[PR other/79543] Fix GNU ld --version scanning to conform to the GNU Coding Standards

[Joseph Myers]

On Thu, 4 Jul 2019, Chung-Lin Tang wrote:

> Bringing back this issue, as this is still bothering our OpenACC toolchains.
> 
> If the main variance in format was the 2007 ' ' to '.' change for non-release
> binutils builds, then is the attached patch okay?
> 
> What the patch does is to first look for an 8-digit part at the end
> (preceded by either a space or '.'), chop it off if it exists, and then take
> the last
> space-preceded string.

This patch is using \+ with sed, which is a GNU extension rather than part 
of POSIX sed.  I don't think we require GNU sed to build GCC.

The patch is OK for trunk with \+ changed to \{1,\} throughout (presuming 
that does indeed work).

However, I strongly encourage a followup to refactor this code 
(*_CHECK_LINKER_FEATURES and *_ENABLE_SYMVERS that use it, not just the 
fragment that determines the linker version number), which is evidently 
duplicated far too much in different target library directories, into 
common macros in a .m4 file in the top-level config/ directory, so it's 
more maintainable in future.  (Note 1: I don't know what differences there 
might be between the versions in different directories; that would need 
investigating as part of such a refactoring; differences need not be 
deliberate, they could easily have arisen by accident.  Note 2: although 
libffi is maintained outside of GCC, I think such a refactoring should 
still be applied to the libffi directory along with the others; standalone 
libffi would simply need its own copy of the relevant .m4 file.  Note 3: 
it should be possible to do such a refactoring bit by bit if that's more 
approachable, rather than necessarily doing a complete refactoring of all 
the definitions of all these macros at once.)

> (seeking approval for trunk and all active release branches)

For release branches you should at least wait a few weeks to see if any 
issues show up on trunk.

-- 
Joseph S. Myers
joseph@codesourcery.com