[PATCH] D20519: [clang-tidy] Ignore ADL-style using decls in unused-using-decls check.

[Haojian Wu via cfe-commits]

hokein created this revision.
hokein added a reviewer: alexfh.
hokein added a subscriber: cfe-commits.

http://reviews.llvm.org/D20519

Files:
  clang-tidy/misc/UnusedUsingDeclsCheck.cpp
  test/clang-tidy/misc-unused-using-decls.cpp

Index: test/clang-tidy/misc-unused-using-decls.cpp
===================================================================
--- test/clang-tidy/misc-unused-using-decls.cpp
+++ test/clang-tidy/misc-unused-using-decls.cpp
@@ -93,6 +93,14 @@
 DEFINE_INT(test);
 #undef DEFIND_INT
 
+namespace N1 {
+  struct S {};
+  template<int X> void f(S);
+}
+namespace N2 {
+  template<class T> void f(T t);
+}
+
 // ----- Usages -----
 void f(B b);
 void g() {
@@ -107,3 +115,7 @@
   cout << endl;
 }
 
+void ADL(N1::S s) {
+  using N2::f;
+  f<3>(s);
+}
Index: clang-tidy/misc/UnusedUsingDeclsCheck.cpp
===================================================================
--- clang-tidy/misc/UnusedUsingDeclsCheck.cpp
+++ clang-tidy/misc/UnusedUsingDeclsCheck.cpp
@@ -18,20 +18,9 @@
 namespace tidy {
 namespace misc {
 
-// A function that helps to tell whether a TargetDecl will be checked.
-// We only check a TargetDecl if :
-//   * The corresponding UsingDecl is not defined in macros or in class
-//     definitions.
-//   * Only variable, function and class types are considered.
+// A function that helps to tell whether a TargetDecl of a UsingDecl will be
+// checked. We only check variable, function and class types.
 static bool ShouldCheckDecl(const Decl *TargetDecl) {
-  // Ignores using-declarations defined in macros.
-  if (TargetDecl->getLocation().isMacroID())
-    return false;
-
-  // Ignores using-declarations defined in class definition.
-  if (isa<CXXRecordDecl>(TargetDecl->getDeclContext()))
-    return false;
-
   return isa<RecordDecl>(TargetDecl) || isa<ClassTemplateDecl>(TargetDecl) ||
          isa<FunctionDecl>(TargetDecl) || isa<VarDecl>(TargetDecl) ||
          isa<FunctionTemplateDecl>(TargetDecl);
@@ -49,6 +38,17 @@
 
 void UnusedUsingDeclsCheck::check(const MatchFinder::MatchResult &Result) {
   if (const auto *Using = Result.Nodes.getNodeAs<UsingDecl>("using")) {
+    // Ignores using-declarations defined in macros.
+    if (Using->getLocation().isMacroID())
+      return;
+    // Ignores using-declarations defined in class definitions.
+    if (isa<CXXRecordDecl>(Using->getDeclContext()))
+      return;
+    // Ignores using-declarations defined in function definitions to avoid
+    // arguement-dependent lookup.
+    if (isa<FunctionDecl>(Using->getDeclContext()))
+      return;
+
     UsingDeclContext Context(Using);
     Context.UsingDeclRange = CharSourceRange::getCharRange(
         Using->getLocStart(),


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