[clang-tidy] Fix diag message for catch-by-value

[fgross]

Summary

catch (std::exception ex)
{
}

Was flagged with "catch handler catches a pointer value".

[aaron.ballman]

This change is missing test cases.

[fgross]

Updated test case.

[aaron.ballman]

LGTM, thank you!

clang-tidy/misc/ThrowByValueCatchByReferenceCheck.cpp

if (CheckAnonymousTemporaries) {
     if (emit)
       diag(subExpr->getLocStart(),
            "throw expression should throw anonymous temporary values instead");
   }
 }
 
 void ThrowByValueCatchByReferenceCheck::diagnoseCatchLocations(
     const CXXCatchStmt *catchStmt, ASTContext &context) {
-  const char *diagMsgCatchReference = "catch handler catches a pointer value; "
-                                      "should throw a non-pointer value and "
-                                      "catch by reference instead";
   if (!catchStmt)
     return;
   auto caughtType = catchStmt->getCaughtType();
   if (caughtType.isNull())
     return;
   auto *varDecl = catchStmt->getExceptionDecl();
   if (const auto *PT = caughtType.getCanonicalType()->getAs<PointerType>()) {
+    const char *diagMsgCatchReference = "catch handler catches a pointer value; "
+                                        "should throw a non-pointer value and "
+                                        "catch by reference instead";
     // We do not diagnose when catching pointer to strings since we also allow
     // throwing string literals.
     if (!PT->getPointeeType()->isAnyCharacterType())
       diag(varDecl->getLocStart(), diagMsgCatchReference);
   } else if (!caughtType->isReferenceType()) {
-    // If it's not a pointer and not a reference then it must be thrown "by
+    const char *diagMsgCatchReference = "catch handler catches by value; "
+                                        "should catch by reference instead";
+    // If it's not a pointer and not a reference then it must be caught "by
     // value". In this case we should emit a diagnosis message unless the type
     // is trivial.
     if (!caughtType.isTrivialType(context))
       diag(varDecl->getLocStart(), diagMsgCatchReference);
   }
 }
 
 } // namespace misc
 } // namespace tidy
 } // namespace clang