[PATCH] Support/Unix: use lambda function to fix building errors with clang

[Mauro Rossi via llvm-commits]

Hi Pavel,

Il giorno lun 16 lug 2018 alle ore 19:14 Pavel Labath <labath at google.com>
ha scritto:

> I think all/most systems have open(2) defined as a variadic (...)
> function, so that can't be the only reason why this is failing for
> you. There must be something more which is specific to your platform.
> Nevertheless, the workaround is not bad, so there's no harm in
>
changing this. Some people would even prefer the lambda based syntax.
>

We are using basically the same Build System/compilers of AOSP,
it seam that just using clang can produce the error because of behavior
different from gcc.
In some comments in the web behaviors of gcc and clang were described as
different.

If you are also using clang, are you using the clang version with AOSP
(8.1.0_r33 at the time of reporting)
I propose to check in order to identify root cause, then evaluate how to
proceed.

Mauro



> On Sun, 8 Jul 2018 at 21:28, Mauro Rossi <issor.oruam at gmail.com> wrote:
> >
> > From: Chih-Wei Huang <cwhuang at linux.org.tw>
> >
> > The ::open() function has unlimited arguments. Seems the compiler can't
> > infer the template argument from it:
> >
> > external/llvm70/lib/Support/Unix/Path.inc:770:19: error: no matching
> function for call to 'RetryAfterSignal'
> >   if ((ResultFD = sys::RetryAfterSignal(-1, ::open, P.begin(),
> OpenFlags, Mode)) <
> >                   ^~~~~~~~~~~~~~~~~~~~~
> > external/llvm70/lib/Support/../../include/llvm/Support/Errno.h:34:13:
> note: candidate template ignored: couldn't infer template argument 'Fun'
> > inline auto RetryAfterSignal(const FailT &Fail, const Fun &F,
> >             ^
> > 1 error generated.
> >
> > To avoid that, use a lambda function to wrap the ::open() function.
> > ---
> >  lib/Support/Unix/Path.inc    | 4 ++--
> >  lib/Support/Unix/Process.inc | 2 +-
> >  2 files changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/lib/Support/Unix/Path.inc b/lib/Support/Unix/Path.inc
> > index b8fea5bda4f..44a8b981c48 100644
> > --- a/lib/Support/Unix/Path.inc
> > +++ b/lib/Support/Unix/Path.inc
> > @@ -766,8 +766,8 @@ std::error_code openFile(const Twine &Name, int
> &ResultFD,
> >
> >    SmallString<128> Storage;
> >    StringRef P = Name.toNullTerminatedStringRef(Storage);
> > -  if ((ResultFD = sys::RetryAfterSignal(-1, ::open, P.begin(),
> OpenFlags, Mode)) <
> > -      0)
> > +  auto openfun([&] { return ::open(P.begin(), OpenFlags, Mode); });
> > +  if ((ResultFD = sys::RetryAfterSignal(-1, openfun)) < 0)
> >      return std::error_code(errno, std::generic_category());
> >  #ifndef O_CLOEXEC
> >    if (!(Flags & OF_ChildInherit)) {
> > diff --git a/lib/Support/Unix/Process.inc b/lib/Support/Unix/Process.inc
> > index fa515d44f3f..1111cd2fe2c 100644
> > --- a/lib/Support/Unix/Process.inc
> > +++ b/lib/Support/Unix/Process.inc
> > @@ -211,7 +211,7 @@ std::error_code
> Process::FixupStandardFileDescriptors() {
> >      assert(errno == EBADF && "expected errno to have EBADF at this
> point!");
> >
> >      if (NullFD < 0) {
> > -      if ((NullFD = RetryAfterSignal(-1, ::open, "/dev/null", O_RDWR))
> < 0)
> > +      if ((NullFD = RetryAfterSignal(-1, [] { return
> ::open("/dev/null", O_RDWR); })) < 0)
> >          return std::error_code(errno, std::generic_category());
> >      }
> >
> > --
> > 2.17.1
> >
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20180717/5fcfe14c/attachment.html>