fix ICE when parsing lifetime as function argument

compiler/rustc_parse/src/parser/expr.rs

@@ -1457,9 +1457,9 @@ impl<'a> Parser<'a> {
         } else if self.check(&token::OpenDelim(token::Brace)) || self.token.is_whole_block() {
             self.parse_block_expr(label, lo, BlockCheckMode::Default, attrs)
         } else if !ate_colon && (self.check(&TokenKind::Comma) || self.check(&TokenKind::Gt)) {
-            // We're probably inside of a `Path<'a>` that needs a turbofish, so suppress the
-            // "must be followed by a colon" error, and the "expected one of" error.
-            self.diagnostic().delay_span_bug(lo, "this label wasn't parsed correctly");
+            // We're probably inside of a `Path<'a>` that needs a turbofish
+            let msg = "expected `while`, `for`, `loop` or `{` after a label";
+            self.struct_span_err(self.token.span, msg).span_label(self.token.span, msg).emit();
             consume_colon = false;
             Ok(self.mk_expr_err(lo))
         } else {

compiler/rustc_typeck/src/check/expr.rs

@@ -865,14 +865,22 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         ),
                     ..
                 }) => {
-                    // We have a situation like `while Some(0) = value.get(0) {`, where `while let`
-                    // was more likely intended.
-                    err.span_suggestion_verbose(
-                        expr.span.shrink_to_lo(),
-                        "you might have meant to use pattern destructuring",
-                        "let ".to_string(),
-                        Applicability::MachineApplicable,
-                    );
+                    // Check if our lhs is a child of the condition of a while loop
+                    let expr_is_ancestor = std::iter::successors(Some(lhs.hir_id), |id| {
+                        self.tcx.hir().find_parent_node(*id)
+                    })
+                    .take_while(|id| *id != parent)
+                    .any(|id| id == expr.hir_id);
+                    // if it is, then we have a situation like `while Some(0) = value.get(0) {`,
+                    // where `while let` was more likely intended.
+                    if expr_is_ancestor {
+                        err.span_suggestion_verbose(
+                            expr.span.shrink_to_lo(),
+                            "you might have meant to use pattern destructuring",
+                            "let ".to_string(),
+                            Applicability::MachineApplicable,
+                        );
+                    }
                     break;
                 }
                 hir::Node::Item(_)

src/test/ui/parser/issues/issue-93282.rs

@@ -1,4 +1,15 @@
 fn main() {
     f<'a,>
     //~^ ERROR expected
+    //~| ERROR expected
+}
+
+fn bar(a: usize, b: usize) -> usize {
+    a + b
+}
+
+fn foo() {
+    let x = 1;
+    bar('y, x);
+    //~^ ERROR expected
 }

src/test/ui/parser/issues/issue-93282.stderr

@@ -1,3 +1,9 @@
+error: expected `while`, `for`, `loop` or `{` after a label
+  --> $DIR/issue-93282.rs:2:9
+   |
+LL |     f<'a,>
+   |         ^ expected `while`, `for`, `loop` or `{` after a label
+
 error: expected one of `.`, `:`, `;`, `?`, `for`, `loop`, `while`, `{`, `}`, or an operator, found `,`
   --> $DIR/issue-93282.rs:2:9
    |
@@ -9,5 +15,11 @@ help: use `::<...>` instead of `<...>` to specify lifetime, type, or const argum
 LL |     f::<'a,>
    |      ++
 
-error: aborting due to previous error
+error: expected `while`, `for`, `loop` or `{` after a label
+  --> $DIR/issue-93282.rs:13:11
+   |
+LL |     bar('y, x);
+   |           ^ expected `while`, `for`, `loop` or `{` after a label
+
+error: aborting due to 3 previous errors
 

src/test/ui/parser/require-parens-for-chained-comparison.rs

@@ -22,10 +22,12 @@ fn main() {
     let _ = f<'_, i8>();
     //~^ ERROR expected one of
     //~| HELP use `::<...>` instead of `<...>` to specify lifetime, type, or const arguments
+    //~| ERROR expected
 
     f<'_>();
     //~^ comparison operators cannot be chained
     //~| HELP use `::<...>` instead of `<...>` to specify lifetime, type, or const arguments
+    //~| ERROR expected
 
     let _ = f<u8>;
     //~^ ERROR comparison operators cannot be chained

src/test/ui/parser/require-parens-for-chained-comparison.stderr

@@ -53,6 +53,12 @@ help: use `::<...>` instead of `<...>` to specify lifetime, type, or const argum
 LL |     let _ = f::<u8, i8>();
    |              ++
 
+error: expected `while`, `for`, `loop` or `{` after a label
+  --> $DIR/require-parens-for-chained-comparison.rs:22:17
+   |
+LL |     let _ = f<'_, i8>();
+   |                 ^ expected `while`, `for`, `loop` or `{` after a label
+
 error: expected one of `.`, `:`, `;`, `?`, `else`, `for`, `loop`, `while`, `{`, or an operator, found `,`
   --> $DIR/require-parens-for-chained-comparison.rs:22:17
    |
@@ -64,8 +70,14 @@ help: use `::<...>` instead of `<...>` to specify lifetime, type, or const argum
 LL |     let _ = f::<'_, i8>();
    |              ++
 
+error: expected `while`, `for`, `loop` or `{` after a label
+  --> $DIR/require-parens-for-chained-comparison.rs:27:9
+   |
+LL |     f<'_>();
+   |         ^ expected `while`, `for`, `loop` or `{` after a label
+
 error: comparison operators cannot be chained
-  --> $DIR/require-parens-for-chained-comparison.rs:26:6
+  --> $DIR/require-parens-for-chained-comparison.rs:27:6
    |
 LL |     f<'_>();
    |      ^  ^
@@ -76,7 +88,7 @@ LL |     f::<'_>();
    |      ++
 
 error: comparison operators cannot be chained
-  --> $DIR/require-parens-for-chained-comparison.rs:30:14
+  --> $DIR/require-parens-for-chained-comparison.rs:32:14
    |
 LL |     let _ = f<u8>;
    |              ^  ^
@@ -84,5 +96,5 @@ LL |     let _ = f<u8>;
    = help: use `::<...>` instead of `<...>` to specify lifetime, type, or const arguments
    = help: or use `(...)` if you meant to specify fn arguments
 
-error: aborting due to 8 previous errors
+error: aborting due to 10 previous errors