/usr/bin/ld: cannot find -ltaskchampion-lib

[djmitche]

All tests are now failing with

#16 89.86    Compiling taskchampion-lib v0.1.0 (/root/code/src/tc/lib)
#16 90.17 [ 96%] Built target commands
#16 90.20 [ 98%] Building CXX object src/CMakeFiles/task_executable.dir/main.cpp.o
#16 90.20 [ 98%] Building CXX object src/CMakeFiles/lex_executable.dir/lex.cpp.o
#16 90.20 [ 98%] Building CXX object src/CMakeFiles/calc_executable.dir/calc.cpp.o
#16 90.30 warning: method `ptr_to_arg_out` is never used
#16 90.30    --> src/tc/lib/src/traits.rs:138:15
#16 90.30     |
#16 90.30 80  | pub(crate) trait PassByPointer: Sized {
#16 90.30     |                  ------------- method in this trait
#16 90.30 ...
#16 90.30 138 |     unsafe fn ptr_to_arg_out(self, arg_out: *mut *mut Self) {
#16 90.30     |               ^^^^^^^^^^^^^^
#16 90.30     |
#16 90.30     = note: `#[warn(dead_code)]` on by default
#16 90.30 
#16 91.53 warning: `taskchampion-lib` (lib) generated 1 warning
#16 91.53     Finished `dev` profile [unoptimized + debuginfo] target(s) in 1m 25s
#16 91.60 Copying byproducts `libtaskchampion_lib.a` to /root/code/build/src/tc
#16 91.72 [100%] Linking CXX executable lex
#16 91.83 [100%] Linking CXX executable calc
#16 91.87 [100%] Linking CXX executable task
#16 91.96 /usr/bin/ld: cannot find -ltaskchampion-lib: No such file or directory
#16 92.00 collect2: error: ld returned 1 exit status

The warning has been around forever, and is (I think) unrelated.

[djmitche]

I can build locally, so I wonder if this is some race condition? But the logging above suggests that the .a file is copied 360ms before it's referenced..

[djmitche]

It looks like it is. Trying to reproduce on the train, cargo couldn't download dependent crates fast enough and I see

[ 98%] Building CXX object src/CMakeFiles/lex_executable.dir/lex.cpp.o
[100%] Linking CXX executable lex
[100%] Linking CXX executable calc
/usr/bin/ld: cannot find -ltaskchampion-lib: No such file or directory
collect2: error: ld returned 1 exit status
gmake[2]: *** [src/CMakeFiles/lex_executable.dir/build.make:106: src/lex] Error 1
gmake[1]: *** [CMakeFiles/Makefile2:464: src/CMakeFiles/lex_executable.dir/all] Error 2
gmake[1]: *** Waiting for unfinished jobs....
[100%] Linking CXX executable task
/usr/bin/ld: cannot find -ltaskchampion-lib: No such file or directory
collect2: error: ld returned 1 exit status
gmake[2]: *** [src/CMakeFiles/calc_executable.dir/build.make:106: src/calc] Error 1
gmake[1]: *** [CMakeFiles/Makefile2:434: src/CMakeFiles/calc_executable.dir/all] Error 2
/usr/bin/ld: cannot find -ltaskchampion-lib: No such file or directory
collect2: error: ld returned 1 exit status
gmake[2]: *** [src/CMakeFiles/task_executable.dir/build.make:106: src/task] Error 1
gmake[1]: *** [CMakeFiles/Makefile2:404: src/CMakeFiles/task_executable.dir/all] Error 2
warning: spurious network error (3 tries remaining): [28] Timeout was reached (SSL connection timeout)
  Downloaded async-stream v0.3.5
  Downloaded scopeguard v1.1.0

which is to say, things are calling ld with -ltaskchampion-lib before the Rust build has even begun.

[djmitche]

corrosion docs say

For Rust library targets an INTERFACE library target is created with the same name as defined in the [lib] section of the Manifest.
...
The created library targets can be linked into other CMake targets by simply using target_link_libraries.

That target, from src/tc/lib/Cargo.toml, is taskchampion-lib. So I think this should work??

The target_link_libraries docs say

target_link_libraries( ... ... ...)
...
Each may be:
A library target name: The generated link line will have the full path to the linkable library file associated with the target. The buildsystem will have a dependency to re-link if the library file changes.
...
A plain library name: The generated link line will ask the linker to search for the library (e.g. foo becomes -lfoo or foo.lib).

since the error is regarding -ltaskchampion-lib and not /some/path/to/taskchampion-lib.so, I wonder if it's being interpreted as a plain library name?

[djmitche]

The docker images are using cmake 3.22, while I'm using 3.29. Maybe that's related?

[djmitche]

Nope, I can repro with 3.29 installed in a n ubuntu-22.04 docker image

[djmitche]

Hm, maybe not a race -- in the docker image, with cmake-3.29:

root@c2e3eb5fbea3:/repo# cmake --build build
[ 15%] Built target task
[ 29%] Built target libshared
[ 51%] Built target columns
[ 91%] Built target commands
[ 96%] Built target tc
[ 96%] Linking CXX executable task
/usr/bin/ld: cannot find -ltaskchampion-lib: No such file or directory
collect2: error: ld returned 1 exit status
gmake[2]: *** [src/CMakeFiles/task_executable.dir/build.make:106: src/task] Error 1
gmake[1]: *** [CMakeFiles/Makefile2:404: src/CMakeFiles/task_executable.dir/all] Error 2
gmake: *** [Makefile:166: all] Error 2

With -v that's

[ 96%] Linking CXX executable task
cd /repo/build/src && /usr/bin/cmake -E cmake_link_script CMakeFiles/task_executable.dir/link.txt --verbose=1
/usr/bin/c++ -Wall -Wextra -Wsign-compare -Wreturn-type -std=c++17  -g CMakeFiles/task_executable.dir/main.cpp.o -o task  libtask.a tc/libtc.a commands/libcommands.a tc/libtc.a columns/libcolumns.a liblibshared.a libtask.a liblibshared.a -ldl -lpthread /usr/lib/x86_64-linux-gnu/libuuid.so -ltaskchampion-lib
/usr/bin/ld: cannot find -ltaskchampion-lib: No such file or directory

[djmitche]

Outside of docker, -v shows

[100%] Linking CXX executable task
cd /home/dustin/p/taskwarrior/build/src && /usr/bin/cmake -E cmake_link_script CMakeFiles/task_executable.dir/link.txt --verbose=1
/usr/bin/c++ -Wall -Wextra -Wsign-compare -Wreturn-type -std=c++17  -g CMakeFiles/task_executable.dir/main.cpp.o -o task  libtask.a tc/libtc.a commands/libcommands.a tc/libtc.a columns/libcolumns.a liblibshared.a libtask.a liblibshared.a -ldl -lpthread /usr/lib/x86_64-linux-gnu/libuuid.so tc/libtaskchampion_lib.a -lgcc_s -lutil -lrt -lpthread -lm -ldl -lc

[djmitche]

Notably, locally it's using tc/libtaskchampion_lib.a, as I would expect.

[djmitche]

Ah, Rust-1.79 was released yesterday, and downgrading to 1.78 in the docker container

corrosion-rs/corrosion#501