[PATCH v5] gold: Properly remove the versioned symbol
H.J. Lu
hjl.tools@gmail.com
Wed Jun 5 11:48:48 GMT 2024
On Tue, Jun 04, 2024 at 12:22:46PM -0700, Fangrui Song wrote:
> On Mon, Jun 3, 2024 at 5:34 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > If there are no objections, I will check in the v5 patch next week.
> >
> > Thanks.
> >
> > H.J.
> > On Sun, Jun 2, 2024, 4:29 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> >>
> >> When the versioned symbol foo is removed from the shared library, the
> >> ".symver foo,foo@VER" directive provides binary compatibility for foo@VER.
> >> In this case, the unversioned symbol foo shouldn't provide the default
> >> version for foo nor generate a multiple definition error.
> >>
> >> PR gold/31830
> >> * resolve.cc (Symbol_table::resolve): Move symbol version handling
> >> to ...
> >> * symtab.cc (Symbol_table::add_from_object): Here. If the hidden
> >> version from .symver is the same as the default version from the
> >> unversioned symbol, don't make the unversioned symbol the default
> >> versioned
> >> symbol.
> >> * testsuite/Makefile.am (check_SCRIPTS): Add ver_test_pr31830.sh.
> >> (check_DATA): ver_test_pr31830_a.syms and ver_test_pr31830_b.syms.
> >> (ver_test_pr31830_a.syms): New.
> >> (ver_test_pr31830_b.syms): Likewise.
> >> (ver_test_pr31830_a.so): Likewise.
> >> (ver_test_pr31830_b.so): Likewise.
> >> * testsuite/Makefile.in: Regenerated.
> >> * testsuite/ver_test_pr31830.script: New file.
> >> * testsuite/ver_test_pr31830.sh: Likewise.
> >> * testsuite/ver_test_pr31830_a.c: Likewise.
> >> * testsuite/ver_test_pr31830_b.c: Likewise.
> >> * testsuite/ver_test_pr31830_lto.c: Likewise.
> >> * testsuite/ver_test_pr31830_lto.sh: Likewise.
> >>
> >> Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
> >> ---
> >> gold/resolve.cc | 14 -----
> >> gold/symtab.cc | 76 ++++++++++++++++++++++----
> >> gold/testsuite/Makefile.am | 22 ++++++++
> >> gold/testsuite/Makefile.in | 36 ++++++++++++
> >> gold/testsuite/ver_test_pr31830.script | 6 ++
> >> gold/testsuite/ver_test_pr31830.sh | 61 +++++++++++++++++++++
> >> gold/testsuite/ver_test_pr31830_a.c | 2 +
> >> gold/testsuite/ver_test_pr31830_b.c | 3 +
> >> gold/testsuite/ver_test_pr31830_lto.c | 5 ++
> >> gold/testsuite/ver_test_pr31830_lto.sh | 61 +++++++++++++++++++++
> >> 10 files changed, 261 insertions(+), 25 deletions(-)
> >> create mode 100644 gold/testsuite/ver_test_pr31830.script
> >> create mode 100755 gold/testsuite/ver_test_pr31830.sh
> >> create mode 100644 gold/testsuite/ver_test_pr31830_a.c
> >> create mode 100644 gold/testsuite/ver_test_pr31830_b.c
> >> create mode 100644 gold/testsuite/ver_test_pr31830_lto.c
> >> create mode 100755 gold/testsuite/ver_test_pr31830_lto.sh
> >>
> >> diff --git a/gold/resolve.cc b/gold/resolve.cc
> >> index 777405dec1a..f05589551f4 100644
> >> --- a/gold/resolve.cc
> >> +++ b/gold/resolve.cc
> >> @@ -250,20 +250,6 @@ Symbol_table::resolve(Sized_symbol<size>* to,
> >> bool to_is_ordinary;
> >> const unsigned int to_shndx = to->shndx(&to_is_ordinary);
> >>
> >> - // It's possible for a symbol to be defined in an object file
> >> - // using .symver to give it a version, and for there to also be
> >> - // a linker script giving that symbol the same version. We
> >> - // don't want to give a multiple-definition error for this
> >> - // harmless redefinition.
> >> - if (to->source() == Symbol::FROM_OBJECT
> >> - && to->object() == object
> >> - && to->is_defined()
> >> - && is_ordinary
> >> - && to_is_ordinary
> >> - && to_shndx == st_shndx
> >> - && to->value() == sym.get_st_value())
> >> - return;
> >> -
> >> // Likewise for an absolute symbol defined twice with the same value.
> >> if (!is_ordinary
> >> && st_shndx == elfcpp::SHN_ABS
> >> diff --git a/gold/symtab.cc b/gold/symtab.cc
> >> index 9a55e6ea511..5857dd7b098 100644
> >> --- a/gold/symtab.cc
> >> +++ b/gold/symtab.cc
> >> @@ -998,12 +998,64 @@ Symbol_table::add_from_object(Object* object,
> >> ret = this->get_sized_symbol<size>(ins.first->second);
> >> gold_assert(ret != NULL);
> >>
> >> + bool ret_is_ordinary;
> >> + const unsigned int ret_shndx = ret->shndx(&ret_is_ordinary);
> >> +
> >> was_undefined_in_reg = ret->is_undefined() && ret->in_reg();
> >> // Commons from plugins are just placeholders.
> >> was_common = ret->is_common() && ret->object()->pluginobj() == NULL;
> >>
> >> - this->resolve(ret, sym, st_shndx, is_ordinary, orig_st_shndx, object,
> >> - version, is_default_version);
> >> + // It's possible for a symbol to be defined in an object file
> >> + // using .symver to give it a version, and for there to also be
> >> + // a linker script giving that symbol the same version. We
> >> + // don't want to give a multiple-definition error for this
> >> + // harmless redefinition.
> >> + bool check_version = false;
> >> + bool erase_default_version = false;
> >> + bool no_default_version = false;
> >> + if (ret->source() == Symbol::FROM_OBJECT
> >> + && is_ordinary
> >> + && ret_shndx == st_shndx)
> >> + {
> >> + if (ret->object() == object)
> >> + check_version = true;
> >> +
> >> + if (version != NULL && version == ret->version())
> >> + {
> >> + // Don't give a multiple-definition error if the hidden
> >> + // version from .symver is the same as the default version
> >> + // from the unversioned symbol.
> >> + if (is_default_version && !ret->is_default ())
> >> + {
> >> + no_default_version = true;
> >> + if (insdefault.second)
> >> + {
> >> + // Don't make the unversioned symbol the default
> >> + // version.
> >> + is_default_version = false;
> >> + erase_default_version = true;
> >> + check_version = true;
> >> + }
> >> + }
> >> + else if (!is_default_version && ret->is_default ())
> >> + {
> >> + // Don't make the unversioned symbol the default
> >> + // version.
> >> + ret->set_is_not_default();
> >> + no_default_version = true;
> >> + check_version = true;
> >> + }
> >> + }
> >> + }
> >> +
> >> + if (!(check_version
> >> + && ret->is_defined()
> >> + && ret_is_ordinary
> >> + && (no_default_version
> >> + || ret->value() == sym.get_st_value())))
> >> + this->resolve(ret, sym, st_shndx, is_ordinary, orig_st_shndx,
> >> + object, version, is_default_version);
> >> +
> >> if (parameters->options().gc_sections())
> >> this->gc_mark_dyn_syms(ret);
> >>
> >> @@ -1012,13 +1064,7 @@ Symbol_table::add_from_object(Object* object,
> >> insdefault.first);
> >> else
> >> {
> >> - bool dummy;
> >> - if (version != NULL
> >> - && ret->source() == Symbol::FROM_OBJECT
> >> - && ret->object() == object
> >> - && is_ordinary
> >> - && ret->shndx(&dummy) == st_shndx
> >> - && ret->is_default())
> >> + if (version != NULL && check_version)
> >> {
> >> // We have seen NAME/VERSION already, and marked it as the
> >> // default version, but now we see a definition for
> >> @@ -1032,9 +1078,17 @@ Symbol_table::add_from_object(Object* object,
> >> // In any other case, the two symbols should have generated
> >> // a multiple definition error.
> >> // (See PR gold/18703.)
> >> - ret->set_is_not_default();
> >> + // If the hidden version from .symver is the same as the
> >> + // default version from the unversioned symbol, don't make
> >> + // the unversioned symbol the default versioned symbol.
> >> const Stringpool::Key vnull_key = 0;
> >> - this->table_.erase(std::make_pair(name_key, vnull_key));
> >> + if (erase_default_version)
> >> + this->table_.erase(std::make_pair(name_key, vnull_key));
> >> + else if (ret->object() == object)
> >> + {
> >> + ret->set_is_not_default();
> >> + this->table_.erase(std::make_pair(name_key, vnull_key));
> >> + }
> >> }
> >> }
> >> }
> >> diff --git a/gold/testsuite/Makefile.am b/gold/testsuite/Makefile.am
> >> index 6e9af67b22d..a40f7624395 100644
> >> --- a/gold/testsuite/Makefile.am
> >> +++ b/gold/testsuite/Makefile.am
> >> @@ -2040,6 +2040,28 @@ ver_test_pr23409_1.so: gcctestdir/ld ver_test_1.o $(srcdir)/ver_test_pr23409_1.s
> >> ver_test_pr23409_2.so: gcctestdir/ld ver_test_1.o $(srcdir)/ver_test_pr23409_2.script
> >> gcctestdir/ld -shared -o $@ ver_test_1.o --version-script $(srcdir)/ver_test_pr23409_2.script
> >>
> >> +check_SCRIPTS += ver_test_pr31830.sh
> >> +check_DATA += ver_test_pr31830_a.syms ver_test_pr31830_b.syms
> >> +ver_test_pr31830_a.syms: ver_test_pr31830_a.so
> >> + $(TEST_READELF) --dyn-syms -W $< >$@
> >> +ver_test_pr31830_b.syms: ver_test_pr31830_b.so
> >> + $(TEST_READELF) --dyn-syms -W $< >$@
> >> +ver_test_pr31830_a.so: gcctestdir/ld ver_test_pr31830_a.o ver_test_pr31830_b.o $(srcdir)/ver_test_pr31830.script
> >> + gcctestdir/ld -shared -o $@ ver_test_pr31830_a.o ver_test_pr31830_b.o --version-script $(srcdir)/ver_test_pr31830.script
> >> +ver_test_pr31830_b.so: gcctestdir/ld ver_test_pr31830_a.o ver_test_pr31830_b.o $(srcdir)/ver_test_pr31830.script
> >> + gcctestdir/ld -shared -o $@ ver_test_pr31830_b.o ver_test_pr31830_a.o --version-script $(srcdir)/ver_test_pr31830.script
> >> +
> >> +check_SCRIPTS += ver_test_pr31830_lto.sh
> >> +check_DATA += ver_test_pr31830_lto_a.syms ver_test_pr31830_lto_b.syms
> >> +ver_test_pr31830_lto_a.syms: ver_test_pr31830_lto_a.so
> >> + $(TEST_READELF) --dyn-syms -W $< >$@
> >> +ver_test_pr31830_lto_a.so: gcctestdir/ld $(srcdir)/ver_test_pr31830_lto.c $(srcdir)/ver_test_pr31830.script
> >> + $(LINK) -Bgcctestdir/ -shared -o $@ -O2 -fPIC -flto-partition=max $(srcdir)/ver_test_pr31830_lto.c -Wl,--version-script,$(srcdir)/ver_test_pr31830.script
> >> +ver_test_pr31830_lto_b.syms: ver_test_pr31830_lto_b.so
> >> + $(TEST_READELF) --dyn-syms -W $< >$@
> >> +ver_test_pr31830_lto_b.so: gcctestdir/ld $(srcdir)/ver_test_pr31830_lto.c $(srcdir)/ver_test_pr31830.script
> >> + $(LINK) -Bgcctestdir/ -shared -o $@ -O2 -fPIC -flto-partition=max -flto=2 $(srcdir)/ver_test_pr31830_lto.c -Wl,--version-script,$(srcdir)/ver_test_pr31830.script
> >> +
> >> check_SCRIPTS += weak_as_needed.sh
> >> check_DATA += weak_as_needed.stdout
> >> weak_as_needed.stdout: weak_as_needed_a.so
> >> diff --git a/gold/testsuite/Makefile.in b/gold/testsuite/Makefile.in
> >> index db299dd97f6..78ca73acb17 100644
> >> --- a/gold/testsuite/Makefile.in
> >> +++ b/gold/testsuite/Makefile.in
> >> @@ -487,6 +487,8 @@ check_PROGRAMS = $(am__EXEEXT_1) $(am__EXEEXT_2) $(am__EXEEXT_3) \
> >> @GCC_TRUE@@NATIVE_LINKER_TRUE@ ver_test_10.sh ver_test_13.sh \
> >> @GCC_TRUE@@NATIVE_LINKER_TRUE@ ver_test_14.sh \
> >> @GCC_TRUE@@NATIVE_LINKER_TRUE@ ver_test_pr23409.sh \
> >> +@GCC_TRUE@@NATIVE_LINKER_TRUE@ ver_test_pr31830.sh \
> >> +@GCC_TRUE@@NATIVE_LINKER_TRUE@ ver_test_pr31830_lto.sh \
> >> @GCC_TRUE@@NATIVE_LINKER_TRUE@ weak_as_needed.sh relro_test.sh \
> >> @GCC_TRUE@@NATIVE_LINKER_TRUE@ ver_matching_test.sh \
> >> @GCC_TRUE@@NATIVE_LINKER_TRUE@ script_test_3.sh \
> >> @@ -544,6 +546,10 @@ check_PROGRAMS = $(am__EXEEXT_1) $(am__EXEEXT_2) $(am__EXEEXT_3) \
> >> @GCC_TRUE@@NATIVE_LINKER_TRUE@ ver_test_13.syms \
> >> @GCC_TRUE@@NATIVE_LINKER_TRUE@ ver_test_14.syms \
> >> @GCC_TRUE@@NATIVE_LINKER_TRUE@ ver_test_pr23409.syms \
> >> +@GCC_TRUE@@NATIVE_LINKER_TRUE@ ver_test_pr31830_a.syms \
> >> +@GCC_TRUE@@NATIVE_LINKER_TRUE@ ver_test_pr31830_b.syms \
> >> +@GCC_TRUE@@NATIVE_LINKER_TRUE@ ver_test_pr31830_lto_a.syms \
> >> +@GCC_TRUE@@NATIVE_LINKER_TRUE@ ver_test_pr31830_lto_b.syms \
> >> @GCC_TRUE@@NATIVE_LINKER_TRUE@ weak_as_needed.stdout \
> >> @GCC_TRUE@@NATIVE_LINKER_TRUE@ protected_3.err \
> >> @GCC_TRUE@@NATIVE_LINKER_TRUE@ relro_test.stdout \
> >> @@ -5978,6 +5984,20 @@ ver_test_pr23409.sh.log: ver_test_pr23409.sh
> >> --log-file $$b.log --trs-file $$b.trs \
> >> $(am__common_driver_flags) $(AM_LOG_DRIVER_FLAGS) $(LOG_DRIVER_FLAGS) -- $(LOG_COMPILE) \
> >> "$$tst" $(AM_TESTS_FD_REDIRECT)
> >> +ver_test_pr31830.sh.log: ver_test_pr31830.sh
> >> + @p='ver_test_pr31830.sh'; \
> >> + b='ver_test_pr31830.sh'; \
> >> + $(am__check_pre) $(LOG_DRIVER) --test-name "$$f" \
> >> + --log-file $$b.log --trs-file $$b.trs \
> >> + $(am__common_driver_flags) $(AM_LOG_DRIVER_FLAGS) $(LOG_DRIVER_FLAGS) -- $(LOG_COMPILE) \
> >> + "$$tst" $(AM_TESTS_FD_REDIRECT)
> >> +ver_test_pr31830_lto.sh.log: ver_test_pr31830_lto.sh
> >> + @p='ver_test_pr31830_lto.sh'; \
> >> + b='ver_test_pr31830_lto.sh'; \
> >> + $(am__check_pre) $(LOG_DRIVER) --test-name "$$f" \
> >> + --log-file $$b.log --trs-file $$b.trs \
> >> + $(am__common_driver_flags) $(AM_LOG_DRIVER_FLAGS) $(LOG_DRIVER_FLAGS) -- $(LOG_COMPILE) \
> >> + "$$tst" $(AM_TESTS_FD_REDIRECT)
> >> weak_as_needed.sh.log: weak_as_needed.sh
> >> @p='weak_as_needed.sh'; \
> >> b='weak_as_needed.sh'; \
> >> @@ -9031,6 +9051,22 @@ uninstall-am:
> >> @GCC_TRUE@@NATIVE_LINKER_TRUE@ gcctestdir/ld -shared -o $@ ver_test_1.o ver_test_pr23409_2.so --version-script $(srcdir)/ver_test_pr23409_1.script
> >> @GCC_TRUE@@NATIVE_LINKER_TRUE@ver_test_pr23409_2.so: gcctestdir/ld ver_test_1.o $(srcdir)/ver_test_pr23409_2.script
> >> @GCC_TRUE@@NATIVE_LINKER_TRUE@ gcctestdir/ld -shared -o $@ ver_test_1.o --version-script $(srcdir)/ver_test_pr23409_2.script
> >> +@GCC_TRUE@@NATIVE_LINKER_TRUE@ver_test_pr31830_a.syms: ver_test_pr31830_a.so
> >> +@GCC_TRUE@@NATIVE_LINKER_TRUE@ $(TEST_READELF) --dyn-syms -W $< >$@
> >> +@GCC_TRUE@@NATIVE_LINKER_TRUE@ver_test_pr31830_b.syms: ver_test_pr31830_b.so
> >> +@GCC_TRUE@@NATIVE_LINKER_TRUE@ $(TEST_READELF) --dyn-syms -W $< >$@
> >> +@GCC_TRUE@@NATIVE_LINKER_TRUE@ver_test_pr31830_a.so: gcctestdir/ld ver_test_pr31830_a.o ver_test_pr31830_b.o $(srcdir)/ver_test_pr31830.script
> >> +@GCC_TRUE@@NATIVE_LINKER_TRUE@ gcctestdir/ld -shared -o $@ ver_test_pr31830_a.o ver_test_pr31830_b.o --version-script $(srcdir)/ver_test_pr31830.script
> >> +@GCC_TRUE@@NATIVE_LINKER_TRUE@ver_test_pr31830_b.so: gcctestdir/ld ver_test_pr31830_a.o ver_test_pr31830_b.o $(srcdir)/ver_test_pr31830.script
> >> +@GCC_TRUE@@NATIVE_LINKER_TRUE@ gcctestdir/ld -shared -o $@ ver_test_pr31830_b.o ver_test_pr31830_a.o --version-script $(srcdir)/ver_test_pr31830.script
> >> +@GCC_TRUE@@NATIVE_LINKER_TRUE@ver_test_pr31830_lto_a.syms: ver_test_pr31830_lto_a.so
> >> +@GCC_TRUE@@NATIVE_LINKER_TRUE@ $(TEST_READELF) --dyn-syms -W $< >$@
> >> +@GCC_TRUE@@NATIVE_LINKER_TRUE@ver_test_pr31830_lto_a.so: gcctestdir/ld $(srcdir)/ver_test_pr31830_lto.c $(srcdir)/ver_test_pr31830.script
> >> +@GCC_TRUE@@NATIVE_LINKER_TRUE@ $(LINK) -Bgcctestdir/ -shared -o $@ -O2 -fPIC -flto-partition=max $(srcdir)/ver_test_pr31830_lto.c -Wl,--version-script,$(srcdir)/ver_test_pr31830.script
> >> +@GCC_TRUE@@NATIVE_LINKER_TRUE@ver_test_pr31830_lto_b.syms: ver_test_pr31830_lto_b.so
> >> +@GCC_TRUE@@NATIVE_LINKER_TRUE@ $(TEST_READELF) --dyn-syms -W $< >$@
> >> +@GCC_TRUE@@NATIVE_LINKER_TRUE@ver_test_pr31830_lto_b.so: gcctestdir/ld $(srcdir)/ver_test_pr31830_lto.c $(srcdir)/ver_test_pr31830.script
> >> +@GCC_TRUE@@NATIVE_LINKER_TRUE@ $(LINK) -Bgcctestdir/ -shared -o $@ -O2 -fPIC -flto-partition=max -flto=2 $(srcdir)/ver_test_pr31830_lto.c -Wl,--version-script,$(srcdir)/ver_test_pr31830.script
> >> @GCC_TRUE@@NATIVE_LINKER_TRUE@weak_as_needed.stdout: weak_as_needed_a.so
> >> @GCC_TRUE@@NATIVE_LINKER_TRUE@ $(TEST_READELF) -dW --dyn-syms $< >$@
> >> @GCC_TRUE@@NATIVE_LINKER_TRUE@weak_as_needed_a.so: gcctestdir/ld weak_as_needed_a.o weak_as_needed_b.so weak_as_needed_c.so
> >> diff --git a/gold/testsuite/ver_test_pr31830.script b/gold/testsuite/ver_test_pr31830.script
> >> new file mode 100644
> >> index 00000000000..0dcc47f4f5c
> >> --- /dev/null
> >> +++ b/gold/testsuite/ver_test_pr31830.script
> >> @@ -0,0 +1,6 @@
> >> +GLIBC_2.2.5 {
> >> + global:
> >> + foo;
> >> + local:
> >> + *;
> >> +};
> >> diff --git a/gold/testsuite/ver_test_pr31830.sh b/gold/testsuite/ver_test_pr31830.sh
> >> new file mode 100755
> >> index 00000000000..2a3c0347461
> >> --- /dev/null
> >> +++ b/gold/testsuite/ver_test_pr31830.sh
> >> @@ -0,0 +1,61 @@
> >> +#!/bin/sh
> >> +
> >> +# ver_test_pr31830.sh -- a test case for version scripts
> >> +
> >> +# Copyright (C) 2024 Free Software Foundation, Inc.
> >> +
> >> +# This file is part of gold.
> >> +
> >> +# This program is free software; you can redistribute it and/or modify
> >> +# it under the terms of the GNU General Public License as published by
> >> +# the Free Software Foundation; either version 3 of the License, or
> >> +# (at your option) any later version.
> >> +
> >> +# This program is distributed in the hope that it will be useful,
> >> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> >> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> >> +# GNU General Public License for more details.
> >> +
> >> +# You should have received a copy of the GNU General Public License
> >> +# along with this program; if not, write to the Free Software
> >> +# Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
> >> +# MA 02110-1301, USA.
> >> +
> >> +# This test verifies that linker-generated symbols (e.g., _end)
> >> +# get correct version information even in the presence of
> >> +# a shared library that provides those symbols with different
> >> +# versions.
> >> +
> >> +check()
> >> +{
> >> + if ! grep -q "$2" "$1"
> >> + then
> >> + echo "Did not find expected symbol in $1:"
> >> + echo " $2"
> >> + echo ""
> >> + echo "Actual output below:"
> >> + cat "$1"
> >> + exit 1
> >> + fi
> >> +}
> >> +
> >> +check_missing()
> >> +{
> >> + if grep -q "$2" "$1"
> >> + then
> >> + echo "Found unexpected symbol in $1:"
> >> + echo " $2"
> >> + echo ""
> >> + echo "Actual output below:"
> >> + cat "$1"
> >> + exit 1
> >> + fi
> >> +}
> >> +
> >> +check ver_test_pr31830_a.syms "foo@GLIBC_2.2.5$"
> >> +check ver_test_pr31830_b.syms "foo@GLIBC_2.2.5$"
> >> +
> >> +check_missing ver_test_pr31830_a.syms "foo@@GLIBC_2.2.5$"
> >> +check_missing ver_test_pr31830_b.syms "foo@@GLIBC_2.2.5$"
> >> +
> >> +exit 0
> >> diff --git a/gold/testsuite/ver_test_pr31830_a.c b/gold/testsuite/ver_test_pr31830_a.c
> >> new file mode 100644
> >> index 00000000000..bb57059bf7e
> >> --- /dev/null
> >> +++ b/gold/testsuite/ver_test_pr31830_a.c
> >> @@ -0,0 +1,2 @@
> >> +extern void foo(void);
> >> +void foo(void) {}
> >> diff --git a/gold/testsuite/ver_test_pr31830_b.c b/gold/testsuite/ver_test_pr31830_b.c
> >> new file mode 100644
> >> index 00000000000..aba07cc6305
> >> --- /dev/null
> >> +++ b/gold/testsuite/ver_test_pr31830_b.c
> >> @@ -0,0 +1,3 @@
> >> +extern void __collector_foo_2_2(void);
> >> +__attribute__((__symver__("foo@GLIBC_2.2.5")))
> >> +void __collector_foo_2_2(void) {}
> >> diff --git a/gold/testsuite/ver_test_pr31830_lto.c b/gold/testsuite/ver_test_pr31830_lto.c
> >> new file mode 100644
> >> index 00000000000..999dd63f884
> >> --- /dev/null
> >> +++ b/gold/testsuite/ver_test_pr31830_lto.c
> >> @@ -0,0 +1,5 @@
> >> +extern __inline __attribute__((__gnu_inline__)) void foo(void) {}
> >> +extern void __collector_foo_2_2(void);
> >> +__attribute__((__symver__("foo@GLIBC_2.2.5")))
> >> +void __collector_foo_2_2(void) {}
> >> +void foo(void) {}
> >> diff --git a/gold/testsuite/ver_test_pr31830_lto.sh b/gold/testsuite/ver_test_pr31830_lto.sh
> >> new file mode 100755
> >> index 00000000000..4b939a161ac
> >> --- /dev/null
> >> +++ b/gold/testsuite/ver_test_pr31830_lto.sh
> >> @@ -0,0 +1,61 @@
> >> +#!/bin/sh
> >> +
> >> +# ver_test_pr31830_lto.sh -- a test case for version scripts with LTO
> >> +
> >> +# Copyright (C) 2024 Free Software Foundation, Inc.
> >> +
> >> +# This file is part of gold.
> >> +
> >> +# This program is free software; you can redistribute it and/or modify
> >> +# it under the terms of the GNU General Public License as published by
> >> +# the Free Software Foundation; either version 3 of the License, or
> >> +# (at your option) any later version.
> >> +
> >> +# This program is distributed in the hope that it will be useful,
> >> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> >> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> >> +# GNU General Public License for more details.
> >> +
> >> +# You should have received a copy of the GNU General Public License
> >> +# along with this program; if not, write to the Free Software
> >> +# Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
> >> +# MA 02110-1301, USA.
> >> +
> >> +# This test verifies that linker-generated symbols (e.g., _end)
> >> +# get correct version information even in the presence of
> >> +# a shared library that provides those symbols with different
> >> +# versions.
> >> +
> >> +check()
> >> +{
> >> + if ! grep -q "$2" "$1"
> >> + then
> >> + echo "Did not find expected symbol in $1:"
> >> + echo " $2"
> >> + echo ""
> >> + echo "Actual output below:"
> >> + cat "$1"
> >> + exit 1
> >> + fi
> >> +}
> >> +
> >> +check_missing()
> >> +{
> >> + if grep -q "$2" "$1"
> >> + then
> >> + echo "Found unexpected symbol in $1:"
> >> + echo " $2"
> >> + echo ""
> >> + echo "Actual output below:"
> >> + cat "$1"
> >> + exit 1
> >> + fi
> >> +}
> >> +
> >> +check ver_test_pr31830_lto_a.syms "foo@GLIBC_2.2.5$"
> >> +check ver_test_pr31830_lto_b.syms "foo@GLIBC_2.2.5$"
> >> +
> >> +check_missing ver_test_pr31830_lto_a.syms "foo@@GLIBC_2.2.5$"
> >> +check_missing ver_test_pr31830_lto_b.syms "foo@@GLIBC_2.2.5$"
> >> +
> >> +exit 0
> >> --
> >> 2.45.1
> >>
> >>
>
> Both GNU ld and not-too-ancient lld have the following behavior:
>
> When defined foo@GLIBC_2.2.5 from x.o and defined foo from y.o are
> combined, and a version script assigns "GLIBC_2.2.5" to foo,
> foo@GLIBC_2.2.5 is retained and foo is dropped. There is no duplicate
> definition error.
>
> ld.bfd --version-script=x.t -shared -o x.so x.o y.o # ok
> gold --version-script=x.t -shared -o x.so x.o y.o # ok
>
> This patch will make gold do so. The description might be reworded to
> make this clearer.
I will change the commit log to
When the versioned symbol foo is removed from the shared library, the
".symver foo,foo@VER" directive provides binary compatibility for foo@VER.
In this case, the unversioned symbol foo should be hidden and shouldn't
generate a multiple definition error.
>
> ---
>
> However, I wonder whether gold's current behavior (reporting a
> duplicate definition error) is better.
> x.o and y.o provide different definitions in this case.
This came from the real world case:
https://sourceware.org/bugzilla/show_bug.cgi?id=30281
H.J.
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