depends: For mingw cross compile use -gcc-posix to prevent library conflict

laanwj commented at 5:49 pm on October 1, 2024: member

CMake parses some paths from the spec of the C compiler, assuming it will be the linker, resulting in the link to end up with -L/usr/lib/gcc/x86_64-w64-mingw32/12-win32 on debian bookworm if both -win32 and -posix variants are installed, and -win32 is the default alternative.

This results in the wrong C++ library being linked, missing std::threads::hardware_concurrency and other threading functions.

To fix this, use the -posix variant of gcc as well when available. This fixes a regression compared to autotools, where this scenario worked.

CMake parses some paths from the spec of the C compiler, assuming it
will be the linker, resulting in the link to end up with
`-L/usr/lib/gcc/x86_64-w64-mingw32/12-win32` on debian bookworm if both
-win32 and -posix variants are installed, and -win32 is the default
alternative.

This results in the wrong C++ library being linked, missing
std::threads::hardware_concurrency and other threading functions.

To fix this, use the -posix variant of gcc as well when available. This
fixes a regression compared to autotools, where this scenario worked.

ae56b3230b

laanwj added the label Windows on Oct 1, 2024

laanwj added the label Build system on Oct 1, 2024

DrahtBot commented at 5:49 pm on October 1, 2024: contributor

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hebasto commented at 6:50 pm on October 1, 2024: member

Here is a related upstream issue: https://gitlab.kitware.com/cmake/cmake/-/issues/25670.

The regression is behavior is caused by setting CMAKE_TRY_COMPILE_TARGET_TYPE globally:https://github.com/bitcoin/bitcoin/blob/fc642c33ef28829eda0119a0fe39fd9bc4b84051/cmake/module/CheckSourceCompilesAndLinks.cmake#L9-L10

laanwj commented at 7:24 pm on October 1, 2024: member

Yes, that seems similar! It would work perfectly fine without adding any -L spec, the linker knows where to find its libraries, no need to add the implicit link directories explicitly at all, but it does and it breaks.

theuni approved

theuni commented at 5:39 pm on October 2, 2024: member

utACK ae56b3230b287eef5a5657d3089abebffde51484.

Annoying upstream bug aside, this seems reasonable enough to me.

hebasto commented at 7:36 pm on October 2, 2024: member

It looks reasonable to be explicit about every aspect of a toolchain.

However, I’m wondering why the bug appears on Debian Bookworm, but not on Ubuntu 24.04? I’ve cross-checked CMake versions and can confirm they are not the cause.

hebasto approved

hebasto commented at 8:08 pm on October 2, 2024: member

ACK ae56b3230b287eef5a5657d3089abebffde51484. I’ve tested on both Debian Bookworm and Ubuntu 24.04 with the g++-mingw-w64-x86-64 package installed. The resulting CMake internal configuration appears more accurate. For instance, on Ubuntu 24.04, for the bitcoin-tx target, the diff in build/src/CMakeFiles/bitcoin-tx.dir/linkLibs.rsp looks as follows:

0-  -L"/usr/lib/gcc/x86_64-w64-mingw32/13-win32"  libbitcoin_common.a util/libbitcoin_util.a univalue/libunivalue.a -liphlpapi libbitcoin_consensus.a crypto/libbitcoin_crypto.a crypto/libbitcoin_crypto_sse41.a crypto/libbitcoin_crypto_avx2.a crypto/libbitcoin_crypto_x86_shani.a secp256k1/src/libsecp256k1.a -lws2_32 -lkernel32 -luser32 -lgdi32 -lwinspool -lshell32 -lole32 -loleaut32 -luuid -lcomdlg32 -ladvapi32 
1+ libbitcoin_common.a util/libbitcoin_util.a univalue/libunivalue.a -liphlpapi libbitcoin_consensus.a crypto/libbitcoin_crypto.a crypto/libbitcoin_crypto_sse41.a crypto/libbitcoin_crypto_avx2.a crypto/libbitcoin_crypto_x86_shani.a secp256k1/src/libsecp256k1.a -lws2_32 -lkernel32 -luser32 -lgdi32 -lwinspool -lshell32 -lole32 -loleaut32 -luuid -lcomdlg32 -ladvapi32

maflcko added the label DrahtBot Guix build requested on Oct 7, 2024

DrahtBot commented at 2:57 am on October 8, 2024: contributor

Guix builds (on x86_64) [untrusted test-only build, possibly unsafe, not for production use]

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guix_build.log.diff		`bb5f9db91a37811e...`

DrahtBot removed the label DrahtBot Guix build requested on Oct 8, 2024

fanquake merged this on Oct 8, 2024

fanquake closed this on Oct 8, 2024

fanquake referenced this in commit 7fec638222 on Oct 31, 2024

fanquake commented at 3:12 pm on October 31, 2024: member

Backporting to 28.x in #31104 for consistency.

depends: For mingw cross compile use -gcc-posix to prevent library conflict #31013

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Guix builds (on x86_64) [untrusted test-only build, possibly unsafe, not for production use]