[clang] [Clang][TypePrinter] Make printNestedNameSpecifier look at typedefs (PR #169364)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Aiden Grossman (boomanaiden154)

<details>
<summary>Changes</summary>

This is to resolve a regression caused by #<!-- -->168534.

Now when we have an anonymous object like a struct or union that has a typedef attached, we print the typedef name instead of listing it as anonymous.

---
Full diff: https://github.com/llvm/llvm-project/pull/169364.diff


2 Files Affected:

- (modified) clang/lib/AST/Decl.cpp (+3-1) 
- (modified) clang/unittests/AST/TypePrinterTest.cpp (+20) 


``````````diff
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 555aa5c050ffd..13919a56af0e8 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -1790,7 +1790,9 @@ void NamedDecl::printNestedNameSpecifier(raw_ostream &OS,
       else
         OS << *ND;
     } else if (const auto *RD = dyn_cast<RecordDecl>(DC)) {
-      if (!RD->getIdentifier())
+      if (TypedefNameDecl *Typedef = RD->getTypedefNameForAnonDecl())
+        OS << Typedef->getIdentifier()->getName();
+      else if (!RD->getIdentifier())
         OS << "(anonymous " << RD->getKindName() << ')';
       else
         OS << *RD;
diff --git a/clang/unittests/AST/TypePrinterTest.cpp b/clang/unittests/AST/TypePrinterTest.cpp
index 410ec021d6e72..7bf2bef5ac641 100644
--- a/clang/unittests/AST/TypePrinterTest.cpp
+++ b/clang/unittests/AST/TypePrinterTest.cpp
@@ -341,3 +341,23 @@ TEST(TypePrinter, NestedNameSpecifiers) {
         Policy.AnonymousTagLocations = false;
       }));
 }
+
+TEST(TypePrinter, NestedNameSpecifiersTypedef) {
+  constexpr char Code[] = R"cpp(
+    typedef union {
+      struct {
+        struct {
+          unsigned int baz;
+        } bar;
+      };
+    } foo;
+  )cpp";
+
+  ASSERT_TRUE(PrintedTypeMatches(
+      Code, {}, fieldDecl(hasName("bar"), hasType(qualType().bind("id"))),
+      "struct foo::(anonymous struct)::(unnamed)",
+      [](PrintingPolicy &Policy) {
+        Policy.FullyQualifiedName = true;
+        Policy.AnonymousTagLocations = false;
+      }));
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/169364