[clang-tools-extra] [include-cleaner] Report refs for enum constants used through namespace aliases (PR #106706)

[kadir çetinkaya via cfe-commits]

https://github.com/kadircet updated https://github.com/llvm/llvm-project/pull/106706

>From 55be096324da41a17612fb67bfa521a8f42c7874 Mon Sep 17 00:00:00 2001
From: Kadir Cetinkaya <kadircet at google.com>
Date: Fri, 30 Aug 2024 12:28:02 +0200
Subject: [PATCH] [include-cleaner] Report refs for enum constants used through
 namespace aliases

---
 .../include-cleaner/lib/WalkAST.cpp           | 23 ++++++++++++++++---
 .../include-cleaner/unittests/WalkASTTest.cpp |  3 +++
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/clang-tools-extra/include-cleaner/lib/WalkAST.cpp b/clang-tools-extra/include-cleaner/lib/WalkAST.cpp
index f7a2ebd5260681..8475577c565ad5 100644
--- a/clang-tools-extra/include-cleaner/lib/WalkAST.cpp
+++ b/clang-tools-extra/include-cleaner/lib/WalkAST.cpp
@@ -15,6 +15,7 @@
 #include "clang/AST/DeclTemplate.h"
 #include "clang/AST/Expr.h"
 #include "clang/AST/ExprCXX.h"
+#include "clang/AST/NestedNameSpecifier.h"
 #include "clang/AST/RecursiveASTVisitor.h"
 #include "clang/AST/TemplateBase.h"
 #include "clang/AST/TemplateName.h"
@@ -23,6 +24,7 @@
 #include "clang/Basic/IdentifierTable.h"
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Basic/Specifiers.h"
+#include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/STLFunctionalExtras.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/Casting.h"
@@ -146,9 +148,24 @@ class ASTWalker : public RecursiveASTVisitor<ASTWalker> {
     //
     // If it's an enum constant, it must be due to prior decl. Report references
     // to it when qualifier isn't a type.
-    if (llvm::isa<EnumConstantDecl>(FD)) {
-      if (!DRE->getQualifier() || DRE->getQualifier()->getAsNamespace())
-        report(DRE->getLocation(), FD);
+    auto QualifierIsNamepsaceOrNone = [&DRE]() {
+      const auto *Qual = DRE->getQualifier();
+      if (!Qual)
+        return true;
+      switch (Qual->getKind()) {
+      case NestedNameSpecifier::Namespace:
+      case NestedNameSpecifier::NamespaceAlias:
+      case NestedNameSpecifier::Global:
+        return true;
+      case NestedNameSpecifier::TypeSpec:
+      case NestedNameSpecifier::TypeSpecWithTemplate:
+      case NestedNameSpecifier::Super:
+      case NestedNameSpecifier::Identifier:
+        return false;
+      }
+    };
+    if (llvm::isa<EnumConstantDecl>(FD) && QualifierIsNamepsaceOrNone()) {
+      report(DRE->getLocation(), FD);
     }
     return true;
   }
diff --git a/clang-tools-extra/include-cleaner/unittests/WalkASTTest.cpp b/clang-tools-extra/include-cleaner/unittests/WalkASTTest.cpp
index 9286758cab081c..e45ea36f7938ea 100644
--- a/clang-tools-extra/include-cleaner/unittests/WalkASTTest.cpp
+++ b/clang-tools-extra/include-cleaner/unittests/WalkASTTest.cpp
@@ -534,6 +534,9 @@ TEST(WalkAST, Enums) {
   testWalk(R"(namespace ns { enum E { A = 42 }; }
               struct S { using ns::E::A; };)",
            "int e = S::^A;");
+  testWalk(R"(namespace ns { enum E { $explicit^A = 42 }; })",
+           "namespace z = ns; int e = z::^A;");
+  testWalk(R"(enum E { $explicit^A = 42 };)", "int e = ::^A;");
 }
 
 TEST(WalkAST, InitializerList) {