[clang] Include type specifiers in typo correction when checking isCX…

…XDeclarationSpecifiers.

- add more tests (the test added in 2f44846 is weak);
- improve the `MyTemplate<type_typo, int>();` case, with this patch, typo correction
  suggests the type decl, and no regressions found.

Differential Revision: https://reviews.llvm.org/D83025

clang/lib/Parse/ParseTentative.cpp

@@ -1110,8 +1110,9 @@ class TentativeParseCCC final : public CorrectionCandidateCallback {
 public:
   TentativeParseCCC(const Token &Next) {
     WantRemainingKeywords = false;
-    WantTypeSpecifiers = Next.isOneOf(tok::l_paren, tok::r_paren, tok::greater,
-                                      tok::l_brace, tok::identifier);
+    WantTypeSpecifiers =
+        Next.isOneOf(tok::l_paren, tok::r_paren, tok::greater, tok::l_brace,
+                     tok::identifier, tok::comma);
   }
 
   bool ValidateCandidate(const TypoCorrection &Candidate) override {

clang/test/Parser/cxx-template-decl.cpp

@@ -286,17 +286,3 @@ namespace PR45239 {
   template<int> int b;
   template<int> auto f() -> b<0>; // expected-error +{{}}
 }
-
-namespace NoCrashOnNullNNSTypoCorrection {
-
-int AddObservation(); // expected-note {{declared here}}
-
-template <typename T, typename... Args> // expected-note {{template parameter is declared here}}
-class UsingImpl {};
-class AddObservation {
-  using Using =
-    UsingImpl<AddObservationFn, const int>; // expected-error {{use of undeclared identifier 'AddObservationFn'; did you mean}} \
-                                               expected-error {{template argument for template type parameter must be a type}}
-};
-
-}

clang/test/SemaCXX/typo-correction.cpp

@@ -611,6 +611,41 @@ int bar() {
 }
 }
 
+namespace testIncludeTypeInTemplateArgument {
+template <typename T, typename U>
+void foo(T t = {}, U = {}); // expected-note {{candidate template ignored}}
+
+class AddObservation {}; // expected-note {{declared here}}
+int bar1() {
+  // should resolve to a class.
+  foo<AddObservationFn, int>(); // expected-error {{unknown type name 'AddObservationFn'; did you mean 'AddObservation'?}}
+
+  // should not resolve to a class.
+  foo(AddObservationFn, 1);    // expected-error-re {{use of undeclared identifier 'AddObservationFn'{{$}}}}
+  int a = AddObservationFn, b; // expected-error-re {{use of undeclared identifier 'AddObservationFn'{{$}}}}
+
+  int AddObservation; // expected-note 3{{declared here}}
+  // should resolve to a local variable.
+  foo(AddObservationFn, 1);    // expected-error {{use of undeclared identifier 'AddObservationFn'; did you mean}}
+  int c = AddObservationFn, d; // expected-error {{use of undeclared identifier 'AddObservationFn'; did you mean}}
+
+  // FIXME: would be nice to not resolve to a variable.
+  foo<AddObservationFn, int>(); // expected-error {{use of undeclared identifier 'AddObservationFn'; did you mean}} \
+                                   expected-error {{no matching function for call}}
+}
+} // namespace testIncludeTypeInTemplateArgument
+
+namespace testNoCrashOnNullNNSTypoCorrection {
+int AddObservation();
+template <typename T, typename... Args>
+class UsingImpl {};
+class AddObservation { // expected-note {{declared here}}
+  using Using =
+      // should resolve to a class.
+      UsingImpl<AddObservationFn, const int>; // expected-error {{unknown type name 'AddObservationFn'; did you mean}}
+};
+} // namespace testNoCrashOnNullNNSTypoCorrection
+
 namespace testNonStaticMemberHandling {
 struct Foo {
   bool usesMetadata;  // expected-note {{'usesMetadata' declared here}}