vasnwprintf-posix: Work around two musl libc bugs

[Bruno Haible]

The attached three patches fix

1) a few wrong cross-compilation guesses,

2) a test-vasnwprintf-posix failure on Alpine Linux 3.18 (musl libc 1.2.4):

FAIL: test-vasnwprintf-posix
============================

../../gltests/test-vasnwprintf-posix.c:3999: assertion 'result != NULL' failed
Aborted
FAIL test-vasnwprintf-posix (exit status: 134)

3) another failure of test-vasnwprintf-posix on Alpine Linux 3.18 (musl libc
1.2.4), once the previous one is fixed:

FAIL: test-vasnwprintf-posix
============================

../../gltests/test-vasnwprintf-posix.c:4074: assertion 'result != NULL' failed
Aborted
FAIL test-vasnwprintf-posix (exit status: 134)


These two failures occurred in with musl libc 1.2.4 but not with
musl libc 1.2.3 because in 1.2.4 HAVE_WORKING_SWPRINTF gets defined
to 1 and thus the vasnwprintf implementation is based on swprintf rather
than snprintf. In other words, The vasnwprintf implementation now takes
a different code path, one that is sensitive to all kinds of swprintf
bugs.


2023-06-12  Bruno Haible  <bruno@clisp.org>

        vasnwprintf-posix: Work around another musl libc bug.
        * m4/printf.m4 (gl_SWPRINTF_DIRECTIVE_LC): New macro.
        * m4/vasnprintf.m4 (gl_PREREQ_VASNWPRINTF): Invoke it, and set
        NEED_WPRINTF_DIRECTIVE_LC if the %lc test failed.
        * lib/vasnprintf.c (VASNPRINTF): If NEED_WPRINTF_DIRECTIVE_LC is set, do
        the processing for %lc and %ls ourselves.
        (local_wcslen): Update condition.
        * doc/posix-functions/swprintf.texi: Mention the %lc problem.

2023-06-12  Bruno Haible  <bruno@clisp.org>

        vasnwprintf-posix: Work around a musl libc bug.
        * m4/vasnprintf.m4 (gl_PREREQ_VASNWPRINTF): Test also whether swprintf
        in the C locale is free of encoding errors, and set
        NEED_WPRINTF_DIRECTIVE_C if not.
        * doc/posix-functions/swprintf.texi: Clarify the list of platforms for
        the %c problem.

2023-06-12  Bruno Haible  <bruno@clisp.org>

        vasnwprintf: Fix some cross-compilation results.
        * m4/printf.m4 (gl_SWPRINTF_WORKS): Fix cross-compilation result for
        musl.
        (gl_SWPRINTF_DIRECTIVE_LA): Fix cross-compilation result for Android.

0001-vasnwprintf-Fix-some-cross-compilation-results.patch
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0002-vasnwprintf-posix-Work-around-a-musl-libc-bug.patch
Description: Text Data

0003-vasnwprintf-posix-Work-around-another-musl-libc-bug.patch
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