[clang] 225b91e - Fix crash getting name of a template decl

[Aaron Ballman via cfe-commits]

Author: Tom Eccles
Date: 2022-04-22T13:03:28-04:00
New Revision: 225b91e6cbba31ff1ce787a152a67977d08fdcab

URL: https://github.com/llvm/llvm-project/commit/225b91e6cbba31ff1ce787a152a67977d08fdcab
DIFF: https://github.com/llvm/llvm-project/commit/225b91e6cbba31ff1ce787a152a67977d08fdcab.diff

LOG: Fix crash getting name of a template decl

NamedDecl::getIdentifier can return a nullptr when
DeclarationName::isIdentifier is false, which leads to a null pointer
dereference when TypePrinter::printTemplateId calls ->getName().

NamedDecl::getName does the same thing in the successful case and
returns an empty string in the failure case.

This crash affects the llvm 14 packages on llvm.org.

Added: 
    

Modified: 
    clang/lib/AST/TypePrinter.cpp
    clang/unittests/AST/TypePrinterTest.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/AST/TypePrinter.cpp b/clang/lib/AST/TypePrinter.cpp
index 32ca7643a7603..d2feb1c10f06c 100644
--- a/clang/lib/AST/TypePrinter.cpp
+++ b/clang/lib/AST/TypePrinter.cpp
@@ -1467,8 +1467,7 @@ void TypePrinter::printTemplateId(const TemplateSpecializationType *T,
     if (!Policy.SuppressScope)
       AppendScope(TD->getDeclContext(), OS, TD->getDeclName());
 
-    IdentifierInfo *II = TD->getIdentifier();
-    OS << II->getName();
+    OS << TD->getName();
   } else {
     T->getTemplateName().print(OS, Policy);
   }

diff  --git a/clang/unittests/AST/TypePrinterTest.cpp b/clang/unittests/AST/TypePrinterTest.cpp
index 7b44b1ecece24..12801a7018125 100644
--- a/clang/unittests/AST/TypePrinterTest.cpp
+++ b/clang/unittests/AST/TypePrinterTest.cpp
@@ -64,6 +64,22 @@ TEST(TypePrinter, TemplateId) {
       [](PrintingPolicy &Policy) { Policy.FullyQualifiedName = true; }));
 }
 
+TEST(TypePrinter, TemplateId2) {
+  std::string Code = R"cpp(
+      template <template <typename ...> class TemplatedType>
+      void func(TemplatedType<int> Param);
+    )cpp";
+  auto Matcher = parmVarDecl(hasType(qualType().bind("id")));
+
+  // Regression test ensuring we do not segfault getting the QualType as a
+  // string.
+  ASSERT_TRUE(PrintedTypeMatches(Code, {}, Matcher, "<int>",
+                                 [](PrintingPolicy &Policy) {
+                                   Policy.FullyQualifiedName = true;
+                                   Policy.PrintCanonicalTypes = true;
+                                 }));
+}
+
 TEST(TypePrinter, ParamsUglified) {
   llvm::StringLiteral Code = R"cpp(
     template <typename _Tp, template <typename> class __f>