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

[Aiden Grossman via cfe-commits]

https://github.com/boomanaiden154 updated https://github.com/llvm/llvm-project/pull/169364

>From 4f075f52c7c0ca1c4248e5565e4f960eb61f098c Mon Sep 17 00:00:00 2001
From: Aiden Grossman <aidengrossman at google.com>
Date: Mon, 24 Nov 2025 16:58:02 +0000
Subject: [PATCH 1/3] [Clang][TypePrinter] Make printNestedNameSpecifier look
 at typedefs

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.
---
 clang/lib/AST/Decl.cpp                  |  4 +++-
 clang/unittests/AST/TypePrinterTest.cpp | 20 ++++++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)

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;
+      }));
+}

>From 5df8461b34ccf614915e057c7ee17b0674403c46 Mon Sep 17 00:00:00 2001
From: Aiden Grossman <aidengrossman at google.com>
Date: Mon, 24 Nov 2025 17:15:38 +0000
Subject: [PATCH 2/3] formatting

---
 clang/unittests/AST/TypePrinterTest.cpp | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/clang/unittests/AST/TypePrinterTest.cpp b/clang/unittests/AST/TypePrinterTest.cpp
index 7bf2bef5ac641..3cadf9b265bd1 100644
--- a/clang/unittests/AST/TypePrinterTest.cpp
+++ b/clang/unittests/AST/TypePrinterTest.cpp
@@ -355,8 +355,7 @@ TEST(TypePrinter, NestedNameSpecifiersTypedef) {
 
   ASSERT_TRUE(PrintedTypeMatches(
       Code, {}, fieldDecl(hasName("bar"), hasType(qualType().bind("id"))),
-      "struct foo::(anonymous struct)::(unnamed)",
-      [](PrintingPolicy &Policy) {
+      "struct foo::(anonymous struct)::(unnamed)", [](PrintingPolicy &Policy) {
         Policy.FullyQualifiedName = true;
         Policy.AnonymousTagLocations = false;
       }));

>From 5ef3e7be54cd7dae1c6a53e434a5c054d2eac1c9 Mon Sep 17 00:00:00 2001
From: Aiden Grossman <aidengrossman at google.com>
Date: Mon, 24 Nov 2025 17:35:35 +0000
Subject: [PATCH 3/3] feedback

---
 clang/lib/AST/Decl.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 13919a56af0e8..591457b1d66b4 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -1790,8 +1790,8 @@ void NamedDecl::printNestedNameSpecifier(raw_ostream &OS,
       else
         OS << *ND;
     } else if (const auto *RD = dyn_cast<RecordDecl>(DC)) {
-      if (TypedefNameDecl *Typedef = RD->getTypedefNameForAnonDecl())
-        OS << Typedef->getIdentifier()->getName();
+      if (TypedefNameDecl *TD = RD->getTypedefNameForAnonDecl())
+        OS << *TD;
       else if (!RD->getIdentifier())
         OS << "(anonymous " << RD->getKindName() << ')';
       else