Canonicalize UnaryTransformType types when they don't have a known underlying type.

Fixes https://llvm.org/bugs/show_bug.cgi?id=26014

Reviewed by Richard Smith.

llvm-svn: 264937

2 files changed, 47 insertions, 18 deletions

diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index 77e5087b8c7..aa9277cdc1a 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -4020,13 +4020,35 @@ QualType ASTContext::getUnaryTransformType(QualType BaseType,
                                            QualType UnderlyingType,
                                            UnaryTransformType::UTTKind Kind)
     const {
-  UnaryTransformType *Ty =
-    new (*this, TypeAlignment) UnaryTransformType (BaseType, UnderlyingType, 
-                                                   Kind,
-                                 UnderlyingType->isDependentType() ?
-                                 QualType() : getCanonicalType(UnderlyingType));
-  Types.push_back(Ty);
-  return QualType(Ty, 0);
+  UnaryTransformType *ut = nullptr;
+
+  if (BaseType->isDependentType()) {
+    // Look in the folding set for an existing type.
+    llvm::FoldingSetNodeID ID;
+    DependentUnaryTransformType::Profile(ID, getCanonicalType(BaseType), Kind);
+
+    void *InsertPos = nullptr;
+    DependentUnaryTransformType *Canon
+      = DependentUnaryTransformTypes.FindNodeOrInsertPos(ID, InsertPos);
+
+    if (!Canon) {
+      // Build a new, canonical __underlying_type(type) type.
+      Canon = new (*this, TypeAlignment)
+             DependentUnaryTransformType(*this, getCanonicalType(BaseType),
+                                         Kind);
+      DependentUnaryTransformTypes.InsertNode(Canon, InsertPos);
+    }
+    ut = new (*this, TypeAlignment) UnaryTransformType (BaseType,
+                                                        QualType(), Kind,
+                                                        QualType(Canon, 0));
+  } else {
+    QualType CanonType = getCanonicalType(UnderlyingType);
+    ut = new (*this, TypeAlignment) UnaryTransformType (BaseType,
+                                                        UnderlyingType, Kind,
+                                                        CanonType);
+  }
+  Types.push_back(ut);
+  return QualType(ut, 0);
 }
 
 /// getAutoType - Return the uniqued reference to the 'auto' type which has been
diff --git a/clang/lib/AST/Type.cpp b/clang/lib/AST/Type.cpp
index 74aa323dbc8..d3c7259c38d 100644
--- a/clang/lib/AST/Type.cpp
+++ b/clang/lib/AST/Type.cpp
@@ -2935,6 +2935,24 @@ void DependentDecltypeType::Profile(llvm::FoldingSetNodeID &ID,
   E->Profile(ID, Context, true);
 }
 
+UnaryTransformType::UnaryTransformType(QualType BaseType,
+                                       QualType UnderlyingType,
+                                       UTTKind UKind,
+                                       QualType CanonicalType)
+  : Type(UnaryTransform, CanonicalType, BaseType->isDependentType(),
+         BaseType->isInstantiationDependentType(),
+         BaseType->isVariablyModifiedType(),
+         BaseType->containsUnexpandedParameterPack())
+  , BaseType(BaseType), UnderlyingType(UnderlyingType), UKind(UKind)
+{}
+
+DependentUnaryTransformType::DependentUnaryTransformType(const ASTContext &C,
+                                                         QualType BaseType,
+                                                         UTTKind UKind)
+   : UnaryTransformType(BaseType, C.DependentTy, UKind, QualType())
+{}
+
+
 TagType::TagType(TypeClass TC, const TagDecl *D, QualType can)
   : Type(TC, can, D->isDependentType(), 
          /*InstantiationDependent=*/D->isDependentType(),
@@ -2951,17 +2969,6 @@ static TagDecl *getInterestingTagDecl(TagDecl *decl) {
   return decl;
 }
 
-UnaryTransformType::UnaryTransformType(QualType BaseType,
-                                       QualType UnderlyingType,
-                                       UTTKind UKind,
-                                       QualType CanonicalType)
-  : Type(UnaryTransform, CanonicalType, UnderlyingType->isDependentType(),
-         UnderlyingType->isInstantiationDependentType(),
-         UnderlyingType->isVariablyModifiedType(),
-         BaseType->containsUnexpandedParameterPack())
-  , BaseType(BaseType), UnderlyingType(UnderlyingType), UKind(UKind)
-{}
-
 TagDecl *TagType::getDecl() const {
   return getInterestingTagDecl(decl);
 }