[clang-tools-extra] [include-cleaner] Mark RecordDecls referenced in UsingDecls as explicit (PR #106430)

[kadir çetinkaya via cfe-commits]

https://github.com/kadircet created https://github.com/llvm/llvm-project/pull/106430

We were reporting ambigious references from using declarations as user
can be depending on different overloads of a function just because they
are visible in the TU.
This doesn't apply to records, or primary templates as declaration being
referenced in such cases is unambigious, the ambiguity applies to
specializations though.

Hence this patch returns an explicit reference to record decls and
primary templates of those.


>From 89694986accf28acb6605214daa72dfe313017dd Mon Sep 17 00:00:00 2001
From: Kadir Cetinkaya <kadircet at google.com>
Date: Wed, 28 Aug 2024 20:30:08 +0200
Subject: [PATCH] [include-cleaner] Mark RecordDecls referenced in UsingDecls
 as explicit

We were reporting ambigious references from using declarations as user
can be depending on different overloads of a function just because they
are visible in the TU.
This doesn't apply to records, or primary templates as declaration being
referenced in such cases is unambigious, the ambiguity applies to
specializations though.

Hence this patch returns an explicit reference to record decls and
primary templates of those.
---
 clang-tools-extra/include-cleaner/lib/WalkAST.cpp     |  2 +-
 .../include-cleaner/unittests/WalkASTTest.cpp         | 11 ++++++++---
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/clang-tools-extra/include-cleaner/lib/WalkAST.cpp b/clang-tools-extra/include-cleaner/lib/WalkAST.cpp
index 598484d09712e5..5e6b862caf0d6c 100644
--- a/clang-tools-extra/include-cleaner/lib/WalkAST.cpp
+++ b/clang-tools-extra/include-cleaner/lib/WalkAST.cpp
@@ -203,7 +203,7 @@ class ASTWalker : public RecursiveASTVisitor<ASTWalker> {
   bool VisitUsingDecl(UsingDecl *UD) {
     for (const auto *Shadow : UD->shadows()) {
       auto *TD = Shadow->getTargetDecl();
-      auto IsUsed = TD->isUsed() || TD->isReferenced();
+      auto IsUsed = TD->isUsed() || TD->isReferenced() || !TD->getAsFunction();
       report(UD->getLocation(), TD,
              IsUsed ? RefType::Explicit : RefType::Ambiguous);
 
diff --git a/clang-tools-extra/include-cleaner/unittests/WalkASTTest.cpp b/clang-tools-extra/include-cleaner/unittests/WalkASTTest.cpp
index 6c8eacbff1cea3..9286758cab081c 100644
--- a/clang-tools-extra/include-cleaner/unittests/WalkASTTest.cpp
+++ b/clang-tools-extra/include-cleaner/unittests/WalkASTTest.cpp
@@ -255,7 +255,7 @@ TEST(WalkAST, TemplateSpecializationsFromUsingDecl) {
   // Class templates
   testWalk(R"cpp(
 namespace ns {
-template<class T> class $ambiguous^Z {};      // primary template
+template<class T> class $explicit^Z {};      // primary template
 template<class T> class $ambiguous^Z<T*> {};  // partial specialization
 template<> class $ambiguous^Z<int> {};        // full specialization
 }
@@ -265,7 +265,7 @@ template<> class $ambiguous^Z<int> {};        // full specialization
   // Var templates
   testWalk(R"cpp(
 namespace ns {
-template<class T> T $ambiguous^foo;      // primary template
+template<class T> T $explicit^foo;      // primary template
 template<class T> T $ambiguous^foo<T*>;  // partial specialization
 template<> int* $ambiguous^foo<int>;     // full specialization
 }
@@ -335,7 +335,12 @@ TEST(WalkAST, Using) {
   testWalk(R"cpp(
     namespace ns {
       template<class T>
-      class $ambiguous^Y {};
+      class $explicit^Y {};
+    })cpp",
+           "using ns::^Y;");
+  testWalk(R"cpp(
+    namespace ns {
+      class $explicit^Y {};
     })cpp",
            "using ns::^Y;");
   testWalk(R"cpp(