Cmake build system breaks with symbolic links

laanwj commented at 8:04 am on October 24, 2024: member

If the build directory is a symbolic link, or when the entire source directory is symlinked (and we build from there), the current cmake build runs into trouble finding its own generated files.

To reproduce:

0git clone --depth=1 https://github.com/bitcoin/bitcoin.git
1mkdir build
2cd bitcoin/
3ln -s ../build .
4cmake -Bbuild -DBUILD_GUI=ON
5cd build
6make

0[ 37%] Building CXX object src/CMakeFiles/bitcoin_node.dir/validation.cpp.o
1In file included from /data/src/tmp/bitcoin/build/src/qt/bitcoinqt_autogen/mocs_compilation.cpp:2:
2/data/src/tmp/bitcoin/build/src/qt/bitcoinqt_autogen/EWIEGA46WW/moc_addressbookpage.cpp:10:10: fatal error: ../../../../../src/qt/addressbookpage.h: No such file or directory
3   10 | #include "../../../../../src/qt/addressbookpage.h"
4      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
5compilation terminated.
6make[2]: *** [src/qt/CMakeFiles/bitcoinqt.dir/build.make:784: src/qt/CMakeFiles/bitcoinqt.dir/bitcoinqt_autogen/mocs_compilation.cpp.o] Error 1
7make[2]: *** Waiting for unfinished jobs...

This affects the build with Qt as well as the build with multiprocess, both which have generated files.

With autotools this wasn’t an issue, so i think it can be considered a regression. But not a high-priority one as it can be worked around by specifying the full paths instead.

laanwj added the label Build system on Oct 24, 2024

fanquake added this to the milestone 29.0 on Nov 13, 2024

hebasto commented at 2:27 pm on November 24, 2024: member

This affects … the build with multiprocess…

Unable to reproduce this part on Ubuntu 24.04.

laanwj commented at 3:36 pm on November 25, 2024: member

Unable to reproduce this part on Ubuntu 24.04.

Okay… i’ll retest the multiprocess case. If it’s still an issue, it’s seperate from the Qt case anyway and would need to be fixed seperately.

willcl-ark commented at 1:53 pm on November 28, 2024: member

I was able to reproduce this on Ubuntu 23.10 on master @ 7590e93 with the repro steps in OP:

 0[ 66%] Automatic RCC for bitcoin_locale.qrc
 1[ 67%] Building CXX object src/qt/CMakeFiles/bitcoinqt.dir/bitcoinaddressvalidator.cpp.o
 2[ 67%] Building CXX object src/qt/CMakeFiles/bitcoinqt.dir/bantablemodel.cpp.o
 3[ 67%] Building CXX object src/qt/CMakeFiles/bitcoinqt.dir/bitcoinqt_autogen/mocs_compilation.cpp.o
 4[ 67%] Building CXX object src/qt/CMakeFiles/bitcoinqt.dir/bitcoingui.cpp.o
 5[ 67%] Building CXX object src/qt/CMakeFiles/bitcoinqt.dir/bitcoinamountfield.cpp.o
 6[ 67%] Building CXX object src/qt/CMakeFiles/bitcoinqt.dir/bitcoin.cpp.o
 7[ 67%] Building CXX object src/qt/CMakeFiles/bitcoinqt.dir/bitcoinunits.cpp.o
 8[ 68%] Building CXX object src/qt/CMakeFiles/bitcoinqt.dir/clientmodel.cpp.o
 9[ 68%] Building CXX object src/qt/CMakeFiles/bitcoinqt.dir/csvmodelwriter.cpp.o
10In file included from /tmp/31145/bitcoin/build/src/qt/bitcoinqt_autogen/mocs_compilation.cpp:2:
11/tmp/31145/bitcoin/build/src/qt/bitcoinqt_autogen/EWIEGA46WW/moc_addressbookpage.cpp:10:10: fatal error: '../../../../../src/qt/addressbookpage.h' file not found
12   10 | #include "../../../../../src/qt/addressbookpage.h"
13      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
141 error generated.
15make[2]: *** [src/qt/CMakeFiles/bitcoinqt.dir/build.make:786: src/qt/CMakeFiles/bitcoinqt.dir/bitcoinqt_autogen/mocs_compilation.cpp.o] Error 1
16make[2]: *** Waiting for unfinished jobs....
17[ 69%] Linking CXX executable bitcoin-wallet
18[ 69%] Built target bitcoin-wallet
19make[1]: *** [CMakeFiles/Makefile2:1432: src/qt/CMakeFiles/bitcoinqt.dir/all] Error 2
20make[1]: *** Waiting for unfinished jobs....
21[ 70%] Linking CXX static library libbitcoin_node.a
22[ 70%] Built target bitcoin_node
23make: *** [Makefile:146: all] Error 2

~~However, if the symlink is constructed using an asbolute path then it works correctly. E.g. for me:~~

0mkdir -p /tmp/31145/build && cd /tmp/31145
1git clone --depth=1 https://github.com/bitcoin/bitcoin.git
2cd bitcoin
3ln -s /tmp/31145/build .
4cmake -Bbuild -DBUILD_GUI=ON
5cd build
6make

~~So the build system seems to be getting tripped up on the relativity of the symlink.~~

Actually I spoke too soon here, sorry. It just failed much later on that before:

0[ 91%] Built target test_bitcoin
1make: *** [Makefile:146: all] Error 2

So I agree, symlinked build dirs seem generally broken currently with cmake.

hebasto commented at 1:59 pm on November 28, 2024: member

@willcl-ark

So I agree, symlinked build dirs seem generally broken currently with cmake.

Does #31361 fix it?

willcl-ark commented at 2:09 pm on November 28, 2024: member

It does indeed.

fanquake closed this on Dec 2, 2024

fanquake referenced this in commit da4f4fac8d on Dec 2, 2024

Cmake build system breaks with symbolic links #31145