Rollup merge of #145604 - compiler-errors:static-closure, r=fmease

Gate static closures behind a parser feature

I'd like to gate `static ||` closures behind a feature gate, since we shouldn't allow people to take advantage of this syntax if it's currently unstable. Right now, since it's only rejected after ast lowering, it's accessible to macros.

Let's crater this to see if we can claw it back without breaking anyone's code.

10 files changed, 67 insertions, 24 deletions

diff --git a/compiler/rustc_ast_passes/src/feature_gate.rs b/compiler/rustc_ast_passes/src/feature_gate.rs
index c9344a76a7b..e763c9d69fc 100644
--- a/compiler/rustc_ast_passes/src/feature_gate.rs
+++ b/compiler/rustc_ast_passes/src/feature_gate.rs
@@ -524,6 +524,7 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session, features: &Features) {
     gate_all!(where_clause_attrs, "attributes in `where` clause are unstable");
     gate_all!(super_let, "`super let` is experimental");
     gate_all!(frontmatter, "frontmatters are experimental");
+    gate_all!(coroutines, "coroutine syntax is experimental");
 
     if !visitor.features.never_patterns() {
         if let Some(spans) = spans.get(&sym::never_patterns) {
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index ea8cd3754a0..cb7f755f524 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -2409,8 +2409,12 @@ impl<'a> Parser<'a> {
 
         let constness = self.parse_closure_constness();
 
-        let movability =
-            if self.eat_keyword(exp!(Static)) { Movability::Static } else { Movability::Movable };
+        let movability = if self.eat_keyword(exp!(Static)) {
+            self.psess.gated_spans.gate(sym::coroutines, self.prev_token.span);
+            Movability::Static
+        } else {
+            Movability::Movable
+        };
 
         let coroutine_kind = if self.token_uninterpolated_span().at_least_rust_2018() {
             self.parse_coroutine_kind(Case::Sensitive)
diff --git a/tests/ui/coroutine/static-closure-unexpanded.rs b/tests/ui/coroutine/static-closure-unexpanded.rs
new file mode 100644
index 00000000000..7cf24774ded
--- /dev/null
+++ b/tests/ui/coroutine/static-closure-unexpanded.rs
@@ -0,0 +1,10 @@
+// Tests that static closures are not stable in the parser grammar unless the
+// coroutine feature is enabled.
+
+#[cfg(any())]
+fn foo() {
+    let _ = static || {};
+    //~^ ERROR coroutine syntax is experimental
+}
+
+fn main() {}
diff --git a/tests/ui/coroutine/static-closure-unexpanded.stderr b/tests/ui/coroutine/static-closure-unexpanded.stderr
new file mode 100644
index 00000000000..f08bafd368f
--- /dev/null
+++ b/tests/ui/coroutine/static-closure-unexpanded.stderr
@@ -0,0 +1,13 @@
+error[E0658]: coroutine syntax is experimental
+  --> $DIR/static-closure-unexpanded.rs:6:13
+   |
+LL |     let _ = static || {};
+   |             ^^^^^^
+   |
+   = note: see issue #43122 <https://github.com/rust-lang/rust/issues/43122> for more information
+   = 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: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/static/static-closures.rs b/tests/ui/static/static-closures.rs
index 1bd518d6ffe..e836f1b85eb 100644
--- a/tests/ui/static/static-closures.rs
+++ b/tests/ui/static/static-closures.rs
@@ -1,4 +1,5 @@
 fn main() {
     static || {};
     //~^ ERROR closures cannot be static
+    //~| ERROR coroutine syntax is experimental
 }
diff --git a/tests/ui/static/static-closures.stderr b/tests/ui/static/static-closures.stderr
index b11c0b5a530..ecc961cc1e4 100644
--- a/tests/ui/static/static-closures.stderr
+++ b/tests/ui/static/static-closures.stderr
@@ -1,9 +1,20 @@
+error[E0658]: coroutine syntax is experimental
+  --> $DIR/static-closures.rs:2:5
+   |
+LL |     static || {};
+   |     ^^^^^^
+   |
+   = note: see issue #43122 <https://github.com/rust-lang/rust/issues/43122> for more information
+   = 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[E0697]: closures cannot be static
   --> $DIR/static-closures.rs:2:5
    |
 LL |     static || {};
    |     ^^^^^^^^^
 
-error: aborting due to 1 previous error
+error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0697`.
+Some errors have detailed explanations: E0658, E0697.
+For more information about an error, try `rustc --explain E0658`.
diff --git a/tests/ui/unpretty/exhaustive.expanded.stdout b/tests/ui/unpretty/exhaustive.expanded.stdout
index 0327ad5f92b..a12ea0786f9 100644
--- a/tests/ui/unpretty/exhaustive.expanded.stdout
+++ b/tests/ui/unpretty/exhaustive.expanded.stdout
@@ -13,6 +13,7 @@
 #![feature(box_patterns)]
 #![feature(builtin_syntax)]
 #![feature(const_trait_impl)]
+#![feature(coroutines)]
 #![feature(decl_macro)]
 #![feature(deref_patterns)]
 #![feature(explicit_tail_calls)]
diff --git a/tests/ui/unpretty/exhaustive.hir.stderr b/tests/ui/unpretty/exhaustive.hir.stderr
index aa411ce81eb..eb5c186bd2c 100644
--- a/tests/ui/unpretty/exhaustive.hir.stderr
+++ b/tests/ui/unpretty/exhaustive.hir.stderr
@@ -1,17 +1,17 @@
 error[E0697]: closures cannot be static
-  --> $DIR/exhaustive.rs:209:9
+  --> $DIR/exhaustive.rs:210:9
    |
 LL |         static || value;
    |         ^^^^^^^^^
 
 error[E0697]: closures cannot be static
-  --> $DIR/exhaustive.rs:210:9
+  --> $DIR/exhaustive.rs:211:9
    |
 LL |         static move || value;
    |         ^^^^^^^^^^^^^^
 
 error[E0728]: `await` is only allowed inside `async` functions and blocks
-  --> $DIR/exhaustive.rs:239:13
+  --> $DIR/exhaustive.rs:240:13
    |
 LL |     fn expr_await() {
    |     --------------- this is not `async`
@@ -20,19 +20,19 @@ LL |         fut.await;
    |             ^^^^^ only allowed inside `async` functions and blocks
 
 error: in expressions, `_` can only be used on the left-hand side of an assignment
-  --> $DIR/exhaustive.rs:288:9
+  --> $DIR/exhaustive.rs:289:9
    |
 LL |         _;
    |         ^ `_` not allowed here
 
 error[E0214]: parenthesized type parameters may only be used with a `Fn` trait
-  --> $DIR/exhaustive.rs:298:9
+  --> $DIR/exhaustive.rs:299:9
    |
 LL |         x::();
    |         ^^^^^ only `Fn` traits may use parentheses
 
 error[E0214]: parenthesized type parameters may only be used with a `Fn` trait
-  --> $DIR/exhaustive.rs:299:9
+  --> $DIR/exhaustive.rs:300:9
    |
 LL |         x::(T, T) -> T;
    |         ^^^^^^^^^^^^^^ only `Fn` traits may use parentheses
@@ -44,31 +44,31 @@ LL +         x::<T, T> -> T;
    |
 
 error[E0214]: parenthesized type parameters may only be used with a `Fn` trait
-  --> $DIR/exhaustive.rs:300:9
+  --> $DIR/exhaustive.rs:301:9
    |
 LL |         crate::() -> ()::expressions::() -> ()::expr_path;
    |         ^^^^^^^^^^^^^^^ only `Fn` traits may use parentheses
 
 error[E0214]: parenthesized type parameters may only be used with a `Fn` trait
-  --> $DIR/exhaustive.rs:300:26
+  --> $DIR/exhaustive.rs:301:26
    |
 LL |         crate::() -> ()::expressions::() -> ()::expr_path;
    |                          ^^^^^^^^^^^^^^^^^^^^^ only `Fn` traits may use parentheses
 
 error[E0214]: parenthesized type parameters may only be used with a `Fn` trait
-  --> $DIR/exhaustive.rs:303:9
+  --> $DIR/exhaustive.rs:304:9
    |
 LL |         core::()::marker::()::PhantomData;
    |         ^^^^^^^^ only `Fn` traits may use parentheses
 
 error[E0214]: parenthesized type parameters may only be used with a `Fn` trait
-  --> $DIR/exhaustive.rs:303:19
+  --> $DIR/exhaustive.rs:304:19
    |
 LL |         core::()::marker::()::PhantomData;
    |                   ^^^^^^^^^^ only `Fn` traits may use parentheses
 
 error: `yield` can only be used in `#[coroutine]` closures, or `gen` blocks
-  --> $DIR/exhaustive.rs:390:9
+  --> $DIR/exhaustive.rs:391:9
    |
 LL |         yield;
    |         ^^^^^
@@ -79,7 +79,7 @@ LL |     #[coroutine] fn expr_yield() {
    |     ++++++++++++
 
 error[E0703]: invalid ABI: found `C++`
-  --> $DIR/exhaustive.rs:470:23
+  --> $DIR/exhaustive.rs:471:23
    |
 LL |         unsafe extern "C++" {}
    |                       ^^^^^ invalid ABI
@@ -87,7 +87,7 @@ LL |         unsafe extern "C++" {}
    = note: invoke `rustc --print=calling-conventions` for a full list of supported calling conventions
 
 error: `..` patterns are not allowed here
-  --> $DIR/exhaustive.rs:677:13
+  --> $DIR/exhaustive.rs:678:13
    |
 LL |         let ..;
    |             ^^
@@ -95,13 +95,13 @@ LL |         let ..;
    = note: only allowed in tuple, tuple struct, and slice patterns
 
 error[E0214]: parenthesized type parameters may only be used with a `Fn` trait
-  --> $DIR/exhaustive.rs:792:16
+  --> $DIR/exhaustive.rs:793:16
    |
 LL |         let _: T() -> !;
    |                ^^^^^^^^ only `Fn` traits may use parentheses
 
 error[E0562]: `impl Trait` is not allowed in the type of variable bindings
-  --> $DIR/exhaustive.rs:806:16
+  --> $DIR/exhaustive.rs:807:16
    |
 LL |         let _: impl Send;
    |                ^^^^^^^^^
@@ -112,7 +112,7 @@ LL |         let _: impl Send;
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0562]: `impl Trait` is not allowed in the type of variable bindings
-  --> $DIR/exhaustive.rs:807:16
+  --> $DIR/exhaustive.rs:808:16
    |
 LL |         let _: impl Send + 'static;
    |                ^^^^^^^^^^^^^^^^^^^
@@ -123,7 +123,7 @@ LL |         let _: impl Send + 'static;
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0562]: `impl Trait` is not allowed in the type of variable bindings
-  --> $DIR/exhaustive.rs:808:16
+  --> $DIR/exhaustive.rs:809:16
    |
 LL |         let _: impl 'static + Send;
    |                ^^^^^^^^^^^^^^^^^^^
@@ -134,7 +134,7 @@ LL |         let _: impl 'static + Send;
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0562]: `impl Trait` is not allowed in the type of variable bindings
-  --> $DIR/exhaustive.rs:809:16
+  --> $DIR/exhaustive.rs:810:16
    |
 LL |         let _: impl ?Sized;
    |                ^^^^^^^^^^^
@@ -145,7 +145,7 @@ LL |         let _: impl ?Sized;
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0562]: `impl Trait` is not allowed in the type of variable bindings
-  --> $DIR/exhaustive.rs:810:16
+  --> $DIR/exhaustive.rs:811:16
    |
 LL |         let _: impl [const] Clone;
    |                ^^^^^^^^^^^^^^^^^^
@@ -156,7 +156,7 @@ LL |         let _: impl [const] Clone;
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0562]: `impl Trait` is not allowed in the type of variable bindings
-  --> $DIR/exhaustive.rs:811:16
+  --> $DIR/exhaustive.rs:812:16
    |
 LL |         let _: impl for<'a> Send;
    |                ^^^^^^^^^^^^^^^^^
diff --git a/tests/ui/unpretty/exhaustive.hir.stdout b/tests/ui/unpretty/exhaustive.hir.stdout
index 68356a33c9e..924fb98ae18 100644
--- a/tests/ui/unpretty/exhaustive.hir.stdout
+++ b/tests/ui/unpretty/exhaustive.hir.stdout
@@ -12,6 +12,7 @@
 #![feature(box_patterns)]
 #![feature(builtin_syntax)]
 #![feature(const_trait_impl)]
+#![feature(coroutines)]
 #![feature(decl_macro)]
 #![feature(deref_patterns)]
 #![feature(explicit_tail_calls)]
diff --git a/tests/ui/unpretty/exhaustive.rs b/tests/ui/unpretty/exhaustive.rs
index b19d4f9fe2c..0983a0a7e43 100644
--- a/tests/ui/unpretty/exhaustive.rs
+++ b/tests/ui/unpretty/exhaustive.rs
@@ -12,6 +12,7 @@
 #![feature(box_patterns)]
 #![feature(builtin_syntax)]
 #![feature(const_trait_impl)]
+#![feature(coroutines)]
 #![feature(decl_macro)]
 #![feature(deref_patterns)]
 #![feature(explicit_tail_calls)]