Rollup merge of #157978 - TaKO8Ki:fix-raw-ref-trailing-comma-recovery, r=JonathanBrouwer

Avoid `&raw` recovery ICE after trailing comma

Fixes #157950

This is a follow up to #157888.

For `&raw x,)`, recovery first skips `x`, then consumes the trailing comma. The old condition then fell through to `parse_token_tree()` when the next token was `)`, which causes an ICE.

Author: JonathanBrouwer

compiler/rustc_parse/src/parser/expr.rs

@@ -1304,8 +1304,10 @@ impl<'a> Parser<'a> {
         let err_span = self.prev_token.span.to(self.token.span);
         let mut args = thin_vec![self.mk_expr_err(err_span, guar)];
         while !self.token.kind.is_close_delim_or_eof() {
-            if self.eat(exp!(Comma)) && !self.token.kind.is_close_delim_or_eof() {
-                args.push(self.mk_expr_err(self.prev_token.span.shrink_to_hi(), guar));
+            if self.eat(exp!(Comma)) {
+                if !self.token.kind.is_close_delim_or_eof() {
+                    args.push(self.mk_expr_err(self.prev_token.span.shrink_to_hi(), guar));
+                }
             } else {
                 self.parse_token_tree();
             }

tests/ui/parser/recover/raw-no-const-mut-trailing-comma.rs

@@ -0,0 +1,7 @@
+// Regression test for https://github.com/rust-lang/rust/issues/157950.
+
+fn main() {
+    takes_raw_ptr_args(&raw x,)
+    //~^ ERROR expected one of
+    //~| ERROR cannot find function `takes_raw_ptr_args` in this scope
+}

tests/ui/parser/recover/raw-no-const-mut-trailing-comma.stderr

@@ -0,0 +1,22 @@
+error: expected one of `!`, `)`, `,`, `.`, `::`, `?`, `const`, `mut`, `{`, or an operator, found `x`
+  --> $DIR/raw-no-const-mut-trailing-comma.rs:4:29
+   |
+LL |     takes_raw_ptr_args(&raw x,)
+   |                             ^ expected one of 10 possible tokens
+   |
+help: `&raw` must be followed by `const` or `mut` to be a raw reference expression
+   |
+LL |     takes_raw_ptr_args(&raw const x,)
+   |                             +++++
+LL |     takes_raw_ptr_args(&raw mut x,)
+   |                             +++
+
+error[E0425]: cannot find function `takes_raw_ptr_args` in this scope
+  --> $DIR/raw-no-const-mut-trailing-comma.rs:4:5
+   |
+LL |     takes_raw_ptr_args(&raw x,)
+   |     ^^^^^^^^^^^^^^^^^^ not found in this scope
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0425`.