Re: [PATCH-for-8.0] block/dmg: Ignore C99 prototype declaration mismatch from <lzfse.h>

[Philippe Mathieu-Daudé]

+Marc-André & Paolo

On 27/3/23 19:08, Stefan Weil wrote:
> Am 27.03.23 um 17:13 schrieb Philippe Mathieu-Daudé:
>
> > When liblzfe (Apple LZFSE compression library) is present
> > (for example installed via 'brew') on Darwin, QEMU build
> > fails as:
> >
> >    Has header "lzfse.h" : YES
> >    Library lzfse found: YES
> >
> >      Dependencies
> >        lzo support                  : NO
> >        snappy support               : NO
> >        bzip2 support                : YES
> >        lzfse support                : YES
> >        zstd support                 : YES 1.5.2
> >
> >      User defined options
> >        dmg                          : enabled
> >        lzfse                        : enabled
> >
> >    [221/903] Compiling C object libblock.fa.p/block_dmg-lzfse.c.o
> >    FAILED: libblock.fa.p/block_dmg-lzfse.c.o
> >    /opt/homebrew/Cellar/lzfse/1.0/include/lzfse.h:56:43: error: this 
> > function declaration is not a prototype [-Werror,-Wstrict-prototypes]
> >    LZFSE_API size_t lzfse_encode_scratch_size();
> >                                              ^
> >                                               void
> >    /opt/homebrew/Cellar/lzfse/1.0/include/lzfse.h:94:43: error: this 
> > function declaration is not a prototype [-Werror,-Wstrict-prototypes]
> >    LZFSE_API size_t lzfse_decode_scratch_size();
> >                                              ^
> >                                               void
> >    2 errors generated.
> >    ninja: build stopped: subcommand failed.
> >
> > This issue has been reported in the lzfse project in 2016:
> > https://github.com/lzfse/lzfse/issues/3#issuecomment-226574719
> >
> > Since the project seems unmaintained, simply ignore the
> > strict-prototypes warning check for the <lzfse.h> header,
> > similarly to how we deal with the GtkItemFactoryCallback
> > prototype from <gtk/gtkitemfactory.h>, indirectly included
> > by <gtk/gtk.h>.
> >
> > Cc: Julio Faracco <jcfaracco@gmail.com>
> > Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> > ---
> >   block/dmg-lzfse.c | 5 +++++
> >   1 file changed, 5 insertions(+)
> >
> > diff --git a/block/dmg-lzfse.c b/block/dmg-lzfse.c
> > index 6798cf4fbf..0abc970bf6 100644
> > --- a/block/dmg-lzfse.c
> > +++ b/block/dmg-lzfse.c
> > @@ -23,7 +23,12 @@
> >    */
> >   #include "qemu/osdep.h"
> >   #include "dmg.h"
> > +
> > +/* Work around an -Wstrict-prototypes warning in LZFSE headers */
>
>
> "Work around a -Wstrict-prototypes" ("a" instead of "an")?
>
>
> > +#pragma GCC diagnostic push
> > +#pragma GCC diagnostic ignored "-Wstrict-prototypes"
> >   #include <lzfse.h>
> > +#pragma GCC diagnostic pop
> >   static int dmg_uncompress_lzfse_do(char *next_in, unsigned int 
> > avail_in,
> >                                      char *next_out, unsigned int 
> > avail_out)
>
>
> The warning can also be suppressed if the build uses `-isystem 
> /opt/homebrew/include` instead of `-I/opt/homebrew/include` as I just 
> have tested.

IIUC by design meson only allows including *relative* directories,
and manage the system ones:
https://mesonbuild.com/Include-directories.html

> If we can find a solution how to implement that I thing it would look 
> nicer. Technically the patch looks good.
>
> Reviewed-by: Stefan Weil <sw@weilnetz.de>

Thanks!