[PATCH] D20326: [clang-tidy] Fix a template function false positive in misc-unused-using-decls check.

[Haojian Wu via cfe-commits]

hokein updated this revision to Diff 57576.
hokein added a comment.

Create a  node matcher for UnresolvedLookupExpr.


http://reviews.llvm.org/D20326

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
@@ -16,6 +16,7 @@
  public:
   static int ii;
 };
+template <typename T> class J {};
 
 class Base {
  public:
@@ -29,6 +30,7 @@
 int UnusedFunc() { return 1; }
 template <typename T> int UsedTemplateFunc() { return 1; }
 template <typename T> int UnusedTemplateFunc() { return 1; }
+template <typename T> int UsedInTemplateFunc() { return 1; }
 
 class ostream {
 public:
@@ -70,6 +72,13 @@
 using n::cout;
 using n::endl;
 
+using n::UsedInTemplateFunc;
+using n::J;
+template <typename T> void Callee() {
+  J<T> j;
+  UsedInTemplateFunc<T>();
+}
+
 #define DEFINE_INT(name)        \
   namespace INT {               \
   static const int _##name = 1; \
Index: clang-tidy/misc/UnusedUsingDeclsCheck.cpp
===================================================================
--- clang-tidy/misc/UnusedUsingDeclsCheck.cpp
+++ clang-tidy/misc/UnusedUsingDeclsCheck.cpp
@@ -10,20 +10,29 @@
 #include "UnusedUsingDeclsCheck.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchersInternal.h"
 #include "clang/Lex/Lexer.h"
 
 using namespace clang::ast_matchers;
 
 namespace clang {
 namespace tidy {
 namespace misc {
 
+namespace {
+// FIXME: Move this node matcher to ASTMatcher.
+const internal::VariadicDynCastAllOfMatcher<Stmt, UnresolvedLookupExpr>
+    unresolvedLookupExpr;
+}
+
 void UnusedUsingDeclsCheck::registerMatchers(MatchFinder *Finder) {
   Finder->addMatcher(usingDecl(isExpansionInMainFile()).bind("using"), this);
   auto DeclMatcher = hasDeclaration(namedDecl().bind("used"));
   Finder->addMatcher(loc(recordType(DeclMatcher)), this);
   Finder->addMatcher(loc(templateSpecializationType(DeclMatcher)), this);
   Finder->addMatcher(declRefExpr().bind("used"), this);
+  Finder->addMatcher(callExpr(callee(unresolvedLookupExpr().bind("used"))),
+                     this);
 }
 
 void UnusedUsingDeclsCheck::check(const MatchFinder::MatchResult &Result) {
@@ -81,6 +90,13 @@
       removeFromFoundDecls(VD);
     }
   }
+  // Check the uninstantiated template function usage.
+  if (auto *ULE = Result.Nodes.getNodeAs<UnresolvedLookupExpr>("used")) {
+    for (auto I = ULE->decls_begin(), E = ULE->decls_end(); I != E; ++I) {
+      if (auto *USD = dyn_cast<UsingShadowDecl>(I.getDecl()))
+        removeFromFoundDecls(USD->getTargetDecl()->getCanonicalDecl());
+    }
+  }
 }
 
 void UnusedUsingDeclsCheck::removeFromFoundDecls(const Decl *D) {


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