[Concepts] Type Constraints

Add support for type-constraints in template type parameters.
Also add support for template type parameters as pack expansions (where the type constraint can now contain an unexpanded parameter pack).

Differential Revision: https://reviews.llvm.org/D44352

1 files changed, 10 insertions, 5 deletions

diff --git a/clang/lib/Sema/SemaTemplateDeduction.cpp b/clang/lib/Sema/SemaTemplateDeduction.cpp
index e626948cb5d..1b9f1b2144d 100644
--- a/clang/lib/Sema/SemaTemplateDeduction.cpp
+++ b/clang/lib/Sema/SemaTemplateDeduction.cpp
@@ -643,6 +643,10 @@ static TemplateParameter makeTemplateParameter(Decl *D) {
 
 /// If \p Param is an expanded parameter pack, get the number of expansions.
 static Optional<unsigned> getExpandedPackSize(NamedDecl *Param) {
+  if (auto *TTP = dyn_cast<TemplateTypeParmDecl>(Param))
+    if (TTP->isExpandedParameterPack())
+      return TTP->getNumExpansionParameters();
+
   if (auto *NTTP = dyn_cast<NonTypeTemplateParmDecl>(Param))
     if (NTTP->isExpandedParameterPack())
       return NTTP->getNumExpansionTypes();
@@ -4542,11 +4546,12 @@ Sema::DeduceAutoType(TypeLoc Type, Expr *&Init, QualType &Result,
 
   // Build template<class TemplParam> void Func(FuncParam);
   TemplateTypeParmDecl *TemplParam = TemplateTypeParmDecl::Create(
-      Context, nullptr, SourceLocation(), Loc, Depth, 0, nullptr, false, false);
+      Context, nullptr, SourceLocation(), Loc, Depth, 0, nullptr, false, false,
+      false);
   QualType TemplArg = QualType(TemplParam->getTypeForDecl(), 0);
   NamedDecl *TemplParamPtr = TemplParam;
   FixedSizeTemplateParameterListStorage<1, false> TemplateParamsSt(
-      Loc, Loc, TemplParamPtr, Loc, nullptr);
+      Context, Loc, Loc, TemplParamPtr, Loc, nullptr);
 
   QualType FuncParam =
       SubstituteDeducedTypeTransform(*this, TemplArg, /*UseTypeSugar*/false)
@@ -5276,9 +5281,8 @@ Sema::getMoreSpecializedPartialSpecialization(
       return nullptr;
     if (IsAtLeastAsConstrained(PS2, AC2, PS1, AC1, AtLeastAsConstrained2))
       return nullptr;
-    if (AtLeastAsConstrained1 == AtLeastAsConstrained2) {
+    if (AtLeastAsConstrained1 == AtLeastAsConstrained2)
       return nullptr;
-    }
     return AtLeastAsConstrained1 ? PS1 : PS2;
   }
 
@@ -5352,7 +5356,8 @@ bool Sema::isTemplateTemplateParameterAtLeastAsSpecializedAs(
     SFINAETrap Trap(*this);
 
     Context.getInjectedTemplateArgs(P, PArgs);
-    TemplateArgumentListInfo PArgList(P->getLAngleLoc(), P->getRAngleLoc());
+    TemplateArgumentListInfo PArgList(P->getLAngleLoc(),
+                                      P->getRAngleLoc());
     for (unsigned I = 0, N = P->size(); I != N; ++I) {
       // Unwrap packs that getInjectedTemplateArgs wrapped around pack
       // expansions, to form an "as written" argument list.