Add const effect syntax to the parser for all function headers

Author: oli-obk

compiler/rustc_ast/src/ast.rs

@@ -323,7 +323,7 @@ impl ParenthesizedArgs {
 
 pub use crate::node_id::{CRATE_NODE_ID, DUMMY_NODE_ID, NodeId};
 
-/// Modifiers on a trait bound like `~const`, `?` and `!`.
+/// Modifiers on a trait bound like `[const]`, `?` and `!`.
 #[derive(Copy, Clone, PartialEq, Eq, Encodable, Decodable, Debug)]
 pub struct TraitBoundModifiers {
     pub constness: BoundConstness,
@@ -3111,7 +3111,7 @@ pub enum BoundConstness {
     Never,
     /// `Type: const Trait`
     Always(Span),
-    /// `Type: ~const Trait`
+    /// `Type: [const] Trait`
     Maybe(Span),
 }
 
@@ -3120,7 +3120,7 @@ impl BoundConstness {
         match self {
             Self::Never => "",
             Self::Always(_) => "const",
-            Self::Maybe(_) => "~const",
+            Self::Maybe(_) => "[const]",
         }
     }
 }

compiler/rustc_ast_passes/messages.ftl

@@ -232,17 +232,17 @@ ast_passes_static_without_body =
     free static item without body
     .suggestion = provide a definition for the static
 
-ast_passes_tilde_const_disallowed = `~const` is not allowed here
-    .closure = closures cannot have `~const` trait bounds
-    .function = this function is not `const`, so it cannot have `~const` trait bounds
-    .trait = this trait is not a `#[const_trait]`, so it cannot have `~const` trait bounds
-    .trait_impl = this impl is not `const`, so it cannot have `~const` trait bounds
-    .impl = inherent impls cannot have `~const` trait bounds
-    .trait_assoc_ty = associated types in non-`#[const_trait]` traits cannot have `~const` trait bounds
-    .trait_impl_assoc_ty = associated types in non-const impls cannot have `~const` trait bounds
-    .inherent_assoc_ty = inherent associated types cannot have `~const` trait bounds
-    .object = trait objects cannot have `~const` trait bounds
-    .item = this item cannot have `~const` trait bounds
+ast_passes_tilde_const_disallowed = `[const]` is not allowed here
+    .closure = closures cannot have `[const]` trait bounds
+    .function = this function is not `const`, so it cannot have `[const]` trait bounds
+    .trait = this trait is not a `#[const_trait]`, so it cannot have `[const]` trait bounds
+    .trait_impl = this impl is not `const`, so it cannot have `[const]` trait bounds
+    .impl = inherent impls cannot have `[const]` trait bounds
+    .trait_assoc_ty = associated types in non-`#[const_trait]` traits cannot have `[const]` trait bounds
+    .trait_impl_assoc_ty = associated types in non-const impls cannot have `[const]` trait bounds
+    .inherent_assoc_ty = inherent associated types cannot have `[const]` trait bounds
+    .object = trait objects cannot have `[const]` trait bounds
+    .item = this item cannot have `[const]` trait bounds
 
 ast_passes_trait_fn_const =
     functions in {$in_impl ->