[clang-tidy] Tweak misc-static-assert fix in c++17

If C++17 mode is enabled and the assert doesn't have a string literal, we can emit a static assert with no message in favour of one with an empty message.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D97313

1 files changed, 4 insertions, 5 deletions

diff --git a/clang-tools-extra/clang-tidy/misc/StaticAssertCheck.cpp b/clang-tools-extra/clang-tidy/misc/StaticAssertCheck.cpp
index 2d6504c..e9ea69aa 100644
--- a/clang-tools-extra/clang-tidy/misc/StaticAssertCheck.cpp
+++ b/clang-tools-extra/clang-tidy/misc/StaticAssertCheck.cpp
@@ -107,17 +107,16 @@ void StaticAssertCheck::check(const MatchFinder::MatchResult &Result) {
     FixItHints.push_back(
         FixItHint::CreateReplacement(SourceRange(AssertLoc), "static_assert"));
 
-    std::string StaticAssertMSG = ", \"\"";
     if (AssertExprRoot) {
       FixItHints.push_back(FixItHint::CreateRemoval(
           SourceRange(AssertExprRoot->getOperatorLoc())));
       FixItHints.push_back(FixItHint::CreateRemoval(
           SourceRange(AssertMSG->getBeginLoc(), AssertMSG->getEndLoc())));
-      StaticAssertMSG = (Twine(", \"") + AssertMSG->getString() + "\"").str();
+      FixItHints.push_back(FixItHint::CreateInsertion(
+          LastParenLoc, (Twine(", \"") + AssertMSG->getString() + "\"").str()));
+    } else if (!Opts.CPlusPlus17) {
+      FixItHints.push_back(FixItHint::CreateInsertion(LastParenLoc, ", \"\""));
     }
-
-    FixItHints.push_back(
-        FixItHint::CreateInsertion(LastParenLoc, StaticAssertMSG));
   }
 
   diag(AssertLoc, "found assert() that could be replaced by static_assert()")