[Mesa-dev] [PATCH 01/24] configure.ac: Add CFLAG -Wno-missing-field-initializers (v3)

[Gert Wollny]

Am Montag, den 11.06.2018, 11:05 +0100 schrieb Eric Engestrom:
> On Monday, 2018-06-11 11:33:20 +0200, Gert Wollny wrote:
> > This warning is misleading: When a struct is partially initialized
> > without
> > assigning to the structure members by name, then the remaining
> > fields
> > will be zeroed out, and this warning will be issued (if enabled).
> > If, on the
> > other hand, the partial initialization is done by assigning to
> > named members,
> > the remaining structure elements may hold random data, but the
> > warning is not
> > issued. Since in Mesa the first approach to initialize structure
> > elements is
> > used very often, and it is usually assumed that the remaining
> > elements are
> > zeroed out, heeding this warning would be counter-productive.
> > 
> > v2: - add -Wno-missing-field-initializers to meson-build
> >     - fix empty line error
> >     (both Eric Engestrom)
> > 
> > v3: * check for -Wmissing-field-initializers warning and then
> > disable it
> >       because gcc and clang always accept -Wno-* (Dylan Baker)
> >     * Also disable this warning for C++
> > 
> > Reviewed-by: Marek Olšák <marek.olsak at amd.com> (v1)
> > Reviewed-by: Emil Velikov <emil.velikov at collabora.com> (v2)
> > Signed-off-by: Gert Wollny <gert.wollny at collabora.com>
> > ---
> >  configure.ac |  4 ++++
> >  meson.build  | 11 +++++++----
> >  2 files changed, 11 insertions(+), 4 deletions(-)
> > 
> > diff --git a/configure.ac b/configure.ac
> > index 75ee1a7c01..6a9e56f974 100644
> > --- a/configure.ac
> > +++ b/configure.ac
> > @@ -302,7 +302,10 @@ AX_CHECK_COMPILE_FLAG([-
> > Wall],                                 [CFLAGS="$CFLAGS
> >  AX_CHECK_COMPILE_FLAG([-Werror=implicit-function-declaration],
> > [CFLAGS="$CFLAGS -Werror=implicit-function-declaration"])
> >  AX_CHECK_COMPILE_FLAG([-Werror=missing-
> > prototypes],            [CFLAGS="$CFLAGS -Werror=missing-
> > prototypes"])
> >  AX_CHECK_COMPILE_FLAG([-Wmissing-
> > prototypes],                  [CFLAGS="$CFLAGS -Wmissing-
> > prototypes"])
> > +dnl Dylan Baker: gcc and clang always accepr -Wno-*, hence check
> > for the original warning, then set the no-* flag
> > +AX_CHECK_COMPILE_FLAG([-Wmissing-field-
> > initializers],          [CFLAGS="$CFLAGS -Wno-missing-field-
> > initializers"])
> >  AX_CHECK_COMPILE_FLAG([-fno-math-
> > errno],                       [CFLAGS="$CFLAGS -fno-math-errno"])
> > +
> >  AX_CHECK_COMPILE_FLAG([-fno-trapping-
> > math],                    [CFLAGS="$CFLAGS -fno-trapping-math"])
> >  AX_CHECK_COMPILE_FLAG([-
> > fvisibility=hidden],                   [VISIBILITY_CFLAGS="-
> > fvisibility=hidden"])
> >  
> > @@ -314,6 +317,7 @@ AX_CHECK_COMPILE_FLAG([-
> > Wall],                                 [CXXFLAGS="$CXXFL
> >  AX_CHECK_COMPILE_FLAG([-fno-math-
> > errno],                       [CXXFLAGS="$CXXFLAGS -fno-math-
> > errno"])
> >  AX_CHECK_COMPILE_FLAG([-fno-trapping-
> > math],                    [CXXFLAGS="$CXXFLAGS -fno-trapping-
> > math"])
> >  AX_CHECK_COMPILE_FLAG([-
> > fvisibility=hidden],                   [VISIBILITY_CXXFLAGS="-
> > fvisibility=hidden"])
> > +AX_CHECK_COMPILE_FLAG([-Wmissing-field-
> > initializers],          [CFLAGS="$CFLAGS -Wno-missing-field-
> > initializers"])
> >  AC_LANG_POP([C++])
> >  
> >  # Flags to help ensure that certain portions of the code -- and
> > only those
> > diff --git a/meson.build b/meson.build
> > index 160bbfa30b..668fa38328 100644
> > --- a/meson.build
> > +++ b/meson.build
> > @@ -760,12 +760,15 @@ endforeach
> >  
> >  # For some reason, the test for -Wno-foo always succeeds with gcc,
> > even if the
> >  # option is not supported. Hence, check for -Wfoo instead.
> > -if cpp.has_argument('-Wnon-virtual-dtor')
> > -  cpp_args += '-Wno-non-virtual-dtor'
> > -endif
> > +
> > +foreach a : ['non-virtual-dtor', 'missing-field-initializers']
> > +  if cpp.has_argument('-W' + a)
> > +    cpp_args += '-Wno-' + a
> > +  endif
> > +endforeach
> >  
> >  no_override_init_args = []
> > -foreach a : ['override-init', 'initializer-overrides']
> > +foreach a : ['override-init', 'initializer-overrides', 'missing-
> > field-initializers']
> 
> I'm not sure `no_override_init_args` is the right array to put
> `missing-field-initializers` in; maybe you should add a c_args to add
> everywhere?
Sorry, Dylan was talking about a list where the -Wno- flags are tested
so I picked this one, but there is of course the actual c_args list
where this should be added to, I'll send a correction later.

best, 
Gert


> Dylan, thoughts?
> 
> >    if cc.has_argument('-W' + a)
> >      no_override_init_args += '-Wno-' + a
> >    endif
> > -- 
> > 2.17.1
> > 
> 
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