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Error on using yield without also using #[coroutine] on the closure
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And suggest adding the `#[coroutine]` to the closure
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oli-obk committed Apr 23, 2024
1 parent 0253be5 commit bf436b5
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Showing 279 changed files with 1,270 additions and 871 deletions.
3 changes: 3 additions & 0 deletions compiler/rustc_ast_lowering/messages.ftl
Original file line number Diff line number Diff line change
Expand Up @@ -163,3 +163,6 @@ 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 `#[coroutine]` closures, or `gen` blocks
.suggestion = use `#[coroutine]` to make this closure a coroutine
9 changes: 9 additions & 0 deletions compiler/rustc_ast_lowering/src/errors.rs
Original file line number Diff line number Diff line change
Expand Up @@ -421,3 +421,12 @@ pub(crate) struct NoPreciseCapturesOnApit {
#[primary_span]
pub span: Span,
}

#[derive(Diagnostic)]
#[diag(ast_lowering_yield_in_closure)]
pub(crate) struct YieldInClosure {
#[primary_span]
pub span: Span,
#[suggestion(code = "#[coroutine] ", applicability = "maybe-incorrect", style = "verbose")]
pub suggestion: Option<Span>,
}
5 changes: 5 additions & 0 deletions compiler/rustc_ast_lowering/src/expr.rs
Original file line number Diff line number Diff line change
Expand Up @@ -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::*;
Expand Down Expand Up @@ -977,6 +978,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
None
};
let body_id = this.lower_fn_body(decl, |this| {
this.coroutine_kind = coroutine_kind;
let e = this.lower_expr_mut(body);
coroutine_kind = this.coroutine_kind;
e
Expand Down Expand Up @@ -1575,7 +1577,10 @@ impl<'hir> LoweringContext<'_, 'hir> {
)
.emit();
}
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
}
};
Expand Down
2 changes: 1 addition & 1 deletion compiler/rustc_ast_lowering/src/item.rs
Original file line number Diff line number Diff line change
Expand Up @@ -203,7 +203,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
body,
..
}) => {
self.with_new_scopes(ident.span, |this| {
self.with_new_scopes(*fn_sig_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
Expand Down
Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
#![feature(coroutines, coroutine_trait)]
#![feature(coroutines, coroutine_trait, stmt_expr_attributes)]

use std::ops::Coroutine;
use std::pin::Pin;
Expand All @@ -8,7 +8,8 @@ fn main() {
}

fn run_coroutine<T>() {
let mut coroutine = || {
let mut coroutine = #[coroutine]
|| {
yield;
return;
};
Expand Down
10 changes: 7 additions & 3 deletions compiler/rustc_codegen_cranelift/example/std_example.rs
Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
#![feature(
core_intrinsics,
coroutines,
stmt_expr_attributes,
coroutine_trait,
is_sorted,
repr_simd,
Expand Down Expand Up @@ -122,9 +123,12 @@ fn main() {
test_simd();
}

Box::pin(move |mut _task_context| {
yield ();
})
Box::pin(
#[coroutine]
move |mut _task_context| {
yield ();
},
)
.as_mut()
.resume(0);

Expand Down
4 changes: 2 additions & 2 deletions compiler/rustc_codegen_gcc/example/std_example.rs
Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
#![allow(internal_features)]
#![feature(core_intrinsics, coroutines, coroutine_trait, is_sorted)]
#![feature(core_intrinsics, coroutines, coroutine_trait, is_sorted, stmt_expr_attributes)]

#[cfg(feature="master")]
#[cfg(target_arch="x86_64")]
Expand Down Expand Up @@ -103,7 +103,7 @@ fn main() {
test_simd();
}

Box::pin(move |mut _task_context| {
Box::pin(#[coroutine] move |mut _task_context| {
yield ();
}).as_mut().resume(0);

Expand Down
20 changes: 10 additions & 10 deletions compiler/rustc_error_codes/src/error_codes/E0626.md
Original file line number Diff line number Diff line change
Expand Up @@ -4,10 +4,10 @@ yield point.
Erroneous code example:

```compile_fail,E0626
# #![feature(coroutines, coroutine_trait, pin)]
# #![feature(coroutines, coroutine_trait, stmt_expr_attributes)]
# use std::ops::Coroutine;
# use std::pin::Pin;
let mut b = || {
let mut b = #[coroutine] || {
let a = &String::new(); // <-- This borrow...
yield (); // ...is still in scope here, when the yield occurs.
println!("{}", a);
Expand All @@ -23,10 +23,10 @@ resolve the previous example by removing the borrow and just storing
the integer by value:

```
# #![feature(coroutines, coroutine_trait, pin)]
# #![feature(coroutines, coroutine_trait, stmt_expr_attributes)]
# use std::ops::Coroutine;
# use std::pin::Pin;
let mut b = || {
let mut b = #[coroutine] || {
let a = 3;
yield ();
println!("{}", a);
Expand All @@ -41,10 +41,10 @@ in those cases, something like the `Rc` or `Arc` types may be useful.
This error also frequently arises with iteration:

```compile_fail,E0626
# #![feature(coroutines, coroutine_trait, pin)]
# #![feature(coroutines, coroutine_trait, stmt_expr_attributes)]
# use std::ops::Coroutine;
# use std::pin::Pin;
let mut b = || {
let mut b = #[coroutine] || {
let v = vec![1,2,3];
for &x in &v { // <-- borrow of `v` is still in scope...
yield x; // ...when this yield occurs.
Expand All @@ -57,10 +57,10 @@ Such cases can sometimes be resolved by iterating "by value" (or using
`into_iter()`) to avoid borrowing:

```
# #![feature(coroutines, coroutine_trait, pin)]
# #![feature(coroutines, coroutine_trait, stmt_expr_attributes)]
# use std::ops::Coroutine;
# use std::pin::Pin;
let mut b = || {
let mut b = #[coroutine] || {
let v = vec![1,2,3];
for x in v { // <-- Take ownership of the values instead!
yield x; // <-- Now yield is OK.
Expand All @@ -72,10 +72,10 @@ Pin::new(&mut b).resume(());
If taking ownership is not an option, using indices can work too:

```
# #![feature(coroutines, coroutine_trait, pin)]
# #![feature(coroutines, coroutine_trait, stmt_expr_attributes)]
# use std::ops::Coroutine;
# use std::pin::Pin;
let mut b = || {
let mut b = #[coroutine] || {
let v = vec![1,2,3];
let len = v.len(); // (*)
for i in 0..len {
Expand Down
6 changes: 3 additions & 3 deletions compiler/rustc_error_codes/src/error_codes/E0627.md
Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@ A yield expression was used outside of the coroutine literal.
Erroneous code example:

```compile_fail,E0627
#![feature(coroutines, coroutine_trait)]
#![feature(coroutines, coroutine_trait, stmt_expr_attributes)]
fn fake_coroutine() -> &'static str {
yield 1;
Expand All @@ -19,10 +19,10 @@ The error occurs because keyword `yield` can only be used inside the coroutine
literal. This can be fixed by constructing the coroutine correctly.

```
#![feature(coroutines, coroutine_trait)]
#![feature(coroutines, coroutine_trait, stmt_expr_attributes)]
fn main() {
let mut coroutine = || {
let mut coroutine = #[coroutine] || {
yield 1;
return "foo"
};
Expand Down
8 changes: 4 additions & 4 deletions compiler/rustc_error_codes/src/error_codes/E0628.md
Original file line number Diff line number Diff line change
Expand Up @@ -3,10 +3,10 @@ More than one parameter was used for a coroutine.
Erroneous code example:

```compile_fail,E0628
#![feature(coroutines, coroutine_trait)]
#![feature(coroutines, coroutine_trait, stmt_expr_attributes)]
fn main() {
let coroutine = |a: i32, b: i32| {
let coroutine = #[coroutine] |a: i32, b: i32| {
// error: too many parameters for a coroutine
// Allowed only 0 or 1 parameter
yield a;
Expand All @@ -20,10 +20,10 @@ at most 1 parameter for the coroutine. For example, we might resolve
the previous example by passing only one parameter.

```
#![feature(coroutines, coroutine_trait)]
#![feature(coroutines, coroutine_trait, stmt_expr_attributes)]
fn main() {
let coroutine = |a: i32| {
let coroutine = #[coroutine] |a: i32| {
yield a;
};
}
Expand Down
8 changes: 4 additions & 4 deletions compiler/rustc_error_codes/src/error_codes/E0727.md
Original file line number Diff line number Diff line change
Expand Up @@ -3,10 +3,10 @@ A `yield` clause was used in an `async` context.
Erroneous code example:

```compile_fail,E0727,edition2018
#![feature(coroutines)]
#![feature(coroutines, stmt_expr_attributes)]
fn main() {
let coroutine = || {
let coroutine = #[coroutine] || {
async {
yield;
}
Expand All @@ -20,10 +20,10 @@ which is not yet supported.
To fix this error, you have to move `yield` out of the `async` block:

```edition2018
#![feature(coroutines)]
#![feature(coroutines, stmt_expr_attributes)]
fn main() {
let coroutine = || {
let coroutine = #[coroutine] || {
yield;
};
}
Expand Down
42 changes: 23 additions & 19 deletions compiler/rustc_metadata/src/rmeta/decoder.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1260,30 +1260,34 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
id: DefIndex,
sess: &'a Session,
) -> impl Iterator<Item = ModChild> + 'a {
iter::from_coroutine(move || {
if let Some(data) = &self.root.proc_macro_data {
// If we are loading as a proc macro, we want to return
// the view of this crate as a proc macro crate.
if id == CRATE_DEF_INDEX {
for child_index in data.macros.decode(self) {
iter::from_coroutine(
#[cfg_attr(not(bootstrap), coroutine)]
move || {
if let Some(data) = &self.root.proc_macro_data {
// If we are loading as a proc macro, we want to return
// the view of this crate as a proc macro crate.
if id == CRATE_DEF_INDEX {
for child_index in data.macros.decode(self) {
yield self.get_mod_child(child_index, sess);
}
}
} else {
// Iterate over all children.
let non_reexports =
self.root.tables.module_children_non_reexports.get(self, id);
for child_index in non_reexports.unwrap().decode(self) {
yield self.get_mod_child(child_index, sess);
}
}
} else {
// Iterate over all children.
let non_reexports = self.root.tables.module_children_non_reexports.get(self, id);
for child_index in non_reexports.unwrap().decode(self) {
yield self.get_mod_child(child_index, sess);
}

let reexports = self.root.tables.module_children_reexports.get(self, id);
if !reexports.is_default() {
for reexport in reexports.decode((self, sess)) {
yield reexport;
let reexports = self.root.tables.module_children_reexports.get(self, id);
if !reexports.is_default() {
for reexport in reexports.decode((self, sess)) {
yield reexport;
}
}
}
}
})
},
)
}

fn is_ctfe_mir_available(self, id: DefIndex) -> bool {
Expand Down
1 change: 1 addition & 0 deletions compiler/rustc_middle/src/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,7 @@
#![feature(const_type_name)]
#![feature(discriminant_kind)]
#![feature(coroutines)]
#![feature(stmt_expr_attributes)]
#![feature(if_let_guard)]
#![feature(inline_const)]
#![feature(iter_from_coroutine)]
Expand Down
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