[Concepts] Profile TypeConstraints in ProfileTemplateParameterList

Profile TypeConstraints in ProfileTemplateParameterList so we can distinguish
between partial specializations which differ in their TemplateParameterList
type constraints.

Recommit, now profiling the IDC so that we can deal with situations where the
TemplateArgsAsWritten are nullptr (happens when canonicalizing type constraints).

Author: saarraz

clang/lib/AST/DeclTemplate.cpp

@@ -488,7 +488,10 @@ static void ProfileTemplateParameterList(ASTContext &C,
     if (const auto *TTP = dyn_cast<TemplateTypeParmDecl>(D)) {
       ID.AddInteger(1);
       ID.AddBoolean(TTP->isParameterPack());
-      // TODO: Concepts: profile type-constraints.
+      ID.AddBoolean(TTP->hasTypeConstraint());
+      if (const TypeConstraint *TC = TTP->getTypeConstraint())
+        TC->getImmediatelyDeclaredConstraint()->Profile(ID, C,
+                                                        /*Canonical=*/true);
       continue;
     }
     const auto *TTP = cast<TemplateTemplateParmDecl>(D);

clang/test/CXX/temp/temp.constr/temp.constr.constr/partial-specializations.cpp

@@ -31,6 +31,23 @@ namespace class_templates
   // expected-note@-2{{during template argument deduction for class template partial specialization 'B<T *>' [with T = int *]}}
   // expected-note@-3{{during template argument deduction for class template partial specialization 'B<T **>' [with T = int]}}
   // expected-note@-4 2{{in instantiation of template class 'class_templates::B<int **>' requested here}}
+
+  template<typename T, typename U = double>
+  concept same_as = is_same<T, U>::value;
+
+  template<same_as<bool> T> requires A<T>::type
+  struct B<T*> {};
+  // expected-note@-1{{previous}}
+
+  template<same_as<bool> T> requires A<T>::type
+  struct B<T*> {};
+  // expected-error@-1{{redefinition}}
+
+  template<same_as T> requires A<T>::type
+  struct B<T*> {};
+
+  template<same_as<int> T> requires A<T>::type
+  struct B<T*> {};
 }
 
 namespace variable_templates