[PATCH] D122569: [lit] Support %if ... %else syntax for RUN lines

[Paul Robinson via Phabricator via llvm-commits]

probinson added a comment.

I see that for `%if feature {A} %else {B}` the space before the `%else` is not preserved in the result.
If there is no `%else` what happens? e.g., `XX %if feature {YY} ZZ`  Asking because I see no test case for this.

I take it the `%if` expressions take only lit feature keywords, like REQUIRES? No triple substrings, as allowed by UNSUPPORTED/XFAIL?
(I have a back-burner task to make all three of those be consistent, this would be a fourth situation.)

I actually agree with @delcypher that `RUN(feature):` seems cleaner and certainly handles the motivating case very well. But it is obviously less powerful, and I won't object to the `%if` solution.


Repository:
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  https://reviews.llvm.org/D122569/new/

https://reviews.llvm.org/D122569