autotools: accept linker flags via CURL_LDFLAGS_{LIB,BIN}
#12312
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autotools passes `LDFLAGS` automatically to the linker command. curl's `lib/Makefile.am` customizes libcurl linker flags. In that customization, it added `LDFLAGS` to the custom options. This resulted in passing `LDFLAGS` _twice_ to the `libtool` command. Most of the time this is benign, but some `LDFLAGS` options can break the build when passed twice. One such example is passing `.o` files, e.g. `crt*.o` files necessary when customizing the C runtime, e.g. for MUSL builds. Passing them twice resulted in duplicate symbol errors: ``` libtool: link: clang-15 --target=aarch64-unknown-linux-musl [...] /usr/lib/aarch64-linux-musl/crt1.o [...] /usr/lib/aarch64-linux-musl/crt1.o [...] ld.lld-15: error: duplicate symbol: _start >>> defined at crt1.c >>> /usr/lib/aarch64-linux-musl/crt1.o:(.text+0x0) >>> defined at crt1.c >>> /usr/lib/aarch64-linux-musl/crt1.o:(.text+0x0) [...] clang: error: linker command failed with exit code 1 (use -v to see invocation) ``` This patch deletes `LDFLAGS` from our customized options, leaving a single copy of them as passed by autotools automatically. This behaviour came with commit 1a59319 (2013-07-23) as a fix for bug https://curl.haxx.se/bug/view.cgi?id=1217. The patch was a works-for-me hack that ended up merged in curl: https://sourceforge.net/p/curl/bugs/1217/#06ef With the root cause remaining unclear. Perhaps the SUNPro 12 linker was sensitive to `-L` `-l` order, requiring `-L` first? This would be unusual and might suggest a bug in either the linker or in `libtool`. The curl build does indeed pass the list of detected libs via its own `LIBCURL_LIBS` variable, which ends up before `LDFLAGS` on the `libtool` command line, but it would seem to be the job of `libtool` to ensure that even a buggy/peculiar linker gets the options in the order it's expecting it. Especially because autotools passes `LDFLAGS` last, making it hardly possibly to pass anything after it. Perhaps in the 10 years since this issue, this already got a fix upstream. IMO passing `LDFLAGS` twice to fix the above is a nuclear option with unintended side-effects. Closes #xxxxx
…BIN` To allow passing `LDFLAGS` specific to libcurl (`CURL_LDFLAGS_LIB`) and curl tool (`CURL_LDFLAGS_BIN`). This makes it possible to build libcurl and curl with a single invocation with lib- and tool-specific custom linker flags. Such flag can be enabling `.map` files, a `.def` file for libcurl DLL, controlling static/shared, incl. requesting a static curl tool (with `-static-libtool-libs`) while building both shared and static libcurl. curl-for-win uses the above and some more. Closes #xxxxx
vszakats
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CURL_LDFLAGS_LIB, CURL_LDFLAGS_BINCURL_LDFLAGS_LIB, CURL_LDFLAGS_BIN
vszakats
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CURL_LDFLAGS_LIB, CURL_LDFLAGS_BINCURL_LDFLAGS_{LIB,BIN}
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Disabled for now. Pending upstream curl/curl#12312
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zuoxiaofeng
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To allow passing `LDFLAGS` specific to libcurl (`CURL_LDFLAGS_LIB`) and curl tool (`CURL_LDFLAGS_BIN`). This makes it possible to build libcurl and curl with a single invocation with lib- and tool-specific custom linker flags. Such flag can be enabling `.map` files, a `.def` file for libcurl DLL, controlling static/shared, incl. requesting a static curl tool (with `-static-libtool-libs`) while building both shared and static libcurl. curl-for-win uses the above and some more. These options are already supported in `Makefile.mk`. CMake has built-in variables for this. Closes curl#12312
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To allow passing
LDFLAGSspecific to libcurl (CURL_LDFLAGS_LIB) andcurl tool (
CURL_LDFLAGS_BIN).This makes it possible to build libcurl and curl with a single
invocation with lib- and tool-specific custom linker flags.
Such flag can be enabling
.mapfiles, a.deffile for libcurl DLL,controlling static/shared, incl. requesting a static curl tool (with
-static-libtool-libs) while building both shared and static libcurl.curl-for-win uses the above and some more.
These options are already supported in
Makefile.mk. CMake has built-invariables for this.
Closes #12312