I think Nathan might've been asking not only about what currently happens, but what we think should happen?
On Mon, Dec 12, 2022 at 7:11 PM chuanqi.xcq <yedeng...@linux.alibaba.com> wrote: > > Hi Nathan, > > > 1) Are these flags silently ignored, if no module output is to be > > generated? Or is some kind of diagnostic generated? > > Currently, clang will generate the unused-command-line-argument warning for > this case: > > ``` > argument unused during compilation: '-fmodule-output' > [-Wunused-command-line-argument] > ``` Is that consistent with `-o`? (I assume so, but don't know - I guess there aren't many cases where `-o` is unused (maybe `-fsyntax-only`), so that behavior might be a bit less well specified) > > 2) what happens if you specify both -- do you get two outputs, a > > diagnostic, or > is one silently selected? > > If someone specify both `-fmodule-output` and `-fmodule-output=/path`, > the `-fmodule-output=/path` will be selected always no matter what the order > is. This seems surprising/possibly wrong to me - do we have precedent from other flags to draw from? > And if multiple `-fmodule-output=/path` are specified, the last one will be > selected. > > > 3) What is the behaviour if compilation fails? Does nothing happen to the > > file > indicated (potentially leaving an older version there), or does the equivalent > of 'rm -f $MODULE.pcm' happen? > > The module file will be deleted. The behavior is the same with `-o`. > > Thanks, > Chuanqi > > > ------------------------------------------------------------------ > From:Nathan Sidwell <nat...@acm.org> > Send Time:2022年12月12日(星期一) 22:30 > To:Iain Sandoe <i...@sandoe.co.uk>; GCC Development <gcc@gcc.gnu.org> > Cc:Nathan Sidwell <nathanmsidw...@gmail.com>; Jonathan Wakely > <jwakely....@gmail.com>; David Blaikie <dblai...@gmail.com>; ben.boeckel > <ben.boec...@kitware.com>; chuanqi.xcq <yedeng...@linux.alibaba.com> > Subject:Re: Naming flag for specifying the output file name for Binary Module > Interface files > > On 12/9/22 12:33, Iain Sandoe wrote: > > Hello all. > > > >> On 9 Dec 2022, at 01:58, chuanqi.xcq <yedeng...@linux.alibaba.com> wrote: > >> > >> It looks like `-fmodule-file` is better from the discussion. So let's take > >> it. Thanks for everyone here > > > > So FAOD (after this discussion) Chuanqi's current patchset implements the > > following in clang: > > > > -fmodule-output > > > > - this causes the BMI to be saved in the CWG with the basename of the > > source file and a suffix of .pcm. > > > > -fmodule-output=<path> > > > > - this causes the BMI to be saved at the path specified. > > > > 1) Are these flags silently ignored, if no module output is to be generated? > Or > is some kind of diagnostic generated? > > 2) what happens if you specify both -- do you get two outputs, a diagnostic, > or > is one silently selected? > > 3) What is the behaviour if compilation fails? Does nothing happen to the > file > indicated (potentially leaving an older version there), or does the equivalent > of 'rm -f $MODULE.pcm' happen? > > nathan > > -- > Nathan Sidwell > >
