On Wed, 16 Dec 2015 14:41:11 +0000 Andy Wingo <wi...@igalia.com> wrote:
> Hi,
>
> I am building GDB from git, because I want to hack on GDB. I have a few
> build-related things in my profile, including GCC. I enter an
> environment for GDB like this:
>
> guix environment gdb --ad-hoc flex autoconf-2.64
>
> Cool. Very good. I build:
>
> mkdir +2.0
> cd +2.0
> ../configure --prefix=/opt/gdb
> make
>
[...]
> The answer is interesting! I quote the GCC manual, section "Environment
> Variables":
>
> Some additional environment variables affect the behavior of the
> preprocessor.
>
> 'CPATH'
> 'C_INCLUDE_PATH'
> 'CPLUS_INCLUDE_PATH'
> 'OBJC_INCLUDE_PATH'
[...]
>
> So! CPATH is like -I but C_INCLUDE_PATH et al are like -isystem.
> Here's the docs for -isystem ("Preprocessor Options"):
>
> '-isystem DIR'
> Search DIR for header files, after all directories specified by
> '-I' but before the standard system directories. Mark it as a
> system directory, so that it gets the same special treatment as is
> applied to the standard system directories. If DIR begins with
> '=', then the '=' will be replaced by the sysroot prefix; see
> '--sysroot' and '-isysroot'.
>
> What is a system directory? Well, it's searched for after all -I
> includes, but also header files in it are marked as system headers.
> Many warnings are not issued for system headers; search the manual for
> the phrase "system headers". For example:
>
> '-Wsystem-headers'
> Issue warnings for code in system headers. These are normally
> unhelpful in finding bugs in your own code, therefore suppressed.
> If you are responsible for the system library, you may want to see
> them.
>
> So. We should be using C_INCLUDE_PATH instead of CPATH, to mark system
> headers as system headers. Except that C_INCLUDE_PATH only works for C,
> so we need to also set CPLUS_INCLUDE_PATH and OBJC_INCLUDE_PATH. And
> that's the proposal of this bug :)
>
> Andy
>
Are there other ones that could be set? Every time I compile it I see options
for java and go.
--
Efraim Flashner <efr...@flashner.co.il> אפרים פלשנר
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