in reply to Re: [XS] : "snprintf" portability options
in thread [XS] : "snprintf" portability options

This is why win32/GNNUmakefile adds -Wno-format after -Wall and -Wextra

And the Cpanel-JSON-XS-4.38 Makefile.PL then oh-so-thoughtfully re-introduces the issue by appending "-Wall -Wextra -W" .... I'll submit a PR for that Makefile.PL, along with a PR to XS.xs that allows Cpanel::JSON::XS to build on Windows quadmath perls (and also silences some other warnings).

Thanks tonyc - I remember that issue, now.
At one stage yesterday it crossed my mind that I don't usually encounter [-Wformat=] warnings ... but I still failed to make the connection :-(

Cheers,
Rob

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Re^3: [XS] : "snprintf" portability options
by ikegami (Patriarch) on Sep 16, 2024 at 10:27 UTC

    oh-so-thoughtfully re-introduces the issue

    No it doesn't. The issue is there with or without the -Wformat. Your sarcasm is misplaced since the warning isn't spurious. The issue is that the wrong format is being used. This is a real error that needs fixing.

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[d/l]

      The warning is spurious, %I64u is valid on Windows. Unfortunately with the macro the full text of the format is hidden so all you have is the misleading "%u" from the base message:

      C:\Users\Tony\dev\perl\git>gcc -Wformat -oint64.exe int64.c
int64.c: In function 'main':
int64.c:6:15: warning: format '%u' expects argument of type 'unsigned 
+int', but argument 2 has type 'long long unsigned int' [-Wformat=]
    6 |   printf("%I64u\n", x);
      |           ~~~~^     ~
      |               |     |
      |               |     long long unsigned int
      |               unsigned int
      |           %I64llu

C:\Users\Tony\dev\perl\git>type int64.c
#include <stdio.h>

unsigned long long x = 0;

int main() {
  printf("%I64u\n", x);
}

      [download]

      If it is a bug, it's a bug in perl, since that's where the macro OP is using comes from.

      I've considered changing the Win32 config in perl to use "%llu"/"%lld" instead, but testing against the older versions of MSVCRT in older Windows that we theoretically support is difficult.

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[select]
        If it is a bug, it's a bug in perl

        Don't you mean a bug in gcc? gcc knows it is building for the MS libc, so it should accept the patterns known to work for that libc.

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        Bad test. You just repeated what was already said. But replacing 0 with 9223372036854775808ull does make your point.

        So the compiler is wrong about the expected format. wow!

        And thankfully, it still provides the expected format.

        If it is a bug, it's a bug in perl

        It's a bug in gcc. The format expects a unsigned long long, but it claims it expects an unsigned.

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[d/l]
[select]
      jdporter or someone - when I saw the reply in my "chatterbox", it didn't link to my article, but to a node "XS" (a Super Search link). I think that might be a bug?
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        jdporter or someone . . .

        I can see now that we need a "mentions" notification feature. :-/

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