is_local();
+ let field_is_accessible =
+ sole_field.vis.is_accessible_from(expr.hir_id.owner.to_def_id(), self.tcx)
+ // Skip suggestions for unstable public fields (for example `Pin::pointer`)
+ && matches!(self.tcx.eval_stability(sole_field.did, None, expr.span, None), EvalResult::Allow | EvalResult::Unmarked);
+
+ if !field_is_local && !field_is_accessible {
+ return None;
+ }
+
+ let note_about_variant_field_privacy = (field_is_local && !field_is_accessible)
+ .then(|| format!(" (its field is private, but it's local to this crate and its privacy can be changed)"));
+
+ let sole_field_ty = sole_field.ty(self.tcx, substs);
+ if self.can_coerce(expr_ty, sole_field_ty) {
+ let variant_path =
+ with_no_trimmed_paths!(self.tcx.def_path_str(variant.def_id));
+ // FIXME #56861: DRYer prelude filtering
+ if let Some(path) = variant_path.strip_prefix("std::prelude::")
+ && let Some((_, path)) = path.split_once("::")
+ {
+ return Some((path.to_string(), variant.ctor_kind, sole_field.name, note_about_variant_field_privacy));
+ }
+ Some((variant_path, variant.ctor_kind, sole_field.name, note_about_variant_field_privacy))
+ } else {
+ None
+ }
+ })
+ .collect();
+
+ let suggestions_for = |variant: &_, ctor, field_name| {
+ let prefix = match self.maybe_get_struct_pattern_shorthand_field(expr) {
+ Some(ident) => format!("{ident}: "),
+ None => String::new(),
+ };
+
+ let (open, close) = match ctor {
+ hir::def::CtorKind::Fn => ("(".to_owned(), ")"),
+ hir::def::CtorKind::Fictive => (format!(" {{ {field_name}: "), " }"),
+
+ // unit variants don't have fields
+ hir::def::CtorKind::Const => unreachable!(),
+ };
+
+ vec![
+ (expr.span.shrink_to_lo(), format!("{prefix}{variant}{open}")),
+ (expr.span.shrink_to_hi(), close.to_owned()),
+ ]
+ };
+
+ match &compatible_variants[..] {
+ [] => { /* No variants to format */ }
+ [(variant, ctor_kind, field_name, note)] => {
+ // Just a single matching variant.
+ err.multipart_suggestion_verbose(
+ &format!(
+ "try wrapping the expression in `{variant}`{note}",
+ note = note.as_deref().unwrap_or("")
+ ),
+ suggestions_for(&**variant, *ctor_kind, *field_name),
+ Applicability::MaybeIncorrect,
+ );
+ }
+ _ => {
+ // More than one matching variant.
+ err.multipart_suggestions(
+ &format!(
+ "try wrapping the expression in a variant of `{}`",
+ self.tcx.def_path_str(expected_adt.did())
+ ),
+ compatible_variants.into_iter().map(
+ |(variant, ctor_kind, field_name, _)| {
+ suggestions_for(&variant, ctor_kind, field_name)
+ },
+ ),
+ Applicability::MaybeIncorrect,
+ );
+ }
+ }
+ }
+ }
+
+ fn suggest_non_zero_new_unwrap(
+ &self,
+ err: &mut Diagnostic,
+ expr: &hir::Expr<'_>,
+ expected: Ty<'tcx>,
+ expr_ty: Ty<'tcx>,
+ ) {
+ let tcx = self.tcx;
+ let (adt, unwrap) = match expected.kind() {
+ // In case Option<NonZero*> is wanted, but * is provided, suggest calling new
+ ty::Adt(adt, substs) if tcx.is_diagnostic_item(sym::Option, adt.did()) => {
+ // Unwrap option
+ let ty::Adt(adt, _) = substs.type_at(0).kind() else { return };
+
+ (adt, "")
+ }
+ // In case NonZero* is wanted, but * is provided also add `.unwrap()` to satisfy types
+ ty::Adt(adt, _) => (adt, ".unwrap()"),
+ _ => return,
+ };
+
+ let map = [
+ (sym::NonZeroU8, tcx.types.u8),
+ (sym::NonZeroU16, tcx.types.u16),
+ (sym::NonZeroU32, tcx.types.u32),
+ (sym::NonZeroU64, tcx.types.u64),
+ (sym::NonZeroU128, tcx.types.u128),
+ (sym::NonZeroI8, tcx.types.i8),
+ (sym::NonZeroI16, tcx.types.i16),
+ (sym::NonZeroI32, tcx.types.i32),
+ (sym::NonZeroI64, tcx.types.i64),
+ (sym::NonZeroI128, tcx.types.i128),
+ ];
+
+ let Some((s, _)) = map
+ .iter()
+ .find(|&&(s, t)| self.tcx.is_diagnostic_item(s, adt.did()) && self.can_coerce(expr_ty, t))
+ else { return };
+
+ let path = self.tcx.def_path_str(adt.non_enum_variant().def_id);
+
+ err.multipart_suggestion(
+ format!("consider calling `{s}::new`"),
+ vec![
+ (expr.span.shrink_to_lo(), format!("{path}::new(")),
+ (expr.span.shrink_to_hi(), format!("){unwrap}")),
+ ],
+ Applicability::MaybeIncorrect,
+ );
+ }
+
+ pub fn get_conversion_methods(
+ &self,
+ span: Span,
+ expected: Ty<'tcx>,
+ checked_ty: Ty<'tcx>,
+ hir_id: hir::HirId,
+ ) -> Vec<AssocItem> {
+ let mut methods =
+ self.probe_for_return_type(span, probe::Mode::MethodCall, expected, checked_ty, hir_id);
+ methods.retain(|m| {
+ self.has_only_self_parameter(m)
+ && self
+ .tcx
+ // This special internal attribute is used to permit
+ // "identity-like" conversion methods to be suggested here.
+ //
+ // FIXME (#46459 and #46460): ideally
+ // `std::convert::Into::into` and `std::borrow:ToOwned` would
+ // also be `#[rustc_conversion_suggestion]`, if not for
+ // method-probing false-positives and -negatives (respectively).
+ //
+ // FIXME? Other potential candidate methods: `as_ref` and
+ // `as_mut`?
+ .has_attr(m.def_id, sym::rustc_conversion_suggestion)
+ });
+
+ methods
+ }
+
+ /// This function checks whether the method is not static and does not accept other parameters than `self`.
+ fn has_only_self_parameter(&self, method: &AssocItem) -> bool {
+ match method.kind {
+ ty::AssocKind::Fn => {
+ method.fn_has_self_parameter
+ && self.tcx.fn_sig(method.def_id).inputs().skip_binder().len() == 1
+ }
+ _ => false,
+ }
+ }
+
+ /// Identify some cases where `as_ref()` would be appropriate and suggest it.
+ ///
+ /// Given the following code:
+ /// ```compile_fail,E0308
+ /// struct Foo;
+ /// fn takes_ref(_: &Foo) {}
+ /// let ref opt = Some(Foo);
+ ///
+ /// opt.map(|param| takes_ref(param));
+ /// ```
+ /// Suggest using `opt.as_ref().map(|param| takes_ref(param));` instead.
+ ///
+ /// It only checks for `Option` and `Result` and won't work with
+ /// ```ignore (illustrative)
+ /// opt.map(|param| { takes_ref(param) });
+ /// ```
+ fn can_use_as_ref(&self, expr: &hir::Expr<'_>) -> Option<(Span, &'static str, String)> {
+ let hir::ExprKind::Path(hir::QPath::Resolved(_, ref path)) = expr.kind else {
+ return None;
+ };
+
+ let hir::def::Res::Local(local_id) = path.res else {
+ return None;
+ };
+
+ let local_parent = self.tcx.hir().get_parent_node(local_id);
+ let Some(Node::Param(hir::Param { hir_id: param_hir_id, .. })) = self.tcx.hir().find(local_parent) else {
+ return None;
+ };
+
+ let param_parent = self.tcx.hir().get_parent_node(*param_hir_id);
+ let Some(Node::Expr(hir::Expr {
+ hir_id: expr_hir_id,
+ kind: hir::ExprKind::Closure(hir::Closure { fn_decl: closure_fn_decl, .. }),
+ ..
+ })) = self.tcx.hir().find(param_parent) else {
+ return None;
+ };
+
+ let expr_parent = self.tcx.hir().get_parent_node(*expr_hir_id);
+ let hir = self.tcx.hir().find(expr_parent);
+ let closure_params_len = closure_fn_decl.inputs.len();
+ let (
+ Some(Node::Expr(hir::Expr {
+ kind: hir::ExprKind::MethodCall(method_path, method_expr, _),
+ ..
+ })),
+ 1,
+ ) = (hir, closure_params_len) else {
+ return None;
+ };
+
+ let self_ty = self.typeck_results.borrow().expr_ty(&method_expr[0]);
+ let self_ty = format!("{:?}", self_ty);
+ let name = method_path.ident.name;
+ let is_as_ref_able = (self_ty.starts_with("&std::option::Option")
+ || self_ty.starts_with("&std::result::Result")
+ || self_ty.starts_with("std::option::Option")
+ || self_ty.starts_with("std::result::Result"))
+ && (name == sym::map || name == sym::and_then);
+ match (is_as_ref_able, self.sess().source_map().span_to_snippet(method_path.ident.span)) {
+ (true, Ok(src)) => {
+ let suggestion = format!("as_ref().{}", src);
+ Some((method_path.ident.span, "consider using `as_ref` instead", suggestion))
+ }
+ _ => None,
+ }
+ }
+
+ pub(crate) fn maybe_get_struct_pattern_shorthand_field(
+ &self,
+ expr: &hir::Expr<'_>,
+ ) -> Option<Symbol> {
+ let hir = self.tcx.hir();
+ let local = match expr {
+ hir::Expr {
+ kind:
+ hir::ExprKind::Path(hir::QPath::Resolved(
+ None,
+ hir::Path {
+ res: hir::def::Res::Local(_),
+ segments: [hir::PathSegment { ident, .. }],
+ ..
+ },
+ )),
+ ..
+ } => Some(ident),
+ _ => None,
+ }?;
+
+ match hir.find(hir.get_parent_node(expr.hir_id))? {
+ Node::Expr(hir::Expr { kind: hir::ExprKind::Struct(_, fields, ..), .. }) => {
+ for field in *fields {
+ if field.ident.name == local.name && field.is_shorthand {
+ return Some(local.name);
+ }
+ }
+ }
+ _ => {}
+ }
+
+ None
+ }
+
+ /// If the given `HirId` corresponds to a block with a trailing expression, return that expression
+ pub(crate) fn maybe_get_block_expr(
+ &self,
+ expr: &hir::Expr<'tcx>,
+ ) -> Option<&'tcx hir::Expr<'tcx>> {
+ match expr {
+ hir::Expr { kind: hir::ExprKind::Block(block, ..), .. } => block.expr,
+ _ => None,
+ }
+ }
+
+ /// Returns whether the given expression is an `else if`.
+ pub(crate) fn is_else_if_block(&self, expr: &hir::Expr<'_>) -> bool {
+ if let hir::ExprKind::If(..) = expr.kind {
+ let parent_id = self.tcx.hir().get_parent_node(expr.hir_id);
+ if let Some(Node::Expr(hir::Expr {
+ kind: hir::ExprKind::If(_, _, Some(else_expr)),
+ ..
+ })) = self.tcx.hir().find(parent_id)
+ {
+ return else_expr.hir_id == expr.hir_id;
+ }
+ }
+ false
+ }
+
+ /// This function is used to determine potential "simple" improvements or users' errors and
+ /// provide them useful help. For example:
+ ///
+ /// ```compile_fail,E0308
+ /// fn some_fn(s: &str) {}
+ ///
+ /// let x = "hey!".to_owned();
+ /// some_fn(x); // error
+ /// ```
+ ///
+ /// No need to find every potential function which could make a coercion to transform a
+ /// `String` into a `&str` since a `&` would do the trick!
+ ///
+ /// In addition of this check, it also checks between references mutability state. If the
+ /// expected is mutable but the provided isn't, maybe we could just say "Hey, try with
+ /// `&mut`!".
+ pub fn check_ref(
+ &self,
+ expr: &hir::Expr<'tcx>,
+ checked_ty: Ty<'tcx>,
+ expected: Ty<'tcx>,
+ ) -> Option<(Span, String, String, Applicability, bool /* verbose */)> {
+ let sess = self.sess();
+ let sp = expr.span;
+
+ // If the span is from an external macro, there's no suggestion we can make.
+ if in_external_macro(sess, sp) {
+ return None;
+ }
+
+ let sm = sess.source_map();
+
+ let replace_prefix = |s: &str, old: &str, new: &str| {
+ s.strip_prefix(old).map(|stripped| new.to_string() + stripped)
+ };
+
+ // `ExprKind::DropTemps` is semantically irrelevant for these suggestions.
+ let expr = expr.peel_drop_temps();
+
+ match (&expr.kind, expected.kind(), checked_ty.kind()) {
+ (_, &ty::Ref(_, exp, _), &ty::Ref(_, check, _)) => match (exp.kind(), check.kind()) {
+ (&ty::Str, &ty::Array(arr, _) | &ty::Slice(arr)) if arr == self.tcx.types.u8 => {
+ if let hir::ExprKind::Lit(_) = expr.kind
+ && let Ok(src) = sm.span_to_snippet(sp)
+ && replace_prefix(&src, "b\"", "\"").is_some()
+ {
+ let pos = sp.lo() + BytePos(1);
+ return Some((
+ sp.with_hi(pos),
+ "consider removing the leading `b`".to_string(),
+ String::new(),
+ Applicability::MachineApplicable,
+ true,
+ ));
+ }
+ }
+ (&ty::Array(arr, _) | &ty::Slice(arr), &ty::Str) if arr == self.tcx.types.u8 => {
+ if let hir::ExprKind::Lit(_) = expr.kind
+ && let Ok(src) = sm.span_to_snippet(sp)
+ && replace_prefix(&src, "\"", "b\"").is_some()
+ {
+ return Some((
+ sp.shrink_to_lo(),
+ "consider adding a leading `b`".to_string(),
+ "b".to_string(),
+ Applicability::MachineApplicable,
+ true,
+ ));
+ }
+ }
+ _ => {}
+ },
+ (_, &ty::Ref(_, _, mutability), _) => {
+ // Check if it can work when put into a ref. For example:
+ //
+ // ```
+ // fn bar(x: &mut i32) {}
+ //
+ // let x = 0u32;
+ // bar(&x); // error, expected &mut
+ // ```
+ let ref_ty = match mutability {
+ hir::Mutability::Mut => {
+ self.tcx.mk_mut_ref(self.tcx.mk_region(ty::ReStatic), checked_ty)
+ }
+ hir::Mutability::Not => {
+ self.tcx.mk_imm_ref(self.tcx.mk_region(ty::ReStatic), checked_ty)
+ }
+ };
+ if self.can_coerce(ref_ty, expected) {
+ let mut sugg_sp = sp;
+ if let hir::ExprKind::MethodCall(ref segment, ref args, _) = expr.kind {
+ let clone_trait =
+ self.tcx.require_lang_item(LangItem::Clone, Some(segment.ident.span));
+ if let ([arg], Some(true), sym::clone) = (
+ &args[..],
+ self.typeck_results.borrow().type_dependent_def_id(expr.hir_id).map(
+ |did| {
+ let ai = self.tcx.associated_item(did);
+ ai.trait_container(self.tcx) == Some(clone_trait)
+ },
+ ),
+ segment.ident.name,
+ ) {
+ // If this expression had a clone call when suggesting borrowing
+ // we want to suggest removing it because it'd now be unnecessary.
+ sugg_sp = arg.span;
+ }
+ }
+ if let Ok(src) = sm.span_to_snippet(sugg_sp) {
+ let needs_parens = match expr.kind {
+ // parenthesize if needed (Issue #46756)
+ hir::ExprKind::Cast(_, _) | hir::ExprKind::Binary(_, _, _) => true,
+ // parenthesize borrows of range literals (Issue #54505)
+ _ if is_range_literal(expr) => true,
+ _ => false,
+ };
+ let sugg_expr = if needs_parens { format!("({src})") } else { src };
+
+ if let Some(sugg) = self.can_use_as_ref(expr) {
+ return Some((
+ sugg.0,
+ sugg.1.to_string(),
+ sugg.2,
+ Applicability::MachineApplicable,
+ false,
+ ));
+ }
+
+ let prefix = match self.maybe_get_struct_pattern_shorthand_field(expr) {
+ Some(ident) => format!("{ident}: "),
+ None => String::new(),
+ };
+
+ if let Some(hir::Node::Expr(hir::Expr {
+ kind: hir::ExprKind::Assign(..),
+ ..
+ })) = self.tcx.hir().find(self.tcx.hir().get_parent_node(expr.hir_id))
+ {
+ if mutability == hir::Mutability::Mut {
+ // Suppressing this diagnostic, we'll properly print it in `check_expr_assign`
+ return None;
+ }
+ }
+
+ return Some(match mutability {
+ hir::Mutability::Mut => (
+ sp,
+ "consider mutably borrowing here".to_string(),
+ format!("{prefix}&mut {sugg_expr}"),
+ Applicability::MachineApplicable,
+ false,
+ ),
+ hir::Mutability::Not => (
+ sp,
+ "consider borrowing here".to_string(),
+ format!("{prefix}&{sugg_expr}"),
+ Applicability::MachineApplicable,
+ false,
+ ),
+ });
+ }
+ }
+ }
+ (
+ hir::ExprKind::AddrOf(hir::BorrowKind::Ref, _, ref expr),
+ _,
+ &ty::Ref(_, checked, _),
+ ) if self.can_sub(self.param_env, checked, expected).is_ok() => {
+ // We have `&T`, check if what was expected was `T`. If so,
+ // we may want to suggest removing a `&`.
+ if sm.is_imported(expr.span) {
+ // Go through the spans from which this span was expanded,
+ // and find the one that's pointing inside `sp`.
+ //
+ // E.g. for `&format!("")`, where we want the span to the
+ // `format!()` invocation instead of its expansion.
+ if let Some(call_span) =
+ iter::successors(Some(expr.span), |s| s.parent_callsite())
+ .find(|&s| sp.contains(s))
+ && sm.is_span_accessible(call_span)
+ {
+ return Some((
+ sp.with_hi(call_span.lo()),
+ "consider removing the borrow".to_string(),
+ String::new(),
+ Applicability::MachineApplicable,
+ true,
+ ));
+ }
+ return None;
+ }
+ if sp.contains(expr.span)
+ && sm.is_span_accessible(expr.span)
+ {
+ return Some((
+ sp.with_hi(expr.span.lo()),
+ "consider removing the borrow".to_string(),
+ String::new(),
+ Applicability::MachineApplicable,
+ true,
+ ));
+ }
+ }
+ (
+ _,
+ &ty::RawPtr(TypeAndMut { ty: ty_b, mutbl: mutbl_b }),
+ &ty::Ref(_, ty_a, mutbl_a),
+ ) => {
+ if let Some(steps) = self.deref_steps(ty_a, ty_b)
+ // Only suggest valid if dereferencing needed.
+ && steps > 0
+ // The pointer type implements `Copy` trait so the suggestion is always valid.
+ && let Ok(src) = sm.span_to_snippet(sp)
+ {
+ let derefs = "*".repeat(steps);
+ if let Some((span, src, applicability)) = match mutbl_b {
+ hir::Mutability::Mut => {
+ let new_prefix = "&mut ".to_owned() + &derefs;
+ match mutbl_a {
+ hir::Mutability::Mut => {
+ replace_prefix(&src, "&mut ", &new_prefix).map(|_| {
+ let pos = sp.lo() + BytePos(5);
+ let sp = sp.with_lo(pos).with_hi(pos);
+ (sp, derefs, Applicability::MachineApplicable)
+ })
+ }
+ hir::Mutability::Not => {
+ replace_prefix(&src, "&", &new_prefix).map(|_| {
+ let pos = sp.lo() + BytePos(1);
+ let sp = sp.with_lo(pos).with_hi(pos);
+ (
+ sp,
+ format!("mut {derefs}"),
+ Applicability::Unspecified,
+ )
+ })
+ }
+ }
+ }
+ hir::Mutability::Not => {
+ let new_prefix = "&".to_owned() + &derefs;
+ match mutbl_a {
+ hir::Mutability::Mut => {
+ replace_prefix(&src, "&mut ", &new_prefix).map(|_| {
+ let lo = sp.lo() + BytePos(1);
+ let hi = sp.lo() + BytePos(5);
+ let sp = sp.with_lo(lo).with_hi(hi);
+ (sp, derefs, Applicability::MachineApplicable)
+ })
+ }
+ hir::Mutability::Not => {
+ replace_prefix(&src, "&", &new_prefix).map(|_| {
+ let pos = sp.lo() + BytePos(1);
+ let sp = sp.with_lo(pos).with_hi(pos);
+ (sp, derefs, Applicability::MachineApplicable)
+ })
+ }
+ }
+ }
+ } {
+ return Some((
+ span,
+ "consider dereferencing".to_string(),
+ src,
+ applicability,
+ true,
+ ));
+ }
+ }
+ }
+ _ if sp == expr.span => {
+ if let Some(mut steps) = self.deref_steps(checked_ty, expected) {
+ let mut expr = expr.peel_blocks();
+ let mut prefix_span = expr.span.shrink_to_lo();
+ let mut remove = String::new();
+
+ // Try peeling off any existing `&` and `&mut` to reach our target type
+ while steps > 0 {
+ if let hir::ExprKind::AddrOf(_, mutbl, inner) = expr.kind {
+ // If the expression has `&`, removing it would fix the error
+ prefix_span = prefix_span.with_hi(inner.span.lo());
+ expr = inner;
+ remove += match mutbl {
+ hir::Mutability::Not => "&",
+ hir::Mutability::Mut => "&mut ",
+ };
+ steps -= 1;
+ } else {
+ break;
+ }
+ }
+ // If we've reached our target type with just removing `&`, then just print now.
+ if steps == 0 {
+ return Some((
+ prefix_span,
+ format!("consider removing the `{}`", remove.trim()),
+ String::new(),
+ // Do not remove `&&` to get to bool, because it might be something like
+ // { a } && b, which we have a separate fixup suggestion that is more
+ // likely correct...
+ if remove.trim() == "&&" && expected == self.tcx.types.bool {
+ Applicability::MaybeIncorrect
+ } else {
+ Applicability::MachineApplicable
+ },
+ true,
+ ));
+ }
+
+ // For this suggestion to make sense, the type would need to be `Copy`,
+ // or we have to be moving out of a `Box<T>`
+ if self.type_is_copy_modulo_regions(self.param_env, expected, sp)
+ // FIXME(compiler-errors): We can actually do this if the checked_ty is
+ // `steps` layers of boxes, not just one, but this is easier and most likely.
+ || (checked_ty.is_box() && steps == 1)
+ {
+ let deref_kind = if checked_ty.is_box() {
+ "unboxing the value"
+ } else if checked_ty.is_region_ptr() {
+ "dereferencing the borrow"
+ } else {
+ "dereferencing the type"
+ };
+
+ // Suggest removing `&` if we have removed any, otherwise suggest just
+ // dereferencing the remaining number of steps.
+ let message = if remove.is_empty() {
+ format!("consider {deref_kind}")
+ } else {
+ format!(
+ "consider removing the `{}` and {} instead",
+ remove.trim(),
+ deref_kind
+ )
+ };
+
+ let prefix = match self.maybe_get_struct_pattern_shorthand_field(expr) {
+ Some(ident) => format!("{ident}: "),
+ None => String::new(),
+ };
+
+ let (span, suggestion) = if self.is_else_if_block(expr) {
+ // Don't suggest nonsense like `else *if`
+ return None;
+ } else if let Some(expr) = self.maybe_get_block_expr(expr) {
+ // prefix should be empty here..
+ (expr.span.shrink_to_lo(), "*".to_string())
+ } else {
+ (prefix_span, format!("{}{}", prefix, "*".repeat(steps)))
+ };
+
+ return Some((
+ span,
+ message,
+ suggestion,
+ Applicability::MachineApplicable,
+ true,
+ ));
+ }
+ }
+ }
+ _ => {}
+ }
+ None
+ }
+
+ pub fn check_for_cast(
+ &self,
+ err: &mut Diagnostic,
+ expr: &hir::Expr<'_>,
+ checked_ty: Ty<'tcx>,
+ expected_ty: Ty<'tcx>,
+ expected_ty_expr: Option<&'tcx hir::Expr<'tcx>>,
+ ) -> bool {
+ if self.tcx.sess.source_map().is_imported(expr.span) {
+ // Ignore if span is from within a macro.
+ return false;
+ }
+
+ let Ok(src) = self.tcx.sess.source_map().span_to_snippet(expr.span) else {
+ return false;
+ };
+
+ // If casting this expression to a given numeric type would be appropriate in case of a type
+ // mismatch.
+ //
+ // We want to minimize the amount of casting operations that are suggested, as it can be a
+ // lossy operation with potentially bad side effects, so we only suggest when encountering
+ // an expression that indicates that the original type couldn't be directly changed.
+ //
+ // For now, don't suggest casting with `as`.
+ let can_cast = false;
+
+ let mut sugg = vec![];
+
+ if let Some(hir::Node::Expr(hir::Expr {
+ kind: hir::ExprKind::Struct(_, fields, _), ..
+ })) = self.tcx.hir().find(self.tcx.hir().get_parent_node(expr.hir_id))
+ {
+ // `expr` is a literal field for a struct, only suggest if appropriate
+ match (*fields)
+ .iter()
+ .find(|field| field.expr.hir_id == expr.hir_id && field.is_shorthand)
+ {
+ // This is a field literal
+ Some(field) => {
+ sugg.push((field.ident.span.shrink_to_lo(), format!("{}: ", field.ident)));
+ }
+ // Likely a field was meant, but this field wasn't found. Do not suggest anything.
+ None => return false,
+ }
+ };
+
+ if let hir::ExprKind::Call(path, args) = &expr.kind
+ && let (hir::ExprKind::Path(hir::QPath::TypeRelative(base_ty, path_segment)), 1) =
+ (&path.kind, args.len())
+ // `expr` is a conversion like `u32::from(val)`, do not suggest anything (#63697).
+ && let (hir::TyKind::Path(hir::QPath::Resolved(None, base_ty_path)), sym::from) =
+ (&base_ty.kind, path_segment.ident.name)
+ {
+ if let Some(ident) = &base_ty_path.segments.iter().map(|s| s.ident).next() {
+ match ident.name {
+ sym::i128
+ | sym::i64
+ | sym::i32
+ | sym::i16
+ | sym::i8
+ | sym::u128
+ | sym::u64
+ | sym::u32
+ | sym::u16
+ | sym::u8
+ | sym::isize
+ | sym::usize
+ if base_ty_path.segments.len() == 1 =>
+ {
+ return false;
+ }
+ _ => {}
+ }
+ }
+ }
+
+ let msg = format!(
+ "you can convert {} `{}` to {} `{}`",
+ checked_ty.kind().article(),
+ checked_ty,
+ expected_ty.kind().article(),
+ expected_ty,
+ );
+ let cast_msg = format!(
+ "you can cast {} `{}` to {} `{}`",
+ checked_ty.kind().article(),
+ checked_ty,
+ expected_ty.kind().article(),
+ expected_ty,
+ );
+ let lit_msg = format!(
+ "change the type of the numeric literal from `{checked_ty}` to `{expected_ty}`",
+ );
+
+ let close_paren = if expr.precedence().order() < PREC_POSTFIX {
+ sugg.push((expr.span.shrink_to_lo(), "(".to_string()));
+ ")"
+ } else {
+ ""
+ };
+
+ let mut cast_suggestion = sugg.clone();
+ cast_suggestion.push((expr.span.shrink_to_hi(), format!("{close_paren} as {expected_ty}")));
+ let mut into_suggestion = sugg.clone();
+ into_suggestion.push((expr.span.shrink_to_hi(), format!("{close_paren}.into()")));
+ let mut suffix_suggestion = sugg.clone();
+ suffix_suggestion.push((
+ if matches!(
+ (&expected_ty.kind(), &checked_ty.kind()),
+ (ty::Int(_) | ty::Uint(_), ty::Float(_))
+ ) {
+ // Remove fractional part from literal, for example `42.0f32` into `42`
+ let src = src.trim_end_matches(&checked_ty.to_string());
+ let len = src.split('.').next().unwrap().len();
+ expr.span.with_lo(expr.span.lo() + BytePos(len as u32))
+ } else {
+ let len = src.trim_end_matches(&checked_ty.to_string()).len();
+ expr.span.with_lo(expr.span.lo() + BytePos(len as u32))
+ },
+ if expr.precedence().order() < PREC_POSTFIX {
+ // Readd `)`
+ format!("{expected_ty})")
+ } else {
+ expected_ty.to_string()
+ },
+ ));
+ let literal_is_ty_suffixed = |expr: &hir::Expr<'_>| {
+ if let hir::ExprKind::Lit(lit) = &expr.kind { lit.node.is_suffixed() } else { false }
+ };
+ let is_negative_int =
+ |expr: &hir::Expr<'_>| matches!(expr.kind, hir::ExprKind::Unary(hir::UnOp::Neg, ..));
+ let is_uint = |ty: Ty<'_>| matches!(ty.kind(), ty::Uint(..));
+
+ let in_const_context = self.tcx.hir().is_inside_const_context(expr.hir_id);
+
+ let suggest_fallible_into_or_lhs_from =
+ |err: &mut Diagnostic, exp_to_found_is_fallible: bool| {
+ // If we know the expression the expected type is derived from, we might be able
+ // to suggest a widening conversion rather than a narrowing one (which may
+ // panic). For example, given x: u8 and y: u32, if we know the span of "x",
+ // x > y
+ // can be given the suggestion "u32::from(x) > y" rather than
+ // "x > y.try_into().unwrap()".
+ let lhs_expr_and_src = expected_ty_expr.and_then(|expr| {
+ self.tcx
+ .sess
+ .source_map()
+ .span_to_snippet(expr.span)
+ .ok()
+ .map(|src| (expr, src))
+ });
+ let (msg, suggestion) = if let (Some((lhs_expr, lhs_src)), false) =
+ (lhs_expr_and_src, exp_to_found_is_fallible)
+ {
+ let msg = format!(
+ "you can convert `{lhs_src}` from `{expected_ty}` to `{checked_ty}`, matching the type of `{src}`",
+ );
+ let suggestion = vec![
+ (lhs_expr.span.shrink_to_lo(), format!("{checked_ty}::from(")),
+ (lhs_expr.span.shrink_to_hi(), ")".to_string()),
+ ];
+ (msg, suggestion)
+ } else {
+ let msg = format!("{msg} and panic if the converted value doesn't fit");
+ let mut suggestion = sugg.clone();
+ suggestion.push((
+ expr.span.shrink_to_hi(),
+ format!("{close_paren}.try_into().unwrap()"),
+ ));
+ (msg, suggestion)
+ };
+ err.multipart_suggestion_verbose(
+ &msg,
+ suggestion,
+ Applicability::MachineApplicable,
+ );
+ };
+
+ let suggest_to_change_suffix_or_into =
+ |err: &mut Diagnostic,
+ found_to_exp_is_fallible: bool,
+ exp_to_found_is_fallible: bool| {
+ let exp_is_lhs =
+ expected_ty_expr.map(|e| self.tcx.hir().is_lhs(e.hir_id)).unwrap_or(false);
+
+ if exp_is_lhs {
+ return;
+ }
+
+ let always_fallible = found_to_exp_is_fallible
+ && (exp_to_found_is_fallible || expected_ty_expr.is_none());
+ let msg = if literal_is_ty_suffixed(expr) {
+ &lit_msg
+ } else if always_fallible && (is_negative_int(expr) && is_uint(expected_ty)) {
+ // We now know that converting either the lhs or rhs is fallible. Before we
+ // suggest a fallible conversion, check if the value can never fit in the
+ // expected type.
+ let msg = format!("`{src}` cannot fit into type `{expected_ty}`");
+ err.note(&msg);
+ return;
+ } else if in_const_context {
+ // Do not recommend `into` or `try_into` in const contexts.
+ return;
+ } else if found_to_exp_is_fallible {
+ return suggest_fallible_into_or_lhs_from(err, exp_to_found_is_fallible);
+ } else {
+ &msg
+ };
+ let suggestion = if literal_is_ty_suffixed(expr) {
+ suffix_suggestion.clone()
+ } else {
+ into_suggestion.clone()
+ };
+ err.multipart_suggestion_verbose(msg, suggestion, Applicability::MachineApplicable);
+ };
+
+ match (&expected_ty.kind(), &checked_ty.kind()) {
+ (&ty::Int(ref exp), &ty::Int(ref found)) => {
+ let (f2e_is_fallible, e2f_is_fallible) = match (exp.bit_width(), found.bit_width())
+ {
+ (Some(exp), Some(found)) if exp < found => (true, false),
+ (Some(exp), Some(found)) if exp > found => (false, true),
+ (None, Some(8 | 16)) => (false, true),
+ (Some(8 | 16), None) => (true, false),
+ (None, _) | (_, None) => (true, true),
+ _ => (false, false),
+ };
+ suggest_to_change_suffix_or_into(err, f2e_is_fallible, e2f_is_fallible);
+ true
+ }
+ (&ty::Uint(ref exp), &ty::Uint(ref found)) => {
+ let (f2e_is_fallible, e2f_is_fallible) = match (exp.bit_width(), found.bit_width())
+ {
+ (Some(exp), Some(found)) if exp < found => (true, false),
+ (Some(exp), Some(found)) if exp > found => (false, true),
+ (None, Some(8 | 16)) => (false, true),
+ (Some(8 | 16), None) => (true, false),
+ (None, _) | (_, None) => (true, true),
+ _ => (false, false),
+ };
+ suggest_to_change_suffix_or_into(err, f2e_is_fallible, e2f_is_fallible);
+ true
+ }
+ (&ty::Int(exp), &ty::Uint(found)) => {
+ let (f2e_is_fallible, e2f_is_fallible) = match (exp.bit_width(), found.bit_width())
+ {
+ (Some(exp), Some(found)) if found < exp => (false, true),
+ (None, Some(8)) => (false, true),
+ _ => (true, true),
+ };
+ suggest_to_change_suffix_or_into(err, f2e_is_fallible, e2f_is_fallible);
+ true
+ }
+ (&ty::Uint(exp), &ty::Int(found)) => {
+ let (f2e_is_fallible, e2f_is_fallible) = match (exp.bit_width(), found.bit_width())
+ {
+ (Some(exp), Some(found)) if found > exp => (true, false),
+ (Some(8), None) => (true, false),
+ _ => (true, true),
+ };
+ suggest_to_change_suffix_or_into(err, f2e_is_fallible, e2f_is_fallible);
+ true
+ }
+ (&ty::Float(ref exp), &ty::Float(ref found)) => {
+ if found.bit_width() < exp.bit_width() {
+ suggest_to_change_suffix_or_into(err, false, true);
+ } else if literal_is_ty_suffixed(expr) {
+ err.multipart_suggestion_verbose(
+ &lit_msg,
+ suffix_suggestion,
+ Applicability::MachineApplicable,
+ );
+ } else if can_cast {
+ // Missing try_into implementation for `f64` to `f32`
+ err.multipart_suggestion_verbose(
+ &format!("{cast_msg}, producing the closest possible value"),
+ cast_suggestion,
+ Applicability::MaybeIncorrect, // lossy conversion
+ );
+ }
+ true
+ }
+ (&ty::Uint(_) | &ty::Int(_), &ty::Float(_)) => {
+ if literal_is_ty_suffixed(expr) {
+ err.multipart_suggestion_verbose(
+ &lit_msg,
+ suffix_suggestion,
+ Applicability::MachineApplicable,
+ );
+ } else if can_cast {
+ // Missing try_into implementation for `{float}` to `{integer}`
+ err.multipart_suggestion_verbose(
+ &format!("{msg}, rounding the float towards zero"),
+ cast_suggestion,
+ Applicability::MaybeIncorrect, // lossy conversion
+ );
+ }
+ true
+ }
+ (&ty::Float(ref exp), &ty::Uint(ref found)) => {
+ // if `found` is `None` (meaning found is `usize`), don't suggest `.into()`
+ if exp.bit_width() > found.bit_width().unwrap_or(256) {
+ err.multipart_suggestion_verbose(
+ &format!(
+ "{msg}, producing the floating point representation of the integer",
+ ),
+ into_suggestion,
+ Applicability::MachineApplicable,
+ );
+ } else if literal_is_ty_suffixed(expr) {
+ err.multipart_suggestion_verbose(
+ &lit_msg,
+ suffix_suggestion,
+ Applicability::MachineApplicable,
+ );
+ } else {
+ // Missing try_into implementation for `{integer}` to `{float}`
+ err.multipart_suggestion_verbose(
+ &format!(
+ "{cast_msg}, producing the floating point representation of the integer, \
+ rounded if necessary",
+ ),
+ cast_suggestion,
+ Applicability::MaybeIncorrect, // lossy conversion
+ );
+ }
+ true
+ }
+ (&ty::Float(ref exp), &ty::Int(ref found)) => {
+ // if `found` is `None` (meaning found is `isize`), don't suggest `.into()`
+ if exp.bit_width() > found.bit_width().unwrap_or(256) {
+ err.multipart_suggestion_verbose(
+ &format!(
+ "{}, producing the floating point representation of the integer",
+ &msg,
+ ),
+ into_suggestion,
+ Applicability::MachineApplicable,
+ );
+ } else if literal_is_ty_suffixed(expr) {
+ err.multipart_suggestion_verbose(
+ &lit_msg,
+ suffix_suggestion,
+ Applicability::MachineApplicable,
+ );
+ } else {
+ // Missing try_into implementation for `{integer}` to `{float}`
+ err.multipart_suggestion_verbose(
+ &format!(
+ "{}, producing the floating point representation of the integer, \
+ rounded if necessary",
+ &msg,
+ ),
+ cast_suggestion,
+ Applicability::MaybeIncorrect, // lossy conversion
+ );
+ }
+ true
+ }
+ (
+ &ty::Uint(ty::UintTy::U32 | ty::UintTy::U64 | ty::UintTy::U128)
+ | &ty::Int(ty::IntTy::I32 | ty::IntTy::I64 | ty::IntTy::I128),
+ &ty::Char,
+ ) => {
+ err.multipart_suggestion_verbose(
+ &format!("{cast_msg}, since a `char` always occupies 4 bytes"),
+ cast_suggestion,
+ Applicability::MachineApplicable,
+ );
+ true
+ }
+ _ => false,
+ }
+ }
+
+ // Report the type inferred by the return statement.
+ fn report_closure_inferred_return_type(&self, err: &mut Diagnostic, expected: Ty<'tcx>) {
+ if let Some(sp) = self.ret_coercion_span.get()
+ // If the closure has an explicit return type annotation, or if
+ // the closure's return type has been inferred from outside
+ // requirements (such as an Fn* trait bound), then a type error
+ // may occur at the first return expression we see in the closure
+ // (if it conflicts with the declared return type). Skip adding a
+ // note in this case, since it would be incorrect.
+ && !self.return_type_pre_known
+ {
+ err.span_note(
+ sp,
+ &format!(
+ "return type inferred to be `{}` here",
+ self.resolve_vars_if_possible(expected)
+ ),
+ );
+ }
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-11 22:15:48 +0000