Auto merge of #106004 - fee1-dead-contrib:const-closures, r=oli-obk

Const closures

cc https://github.com/rust-lang/rust/issues/106003

2 files changed, 17 insertions, 1 deletions

diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index f5093fb02a8..dd2b03988c3 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -1325,7 +1325,10 @@ impl<'a> Parser<'a> {
             self.parse_array_or_repeat_expr(Delimiter::Bracket)
         } else if self.check_path() {
             self.parse_path_start_expr()
-        } else if self.check_keyword(kw::Move) || self.check_keyword(kw::Static) {
+        } else if self.check_keyword(kw::Move)
+            || self.check_keyword(kw::Static)
+            || self.check_const_closure()
+        {
             self.parse_closure_expr()
         } else if self.eat_keyword(kw::If) {
             self.parse_if_expr()
@@ -2065,6 +2068,8 @@ impl<'a> Parser<'a> {
             ClosureBinder::NotPresent
         };
 
+        let constness = self.parse_constness(Case::Sensitive);
+
         let movability =
             if self.eat_keyword(kw::Static) { Movability::Static } else { Movability::Movable };
 
@@ -2111,6 +2116,7 @@ impl<'a> Parser<'a> {
             ExprKind::Closure(Box::new(ast::Closure {
                 binder,
                 capture_clause,
+                constness,
                 asyncness,
                 movability,
                 fn_decl,
diff --git a/compiler/rustc_parse/src/parser/mod.rs b/compiler/rustc_parse/src/parser/mod.rs
index 49d31981539..2fd2a4e5154 100644
--- a/compiler/rustc_parse/src/parser/mod.rs
+++ b/compiler/rustc_parse/src/parser/mod.rs
@@ -736,6 +736,16 @@ impl<'a> Parser<'a> {
         self.check_or_expected(self.token.can_begin_const_arg(), TokenType::Const)
     }
 
+    fn check_const_closure(&self) -> bool {
+        self.is_keyword_ahead(0, &[kw::Const])
+            && self.look_ahead(1, |t| match &t.kind {
+                token::Ident(kw::Move | kw::Static | kw::Async, _)
+                | token::OrOr
+                | token::BinOp(token::Or) => true,
+                _ => false,
+            })
+    }
+
     fn check_inline_const(&self, dist: usize) -> bool {
         self.is_keyword_ahead(dist, &[kw::Const])
             && self.look_ahead(dist + 1, |t| match &t.kind {