Reorder modifiers and polarity to be *after* binder in trait bounds

Author: compiler-errors

compiler/rustc_parse/src/parser/ty.rs

@@ -978,7 +978,7 @@ impl<'a> Parser<'a> {
     /// Parses a type bound according to:
     /// ```ebnf
     /// TY_BOUND = TY_BOUND_NOPAREN | (TY_BOUND_NOPAREN)
-    /// TY_BOUND_NOPAREN = [TRAIT_BOUND_MODIFIERS] [for<LT_PARAM_DEFS>] SIMPLE_PATH
+    /// TY_BOUND_NOPAREN = [for<LT_PARAM_DEFS>] [TRAIT_BOUND_MODIFIERS] SIMPLE_PATH
     /// ```
     ///
     /// For example, this grammar accepts `for<'a: 'b> ~const ?m::Trait<'a>`.
@@ -988,8 +988,8 @@ impl<'a> Parser<'a> {
         has_parens: bool,
         leading_token: &Token,
     ) -> PResult<'a, GenericBound> {
-        let modifiers = self.parse_trait_bound_modifiers()?;
         let (mut lifetime_defs, binder_span) = self.parse_late_bound_lifetime_defs()?;
+        let modifiers = self.parse_trait_bound_modifiers()?;
 
         // Recover erroneous lifetime bound with modifiers or binder.
         // e.g. `T: for<'a> 'a` or `T: ~const 'a`.

tests/ui/async-await/async-fn/higher-ranked-async-fn.rs

@@ -15,7 +15,7 @@ async fn f(arg: &i32) {}
 
 async fn func<F>(f: F)
 where
-    F: async for<'a> Fn(&'a i32),
+    F: for<'a> async Fn(&'a i32),
 {
     let x: i32 = 0;
     f(&x).await;

tests/ui/impl-trait/normalize-tait-in-const.stderr

@@ -1,41 +1,8 @@
-error: `~const` can only be applied to `#[const_trait]` traits
-  --> $DIR/normalize-tait-in-const.rs:27:42
+error: expected a trait, found type
+  --> $DIR/normalize-tait-in-const.rs:27:34
    |
 LL | const fn with_positive<F: ~const for<'a> Fn(&'a Alias<'a>) + ~const Destruct>(fun: F) {
-   |                                          ^^^^^^^^^^^^^^^^^
+   |                                  ^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: `~const` can only be applied to `#[const_trait]` traits
-  --> $DIR/normalize-tait-in-const.rs:27:69
-   |
-LL | const fn with_positive<F: ~const for<'a> Fn(&'a Alias<'a>) + ~const Destruct>(fun: F) {
-   |                                                                     ^^^^^^^^
-
-error[E0015]: cannot call non-const closure in constant functions
-  --> $DIR/normalize-tait-in-const.rs:28:5
-   |
-LL |     fun(filter_positive());
-   |     ^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: calls in constant functions are limited to constant functions, tuple structs and tuple variants
-help: consider further restricting this bound
-   |
-LL | const fn with_positive<F: ~const for<'a> Fn(&'a Alias<'a>) + ~const Destruct + ~const Fn(&foo::Alias<'_>)>(fun: F) {
-   |                                                                              ++++++++++++++++++++++++++++
-help: add `#![feature(effects)]` to the crate attributes to enable
-   |
-LL + #![feature(effects)]
-   |
-
-error[E0493]: destructor of `F` cannot be evaluated at compile-time
-  --> $DIR/normalize-tait-in-const.rs:27:79
-   |
-LL | const fn with_positive<F: ~const for<'a> Fn(&'a Alias<'a>) + ~const Destruct>(fun: F) {
-   |                                                                               ^^^ the destructor for this type cannot be evaluated in constant functions
-LL |     fun(filter_positive());
-LL | }
-   | - value is dropped here
-
-error: aborting due to 4 previous errors
+error: aborting due to 1 previous error
 
-Some errors have detailed explanations: E0015, E0493.
-For more information about an error, try `rustc --explain E0015`.

tests/ui/issues/issue-39089.rs

@@ -1,5 +1,4 @@
-//@ check-pass
-#![allow(dead_code)]
 fn f<T: ?for<'a> Sized>() {}
+//~^ ERROR expected a trait, found type
 
 fn main() {}

tests/ui/issues/issue-39089.stderr

@@ -0,0 +1,8 @@
+error: expected a trait, found type
+  --> $DIR/issue-39089.rs:1:10
+   |
+LL | fn f<T: ?for<'a> Sized>() {}
+   |          ^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+

tests/ui/parser/bounds-type.rs

@@ -5,7 +5,7 @@ struct S<
     T: Tr + 'a, // OK
     T: 'a, // OK
     T:, // OK
-    T: ?for<'a> Trait, // OK
+    T: for<'a> ?Trait, // OK
     T: Tr +, // OK
     T: ?'a, //~ ERROR `?` may only modify trait bounds, not lifetime bounds
 

tests/ui/rfcs/rfc-2632-const-trait-impl/tilde-const-syntax.rs

@@ -4,6 +4,6 @@
 #![feature(const_trait_impl)]
 
 struct S<
-    T: ~const ?for<'a> Tr<'a> + 'static + ~const std::ops::Add,
-    T: ~const ?for<'a: 'b> m::Trait<'a>,
+    T: for<'a> ~const ?Tr<'a> + 'static + ~const std::ops::Add,
+    T: for<'a: 'b> ~const ?m::Trait<'a>,
 >;