[llvm-dev] RFC: "REQUIRES: no*" considered harmful

[via llvm-dev]

> -----Original Message-----
> From: Michael Kruse [mailto:llvmdev at meinersbur.de]
> Sent: Wednesday, May 22, 2019 3:37 PM
> To: Robinson, Paul
> Cc: llvm-dev
> Subject: Re: [llvm-dev] RFC: "REQUIRES: no*" considered harmful
> 
> Good idea to remove these. Also because of their inconsistent spelling.

Thanks for the +1.  I should have noted here, these 'lit' attributes
were removed in r360603.
--paulr

> 
> Michael
> 
> Am Do., 9. Mai 2019 um 13:37 Uhr schrieb via llvm-dev <llvm-
> dev at lists.llvm.org>:
> >
> > Dear test fans,
> >
> > Recently a couple of cases came to light, where a test had the line
> >     REQUIRES: nowindows
> > with the obvious expectation that it would be disabled, but only for
> > the Windows platform.  Sadly, this is not true; the "no" prefix means
> > nothing to Lit.  I've already fixed one test, within Lit's own test
> > suite, and I've done a bunch of grepping to see what else is lurking.
> >
> > The various config scripts define feature keywords with "no" or "not_"
> > or "non-" prefixes in only a handful of cases.  And really these extra
> > keywords are unnecessary, because we can disable a test using the
> positive
> > form with UNSUPPORTED:.  And, I claim (with the obvious evidence of two
> > tests that fell into this trap) that having negative keywords for some
> > cases can mislead people and end up having entirely the wrong effect.
> >
> > I propose to eliminate the negative forms of the feature keywords and
> > modify all the affected tests to use UNSUPPORTED instead. Well actually
> > I'd modify the affected tests first, but you get the idea.
> >
> > There are 7 feature keywords that start with "no" or "not_" or "non-"
> > that I can find, and it's trivial to have only positive versions
> > (and in fact the last 4 already have positive versions):
> >     non-ms-sdk  (clang only)
> >     non-ps4-sdk (clang only)
> >     not_COFF    (llvm only)
> >     not_asan
> >     not_msan
> >     not_ubsan
> >     nozlib
> >
> > Very few in-tree tests are affected, and I'm happy to do that part.
> > I'm finding 9 tests in clang, 6 tests in LLVM, and 1 test in LLDB
> > that match the regex 'REQUIRES:.* no'.  (The LLDB test is the other
> > victim of "nowindows" that I've found.)
> >
> > If you believe this is a BAD idea, please speak up and explain why.
> > In the meantime I'll start putting together a patch set for this.
> >
> > Thanks,
> > --paulr
> >
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