[FixIt] Improve Source Ranges and Fix-It Hints for Unused Lambda Captures #106445

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -105,6 +105,13 @@ def note_replace_abs_function : Note<"use function '%0' instead">;
 def warn_pointer_abs : Warning<
   "taking the absolute value of %select{pointer|function|array}0 type %1 is suspicious">,
   InGroup<AbsoluteValue>;
+
+// Lambda capture diagnostics
+
+def err_invalid_lambda_capture_initializer_type : Error<
+    "invalid initializer type for lambda capture">;
+def err_expected_identifier_for_lambda_capture : Error<
+    "expected identifier for lambda capture">;
 
 def warn_max_unsigned_zero : Warning<
   "taking the max of "

clang/lib/Parse/ParseExprCXX.cpp

@@ -1269,7 +1269,9 @@ static void tryConsumeLambdaSpecifierToken(Parser &P,
     DeclEndLoc = SpecifierLoc;
   };
 
-  while (true) {
+  // Process lambda specifiers until an invalid token is found
+  while (P.getCurToken().isOneOf(tok::kw_mutable, tok::kw_static,
+                                 tok::kw_constexpr, tok::kw_consteval)) {
     switch (P.getCurToken().getKind()) {
     case tok::kw_mutable:
       ConsumeLocation(MutableLoc, 0);
@@ -1284,7 +1286,7 @@ static void tryConsumeLambdaSpecifierToken(Parser &P,
       ConsumeLocation(ConstevalLoc, 3);
       break;
     default:
-      return;
+      llvm_unreachable("Unexpected token in lambda specifier parsing");
     }
   }
 }

clang/test/CXX/temp/temp.decls/temp.variadic/init-capture.cpp

@@ -22,7 +22,7 @@ template<typename ...T> void f(T ...t) {
   // Not OK: can't expand 'x' outside its scope.
   weird((void)[&...x = t] {
     return &x; // expected-error {{unexpanded parameter pack 'x'}}
-  }...         // expected-error {{does not contain any unexpanded}}
+  }...         // expected-error {{pack expansion does not contain any unexpanded parameter packs}}
   );
 
   // OK, capture only one 'slice' of 'x'.
@@ -34,7 +34,7 @@ template<typename ...T> void f(T ...t) {
   // 'x' is not expanded by the outer '...', but 'T' is.
   weird((void)[&... x = t] {
     return T() + &x; // expected-error {{unexpanded parameter pack 'x'}}
-  }...               // expected-error {{does not contain any unexpanded}}
+  }...               // expected-error {{pack expansion does not contain any unexpanded parameter packs}}
   );
 }
 
@@ -43,7 +43,7 @@ static_assert(x<1,2,3>([](int a, int b, int c) { return 100 * a + 10 * b + c; })
 static_assert(x<1,2,3>([](int a, int b, int c) { return 100 * a + 10 * b + c; }) == 124); // expected-error {{failed}} \
                                                                                           // expected-note {{evaluates to '123 == 124'}}
 
-template<int ...a> constexpr auto y = [z = a...] (auto F) { return F(z...); }; // expected-error {{must appear before the name of the capture}}
+template<int ...a> constexpr auto y = [z = a...] (auto F) { return F(z...); }; // expected-error {{ellipsis in pack init-capture must appear before the name of the capture}}
 static_assert(y<1,2,3>([](int a, int b, int c) { return 100 * a + 10 * b + c; }) == 123);
 static_assert(y<1,2,3>([](int a, int b, int c) { return 100 * a + 10 * b + c; }) == 124); // expected-error {{failed}} \
                                                                                           // expected-note {{evaluates to '123 == 124'}}