[Concept] Fix incorrect check for containsUnexpandedParameterPack in CSE

We previously checked for containsUnexpandedParameterPack in CSEs by observing the property
in the converted arguments of the CSE. This may not work if the argument is an expanded
type-alias that contains a pack-expansion (see added test).

Check the as-written arguments when determining containsUnexpandedParameterPack and isInstantiationDependent.

(cherry picked from commit c83d9bedc0cc430dc620e7a807daeb985d390325)

4 files changed, 78 insertions, 21 deletions

diff --git a/clang/include/clang/AST/ExprConcepts.h b/clang/include/clang/AST/ExprConcepts.h
index 2a64326e860..271d487e2fc 100644
--- a/clang/include/clang/AST/ExprConcepts.h
+++ b/clang/include/clang/AST/ExprConcepts.h
@@ -63,6 +63,12 @@ protected:
                             ArrayRef<TemplateArgument> ConvertedArgs,
                             const ConstraintSatisfaction *Satisfaction);
 
+  ConceptSpecializationExpr(const ASTContext &C, ConceptDecl *NamedConcept,
+                            ArrayRef<TemplateArgument> ConvertedArgs,
+                            const ConstraintSatisfaction *Satisfaction,
+                            bool Dependent,
+                            bool ContainsUnexpandedParameterPack);
+
   ConceptSpecializationExpr(EmptyShell Empty, unsigned NumTemplateArgs);
 
 public:
@@ -76,6 +82,13 @@ public:
          const ConstraintSatisfaction *Satisfaction);
 
   static ConceptSpecializationExpr *
+  Create(const ASTContext &C, ConceptDecl *NamedConcept,
+         ArrayRef<TemplateArgument> ConvertedArgs,
+         const ConstraintSatisfaction *Satisfaction,
+         bool Dependent,
+         bool ContainsUnexpandedParameterPack);
+
+  static ConceptSpecializationExpr *
   Create(ASTContext &C, EmptyShell Empty, unsigned NumTemplateArgs);
 
   ArrayRef<TemplateArgument> getTemplateArguments() const {
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index 6d1db38e36c..1be72efe4de 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -756,12 +756,8 @@ canonicalizeImmediatelyDeclaredConstraint(const ASTContext &C, Expr *IDC,
       NewConverted.push_back(Arg);
   }
   Expr *NewIDC = ConceptSpecializationExpr::Create(
-      C, NestedNameSpecifierLoc(), /*TemplateKWLoc=*/SourceLocation(),
-      CSE->getConceptNameInfo(), /*FoundDecl=*/CSE->getNamedConcept(),
-      CSE->getNamedConcept(),
-      // Actually canonicalizing a TemplateArgumentLoc is difficult so we
-      // simply omit the ArgsAsWritten
-      /*ArgsAsWritten=*/nullptr, NewConverted, nullptr);
+      C, CSE->getNamedConcept(), NewConverted, nullptr,
+      CSE->isInstantiationDependent(), CSE->containsUnexpandedParameterPack());
 
   if (auto *OrigFold = dyn_cast<CXXFoldExpr>(IDC))
     NewIDC = new (C) CXXFoldExpr(OrigFold->getType(), SourceLocation(), NewIDC,
diff --git a/clang/lib/AST/ExprConcepts.cpp b/clang/lib/AST/ExprConcepts.cpp
index 76d57ed5d5b..b5a3686dc99 100644
--- a/clang/lib/AST/ExprConcepts.cpp
+++ b/clang/lib/AST/ExprConcepts.cpp
@@ -46,24 +46,12 @@ ConceptSpecializationExpr::ConceptSpecializationExpr(const ASTContext &C,
                    ASTConstraintSatisfaction::Create(C, *Satisfaction) :
                    nullptr) {
   setTemplateArguments(ConvertedArgs);
-}
-
-ConceptSpecializationExpr::ConceptSpecializationExpr(EmptyShell Empty,
-    unsigned NumTemplateArgs)
-    : Expr(ConceptSpecializationExprClass, Empty), ConceptReference(),
-      NumTemplateArgs(NumTemplateArgs) { }
-
-void ConceptSpecializationExpr::setTemplateArguments(
-    ArrayRef<TemplateArgument> Converted) {
-  assert(Converted.size() == NumTemplateArgs);
-  std::uninitialized_copy(Converted.begin(), Converted.end(),
-                          getTrailingObjects<TemplateArgument>());
   bool IsInstantiationDependent = false;
   bool ContainsUnexpandedParameterPack = false;
-  for (const TemplateArgument& Arg : Converted) {
-    if (Arg.isInstantiationDependent())
+  for (const TemplateArgumentLoc& ArgLoc : ArgsAsWritten->arguments()) {
+    if (ArgLoc.getArgument().isInstantiationDependent())
       IsInstantiationDependent = true;
-    if (Arg.containsUnexpandedParameterPack())
+    if (ArgLoc.getArgument().containsUnexpandedParameterPack())
       ContainsUnexpandedParameterPack = true;
     if (ContainsUnexpandedParameterPack && IsInstantiationDependent)
       break;
@@ -80,6 +68,18 @@ void ConceptSpecializationExpr::setTemplateArguments(
          "should not be value-dependent");
 }
 
+ConceptSpecializationExpr::ConceptSpecializationExpr(EmptyShell Empty,
+    unsigned NumTemplateArgs)
+    : Expr(ConceptSpecializationExprClass, Empty), ConceptReference(),
+      NumTemplateArgs(NumTemplateArgs) { }
+
+void ConceptSpecializationExpr::setTemplateArguments(
+    ArrayRef<TemplateArgument> Converted) {
+  assert(Converted.size() == NumTemplateArgs);
+  std::uninitialized_copy(Converted.begin(), Converted.end(),
+                          getTrailingObjects<TemplateArgument>());
+}
+
 ConceptSpecializationExpr *
 ConceptSpecializationExpr::Create(const ASTContext &C,
                                   NestedNameSpecifierLoc NNS,
@@ -98,6 +98,39 @@ ConceptSpecializationExpr::Create(const ASTContext &C,
                                                 ConvertedArgs, Satisfaction);
 }
 
+ConceptSpecializationExpr::ConceptSpecializationExpr(
+    const ASTContext &C, ConceptDecl *NamedConcept,
+    ArrayRef<TemplateArgument> ConvertedArgs,
+    const ConstraintSatisfaction *Satisfaction, bool Dependent,
+    bool ContainsUnexpandedParameterPack)
+    : Expr(ConceptSpecializationExprClass, C.BoolTy, VK_RValue, OK_Ordinary,
+           /*TypeDependent=*/false,
+           /*ValueDependent=*/!Satisfaction, Dependent,
+           ContainsUnexpandedParameterPack),
+      ConceptReference(NestedNameSpecifierLoc(), SourceLocation(),
+                       DeclarationNameInfo(), NamedConcept,
+                       NamedConcept, nullptr),
+      NumTemplateArgs(ConvertedArgs.size()),
+      Satisfaction(Satisfaction ?
+                   ASTConstraintSatisfaction::Create(C, *Satisfaction) :
+                   nullptr) {
+  setTemplateArguments(ConvertedArgs);
+}
+
+ConceptSpecializationExpr *
+ConceptSpecializationExpr::Create(const ASTContext &C,
+                                  ConceptDecl *NamedConcept,
+                                  ArrayRef<TemplateArgument> ConvertedArgs,
+                                  const ConstraintSatisfaction *Satisfaction,
+                                  bool Dependent,
+                                  bool ContainsUnexpandedParameterPack) {
+  void *Buffer = C.Allocate(totalSizeToAlloc<TemplateArgument>(
+                                ConvertedArgs.size()));
+  return new (Buffer) ConceptSpecializationExpr(
+      C, NamedConcept, ConvertedArgs, Satisfaction, Dependent,
+      ContainsUnexpandedParameterPack);
+}
+
 ConceptSpecializationExpr *
 ConceptSpecializationExpr::Create(ASTContext &C, EmptyShell Empty,
                                   unsigned NumTemplateArgs) {
diff --git a/clang/test/CXX/expr/expr.prim/expr.prim.id/p3.cpp b/clang/test/CXX/expr/expr.prim/expr.prim.id/p3.cpp
index fb3978240af..30ec2a3ab70 100644
--- a/clang/test/CXX/expr/expr.prim/expr.prim.id/p3.cpp
+++ b/clang/test/CXX/expr/expr.prim/expr.prim.id/p3.cpp
@@ -183,3 +183,18 @@ concept C8 = sizeof(T) > sizeof(U);
 template<typename... T>
 constexpr bool B8 = C8<T...>;
 // expected-error@-1{{pack expansion used as argument for non-pack parameter of concept}}
+
+
+// Make sure we correctly check for containsUnexpandedParameterPack
+
+template<typename T>
+concept C9 = true;
+
+template <typename Fn, typename... Args>
+using invoke = typename Fn::template invoke<Args...>;
+
+template <typename C, typename... L>
+// The converted argument here will not containsUnexpandedParameterPack, but the
+// as-written one will.
+requires (C9<invoke<C, L>> &&...)
+struct S { };