Linux GN: Optionally link statically against libstdc++ [chromium/mini_chromium : master]
Scott Graham (Gerrit)
1 comment:
Patch Set #2, Line 171:
# statically to avoid the problem on the bots.Apparently not, it doesn't have make_unique in usr/include/c++/. […]
I guess this comes down to it not really being possible to (dynamically) use C++14 on 14.04.
So I guess another option is that we could switch back to -std=c++11, but that seems sad (and I'm not sure how much work would be involved.)
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Mark Mentovai (Gerrit)
1 comment:
Patch Set #2, Line 171:
# statically to avoid the problem on the bots.
I dunno. I guess a "link_libstdcpp_statically" hack flag. Bleh.
I think, given the constraints, that’s the winner that nobody was rooting for.
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Mark Mentovai (Gerrit)
4 comments:
Patch Set #4, Line 25:
libstdc++It says this (libstdc++)…
Patch Set #4, Line 26:
link_libstdcpp_statically…and it’s named that way too…
Patch Set #4, Line 170:
libstdc++…and this comment even repeats it…
Patch Set #4, Line 174:
-lstdc++…but you’re really using libc++.
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Scott Graham (Gerrit)
1 comment:
…but you’re really using libc++.
Oh, really? I thought -l just meant add a "lib" prefix and look for it on the libpath, so this would find "libstdc++". Is "c++" special cased somehow?
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Mark Mentovai (Gerrit)
1 comment:
Patch Set #4, Line 174:
-lstdc++
Oh, really? I thought -l just meant add a "lib" prefix and look for it on the libpath, so this would find "libstdc++". Is "c++" special cased somehow?
I'm just misreading things all over the place.
But the distinction raises an interesting question: if we use -stdlib libc++ for both compile and link, does that help?
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Scott Graham (Gerrit)
1 comment:
Patch Set #4, Line 174:
-lstdc++
> Oh, really? I thought -l just meant add a "lib" prefix and look for it on the libpath, so this wou […]
Unfortunately it doesn't seem to link ("unable to find library -lc++").
That lib is in the clang directory, but not in the sysroot. I don't think the Linux distributions ship libc++ by default (at least not old ones), so we'd be back to needing static linking then too I guess.
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Mark Mentovai (Gerrit)
Thanks for bearing with me.
Patch set 4:Code-Review +1
1 comment:
Patch Set #4, Line 173:
"-Wl,-Bstatic",Instead of these three arguments, I think we can just do
ldflags += [
"-Wl,-static-libstdc++",
]That should tell the compiler driver to do “-Bstatic -lstdc++ -Bdynamic” for us, which means that we won’t wind up with a freaky linker invocation that mentions -lstdc++ twice. It should also deal with -stdlib=libc++ better if anyone ever tries that.
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Scott Graham (Gerrit)
1 comment:
Patch Set #4, Line 173:
"-Wl,-Bstatic",
Instead of these three arguments, I think we can just do […]
ld.lld doesn't seem to care for that...
/usr/local/google/work/cp2/crashpad/out/lin/../../third_party/linux/clang/linux-amd64/bin/ld.lld: error: unknown argument: -static-libstdc++
Here's what --help says: https://gist.github.com/sgraham/f312216df00033ab1051329ca00027f8
Skimming through that now to see if there's something similar...
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Scott Graham (Gerrit)
1 comment:
Patch Set #4, Line 173:
"-Wl,-Bstatic",
ld.lld doesn't seem to care for that... […]
Oh, it doesn't want "-Wl," apparently.
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Scott Graham (Gerrit)
Scott Graham merged this change.
Linux GN: Optionally link statically against libstdc++
This accomodates the sysroot being slightly newer than the old bots that
represent the minspec for Chromium.
Before:
scottmg@around:/work/cp2/crashpad$ ldd -v out/lin/crashpad_client_test
linux-vdso.so.1 (0x00007ffc103c1000)
libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007fad8917e000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fad88e7a000)
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007fad88c5d000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fad888be000)
/lib64/ld-linux-x86-64.so.2 (0x00007fad89500000)
libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007fad886a7000)
Version information:
out/lin/crashpad_client_test:
libc.so.6 (GLIBC_2.2.5) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_2.3.4) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_2.4) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_2.6) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_2.14) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_2.17) => /lib/x86_64-linux-gnu/libc.so.6
libstdc++.so.6 (GLIBCXX_3.4) => /usr/lib/x86_64-linux-gnu/libstdc++.so.6
libstdc++.so.6 (GLIBCXX_3.4.15) => /usr/lib/x86_64-linux-gnu/libstdc++.so.6
libstdc++.so.6 (GLIBCXX_3.4.20) => /usr/lib/x86_64-linux-gnu/libstdc++.so.6
libstdc++.so.6 (GLIBCXX_3.4.21) => /usr/lib/x86_64-linux-gnu/libstdc++.so.6
libstdc++.so.6 (CXXABI_1.3) => /usr/lib/x86_64-linux-gnu/libstdc++.so.6
libpthread.so.0 (GLIBC_2.2.5) => /lib/x86_64-linux-gnu/libpthread.so.0
libm.so.6 (GLIBC_2.2.5) => /lib/x86_64-linux-gnu/libm.so.6
/usr/lib/x86_64-linux-gnu/libstdc++.so.6:
ld-linux-x86-64.so.2 (GLIBC_2.3) => /lib64/ld-linux-x86-64.so.2
libm.so.6 (GLIBC_2.2.5) => /lib/x86_64-linux-gnu/libm.so.6
libgcc_s.so.1 (GCC_4.2.0) => /lib/x86_64-linux-gnu/libgcc_s.so.1
libgcc_s.so.1 (GCC_3.3) => /lib/x86_64-linux-gnu/libgcc_s.so.1
libgcc_s.so.1 (GCC_3.0) => /lib/x86_64-linux-gnu/libgcc_s.so.1
libc.so.6 (GLIBC_2.14) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_2.18) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_2.3) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_2.17) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_2.3.2) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_2.2.5) => /lib/x86_64-linux-gnu/libc.so.6
/lib/x86_64-linux-gnu/libm.so.6:
ld-linux-x86-64.so.2 (GLIBC_PRIVATE) => /lib64/ld-linux-x86-64.so.2
libc.so.6 (GLIBC_2.2.5) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_PRIVATE) => /lib/x86_64-linux-gnu/libc.so.6
/lib/x86_64-linux-gnu/libpthread.so.0:
ld-linux-x86-64.so.2 (GLIBC_2.2.5) => /lib64/ld-linux-x86-64.so.2
ld-linux-x86-64.so.2 (GLIBC_PRIVATE) => /lib64/ld-linux-x86-64.so.2
libc.so.6 (GLIBC_2.14) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_2.3.2) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_2.2.5) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_PRIVATE) => /lib/x86_64-linux-gnu/libc.so.6
/lib/x86_64-linux-gnu/libc.so.6:
ld-linux-x86-64.so.2 (GLIBC_2.3) => /lib64/ld-linux-x86-64.so.2
ld-linux-x86-64.so.2 (GLIBC_PRIVATE) => /lib64/ld-linux-x86-64.so.2
/lib/x86_64-linux-gnu/libgcc_s.so.1:
libc.so.6 (GLIBC_2.14) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_2.2.5) => /lib/x86_64-linux-gnu/libc.so.6
After with link_libstdcpp_statically=true (noting no libstdc++.so.6):
scottmg@around:/work/cp2/crashpad$ ldd -v out/lin/crashpad_client_test
linux-vdso.so.1 (0x00007fff749ab000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fc6e2d6d000)
libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007fc6e2b56000)
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007fc6e2939000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fc6e259a000)
/lib64/ld-linux-x86-64.so.2 (0x00007fc6e3340000)
Version information:
out/lin/crashpad_client_test:
libc.so.6 (GLIBC_2.2.5) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_2.3) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_2.3.4) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_2.4) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_2.6) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_2.14) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_2.17) => /lib/x86_64-linux-gnu/libc.so.6
libpthread.so.0 (GLIBC_2.2.5) => /lib/x86_64-linux-gnu/libpthread.so.0
libpthread.so.0 (GLIBC_2.3.2) => /lib/x86_64-linux-gnu/libpthread.so.0
ld-linux-x86-64.so.2 (GLIBC_2.3) => /lib64/ld-linux-x86-64.so.2
libgcc_s.so.1 (GCC_3.0) => /lib/x86_64-linux-gnu/libgcc_s.so.1
libgcc_s.so.1 (GCC_3.3) => /lib/x86_64-linux-gnu/libgcc_s.so.1
libgcc_s.so.1 (GCC_4.2.0) => /lib/x86_64-linux-gnu/libgcc_s.so.1
libm.so.6 (GLIBC_2.2.5) => /lib/x86_64-linux-gnu/libm.so.6
/lib/x86_64-linux-gnu/libm.so.6:
ld-linux-x86-64.so.2 (GLIBC_PRIVATE) => /lib64/ld-linux-x86-64.so.2
libc.so.6 (GLIBC_2.2.5) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_PRIVATE) => /lib/x86_64-linux-gnu/libc.so.6
/lib/x86_64-linux-gnu/libgcc_s.so.1:
libc.so.6 (GLIBC_2.14) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_2.2.5) => /lib/x86_64-linux-gnu/libc.so.6
/lib/x86_64-linux-gnu/libpthread.so.0:
ld-linux-x86-64.so.2 (GLIBC_2.2.5) => /lib64/ld-linux-x86-64.so.2
ld-linux-x86-64.so.2 (GLIBC_PRIVATE) => /lib64/ld-linux-x86-64.so.2
libc.so.6 (GLIBC_2.14) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_2.3.2) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_2.2.5) => /lib/x86_64-linux-gnu/libc.so.6
libc.so.6 (GLIBC_PRIVATE) => /lib/x86_64-linux-gnu/libc.so.6
/lib/x86_64-linux-gnu/libc.so.6:
ld-linux-x86-64.so.2 (GLIBC_2.3) => /lib64/ld-linux-x86-64.so.2
ld-linux-x86-64.so.2 (GLIBC_PRIVATE) => /lib64/ld-linux-x86-64.so.2
Bug: crashpad:30, crashpad:79, crashpad:220
Change-Id: Ifa49c284a23009f3685283444f2bf7f52f80c3b3
Reviewed-on: https://chromium-review.googlesource.com/939731
Reviewed-by: Mark Mentovai <ma...@chromium.org>
---
M build/BUILD.gn
1 file changed, 14 insertions(+), 0 deletions(-)
diff --git a/build/BUILD.gn b/build/BUILD.gn
index 6b51173..a169315 100644
--- a/build/BUILD.gn
+++ b/build/BUILD.gn
@@ -21,6 +21,9 @@
declare_args() {
# Path to the Clang toolchain. If unset, uses the system-installed Clang.
clang_path = ""
+
+ # If set, link against libstdc++ statically.
+ link_libstdcpp_statically = false
}
} else if (mini_chromium_is_fuchsia) {
declare_args() {
@@ -157,6 +160,17 @@
if (mini_chromium_is_linux) {
defines = [ "_FILE_OFFSET_BITS=64" ]
common_flags += [ "-pthread" ]
+
+ if (link_libstdcpp_statically) {
+ # The sysroot being built against is based on Stretch, which is newer than
+ # the libstdc++ that's on Trusty (14.04) which is the Chromium minspec.
+ # This minspec determines what the available buildbots are. Chromium
+ # doesn't have a problem with libstdc++ despite this, because it links
+ # against a local copy of libc++ instead. As this build file only affects
+ # the standalone Crashpad build, when this flag is set link libstdc++
+ # statically to avoid the problem on the bots.
+ ldflags += [ "-static-libstdc++" ]
+ }
}
if (mini_chromium_is_fuchsia) {
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Mark Mentovai (Gerrit)
1 comment:
Oh, it doesn't want "-Wl," apparently.
Are we invoking ld.lld directly or letting the compiler driver do it for us? The driver should have stripped away the “-Wl,”.
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Scott Graham (Gerrit)
1 comment:
> Oh, it doesn't want "-Wl," apparently. […]
We're using clang++ as the linker. I have no idea why no -Wl, I find the (lack of) command line documentation for these tools totally insane.
Here's with -Wl:
scottmg@around:/work/cp2/crashpad$ ninja -C out/lin crashpad_client_test
ninja: Entering directory `out/lin'
[0->1/1 ~1] Regenerating ninja files
[1->1/2 ~1] LINK ./crashpad_handler
FAILED: crashpad_handler
../../third_party/linux/clang/linux-amd64/bin/clang++ -Wl,-static-libstdc++ -Wl,--as-needed -Wl,-z,noexecstack --sysroot=../../third_party/linux/sysroot -pthread -pie -o "./crashpad_handler" -Wl,--start-group obj/handler/crashpad_handler.main.o obj/tools/tool_support.tool_support.o obj/handler/libhandler.a obj/compat/libcompat.a obj/client/libclient.a obj/third_party/mini_chromium/mini_chromium/base/libbase.a obj/util/libutil.a obj/minidump/libminidump.a obj/snapshot/libsnapshot.a -Wl,--end-group -lz
/usr/local/google/work/cp2/crashpad/out/lin/../../third_party/linux/clang/linux-amd64/bin/ld.lld: error: unknown argument: -static-libstdc++
clang-7.0: error: linker command failed with exit code 1 (use -v to see invocation)
ninja: build stopped: subcommand failed.
and without -Wl:scottmg@around:/work/cp2/crashpad$ ninja -C out/lin crashpad_client_test -v -j1
ninja: Entering directory `out/lin'
[0->1/1 ~1] ../../../buildtools/linux64/gn --root=../.. -q gen .
[0->1/1 ~1] ../../third_party/linux/clang/linux-amd64/bin/clang++ -static-libstdc++ -Wl,--as-needed -Wl,-z,noexecstack --sysroot=../../third_party/linux/sysroot -pthread -pie -o "./crashpad_handler" -Wl,--start-group obj/handler/crashpad_handler.main.o obj/tools/tool_support.tool_support.o obj/handler/libhandler.a obj/compat/libcompat.a obj/client/libclient.a obj/third_party/mini_chromium/mini_chromium/base/libbase.a obj/util/libutil.a obj/minidump/libminidump.a obj/snapshot/libsnapshot.a -Wl,--end-group -lz
scottmg@around:/work/cp2/crashpad$ ldd out/lin/crashpad_client_test
linux-vdso.so.1 (0x00007ffc787c9000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fdaaa985000)
libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007fdaaa76e000)
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007fdaaa551000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fdaaa1b2000)
/lib64/ld-linux-x86-64.so.2 (0x00007fdaaaefa000)
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Mark Mentovai (Gerrit)
Oh, right. -static-libstdc++ is a driver option, not a linker option, so the -Wl, was wrong.
The documentation is terrible. clang implements -static-libstdc++ but you won’t find it documented anywhere. Well, it’s listed on https://clang.llvm.org/docs/ClangCommandLineReference.html, but there isn’t really any explanation of what it does other than “C++ standard library to use”, along with 10 other things. They expect you to look at the GCC documentation. https://gcc.gnu.org/onlinedocs/gcc/Link-Options.html
What you checked in is good.
Scott Graham (Gerrit)
Patch Set 6:
Oh, right. -static-libstdc++ is a driver option, not a linker option, so the -Wl, was wrong.
The documentation is terrible. clang implements -static-libstdc++ but you won’t find it documented anywhere. Well, it’s listed on https://clang.llvm.org/docs/ClangCommandLineReference.html, but there isn’t really any explanation of what it does other than “C++ standard library to use”, along with 10 other things. They expect you to look at the GCC documentation. https://gcc.gnu.org/onlinedocs/gcc/Link-Options.html
What you checked in is good.
OK, thanks for confirming.
The thing that bugs me the most is that it's not in here:
scottmg@around:/work/cp2/crashpad$ third_party/linux/clang/linux-amd64/bin/ld.lld --help |grep static
--Bstatic Do not link against shared libraries
--exclude-libs=<value> Exclude static libraries from automatic export
--exclude-libs <value> Exclude static libraries from automatic export
--no-whole-archive Do not force load of all members in a static library
--static Do not link against shared libraries
--whole-archive Force load of all members in a static library
scottmg@around:/work/cp2/crashpad$ third_party/linux/clang/linux-amd64/bin/clang++ --help |grep static
--analyze Run the static analyzer
-fno-threadsafe-statics Do not emit code to make initialization of local statics thread safe
-Xanalyzer <arg> Pass <arg> to the static analyzer
scottmg@around:/work/cp2/crashpad$
Mark Mentovai (Gerrit)
Patch Set 6:
Patch Set 6:
Oh, right. -static-libstdc++ is a driver option, not a linker option, so the -Wl, was wrong.
The documentation is terrible. clang implements -static-libstdc++ but you won’t find it documented anywhere. Well, it’s listed on https://clang.llvm.org/docs/ClangCommandLineReference.html, but there isn’t really any explanation of what it does other than “C++ standard library to use”, along with 10 other things. They expect you to look at the GCC documentation. https://gcc.gnu.org/onlinedocs/gcc/Link-Options.html
What you checked in is good.
OK, thanks for confirming.
The thing that bugs me the most is that it's not in here:
GCC’s --help is even more sparse. Clang’s at least looks like it’s trying, even though it’s not.
Maybe they’d take a patch.