[libvirt PATCH 342/351] meson: add syntax-check

[Pavel Hrdina]

On Tue, Jul 28, 2020 at 03:08:11PM +0100, Daniel P. Berrangé wrote:
> On Tue, Jul 28, 2020 at 04:04:39PM +0200, Pavel Hrdina wrote:
> > On Tue, Jul 28, 2020 at 03:48:29PM +0200, Peter Krempa wrote:
> > > On Thu, Jul 16, 2020 at 11:59:38 +0200, Pavel Hrdina wrote:
> > > > Signed-off-by: Pavel Hrdina <phrdina at redhat.com>
> > > > ---
> > > >  build-aux/Makefile.in                         |  9 +++
> > > >  .../Makefile.nonreentrant                     |  0
> > > >  build-aux/meson.build                         | 30 +++++++++
> > > >  build-aux/syntax-check.mk                     | 62 +++++++++----------
> > > >  meson.build                                   |  2 +
> > > >  5 files changed, 72 insertions(+), 31 deletions(-)
> > > >  create mode 100644 build-aux/Makefile.in
> > > >  rename Makefile.nonreentrant => build-aux/Makefile.nonreentrant (100%)
> > > >  create mode 100644 build-aux/meson.build
> > > 
> > > [...]
> > > 
> > > > +make_prog = find_program('make')
> > > > +
> > > > +# There is no way how to pass value to -j using run_target so let's use
> > > > +# it without any value to run all tests in parallel.
> > > > +run_target(
> > > > +  'syntax-check',
> > > > +  command: [
> > > > +    make_prog, '-C', meson.current_build_dir(), '-j', 'syntax-check',
> > > > +  ],
> > > 
> > > While I do run syntax check with unlimited '-j'. I don't think it's
> > > entirely cool to impose that on everybody. Specifically overcommiting
> > > the system is not cool. Since meson is automagically scaling can't we
> > > use the meson-detected cpu number here?
> > 
> > Unfortunately no, that was the first thing I was trying to figure out
> > by going through meson code as well. It's not ideal I know.
> > 
> > Other options are to not use -j at all which is no-go or we can add some
> > code to detect the available number of CPUs. But again it would not
> > reflect the fact if user runs 'ninja -j N'.
> 
> In libosinfo we put "syntax-check" as part of the unit tests, rather
> than as a separate meson target. With that you don't need to pass
> -j to syntax-check, because other unit tests are running in parallel
> already, and chances are syntax-check will finish first even when
> serialized.

That was my idea as well, but I know that we don't want to run
syntax-check in downstream packaging as it usually fails because of
outdated tools or GCC or other bit's involved in syntax check.

On the other hand we would have syntax-check part of the meson dist
command which is equivalent to make distcheck. Not sure if desired.

To solve the issue with downstream packaging meson supports labels by
using 'suite' argument when calling test() function. We can use
suite: 'syntax-check' for this purpose and in spec file we can have this
line:

    VIR_TEST_DEBUG=1 %meson_test --no-suite syntax-check

With all that in mind, running 'meson test' or 'ninja test' will show
that our syntax-check running using single thread takes really long.

On my box all the whole test suite without syntax-check takes 5.793s
so let's say 6s but the syntax-check part takes 24.716s.

I don't think we want to do that.

Pavel
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