Merge pull request #4229 from rust-lang/rustup-2025-03-16

Automatic Rustup

2 files changed, 20 insertions, 2 deletions

diff --git a/compiler/rustc_parse/src/parser/attr.rs b/compiler/rustc_parse/src/parser/attr.rs
index 066b570c23f..53614049f08 100644
--- a/compiler/rustc_parse/src/parser/attr.rs
+++ b/compiler/rustc_parse/src/parser/attr.rs
@@ -127,12 +127,29 @@ impl<'a> Parser<'a> {
         let lo = self.token.span;
         // Attributes can't have attributes of their own [Editor's note: not with that attitude]
         self.collect_tokens_no_attrs(|this| {
+            let pound_hi = this.token.span.hi();
             assert!(this.eat(exp!(Pound)), "parse_attribute called in non-attribute position");
 
+            let not_lo = this.token.span.lo();
             let style =
                 if this.eat(exp!(Bang)) { ast::AttrStyle::Inner } else { ast::AttrStyle::Outer };
 
-            this.expect(exp!(OpenBracket))?;
+            let mut bracket_res = this.expect(exp!(OpenBracket));
+            // If `#!` is not followed by `[`
+            if let Err(err) = &mut bracket_res
+                && style == ast::AttrStyle::Inner
+                && pound_hi == not_lo
+            {
+                err.note(
+                    "the token sequence `#!` here looks like the start of \
+                    a shebang interpreter directive but it is not",
+                );
+                err.help(
+                    "if you meant this to be a shebang interpreter directive, \
+                    move it to the very start of the file",
+                );
+            }
+            bracket_res?;
             let item = this.parse_attr_item(ForceCollect::No)?;
             this.expect(exp!(CloseBracket))?;
             let attr_sp = lo.to(this.prev_token.span);
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index fc9a511d56a..41720e99e3b 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -2598,7 +2598,8 @@ impl<'a> Parser<'a> {
     }
 
     /// Parses the condition of a `if` or `while` expression.
-    fn parse_expr_cond(&mut self) -> PResult<'a, P<Expr>> {
+    // Public because it is used in rustfmt forks such as https://github.com/tucant/rustfmt/blob/30c83df9e1db10007bdd16dafce8a86b404329b2/src/parse/macros/html.rs#L57 for custom if expressions.
+    pub fn parse_expr_cond(&mut self) -> PResult<'a, P<Expr>> {
         let attrs = self.parse_outer_attributes()?;
         let (mut cond, _) =
             self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL | Restrictions::ALLOW_LET, attrs)?;