Fix ICE in diagnostics for parenthesized type arguments

Author: wutchzone

compiler/rustc_parse/src/parser/path.rs

@@ -449,9 +449,13 @@ impl<'a> Parser<'a> {
         prev_token_before_parsing: Token,
         error: &mut Diag<'_>,
     ) {
-        if ((style == PathStyle::Expr && self.parse_paren_comma_seq(|p| p.parse_expr()).is_ok())
-            || (style == PathStyle::Pat
-                && self
+        match style {
+            PathStyle::Expr
+                if let Ok(_) = self
+                    .parse_paren_comma_seq(|p| p.parse_expr())
+                    .map_err(|error| error.cancel()) => {}
+            PathStyle::Pat
+                if let Ok(_) = self
                     .parse_paren_comma_seq(|p| {
                         p.parse_pat_allow_top_alt(
                             None,
@@ -460,9 +464,13 @@ impl<'a> Parser<'a> {
                             CommaRecoveryMode::LikelyTuple,
                         )
                     })
-                    .is_ok()))
-            && !matches!(self.token.kind, token::ModSep | token::RArrow)
-        {
+                    .map_err(|error| error.cancel()) => {}
+            _ => {
+                return;
+            }
+        }
+
+        if !matches!(self.token.kind, token::ModSep | token::RArrow) {
             error.span_suggestion_verbose(
                 prev_token_before_parsing.span,
                 format!(

tests/ui/parser/diagnostics-parenthesized-type-arguments-ice-issue-122345.rs

@@ -0,0 +1,7 @@
+fn main() {
+    unsafe {
+        dealloc(ptr2, Layout::(x: !)(1, 1)); //~ ERROR: expected one of `!`, `(`, `)`, `+`, `,`, `::`, or `<`, found `:`
+        //~^ ERROR: expected one of `.`, `;`, `?`, `}`, or an operator, found `)`
+        //~| while parsing this parenthesized list of type arguments starting here
+    }
+}

tests/ui/parser/diagnostics-parenthesized-type-arguments-ice-issue-122345.stderr

@@ -0,0 +1,16 @@
+error: expected one of `!`, `(`, `)`, `+`, `,`, `::`, or `<`, found `:`
+  --> $DIR/diagnostics-parenthesized-type-arguments-ice-issue-122345.rs:3:33
+   |
+LL |         dealloc(ptr2, Layout::(x: !)(1, 1));
+   |                             --- ^ expected one of 7 possible tokens
+   |                             |
+   |                             while parsing this parenthesized list of type arguments starting here
+
+error: expected one of `.`, `;`, `?`, `}`, or an operator, found `)`
+  --> $DIR/diagnostics-parenthesized-type-arguments-ice-issue-122345.rs:3:43
+   |
+LL |         dealloc(ptr2, Layout::(x: !)(1, 1));
+   |                                           ^ expected one of `.`, `;`, `?`, `}`, or an operator
+
+error: aborting due to 2 previous errors
+