Replace TypeLoc llvm::cast support to be well-defined.

The TypeLoc hierarchy used the llvm::cast machinery to perform undefined
behavior by casting pointers/references to TypeLoc objects to derived types
and then using the derived copy constructors (or even returning pointers to
derived types that actually point to the original TypeLoc object).

Some context is in this thread:
http://lists.cs.uiuc.edu/pipermail/llvmdev/2012-December/056804.html
Though it's spread over a few months which can be hard to read in the mail
archive.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@175462 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 18 insertions, 17 deletions

diff --git a/lib/Sema/TreeTransform.h b/lib/Sema/TreeTransform.h
index bacf6d5d9b..986e4323d8 100644
--- a/lib/Sema/TreeTransform.h
+++ b/lib/Sema/TreeTransform.h
@@ -2817,8 +2817,8 @@ TreeTransform<Derived>::TransformNestedNameSpecifierLoc(
       }
       // If the nested-name-specifier is an invalid type def, don't emit an
       // error because a previous error should have already been emitted.
-      TypedefTypeLoc* TTL = dyn_cast<TypedefTypeLoc>(&TL);
-      if (!TTL || !TTL->getTypedefNameDecl()->isInvalidDecl()) {
+      TypedefTypeLoc TTL = TL.getAs<TypedefTypeLoc>();
+      if (!TTL || !TTL.getTypedefNameDecl()->isInvalidDecl()) {
         SemaRef.Diag(TL.getBeginLoc(), diag::err_nested_name_spec_non_tag)
           << TL.getType() << SS.getRange();
       }
@@ -3326,9 +3326,10 @@ QualType
 TreeTransform<Derived>::TransformType(TypeLocBuilder &TLB, TypeLoc T) {
   switch (T.getTypeLocClass()) {
 #define ABSTRACT_TYPELOC(CLASS, PARENT)
-#define TYPELOC(CLASS, PARENT) \
-  case TypeLoc::CLASS: \
-    return getDerived().Transform##CLASS##Type(TLB, cast<CLASS##TypeLoc>(T));
+#define TYPELOC(CLASS, PARENT)                                                 \
+  case TypeLoc::CLASS:                                                         \
+    return getDerived().Transform##CLASS##Type(TLB,                            \
+                                               T.castAs<CLASS##TypeLoc>());
 #include "clang/AST/TypeLocNodes.def"
   }
 
@@ -3421,8 +3422,8 @@ TreeTransform<Derived>::TransformTypeInObjectScope(TypeLoc TL,
   QualType Result;
 
   if (isa<TemplateSpecializationType>(T)) {
-    TemplateSpecializationTypeLoc SpecTL
-      = cast<TemplateSpecializationTypeLoc>(TL);
+    TemplateSpecializationTypeLoc SpecTL =
+        TL.castAs<TemplateSpecializationTypeLoc>();
 
     TemplateName Template =
       getDerived().TransformTemplateName(SS,
@@ -3435,8 +3436,8 @@ TreeTransform<Derived>::TransformTypeInObjectScope(TypeLoc TL,
     Result = getDerived().TransformTemplateSpecializationType(TLB, SpecTL,
                                                               Template);
   } else if (isa<DependentTemplateSpecializationType>(T)) {
-    DependentTemplateSpecializationTypeLoc SpecTL
-      = cast<DependentTemplateSpecializationTypeLoc>(TL);
+    DependentTemplateSpecializationTypeLoc SpecTL =
+        TL.castAs<DependentTemplateSpecializationTypeLoc>();
 
     TemplateName Template
       = getDerived().RebuildTemplateName(SS,
@@ -3478,8 +3479,8 @@ TreeTransform<Derived>::TransformTypeInObjectScope(TypeSourceInfo *TSInfo,
 
   TypeLoc TL = TSInfo->getTypeLoc();
   if (isa<TemplateSpecializationType>(T)) {
-    TemplateSpecializationTypeLoc SpecTL
-      = cast<TemplateSpecializationTypeLoc>(TL);
+    TemplateSpecializationTypeLoc SpecTL =
+        TL.castAs<TemplateSpecializationTypeLoc>();
 
     TemplateName Template
     = getDerived().TransformTemplateName(SS,
@@ -3492,8 +3493,8 @@ TreeTransform<Derived>::TransformTypeInObjectScope(TypeSourceInfo *TSInfo,
     Result = getDerived().TransformTemplateSpecializationType(TLB, SpecTL,
                                                               Template);
   } else if (isa<DependentTemplateSpecializationType>(T)) {
-    DependentTemplateSpecializationTypeLoc SpecTL
-      = cast<DependentTemplateSpecializationTypeLoc>(TL);
+    DependentTemplateSpecializationTypeLoc SpecTL =
+        TL.castAs<DependentTemplateSpecializationTypeLoc>();
 
     TemplateName Template
       = getDerived().RebuildTemplateName(SS,
@@ -3959,7 +3960,7 @@ TreeTransform<Derived>::TransformFunctionTypeParam(ParmVarDecl *OldParm,
     // If we're substituting into a pack expansion type and we know the
     // length we want to expand to, just substitute for the pattern.
     TypeLoc OldTL = OldDI->getTypeLoc();
-    PackExpansionTypeLoc OldExpansionTL = cast<PackExpansionTypeLoc>(OldTL);
+    PackExpansionTypeLoc OldExpansionTL = OldTL.castAs<PackExpansionTypeLoc>();
 
     TypeLocBuilder TLB;
     TypeLoc NewTL = OldDI->getTypeLoc();
@@ -4025,7 +4026,7 @@ bool TreeTransform<Derived>::
 
         // Find the parameter packs that could be expanded.
         TypeLoc TL = OldParm->getTypeSourceInfo()->getTypeLoc();
-        PackExpansionTypeLoc ExpansionTL = cast<PackExpansionTypeLoc>(TL);
+        PackExpansionTypeLoc ExpansionTL = TL.castAs<PackExpansionTypeLoc>();
         TypeLoc Pattern = ExpansionTL.getPatternLoc();
         SemaRef.collectUnexpandedParameterPacks(Pattern, Unexpanded);
         assert(Unexpanded.size() > 0 && "Could not find parameter packs!");
@@ -7608,7 +7609,7 @@ TreeTransform<Derived>::TransformTypeTraitExpr(TypeTraitExpr *E) {
   for (unsigned I = 0, N = E->getNumArgs(); I != N; ++I) {
     TypeSourceInfo *From = E->getArg(I);
     TypeLoc FromTL = From->getTypeLoc();
-    if (!isa<PackExpansionTypeLoc>(FromTL)) {
+    if (!FromTL.getAs<PackExpansionTypeLoc>()) {
       TypeLocBuilder TLB;
       TLB.reserve(FromTL.getFullDataSize());
       QualType To = getDerived().TransformType(TLB, FromTL);
@@ -7627,7 +7628,7 @@ TreeTransform<Derived>::TransformTypeTraitExpr(TypeTraitExpr *E) {
     ArgChanged = true;
 
     // We have a pack expansion. Instantiate it.
-    PackExpansionTypeLoc ExpansionTL = cast<PackExpansionTypeLoc>(FromTL);
+    PackExpansionTypeLoc ExpansionTL = FromTL.castAs<PackExpansionTypeLoc>();
     TypeLoc PatternTL = ExpansionTL.getPatternLoc();
     SmallVector<UnexpandedParameterPack, 2> Unexpanded;
     SemaRef.collectUnexpandedParameterPacks(PatternTL, Unexpanded);