[Bug libgcc/125449] New: libatomic: gcc_objdir breaks when MULTIBUILDTOP is an absolute path

[Hemanth.KumarMD at windriver dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125449

            Bug ID: 125449
           Summary: libatomic: gcc_objdir breaks when MULTIBUILDTOP is an
                    absolute path
           Product: gcc
           Version: 16.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libgcc
          Assignee: unassigned at gcc dot gnu.org
          Reporter: Hemanth.KumarMD at windriver dot com
  Target Milestone: ---

GCC 16 introduced the following logic in libatomic/Makefile.in:

    gcc_objdir = `pwd`/$(MULTIBUILDTOP)../../gcc/

This assumes MULTIBUILDTOP is always a relative path. When an
absolute path is passed, gcc_objdir becomes malformed:

    pwd     = /build/work/libatomic
    MULTIBUILDTOP = /build/work/libatomic/

    Result: /build/work/libatomic//build/work/libatomic/../../gcc/

This causes libtool install to fail with "No such file or directory".

libgcc constructs gcc_objdir differently and works fine with both
relative and absolute paths:

    gcc_objdir = $(MULTIBUILDTOP)../../$(host_subdir)/gcc

Would it make sense to align libatomic with libgcc and drop the
pwd prefix?

Introduced by:
https://github.com/gcc-mirror/gcc/commit/e63cf4b130b86dd7dde1bf499d3d40faca10ea2e