Cmake build system breaks with symbolic links #31145

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:

git clone --depth=1 https://github.com/bitcoin/bitcoin.git
mkdir build
cd bitcoin/
ln -s ../build .
cmake -Bbuild -DBUILD_GUI=ON
cd build
make

[ 37%] Building CXX object src/CMakeFiles/bitcoin_node.dir/validation.cpp.o
In file included from /data/src/tmp/bitcoin/build/src/qt/bitcoinqt_autogen/mocs_compilation.cpp: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
   10 | #include "../../../../../src/qt/addressbookpage.h"
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.
make[2]: *** [src/qt/CMakeFiles/bitcoinqt.dir/build.make:784: src/qt/CMakeFiles/bitcoinqt.dir/bitcoinqt_autogen/mocs_compilation.cpp.o] Error 1
make[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:

<details> <summary>Details</summary>

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

</details>

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

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

~~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:

[ 91%] Built target test_bitcoin
make: *** [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

bitcoin locked this on Dec 2, 2025