On Fri, Jul 28, 2017 at 02:07:29PM +0000, Blower, Melanie wrote:
>
>
> fedor.sergeev added a comment.
>
> Hmm... I tried this patch and now the following worries me:
>
> - it passes -finclude-if-exists stdc-predef.h on all platforms (say,
> including my Solaris platform that has no system stdc-predef.h)
> - it searches all the paths, not just "system include" ones
>
> That essentially disallows user to have stdc-predef.h include in my own
> project, since there is a chance that this user header will be accidentally
> included by this hidden machinery.
>
> >> Yes, I recognize this problem. However, I don't know an acceptable way to
> >> solve it. Does anyone have a recommendation? I had tried putting angle
> >> brackets around the file name string to imply a system-only search but
> >> that didn't work: I guess the >angle brackets are taken to be part of the
> >> file name. I believe it's intentional that has_include doesn't recognize
> >> the angle, I see test cases that have __has_include( "<...") Quoting from
> >> the patch:
> // For standards compliance, clang will preinclude <stdc-predef.h>
> // -ffreestanding suppresses this behavior.
> CmdArgs.push_back("-finclude-if-exists");
> CmdArgs.push_back("<stdc-predef.h>"); // This doesn't work to restrict
> the search to system includes
> }
>
> >I could change the argument scanner for __has_include to recognize the angle
> >brackets -- would that be acceptable? Alternatively, I could change the
> >flag to be "finclude-if-exists" into "fsystem-include-if-exists". Then I
> >could create a new preprocessing keyword(is that the right term?)
> >__has_system_include and use that instead of __has_include.
>
> >I tried this test case with -c -E:
> >cat test1.c
> >#if __has_include( "stdio.h" )
> >#error it has stdio without angle // This is printed
> >#else
> >#error it does not have stdio without angle
> >#endif
>
> >#if __has_include( "<stdio.h>" )
According to:
https://clang.llvm.org/docs/LanguageExtensions.html
a proper syntax here is without "s:
#if __has_include(<stdio.h>)
regards,
Fedor.
> >#error it has stdio with angle
> >#else
> >#error it does not have stdio with angle // This is printed
> >#endif
>
> ] cat stdc-predef.h
> #error I was not expecting to see that
> ] bin/clang hello-world.c
> In file included from <built-in>:2:
> ./stdc-predef.h:1:2: error: I was not expecting to see this!
> #error I was not expecting to see this!
> ^
> 1 error generated.
> ]
>
>
> Repository:
> rL LLVM
>
> https://reviews.llvm.org/D34158
>
>
>
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