Re: [Buildroot] [PATCH] package/git: fix wchar-less uclibc build

[Thomas Petazzoni via buildroot <buildroot@buildroot.org>]

Hello,

On Sun, 20 Oct 2024 16:25:29 +0700
Bagas Sanjaya <bagasdotme@gmail.com> wrote:

> diff --git a/package/git/0001-t-unit-tests-fix-clar-build-for-wchar-less-uclibc.patch b/package/git/0001-t-unit-tests-fix-clar-build-for-wchar-less-uclibc.patch
> new file mode 100644
> index 0000000000..50e844f5d4
> --- /dev/null
> +++ b/package/git/0001-t-unit-tests-fix-clar-build-for-wchar-less-uclibc.patch
> @@ -0,0 +1,97 @@
> +From 3d24a1610bf5a84486c84526ded567a53e10b96f Mon Sep 17 00:00:00 2001
> +From: Edgar Bonet <bonet@grenoble.cnrs.fr>
> +Date: Fri, 18 Oct 2024 14:59:48 +0200
> +Subject: [PATCH] t/unit-tests: fix clar build for wchar-less uclibc
> +
> +Git fails to build on uclibc systems without wchar support:
> +
> +```
> +    CC t/unit-tests/unit-test.o
> +t/unit-tests/clar/clar.c: In function 'clar__assert_equal':
> +t/unit-tests/clar/clar.c:767:23: error: unknown type name 'wchar_t'
> +  767 |                 const wchar_t *wcs1 = va_arg(args, const wchar_t *);
> +      |                       ^~~~~~~
> +In file included from t/unit-tests/clar/clar.c:13:
> +t/unit-tests/clar/clar.c:767:58: error: unknown type name 'wchar_t'
> +  767 |                 const wchar_t *wcs1 = va_arg(args, const wchar_t *);
> +      |                                                          ^~~~~~~
> +t/unit-tests/clar/clar.c:768:23: error: unknown type name 'wchar_t'
> +  768 |                 const wchar_t *wcs2 = va_arg(args, const wchar_t *);
> +      |                       ^~~~~~~
> +t/unit-tests/clar/clar.c:768:58: error: unknown type name 'wchar_t'
> +  768 |                 const wchar_t *wcs2 = va_arg(args, const wchar_t *);
> +      |                                                          ^~~~~~~
> +t/unit-tests/clar/clar.c:769:65: warning: implicit declaration of function 'wcscmp' [-Wimplicit-function-declaration]
> +  769 |                 is_equal = (!wcs1 || !wcs2) ? (wcs1 == wcs2) : !wcscmp(wcs1, wcs2);
> +      |                                                                 ^~~~~~
> +t/unit-tests/clar/clar.c:784:23: error: unknown type name 'wchar_t'
> +  784 |                 const wchar_t *wcs1 = va_arg(args, const wchar_t *);
> +      |                       ^~~~~~~
> +t/unit-tests/clar/clar.c:784:58: error: unknown type name 'wchar_t'
> +  784 |                 const wchar_t *wcs1 = va_arg(args, const wchar_t *);
> +      |                                                          ^~~~~~~
> +t/unit-tests/clar/clar.c:785:23: error: unknown type name 'wchar_t'
> +  785 |                 const wchar_t *wcs2 = va_arg(args, const wchar_t *);
> +      |                       ^~~~~~~
> +t/unit-tests/clar/clar.c:785:58: error: unknown type name 'wchar_t'
> +  785 |                 const wchar_t *wcs2 = va_arg(args, const wchar_t *);
> +      |                                                          ^~~~~~~
> +t/unit-tests/clar/clar.c:787:65: warning: implicit declaration of function 'wcsncmp' [-Wimplicit-function-declaration]
> +  787 |                 is_equal = (!wcs1 || !wcs2) ? (wcs1 == wcs2) : !wcsncmp(wcs1, wcs2, len);
> +      |                                                                 ^~~~~~~
> +make[1]: *** [Makefile:2795: t/unit-tests/clar/clar.o] Error 1
> +```
> +
> +This is because on these systems, although there is #error macro
> +in uclibc source when __UCLIBC_HAS_WCHAR__ is not defined, somehow
> +the #error doesn't get triggered when wchar_t is used in clar.

When wchar support is disabled in uClibc, the wchar.h file that gets
installed is ./include/wchar-stub.h, and it doesn't have any #error.
See in the uClibc Makefile:

ifeq ($(UCLIBC_HAS_WCHAR),)
        $(Q)cd $(PREFIX)$(DEVEL_PREFIX)include && mv -f wchar-stub.h wchar.h
else
        $(Q)cd $(PREFIX)$(DEVEL_PREFIX)include && $(RM) -f wchar-stub.h
endif

> +
> +Fix the build failure by only using wchar_t when __UCLIBC_HAS_WCHAR__
> +is actually defined.

The solution isn't really nice, because it adds some uClibc specific
logic. Isn't there some configure.ac logic that runs to properly detect
the availability of wchar?

Otherwise, we could also make git depend on wchar, and be done with it.

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
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