Error on using yield without also using gen on the closure

And suggest adding the `gen` to the closure or function
rust-lang · Apr 11, 2024 · f0906f5 · f0906f5
1 parent e8a6ccc
commit f0906f5
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Showing 19 changed files with 217 additions and 62 deletions.
diff --git a/compiler/rustc_ast_lowering/messages.ftl b/compiler/rustc_ast_lowering/messages.ftl
@@ -161,3 +161,6 @@ ast_lowering_underscore_expr_lhs_assign =
     .label = `_` not allowed here
 
 ast_lowering_use_angle_brackets = use angle brackets instead
+ast_lowering_yield_in_closure =
+    `yield` can only be used in `gen` closures or blocks
+    .suggestion = use `gen` to make the closure a coroutine
diff --git a/compiler/rustc_ast_lowering/src/errors.rs b/compiler/rustc_ast_lowering/src/errors.rs
@@ -414,3 +414,12 @@ pub(crate) struct AsyncBoundOnlyForFnTraits {
     #[primary_span]
     pub span: Span,
 }
+
+#[derive(Diagnostic)]
+#[diag(ast_lowering_yield_in_closure)]
+pub(crate) struct YieldInClosure {
+    #[primary_span]
+    pub span: Span,
+    #[suggestion(code = "gen ", applicability = "maybe-incorrect", style = "verbose")]
+    pub suggestion: Option<Span>,
+}
diff --git a/compiler/rustc_ast_lowering/src/expr.rs b/compiler/rustc_ast_lowering/src/expr.rs
@@ -8,6 +8,7 @@ use super::errors::{
 };
 use super::ResolverAstLoweringExt;
 use super::{ImplTraitContext, LoweringContext, ParamMode, ParenthesizedGenericArgs};
+use crate::errors::YieldInClosure;
 use crate::{FnDeclKind, ImplTraitPosition};
 use rustc_ast::ptr::P as AstP;
 use rustc_ast::*;
@@ -1578,7 +1579,12 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     )
                     .emit();
                 }
+                if self.tcx.sess.edition().at_least_rust_2024() {
+                    let suggestion = self.current_item.map(|s| s.shrink_to_lo());
+                    self.dcx().emit_err(YieldInClosure { span, suggestion });
+                }
                 self.coroutine_kind = Some(hir::CoroutineKind::Coroutine(Movability::Movable));
+
                 false
             }
         };

diff --git a/compiler/rustc_ast_lowering/src/item.rs b/compiler/rustc_ast_lowering/src/item.rs
@@ -203,7 +203,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 body,
                 ..
             }) => {
-                self.with_new_scopes(ident.span, |this| {
+                self.with_new_scopes(span, |this| {
                     // Note: we don't need to change the return type from `T` to
                     // `impl Future<Output = T>` here because lower_body
                     // only cares about the input argument patterns in the function

diff --git a/tests/ui/async-await/async-outside-of-await-issue-121096.stderr b/tests/ui/async-await/async-outside-of-await-issue-121096.stderr
@@ -1,11 +1,15 @@
 error[E0728]: `await` is only allowed inside `async` functions and blocks
   --> $DIR/async-outside-of-await-issue-121096.rs:7:7
    |
-LL | fn main() {
-   |    ---- this is not `async`
-...
-LL |     }.await
-   |       ^^^^^ only allowed inside `async` functions and blocks
+LL | / fn main() {
+LL | |     async {
+LL | |         use std::ops::Add;
+LL | |         let _ = 1.add(3);
+LL | |     }.await
+   | |       ^^^^^ only allowed inside `async` functions and blocks
+LL | |
+LL | | }
+   | |_- this is not `async`
 
 error: aborting due to 1 previous error
 

diff --git a/tests/ui/async-await/await-keyword/incorrect-syntax-suggestions.stderr b/tests/ui/async-await/await-keyword/incorrect-syntax-suggestions.stderr
@@ -140,42 +140,54 @@ LL | }
 error[E0728]: `await` is only allowed inside `async` functions and blocks
   --> $DIR/incorrect-syntax-suggestions.rs:68:19
    |
-LL | fn foo13() -> Result<(), ()> {
-   |    ----- this is not `async`
-LL |     let _ = bar().await();
-   |                   ^^^^^ only allowed inside `async` functions and blocks
+LL | / fn foo13() -> Result<(), ()> {
+LL | |     let _ = bar().await();
+   | |                   ^^^^^ only allowed inside `async` functions and blocks
+LL | |
+LL | |     Ok(())
+LL | | }
+   | |_- this is not `async`
 
 error[E0728]: `await` is only allowed inside `async` functions and blocks
   --> $DIR/incorrect-syntax-suggestions.rs:73:19
    |
-LL | fn foo14() -> Result<(), ()> {
-   |    ----- this is not `async`
-LL |     let _ = bar().await()?;
-   |                   ^^^^^ only allowed inside `async` functions and blocks
+LL | / fn foo14() -> Result<(), ()> {
+LL | |     let _ = bar().await()?;
+   | |                   ^^^^^ only allowed inside `async` functions and blocks
+LL | |
+LL | |     Ok(())
+LL | | }
+   | |_- this is not `async`
 
 error[E0728]: `await` is only allowed inside `async` functions and blocks
   --> $DIR/incorrect-syntax-suggestions.rs:78:19
    |
-LL | fn foo15() -> Result<(), ()> {
-   |    ----- this is not `async`
-LL |     let _ = bar().await;
-   |                   ^^^^^ only allowed inside `async` functions and blocks
+LL | / fn foo15() -> Result<(), ()> {
+LL | |     let _ = bar().await;
+   | |                   ^^^^^ only allowed inside `async` functions and blocks
+LL | |     Ok(())
+LL | | }
+   | |_- this is not `async`
 
 error[E0728]: `await` is only allowed inside `async` functions and blocks
   --> $DIR/incorrect-syntax-suggestions.rs:82:19
    |
-LL | fn foo16() -> Result<(), ()> {
-   |    ----- this is not `async`
-LL |     let _ = bar().await?;
-   |                   ^^^^^ only allowed inside `async` functions and blocks
+LL | / fn foo16() -> Result<(), ()> {
+LL | |     let _ = bar().await?;
+   | |                   ^^^^^ only allowed inside `async` functions and blocks
+LL | |     Ok(())
+LL | | }
+   | |_- this is not `async`
 
 error[E0728]: `await` is only allowed inside `async` functions and blocks
   --> $DIR/incorrect-syntax-suggestions.rs:87:23
    |
-LL |     fn foo() -> Result<(), ()> {
-   |        --- this is not `async`
-LL |         let _ = bar().await?;
-   |                       ^^^^^ only allowed inside `async` functions and blocks
+LL | /     fn foo() -> Result<(), ()> {
+LL | |         let _ = bar().await?;
+   | |                       ^^^^^ only allowed inside `async` functions and blocks
+LL | |         Ok(())
+LL | |     }
+   | |_____- this is not `async`
 
 error[E0728]: `await` is only allowed inside `async` functions and blocks
   --> $DIR/incorrect-syntax-suggestions.rs:94:23

diff --git a/tests/ui/async-await/issues/issue-51751.stderr b/tests/ui/async-await/issues/issue-51751.stderr
@@ -1,11 +1,13 @@
 error[E0728]: `await` is only allowed inside `async` functions and blocks
   --> $DIR/issue-51751.rs:9:27
    |
-LL | fn main() {
-   |    ---- this is not `async`
-LL |     let result = inc(10000);
-LL |     let finished = result.await;
-   |                           ^^^^^ only allowed inside `async` functions and blocks
+LL | / fn main() {
+LL | |     let result = inc(10000);
+LL | |     let finished = result.await;
+   | |                           ^^^^^ only allowed inside `async` functions and blocks
+LL | |
+LL | | }
+   | |_- this is not `async`
 
 error: aborting due to 1 previous error
 

diff --git a/tests/ui/async-await/issues/issue-62009-1.stderr b/tests/ui/async-await/issues/issue-62009-1.stderr
@@ -1,28 +1,44 @@
 error[E0728]: `await` is only allowed inside `async` functions and blocks
   --> $DIR/issue-62009-1.rs:6:23
    |
-LL | fn main() {
-   |    ---- this is not `async`
-LL |     async { let (); }.await;
-   |                       ^^^^^ only allowed inside `async` functions and blocks
+LL | / fn main() {
+LL | |     async { let (); }.await;
+   | |                       ^^^^^ only allowed inside `async` functions and blocks
+LL | |
+LL | |     async {
+...  |
+LL | |
+LL | | }
+   | |_- this is not `async`
 
 error[E0728]: `await` is only allowed inside `async` functions and blocks
   --> $DIR/issue-62009-1.rs:10:7
    |
-LL | fn main() {
-   |    ---- this is not `async`
-...
-LL |     }.await;
-   |       ^^^^^ only allowed inside `async` functions and blocks
+LL | / fn main() {
+LL | |     async { let (); }.await;
+LL | |
+LL | |     async {
+LL | |         let task1 = print_dur().await;
+LL | |     }.await;
+   | |       ^^^^^ only allowed inside `async` functions and blocks
+...  |
+LL | |
+LL | | }
+   | |_- this is not `async`
 
 error[E0728]: `await` is only allowed inside `async` functions and blocks
   --> $DIR/issue-62009-1.rs:12:16
    |
-LL | fn main() {
-   |    ---- this is not `async`
-...
-LL |     (|_| 2333).await;
-   |                ^^^^^ only allowed inside `async` functions and blocks
+LL | / fn main() {
+LL | |     async { let (); }.await;
+LL | |
+LL | |     async {
+...  |
+LL | |     (|_| 2333).await;
+   | |                ^^^^^ only allowed inside `async` functions and blocks
+LL | |
+LL | | }
+   | |_- this is not `async`
 
 error: aborting due to 3 previous errors
 

diff --git a/tests/ui/async-await/issues/issue-62009-2.stderr b/tests/ui/async-await/issues/issue-62009-2.stderr
@@ -1,10 +1,12 @@
 error[E0728]: `await` is only allowed inside `async` functions and blocks
   --> $DIR/issue-62009-2.rs:8:23
    |
-LL | fn main() {
-   |    ---- this is not `async`
-LL |     (async || 2333)().await;
-   |                       ^^^^^ only allowed inside `async` functions and blocks
+LL | / fn main() {
+LL | |     (async || 2333)().await;
+   | |                       ^^^^^ only allowed inside `async` functions and blocks
+LL | |
+LL | | }
+   | |_- this is not `async`
 
 error: aborting due to 1 previous error
 

diff --git a/tests/ui/async-await/issues/non-async-enclosing-span.stderr b/tests/ui/async-await/issues/non-async-enclosing-span.stderr
@@ -1,11 +1,13 @@
 error[E0728]: `await` is only allowed inside `async` functions and blocks
   --> $DIR/non-async-enclosing-span.rs:9:28
    |
-LL | fn main() {
-   |    ---- this is not `async`
-LL |     let x = move || {};
-LL |     let y = do_the_thing().await;
-   |                            ^^^^^ only allowed inside `async` functions and blocks
+LL | / fn main() {
+LL | |     let x = move || {};
+LL | |     let y = do_the_thing().await;
+   | |                            ^^^^^ only allowed inside `async` functions and blocks
+LL | |
+LL | | }
+   | |_- this is not `async`
 
 error: aborting due to 1 previous error
 

diff --git a/tests/ui/coroutine/gen_block.e2024.stderr b/tests/ui/coroutine/gen_block.e2024.stderr
@@ -8,13 +8,24 @@ LL |     let _ = || yield true;
    = help: add `#![feature(coroutines)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
+error: `yield` can only be used in `gen` closures or blocks
+  --> $DIR/gen_block.rs:15:16
+   |
+LL |     let _ = || yield true;
+   |                ^^^^^^^^^^
+   |
+help: use `gen` to make the closure a coroutine
+   |
+LL |     let _ = gen || yield true;
+   |             +++
+
 error[E0282]: type annotations needed
   --> $DIR/gen_block.rs:6:13
    |
 LL |     let x = gen {};
    |             ^^^^^^ cannot infer type
 
-error: aborting due to 2 previous errors
+error: aborting due to 3 previous errors
 
 Some errors have detailed explanations: E0282, E0658.
 For more information about an error, try `rustc --explain E0282`.
diff --git a/tests/ui/coroutine/gen_block.rs b/tests/ui/coroutine/gen_block.rs
@@ -14,4 +14,5 @@ fn main() {
 
     let _ = || yield true; //[none]~ ERROR yield syntax is experimental
     //~^ ERROR yield syntax is experimental
+    //[e2024]~^^ ERROR `yield` can only be used in `gen` closures or blocks
 }
diff --git a/tests/ui/coroutine/missing_gen_in_2024.fixed b/tests/ui/coroutine/missing_gen_in_2024.fixed
@@ -0,0 +1,16 @@
+//@ edition: 2024
+//@ compile-flags: -Zunstable-options
+//@ run-rustfix
+
+#![feature(coroutines, gen_blocks)]
+
+fn main() {
+    let _ = gen || yield;
+    //~^ ERROR `yield` can only be used in `gen` closures or blocks
+}
+
+gen fn _foo() {
+    yield;
+    //~^ ERROR `yield` can only be used in `gen` closures or blocks
+    //~| ERROR yield expression outside of coroutine literal
+}
diff --git a/tests/ui/coroutine/missing_gen_in_2024.rs b/tests/ui/coroutine/missing_gen_in_2024.rs
@@ -0,0 +1,16 @@
+//@ edition: 2024
+//@ compile-flags: -Zunstable-options
+//@ run-rustfix
+
+#![feature(coroutines, gen_blocks)]
+
+fn main() {
+    let _ = || yield;
+    //~^ ERROR `yield` can only be used in `gen` closures or blocks
+}
+
+fn _foo() {
+    yield;
+    //~^ ERROR `yield` can only be used in `gen` closures or blocks
+    //~| ERROR yield expression outside of coroutine literal
+}
diff --git a/tests/ui/coroutine/missing_gen_in_2024.stderr b/tests/ui/coroutine/missing_gen_in_2024.stderr
@@ -0,0 +1,31 @@
+error: `yield` can only be used in `gen` closures or blocks
+  --> $DIR/missing_gen_in_2024.rs:8:16
+   |
+LL |     let _ = || yield;
+   |                ^^^^^
+   |
+help: use `gen` to make the closure a coroutine
+   |
+LL |     let _ = gen || yield;
+   |             +++
+
+error: `yield` can only be used in `gen` closures or blocks
+  --> $DIR/missing_gen_in_2024.rs:13:5
+   |
+LL |     yield;
+   |     ^^^^^
+   |
+help: use `gen` to make the closure a coroutine
+   |
+LL | gen fn _foo() {
+   | +++
+
+error[E0627]: yield expression outside of coroutine literal
+  --> $DIR/missing_gen_in_2024.rs:13:5
+   |
+LL |     yield;
+   |     ^^^^^
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0627`.