Fix some simple issues

Author: YexuanXiao

clang/include/clang/AST/Type.h

@@ -2262,7 +2262,7 @@ class alignas(TypeAlignment) Type : public ExtQualsTypeCommonBase {
     /// The "size_t" type.
     SizeT,
 
-    /// The "signed size_t" type.
+    /// The signed integer type corresponding to "size_t".
     SignedSizeT,
 
     /// The "ptrdiff_t" type.

clang/lib/AST/ASTContext.cpp

@@ -5239,7 +5239,7 @@ QualType ASTContext::getDependentBitIntType(bool IsUnsigned,
 
 QualType ASTContext::getPredefinedSugarType(uint32_t KD) const {
   using Kind = PredefinedSugarType::Kind;
-  auto getUnderlyingType = [](const ASTContext &Ctx, Kind KDI) -> QualType {
+  auto getCanonicalType = [](const ASTContext &Ctx, Kind KDI) -> QualType {
     switch (KDI) {
     case Kind::SizeT:
       return Ctx.getFromTargetType(Ctx.Target->getSizeType());
@@ -5251,7 +5251,7 @@ QualType ASTContext::getPredefinedSugarType(uint32_t KD) const {
     llvm_unreachable("unexpected kind");
   };
   auto *New = new (*this, alignof(PredefinedSugarType)) PredefinedSugarType(
-      static_cast<Kind>(KD), getUnderlyingType(*this, static_cast<Kind>(KD)));
+      static_cast<Kind>(KD), getCanonicalType(*this, static_cast<Kind>(KD)));
   Types.push_back(New);
   return QualType(New, 0);
 }
@@ -14565,7 +14565,8 @@ static QualType getCommonSugarTypeNode(ASTContext &Ctx, const Type *X,
                                       CDX);
   }
   case Type::PredefinedSugar:
-    // FIXME: Should this be reachable here?
+    assert(cast<PredefinedSugarType>(X)->getKind() !=
+           cast<PredefinedSugarType>(Y)->getKind());
     return QualType();
   }
   llvm_unreachable("Unhandled Type Class");

clang/lib/AST/ASTStructuralEquivalence.cpp

@@ -1485,9 +1485,6 @@ static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
     const auto *TP2 = cast<PredefinedSugarType>(T2);
     if (TP1->getKind() != TP2->getKind())
       return false;
-    else
-      assert(TP1->getCanonicalTypeInternal() ==
-             TP2->getCanonicalTypeInternal());
     break;
   }
   } // end switch

clang/lib/AST/Type.cpp

@@ -5633,4 +5633,4 @@ StringRef PredefinedSugarType::getName() const {
     return "__ptrdiff_t";
   }
   llvm_unreachable("unexpected kind");
-}
+}