[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).

(cherry picked from commit 62c221b5090c2e1d3ca408bcab6f69c4d9e175b7)

2 files changed, 21 insertions, 1 deletions

diff --git a/clang/lib/AST/DeclTemplate.cpp b/clang/lib/AST/DeclTemplate.cpp
index 95a2e26e0df..58ce49aab40 100755
--- a/clang/lib/AST/DeclTemplate.cpp
+++ b/clang/lib/AST/DeclTemplate.cpp
@@ -483,7 +483,10 @@ 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);
diff --git a/clang/test/CXX/temp/temp.constr/temp.constr.constr/partial-specializations.cpp b/clang/test/CXX/temp/temp.constr/temp.constr.constr/partial-specializations.cpp
index 1ea4da29ee9..9f3c21f9917 100644
--- a/clang/test/CXX/temp/temp.constr/temp.constr.constr/partial-specializations.cpp
+++ b/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