I and @whisperity spent some time debugging a LIT test case using the
-std=c++11-or-later check_clang_tidy.py flag when the test had
fixits.
It turns out if the test wants to report a diagnostic into a header
file AND into the test file as well, one needs to first copy the header
somewhere under the build directory.
It needs to be copied since clang-tidy sorts the reports into
alphabetical order, thus to have a deterministic order relative to the
diagnostic in the header AND the diagnostic in the test cpp file.
There is more to this story.
The -std=c++11-or-later turns out executes the test with multiple
-std=XX version substitution and each execution will also have the
-fix tidy parameter. This means that the freshly copied header file I
stated in the previous paragraph gets fixed up and the very next tidy
execution will fail miserably.
Following @whisperity's advice, I'm leaving a reminder about such
shared state in the related doc comment.
These aren't the only two valid options for this argument.... Valid values are:
and of course all the specific standard versions: