Re: clar unit testing framework FTBFS on uclibc systems (wchar_t unsupported)

[Patrick Steinhardt <ps@pks.im>]

On Thu, Oct 17, 2024 at 03:33:51PM +0200, Patrick Steinhardt wrote:
> On Thu, Oct 17, 2024 at 10:51:05AM +0700, Bagas Sanjaya wrote:
> > Hi,
> > 
> > Since clar unit testing framework was imported by commit 9b7caa2809cb (t:
> > import the clar unit testing framework, 2024-09-04), Git FTBFS on uclibc
> > systems built by Buildroot:
> 
> Wait a second, that doesn't sound right to me. `wchar_t` is part of ISO
> C90, so any system not supporting it would basically be unsupported by
> us from my point of view. And indeed, uclibc _does_ support that type
> alright. I guess the issue is rather that we're relying on some kind of
> platform-specific behaviour and thus don't include the correct header.
> 
> I'll have a look, thanks for the report!

Okay, uclibc indeed has _optional_ support for `wchar_t`. But what
really throws me off: "include/wchar.h" from uclibc has the following
snippet right at the top:

    #ifndef __UCLIBC_HAS_WCHAR__
    #error Attempted to include wchar.h when uClibc built without wide char support.
    #endif

We unconditionally include <wchar.h>, and your system does not seem to
have support for it built in. So why doesn't the `#error` trigger? It's
also not like this is a recent error, it has been added with 581deed72
(The obligatory forgotten files..., 2002-05-06).

We can do something like the below patch in clar, but I'd first like to
understand why your platform seems to be broken in such a way.

Patrick

diff --git a/clar.c b/clar.c
index 64879cf..06fe3d1 100644
--- a/clar.c
+++ b/clar.c
@@ -9,6 +9,11 @@
 #define _DARWIN_C_SOURCE
 #define _DEFAULT_SOURCE
 
+#if defined(__UCLIBC__) && ! defined(__UCLIBC_HAS_WCHAR__)
+#else
+#	define HAVE_WCHAR
+#endif
+
 #include <errno.h>
 #include <setjmp.h>
 #include <stdlib.h>
@@ -16,7 +21,9 @@
 #include <string.h>
 #include <math.h>
 #include <stdarg.h>
+#ifdef HAVE_WCHAR
 #include <wchar.h>
+#endif
 #include <time.h>
 #include <inttypes.h>
 
@@ -766,6 +773,7 @@ void clar__assert_equal(
 			}
 		}
 	}
+#ifdef HAVE_WCHAR
 	else if (!strcmp("%ls", fmt)) {
 		const wchar_t *wcs1 = va_arg(args, const wchar_t *);
 		const wchar_t *wcs2 = va_arg(args, const wchar_t *);
@@ -801,6 +809,7 @@ void clar__assert_equal(
 			}
 		}
 	}
+#endif // HAVE_WCHAR
 	else if (!strcmp("%"PRIuMAX, fmt) || !strcmp("%"PRIxMAX, fmt)) {
 		uintmax_t sz1 = va_arg(args, uintmax_t), sz2 = va_arg(args, uintmax_t);
 		is_equal = (sz1 == sz2);