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Re: GCC_NO_EXECUTABLES vs. libtool
- From: "Joseph S. Myers" <joseph at codesourcery dot com>
- To: Ian Lance Taylor <iant at google dot com>
- Cc: gcc at gcc dot gnu dot org
- Date: Tue, 29 Mar 2011 11:33:21 +0000 (UTC)
- Subject: Re: GCC_NO_EXECUTABLES vs. libtool
- References: <firstname.lastname@example.org>
On Mon, 28 Mar 2011, Ian Lance Taylor wrote:
> We have several bug reports for 4.6.0 about failures of the form
> checking dynamic linker characteristics... configure: error: Link tests are not allowed after GCC_NO_EXECUTABLES.
> The problem arising when building a cross-compiler for a GNU/Linux
> target. Configure scripts like libiberty/configure.ac,
> libquadmath/configure.ac, etc., use GCC_NO_EXECUTABLES. The
> GCC_NO_EXECUTABLES macro checks whether a link succeeds. If it does
> not, it sets gcc_no_link. If a later attempt to run a link test, the
> above error is reported.
Most of the problem is that certain libraries are built when they
shouldn't be built.
In general link tests *are* required for GNU/Linux targets, because of
e.g. uClibc configurations where some functions may be disabled and this
can sometimes only be detected through a link test. Furthermore, when
building shared libraries you need a shared libc to link them against,
which means that in that case link tests will need to work anyway.
For the initial bootstrap for such a target a static-only, C-only compiler
is built and used for building libc headers and a dummy libc.so.
There certainly are issues with the list of libraries to disable in the
course of such a bootstrap growing over time (with libquadmath, for
example, being a recent addition, but I think the conclusion was that it
*should* be built in general even if Fortran isn't being built), and maybe
there should be special configure options for the initial bootstrap
compiler (which could also replace the --with-newlib hack). But some of
those bug reports refer to target libiberty - which I still maintain
should never be built by GCC - and some to target zlib, which I think
should only be relevant when building Java.
Joseph S. Myers