[clang][AST] Assert that DependentNameType's Name and NNS are not null

[HighCommander4]

Also clarify the comment above DependentNameType::getIdentifier()

[llvmbot]

@llvm/pr-subscribers-clang

Author: Nathan Ridge (HighCommander4)

Changes

Also clarify the comment above DependentNameType::getIdentifier()

---

Full diff: https://github.com/llvm/llvm-project/pull/122418.diff

1 Files Affected:

• (modified) clang/include/clang/AST/Type.h (+5-6)

diff --git a/clang/include/clang/AST/Type.h b/clang/include/clang/AST/Type.h
index 09c98f642852fc..2ec59c2cb9a8f6 100644
--- a/clang/include/clang/AST/Type.h
+++ b/clang/include/clang/AST/Type.h
@@ -7035,17 +7035,16 @@ class DependentNameType : public TypeWithKeyword, public llvm::FoldingSetNode {
       : TypeWithKeyword(Keyword, DependentName, CanonType,
                         TypeDependence::DependentInstantiation |
                             toTypeDependence(NNS->getDependence())),
-        NNS(NNS), Name(Name) {}
+        NNS(NNS), Name(Name) {
+    assert(Name);
+  }
 
 public:
   /// Retrieve the qualification on this type.
   NestedNameSpecifier *getQualifier() const { return NNS; }
 
-  /// Retrieve the type named by the typename specifier as an identifier.
-  ///
-  /// This routine will return a non-NULL identifier pointer when the
-  /// form of the original typename was terminated by an identifier,
-  /// e.g., "typename T::type".
+  /// Retrieve the identifier that terminates this type name.
+  /// For example, "type" in "typename T::type".
   const IdentifierInfo *getIdentifier() const {
     return Name;
   }

[HighCommander4]

Context: I was confused by the comment above DependentNameType::getIdentifier(), which suggested the function only sometimes returns non-null, but I couldn't find any case where it would return null.

It turns out the comment dates back to a time when the type stored a PointerUnion<const IdentifierInfo *, const TemplateSpecializationType *>, and only returned non-null if an IdentifierInfo * was stored. That was changed in c392f37.

[mizvekov]

LGTM, Indeed a DependentNameType with no 'Name' doesn't make sense.