Merging upstream version 1.75.0+dfsg1.

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

1 files changed, 120 insertions, 39 deletions

diff --git a/compiler/rustc_ast_lowering/src/expr.rs b/compiler/rustc_ast_lowering/src/expr.rs
index 57c54f854..0fff9a6be 100644
--- a/compiler/rustc_ast_lowering/src/expr.rs
+++ b/compiler/rustc_ast_lowering/src/expr.rs
@@ -1,8 +1,8 @@
 use super::errors::{
-    AsyncGeneratorsNotSupported, AsyncNonMoveClosureNotSupported, AwaitOnlyInAsyncFnAndBlocks,
-    BaseExpressionDoubleDot, ClosureCannotBeStatic, FunctionalRecordUpdateDestructuringAssignment,
-    GeneratorTooManyParameters, InclusiveRangeWithNoEnd, NotSupportedForLifetimeBinderAsyncClosure,
-    UnderscoreExprLhsAssign,
+    AsyncCoroutinesNotSupported, AsyncNonMoveClosureNotSupported, AwaitOnlyInAsyncFnAndBlocks,
+    BaseExpressionDoubleDot, ClosureCannotBeStatic, CoroutineTooManyParameters,
+    FunctionalRecordUpdateDestructuringAssignment, InclusiveRangeWithNoEnd,
+    NotSupportedForLifetimeBinderAsyncClosure, UnderscoreExprLhsAssign,
 };
 use super::ResolverAstLoweringExt;
 use super::{ImplTraitContext, LoweringContext, ParamMode, ParenthesizedGenericArgs};
@@ -15,9 +15,10 @@ use rustc_hir as hir;
 use rustc_hir::def::Res;
 use rustc_hir::definitions::DefPathData;
 use rustc_session::errors::report_lit_error;
-use rustc_span::source_map::{respan, DesugaringKind, Span, Spanned};
+use rustc_span::source_map::{respan, Spanned};
 use rustc_span::symbol::{sym, Ident, Symbol};
 use rustc_span::DUMMY_SP;
+use rustc_span::{DesugaringKind, Span};
 use thin_vec::{thin_vec, ThinVec};
 
 impl<'hir> LoweringContext<'_, 'hir> {
@@ -183,12 +184,12 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     self.arena.alloc_from_iter(arms.iter().map(|x| self.lower_arm(x))),
                     hir::MatchSource::Normal,
                 ),
-                ExprKind::Async(capture_clause, block) => self.make_async_expr(
+                ExprKind::Gen(capture_clause, block, GenBlockKind::Async) => self.make_async_expr(
                     *capture_clause,
                     e.id,
                     None,
                     e.span,
-                    hir::AsyncGeneratorKind::Block,
+                    hir::CoroutineSource::Block,
                     |this| this.with_new_scopes(|this| this.lower_block_expr(block)),
                 ),
                 ExprKind::Await(expr, await_kw_span) => self.lower_expr_await(*await_kw_span, expr),
@@ -317,6 +318,14 @@ impl<'hir> LoweringContext<'_, 'hir> {
                         rest,
                     )
                 }
+                ExprKind::Gen(capture_clause, block, GenBlockKind::Gen) => self.make_gen_expr(
+                    *capture_clause,
+                    e.id,
+                    None,
+                    e.span,
+                    hir::CoroutineSource::Block,
+                    |this| this.with_new_scopes(|this| this.lower_block_expr(block)),
+                ),
                 ExprKind::Yield(opt_expr) => self.lower_expr_yield(e.span, opt_expr.as_deref()),
                 ExprKind::Err => hir::ExprKind::Err(
                     self.tcx.sess.delay_span_bug(e.span, "lowered ExprKind::Err"),
@@ -583,7 +592,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         }
     }
 
-    /// Lower an `async` construct to a generator that implements `Future`.
+    /// Lower an `async` construct to a coroutine that implements `Future`.
     ///
     /// This results in:
     ///
@@ -598,7 +607,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         closure_node_id: NodeId,
         ret_ty: Option<hir::FnRetTy<'hir>>,
         span: Span,
-        async_gen_kind: hir::AsyncGeneratorKind,
+        async_coroutine_source: hir::CoroutineSource,
         body: impl FnOnce(&mut Self) -> hir::Expr<'hir>,
     ) -> hir::ExprKind<'hir> {
         let output = ret_ty.unwrap_or_else(|| hir::FnRetTy::DefaultReturn(self.lower_span(span)));
@@ -613,7 +622,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             span: unstable_span,
         };
 
-        // The closure/generator `FnDecl` takes a single (resume) argument of type `input_ty`.
+        // The closure/coroutine `FnDecl` takes a single (resume) argument of type `input_ty`.
         let fn_decl = self.arena.alloc(hir::FnDecl {
             inputs: arena_vec![self; input_ty],
             output,
@@ -637,7 +646,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         let params = arena_vec![self; param];
 
         let body = self.lower_body(move |this| {
-            this.generator_kind = Some(hir::GeneratorKind::Async(async_gen_kind));
+            this.coroutine_kind = Some(hir::CoroutineKind::Async(async_coroutine_source));
 
             let old_ctx = this.task_context;
             this.task_context = Some(task_context_hid);
@@ -661,6 +670,57 @@ impl<'hir> LoweringContext<'_, 'hir> {
         }))
     }
 
+    /// Lower a `gen` construct to a generator that implements `Iterator`.
+    ///
+    /// This results in:
+    ///
+    /// ```text
+    /// static move? |()| -> () {
+    ///     <body>
+    /// }
+    /// ```
+    pub(super) fn make_gen_expr(
+        &mut self,
+        capture_clause: CaptureBy,
+        closure_node_id: NodeId,
+        _yield_ty: Option<hir::FnRetTy<'hir>>,
+        span: Span,
+        coroutine_source: hir::CoroutineSource,
+        body: impl FnOnce(&mut Self) -> hir::Expr<'hir>,
+    ) -> hir::ExprKind<'hir> {
+        let output = hir::FnRetTy::DefaultReturn(self.lower_span(span));
+
+        // The closure/generator `FnDecl` takes a single (resume) argument of type `input_ty`.
+        let fn_decl = self.arena.alloc(hir::FnDecl {
+            inputs: &[],
+            output,
+            c_variadic: false,
+            implicit_self: hir::ImplicitSelfKind::None,
+            lifetime_elision_allowed: false,
+        });
+
+        let body = self.lower_body(move |this| {
+            this.coroutine_kind = Some(hir::CoroutineKind::Gen(coroutine_source));
+
+            let res = body(this);
+            (&[], res)
+        });
+
+        // `static |()| -> () { body }`:
+        hir::ExprKind::Closure(self.arena.alloc(hir::Closure {
+            def_id: self.local_def_id(closure_node_id),
+            binder: hir::ClosureBinder::Default,
+            capture_clause,
+            bound_generic_params: &[],
+            fn_decl,
+            body,
+            fn_decl_span: self.lower_span(span),
+            fn_arg_span: None,
+            movability: Some(Movability::Movable),
+            constness: hir::Constness::NotConst,
+        }))
+    }
+
     /// Forwards a possible `#[track_caller]` annotation from `outer_hir_id` to
     /// `inner_hir_id` in case the `async_fn_track_caller` feature is enabled.
     pub(super) fn maybe_forward_track_caller(
@@ -673,12 +733,18 @@ impl<'hir> LoweringContext<'_, 'hir> {
             && let Some(attrs) = self.attrs.get(&outer_hir_id.local_id)
             && attrs.into_iter().any(|attr| attr.has_name(sym::track_caller))
         {
-            let unstable_span =
-                self.mark_span_with_reason(DesugaringKind::Async, span, self.allow_gen_future.clone());
+            let unstable_span = self.mark_span_with_reason(
+                DesugaringKind::Async,
+                span,
+                self.allow_gen_future.clone(),
+            );
             self.lower_attrs(
                 inner_hir_id,
                 &[Attribute {
-                    kind: AttrKind::Normal(ptr::P(NormalAttr::from_ident(Ident::new(sym::track_caller, span)))),
+                    kind: AttrKind::Normal(ptr::P(NormalAttr::from_ident(Ident::new(
+                        sym::track_caller,
+                        span,
+                    )))),
                     id: self.tcx.sess.parse_sess.attr_id_generator.mk_attr_id(),
                     style: AttrStyle::Outer,
                     span: unstable_span,
@@ -704,9 +770,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
     /// ```
     fn lower_expr_await(&mut self, await_kw_span: Span, expr: &Expr) -> hir::ExprKind<'hir> {
         let full_span = expr.span.to(await_kw_span);
-        match self.generator_kind {
-            Some(hir::GeneratorKind::Async(_)) => {}
-            Some(hir::GeneratorKind::Gen) | None => {
+        match self.coroutine_kind {
+            Some(hir::CoroutineKind::Async(_)) => {}
+            Some(hir::CoroutineKind::Coroutine) | Some(hir::CoroutineKind::Gen(_)) | None => {
                 self.tcx.sess.emit_err(AwaitOnlyInAsyncFnAndBlocks {
                     await_kw_span,
                     item_span: self.current_item,
@@ -881,19 +947,19 @@ impl<'hir> LoweringContext<'_, 'hir> {
     ) -> hir::ExprKind<'hir> {
         let (binder_clause, generic_params) = self.lower_closure_binder(binder);
 
-        let (body_id, generator_option) = self.with_new_scopes(move |this| {
+        let (body_id, coroutine_option) = self.with_new_scopes(move |this| {
             let prev = this.current_item;
             this.current_item = Some(fn_decl_span);
-            let mut generator_kind = None;
+            let mut coroutine_kind = None;
             let body_id = this.lower_fn_body(decl, |this| {
                 let e = this.lower_expr_mut(body);
-                generator_kind = this.generator_kind;
+                coroutine_kind = this.coroutine_kind;
                 e
             });
-            let generator_option =
-                this.generator_movability_for_fn(&decl, fn_decl_span, generator_kind, movability);
+            let coroutine_option =
+                this.coroutine_movability_for_fn(&decl, fn_decl_span, coroutine_kind, movability);
             this.current_item = prev;
-            (body_id, generator_option)
+            (body_id, coroutine_option)
         });
 
         let bound_generic_params = self.lower_lifetime_binder(closure_id, generic_params);
@@ -909,29 +975,29 @@ impl<'hir> LoweringContext<'_, 'hir> {
             body: body_id,
             fn_decl_span: self.lower_span(fn_decl_span),
             fn_arg_span: Some(self.lower_span(fn_arg_span)),
-            movability: generator_option,
+            movability: coroutine_option,
             constness: self.lower_constness(constness),
         });
 
         hir::ExprKind::Closure(c)
     }
 
-    fn generator_movability_for_fn(
+    fn coroutine_movability_for_fn(
         &mut self,
         decl: &FnDecl,
         fn_decl_span: Span,
-        generator_kind: Option<hir::GeneratorKind>,
+        coroutine_kind: Option<hir::CoroutineKind>,
         movability: Movability,
     ) -> Option<hir::Movability> {
-        match generator_kind {
-            Some(hir::GeneratorKind::Gen) => {
+        match coroutine_kind {
+            Some(hir::CoroutineKind::Coroutine) => {
                 if decl.inputs.len() > 1 {
-                    self.tcx.sess.emit_err(GeneratorTooManyParameters { fn_decl_span });
+                    self.tcx.sess.emit_err(CoroutineTooManyParameters { fn_decl_span });
                 }
                 Some(movability)
             }
-            Some(hir::GeneratorKind::Async(_)) => {
-                panic!("non-`async` closure body turned `async` during lowering");
+            Some(hir::CoroutineKind::Gen(_)) | Some(hir::CoroutineKind::Async(_)) => {
+                panic!("non-`async`/`gen` closure body turned `async`/`gen` during lowering");
             }
             None => {
                 if movability == Movability::Static {
@@ -999,7 +1065,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     inner_closure_id,
                     async_ret_ty,
                     body.span,
-                    hir::AsyncGeneratorKind::Closure,
+                    hir::CoroutineSource::Closure,
                     |this| this.with_new_scopes(|this| this.lower_expr_mut(body)),
                 );
                 let hir_id = this.lower_node_id(inner_closure_id);
@@ -1102,7 +1168,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
         if let ExprKind::Path(qself, path) = &expr.kind {
             // Does the path resolve to something disallowed in a tuple struct/variant pattern?
             if let Some(partial_res) = self.resolver.get_partial_res(expr.id) {
-                if let Some(res) = partial_res.full_res() && !res.expected_in_tuple_struct_pat() {
+                if let Some(res) = partial_res.full_res()
+                    && !res.expected_in_tuple_struct_pat()
+                {
                     return None;
                 }
             }
@@ -1122,7 +1190,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
         if let ExprKind::Path(qself, path) = &expr.kind {
             // Does the path resolve to something disallowed in a unit struct/variant pattern?
             if let Some(partial_res) = self.resolver.get_partial_res(expr.id) {
-                if let Some(res) = partial_res.full_res() && !res.expected_in_unit_struct_pat() {
+                if let Some(res) = partial_res.full_res()
+                    && !res.expected_in_unit_struct_pat()
+                {
                     return None;
                 }
             }
@@ -1434,12 +1504,23 @@ impl<'hir> LoweringContext<'_, 'hir> {
     }
 
     fn lower_expr_yield(&mut self, span: Span, opt_expr: Option<&Expr>) -> hir::ExprKind<'hir> {
-        match self.generator_kind {
-            Some(hir::GeneratorKind::Gen) => {}
-            Some(hir::GeneratorKind::Async(_)) => {
-                self.tcx.sess.emit_err(AsyncGeneratorsNotSupported { span });
+        match self.coroutine_kind {
+            Some(hir::CoroutineKind::Gen(_)) => {}
+            Some(hir::CoroutineKind::Async(_)) => {
+                self.tcx.sess.emit_err(AsyncCoroutinesNotSupported { span });
+            }
+            Some(hir::CoroutineKind::Coroutine) | None => {
+                if !self.tcx.features().coroutines {
+                    rustc_session::parse::feature_err(
+                        &self.tcx.sess.parse_sess,
+                        sym::coroutines,
+                        span,
+                        "yield syntax is experimental",
+                    )
+                    .emit();
+                }
+                self.coroutine_kind = Some(hir::CoroutineKind::Coroutine)
             }
-            None => self.generator_kind = Some(hir::GeneratorKind::Gen),
         }
 
         let expr =