Re: [PATCH] libgcc/config/t-vxworks: remove -nostdinc from LIBGCC2_INCLUDES

[Olivier Hainque <hainque at adacore dot com>]

Hello Rasmus,

> On 01 Jun 2018, at 14:23, Rasmus Villemoes <rasmus.villemoes@prevas.dk> wrote:
> 
> -nostdinc apparently does not affect the directories added by the -B
> options when the xgcc wrapper is used when building an ordinary
> cross-compiler, but having -nostdinc in LIBGCC2_INCLUDES breaks a
> canadian cross build (i.e., when we use an already installed
> cross-compiler), because we cannot find the ppc-asm.h file.
> 
> -I. alone already ensures we search find the gcc-provided unwind.h
> rather than a system header by that name, but just for good measure
> change the following -I includes to -isystem.
> 
> I have tested that both a cross (build=host=x86-linux,
> target=powerpc-wrs-vxworks) and canadian cross (build=x86-linux,
> host=x86-windows, target=powerpc-wrs-vxworks) builds work, and that
> the resulting compilers produce working code on target.
> 
> 2018-06-01  Rasmus Villemoes  <rasmus.villemoes@prevas.dk>
> 
> libgcc/
> 
> 	* config/t-vxworks: Remove -nostdinc from LIBGCC2_INCLUDES.

Thanks for proposing this patch. It unfortunately breaks
a regular cross build for me, configured like:

  /gcc.git/configure  --prefix=/gournay.a/users/hainque/ins  --target=powerpc-wrs-vxworks --enable-languages=c --disable-libada --with-gnu-ld --with-gnu-as --disable-libssp

on a x86-linux host. With a properly set WIND_BASE, "make" passes with the
current trunk, and with the patch now fails with errors like:

  In file included from .../users/hainque/gcc.git/libgcc/config/vxlib-tls.c:45:
  .../vxworks-6.8/vxworks-6.8/target/h/taskLib.h:425:5: error: unknown type name 'REG_SET'
     REG_SET *  pExcRegSet; /* 0x120: exception regSet ptr or NULL*/

vxlib-tls.c #includes some vxworks headers, which end up including "regs.h",
intended to get the vxworks instance of this file. Without -nostdinc, we get
gcc's "regs.h" instead.

Turns out we have encountered the canadian build problem as well and have
an alternate resolution for it, which I was about to commit.

Does the attached patch work for you ?

--

    Refine -I flags for VxWorks libgcc

    Arrange to always have <toplevel-build-dir>/gcc/include in the
    -I flags for libgcc on VxWorks. This contains user accessible header
    files provided by gcc so is legitimate and needed in many cases.

    This is implicitly achieved with -B when building a regular cross
    compiler, but there's no such -B when cross compiling libraries as
    part of a canadian build.

2018-06-03  Olivier Hainque  <hainque@adacore.com>

        * libgcc/config/t-vxworks (LIBGCC_INCLUDES):
        Add -I$(MULTIBUILDTOP)../../gcc/include.
        * libgcc/config/t-vxworks7: Likewise. Reformat a bit to
        match the t-vxworks layout.

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