[clang-tidy] Ignore using-declarations defined in marcro in misc-unused-using-decls checks.

[hokein]

Fix code-style.

[djasper]

Looks good.

clang-tidy/misc/UnusedUsingDeclsCheck.cpp

38

nit: "in a macro" or "in macros".

40

nit: remove braces

[djasper]

clang-tidy/misc/UnusedUsingDeclsCheck.cpp

39

Thinking some more, maybe just use TargetDecl->getLocation().isMacroID()?

[hokein]

Address review comments.

[hokein]

clang-tidy/misc/UnusedUsingDeclsCheck.cpp

39

Good point. Using isMacroID is enough.

clang-tidy/misc/UnusedUsingDeclsCheck.cpp

void UnusedUsingDeclsCheck::check(const MatchFinder::MatchResult &Result) {
   if (const auto *Using = Result.Nodes.getNodeAs<UsingDecl>("using")) {
     // FIXME: Implement the correct behavior for using declarations with more
     // than one shadow.
     if (Using->shadow_size() != 1)
       return;
     const auto *TargetDecl =
         Using->shadow_begin()->getTargetDecl()->getCanonicalDecl();
 
+    // Ignores using-declarations defined in macro.
+    if (Result.SourceManager->isMacroBodyExpansion(TargetDecl->getLocStart()),
+        Result.SourceManager->isMacroBodyExpansion(TargetDecl->getLocEnd())) {
+      return;
+    }
+
     // Ignores using-declarations defined in class definition.
     if (isa<CXXRecordDecl>(TargetDecl->getDeclContext()))
       return;
 
     if (!isa<RecordDecl>(TargetDecl) && !isa<ClassTemplateDecl>(TargetDecl) &&
         !isa<FunctionDecl>(TargetDecl) && !isa<VarDecl>(TargetDecl) &&
         !isa<FunctionTemplateDecl>(TargetDecl))
       return;

test/clang-tidy/misc-unused-using-decls.cpp

 // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: using decl 'UnusedInstance' is unused
 // CHECK-FIXES: {{^}}// UnusedInstance
 using n::UnusedFunc; // UnusedFunc
 // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: using decl 'UnusedFunc' is unused
 // CHECK-FIXES: {{^}}// UnusedFunc
 using n::cout;
 using n::endl;
 
+#define DEFINE_INT(name)        \
+  namespace INT {               \
+  static const int _##name = 1; \
+  }                             \
+  using INT::_##name
+DEFINE_INT(test);
+#undef DEFIND_INT
+
 // ----- Usages -----
 void f(B b);
 void g() {
   vector<C> data;
   D::i = 1;
   F<int> f;
   void (*func)() = &G::func;
   int *i = &H::i;
   UsedInstance.i;
   UsedFunc();
   UsedTemplateFunc<int>();
   cout << endl;
 }
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