Use the -E flag (preprocess only) in test_standalone_system_headers #22815
Conversation
This test only checks header inclusion, so it doesn't need to link or even compile. This change makes this (still slow) test 5x faster.
| @@ -9365,12 +9365,12 @@ def test_standalone_system_headers(self): | |||
| if cxx_only: | |||
| create_file('a.cxx', inc) | |||
There was a problem hiding this comment.
why does this test do the inclusion twice in 2 different files?
There was a problem hiding this comment.
I guess so that we know the headers don't define global symbols (that would then cause link failures when two objects contain the same symbol). This change would obviously break that check, but I'm not sure how valuable it actually is.
There was a problem hiding this comment.
Ah right. In that case we can make the test even faster by including each file only once. Or just close this PR and keep the test as it is. I just noticed that the test was taking more than 300s and wondered why it was so slow.
There was a problem hiding this comment.
I think it might be reasonable to skip the double compilation + linking.
It looks like this was originally added in c3c9b6e, but it does seems like maybe overkill.
This test only checks header inclusion, so it doesn't need to link or even compile. This change makes this (still slow) test 5x faster.