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Prior to this patch ld -shared --version-script=pr26979.ver pr26978a.o pr26978b.o results in ld: pr26978b.o: in function `foo_v1': (.text+0x0): multiple definition of `foo@v1' ld: pr26978b.o:(*IND*+0x0): multiple definition of `foo' while ld -shared --version-script=pr26979.ver pr26978b.o pr26978a.o results in no error, but some odd dynamic symbols. ... 0 NOTYPE GLOBAL DEFAULT 7 foo@v1 ... 0 NOTYPE WEAK DEFAULT 7 foo@@v1 When linking an undecorated reference to foo against such a shared library, ld complains about multiple definitions of foo@v1 while gold creates a dynamic reference to foo@v1. That results in foo@v1 being used at runtime. While we could error in both cases, it is reasonable to say foo@v1 and foo@@v1 are in fact the same symbol. (Same name, same version. The only real difference is that foo@@v1 satisfies a reference to plain foo, while foo@v1 does not.) Just as merging a weak undecorated sym with a strong sym results in the strong sym prevailing, so should the strong foo@v1 prevail. And since there is a definition that satisfies plain foo, the foo@@v1 variety of dynamic symbol should be emitted at the foo@v1 value. That makes the testcase that currently links continue to produce a shared library, and that shared library can now be used by both ld and gold with the same runtime behaviour as when using gold with the odd dynamic symbol library. bfd/ PR 26978 * elflink.c (_bfd_elf_add_default_symbol): Handle the case where a new weak sym@@ver should be overridden by an existing sym@ver. (elf_link_add_object_symbols): Don't _bfd_elf_add_default_symbol for a new weak sym@ver when sym@@ver already exists. * linker.c (link_action): Choose MIND for previous indirect, current def, rather than MDEF. (_bfd_generic_link_add_one_symbol <MIND>): Handle redefinition of weak indirect symbol. ld/ * testsuite/ld-elf/pr26978a.d, * testsuite/ld-elf/pr26978a.s, * testsuite/ld-elf/pr26978b.d, * testsuite/ld-elf/pr26978b.s: New tests.
README for LD
This is the GNU linker. It is distributed with other "binary
utilities" which should be in ../binutils. See ../binutils/README for
more general notes, including where to send bug reports.
There are many features of the linker:
* The linker uses a Binary File Descriptor library (../bfd)
that it uses to read and write object files. This helps
insulate the linker itself from the format of object files.
* The linker supports a number of different object file
formats. It can even handle multiple formats at once:
Read two input formats and write a third.
* The linker can be configured for cross-linking.
* The linker supports a control language.
* There is a user manual (ld.texi), as well as the
beginnings of an internals manual (ldint.texi).
Installation
============
See ../binutils/README.
If you want to make a cross-linker, you may want to specify
a different search path of -lfoo libraries than the default.
You can do this by setting the LIB_PATH variable in ./Makefile
or using the --with-lib-path configure switch.
To build just the linker, make the target all-ld from the top level
directory (one directory above this one).
Porting to a new target
=======================
See the ldint.texi manual.
Reporting bugs etc
===========================
See ../binutils/README.
Known problems
==============
The Solaris linker normally exports all dynamic symbols from an
executable. The GNU linker does not do this by default. This is
because the GNU linker tries to present the same interface for all
similar targets (in this case, all native ELF targets). This does not
matter for normal programs, but it can make a difference for programs
which try to dlopen an executable, such as PERL or Tcl. You can make
the GNU linker export all dynamic symbols with the -E or
--export-dynamic command line option.
HP/UX 9.01 has a shell bug that causes the linker scripts to be
generated incorrectly. The symptom of this appears to be "fatal error
- scanner input buffer overflow" error messages. There are various
workarounds to this:
* Build and install bash, and build with "make SHELL=bash".
* Update to a version of HP/UX with a working shell (e.g., 9.05).
* Replace "(. ${srcdir}/scripttempl/${SCRIPT_NAME}.sc)" in
genscripts.sh with "sh ${srcdir}..." (no parens) and make sure the
emulparams script used exports any shell variables it sets.
Copyright (C) 2012-2020 Free Software Foundation, Inc.
Copying and distribution of this file, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved.