[PATCH] D51041: [clang-tidy] Don't run misc-unused-using-decls check in C++17.

[Haojian Wu via Phabricator via cfe-commits]

hokein created this revision.
hokein added a reviewer: ilya-biryukov.
Herald added a subscriber: xazax.hun.

It introduces some false positives which are non-trivial to fix.
Ignore running the check in C++17.


Repository:
  rCTE Clang Tools Extra

https://reviews.llvm.org/D51041

Files:
  clang-tidy/misc/UnusedUsingDeclsCheck.cpp
  test/clang-tidy/misc-unused-using-decls-cxx17.cpp


Index: test/clang-tidy/misc-unused-using-decls-cxx17.cpp
===================================================================
--- /dev/null
+++ test/clang-tidy/misc-unused-using-decls-cxx17.cpp
@@ -0,0 +1,15 @@
+// RUN: %check_clang_tidy %s misc-unused-using-decls %t -- -- -fno-delayed-template-parsing -std=gnu++17
+
+namespace ns {
+template <typename K, typename V>
+class KV {
+public:
+  KV(K, V);
+};
+}
+
+using ns::KV;
+
+void f() {
+  KV(1, 2);
+}
Index: clang-tidy/misc/UnusedUsingDeclsCheck.cpp
===================================================================
--- clang-tidy/misc/UnusedUsingDeclsCheck.cpp
+++ clang-tidy/misc/UnusedUsingDeclsCheck.cpp
@@ -29,6 +29,12 @@
 }
 
 void UnusedUsingDeclsCheck::registerMatchers(MatchFinder *Finder) {
+  // FIXME: make the check support C++17 or later. The check relies on the fact
+  // that the used declarations are visited after the "using" declaration, but
+  // it is not ture in C++17's template argument deduction.
+  if (!getLangOpts().CPlusPlus || getLangOpts().CPlusPlus17 ||
+      getLangOpts().CPlusPlus2a)
+    return;
   Finder->addMatcher(usingDecl(isExpansionInMainFile()).bind("using"), this);
   auto DeclMatcher = hasDeclaration(namedDecl().bind("used"));
   Finder->addMatcher(loc(enumType(DeclMatcher)), this);


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