Re: io.c incompatible pointer between public.read_func and ssize_t(*)() with c23

[Jeffrey Cliff]

Of course.

* this also occurs on main / c190576f

* read in this question is just read(2)
       ssize_t read(int fd, void buf[.count], size_t count);

* interestingly, it seems like gcc is smart enough to figure out what
the type read_func needs without explicit casting(?) -- ie just
getting rid of explicit cast allows not only compile, but all tests to
work(?) and gawk seems to run fine

so one possible fix is just something like

# git diff c190576fd345d9c098901061f0fd4164a7bfc87f io.c
diff --git a/io.c b/io.c
index 3943c5a9..54abf110 100644
--- a/io.c
+++ b/io.c
@@ -3388,7 +3388,12 @@ iop_alloc(int fd, const char *name, int errno_val)

        iop->public.fd = fd;
        iop->public.name = name;
-       iop->public.read_func = ( ssize_t(*)() ) read;
+       #if   __STDC_VERSION__  >= 202311L
+       iop->public.read_func = read;
+        #else
+        iop->public.read_func = ( (ssize_t(*)() ) read;
+        #endif
+
        iop->valid = false;
        iop->errcode = errno_val;


On Sat, Aug 10, 2024 at 12:07 PM <arnold@skeeve.com> wrote:
>
> Hi.
>
> Thanks for the report. I recommend not using -std=gnu23. I have to
> support many older compilers, so gawk purposely is not expected
> to follow the latest standards.
>
> Thanks,
>
> Arnold
>
> Jeffrey Cliff <jeffrey.cliff@gmail.com> wrote:
>
> > Configuration Information [Automatically generated, do not change]:
> > Machine: x86_64
> > OS: linux-gnm
> > Compiler: gcc (GCC) 15.0.0 20240509 (experimental)
> > Compilation CFLAGS: -std=gnu23 -DNDEBUG
> > uname output: Linux fatima 6.10.3-gnu-c23-qxfixgnm #2 SMP
> > PREEMPT_DYNAMIC Wed Aug  7 20:46:44 CST 2024 x86_64 GNU/Linux
> > Machine Type: x86_64-pc-linux-gnu
> >
> > Gawk Version: 5.3.0*
> >
> > Attestation 1:
> >         I have read
> > https://www.gnu.org/software/gawk/manual/html_node/Bugs.html.
> >         Yes
> >
> > Attestation 2:
> >         I have not modified the sources before building gawk.
> >         True
> >
> > Description:
> >
> > compilation fails at io.c:
> >
> >         # gcc -DDEFPATH='".:/usr/local/share/awk"'
> > -DDEFLIBPATH="\"/usr/local/lib/gawk\"" -DSHLIBEXT="\"so"\"
> > -DHAVE_CONFIG_H -DGAWK -DLOCALEDIR='"/usr/local/share/locale"'
> > -I"./support" -I.    -std=gnu23  -DND\
> > EBUG -std=gnu23  -DNDEBUG -MT io.o -MD -MP -MF $depbase.Tpo -c -o io.o io.c 
> > &&\
> >         mv -f $depbase.Tpo $depbase.Po
> >         io.c: In function 'iop_alloc':
> >         io.c:3389:31: error: assignment to 'ssize_t (*)(int,  void *,
> > size_t)' {aka 'long int (*)(int,  void *, long unsigned int)'} from
> > incompatible pointer type 'ssize_t (*)(void)' {aka 'long int
> > (*)(void)'}\
> >  [-Wincompatible-pointer-types]
> >          3389 |         iop->public.read_func = ( ssize_t(*)() ) read;
> >                |                               ^
> >                io.c: In function 'get_read_timeout':
> >                io.c:4449:36: warning: comparison of distinct pointer
> > types lacks a cast [-Wcompare-distinct-pointer-types]
> >                 4449 |         if ((iop->public.read_func == (
> > ssize_t(*)() ) read) && tmout > 0)
> >                       |                                    ^~
> >
> > Repeat-By:
> >         setting CFLAGS to -std=gnu23 on gcc new enough to support it
> >
> > ( installed gawk is 5.2.2 trying to upgrade to 5.3.0 )



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