Re: Compile error doing cross build on arm

[Rich Felker <dalias@aerifal.cx>]

On Mon, Jul 08, 2013 at 07:51:52PM +0200, Harald Becker wrote:
> Hi Ian !
> 
> 08-07-2013 11:58 Ian Denhardt <ian@zenhack.net>:
> 
> > So I just hit a compilation error trying to cross compile musl
> > for arm:
> > -fno-stack-protector  -c -o src/stdio/vfwprintf.o
> > src/stdio/vfwprintf.c src/stdio/vfwprintf.c: In function
> > 'wprintf_core': src/stdio/vfwprintf.c:195:3: error: pointer
> > targets in passing argument 2 of 'wcsspn' differ in signedness
> > [-Werror=pointer-sign] In file included from
> > src/stdio/vfwprintf.c:7:0: ./include/wchar.h:62:8: note:
> > expected 'const wchar_t *' but argument is of type 'int *' cc1:
> 
> > CFLAGS= -Os -pipe -fomit-frame-pointer -fno-unwind-tables
> > -fno-asynchronous-unwind-tables -Wa,--noexecstack
> > -falign-functions=1 -falign-labels=1 -falign-loops=1
> > -falign-jumps=1 -Werror=implicit-function-declaration
> > -Werror=implicit-int -Werror=pointer-sign -Werror=pointer-arith
> > -fno-stack-protector CFLAGS_C99FSE = -std=c99 -nostdinc
> > -ffreestanding -fexcess-precision=standard -frounding-math
> 
> It is curious, but I had similar compile error on native ARM
> compile (gcc 4.6.4). They vanished after removing some of the
> option on my CFLAGS list. Didn't analyze this, but probable
> candidates the unwind-tables and math options. So play a bit with
> your CFLAGS list, try "CFLAGS=-Os" if problem vanishes.

The direct source of this error is that the compiler's wchar_t is
defined as int rather than unsigned. ARM EABI requires (stupidly) that
wchar_t be unsigned, so we follow that.

The indirect cause of the error, and the real problem, is almost
surely that the compiler was configured for old, pre-EABI ARM ABI.
This ABI is NOT supported by musl, and will lead to various major
problems that could otherwise go undetected for a long time, like
misaligned structures (the old ABI only had 4-byte alignment for
64-bit types, for example). So this issue needs to be checked and
fixed before moving ahead.

Rich