Linking a shared library target with custom prefix

[rws-git]

Hello!
I'd like to ask if the following behavior is a bug or a feature.

xmake version: v2.8.8+20240303
OS: Manjaro x86_64
GNU ld (GNU Binutils) 2.42.0
g++ (GCC) 13.2.1 20230801

I have a simple project structure: shared library and an executable that's linking the library. On linux I prefer not to use "lib" prefix for library name, so I use set_prefixname(""). Under exe project there's add_deps call. But unfortunately, I get a linker error that can't find the library.
Here is a minimal project for a repro: xmake-test.zip
For those who do not want to download any zip archives (I approve, safety first!), here's an outline of the project.
I build with a command xmake build -vD xmake-test.
xmake.lua:

target("xmake-test-lib")
    set_kind("shared")
    set_prefixname("")
    add_files("lib.cpp")

target("xmake-test")
    add_deps("xmake-test-lib")
    set_kind("binary")
    add_files("main.cpp")

main.cpp

#include "lib.h"
#include <iostream>


int main(int argc, char* argv[]) {
	std::cout << getNumber() << std::endl;
	return 0;
}

lib.h

#pragma once

int getNumber();

lib.cpp

#include "lib.h"

int getNumber() {
	return 42;
}

The output I get:

[ 25%]: cache compiling.release lib.cpp
/usr/bin/gcc -c -m64 -fPIC -o build/.objs/xmake-test-lib/linux/x86_64/release/lib.cpp.o lib.cpp
[ 25%]: cache compiling.release main.cpp
/usr/bin/gcc -c -m64 -o build/.objs/xmake-test/linux/x86_64/release/main.cpp.o main.cpp
[ 50%]: linking.release xmake-test-lib.so
/usr/bin/g++ -o build/linux/x86_64/release/xmake-test-lib.so build/.objs/xmake-test-lib/linux/x86_64/release/lib.cpp.o -shared -m64 -fPIC
[ 75%]: linking.release xmake-test
/usr/bin/g++ -o build/linux/x86_64/release/xmake-test build/.objs/xmake-test/linux/x86_64/release/main.cpp.o -m64 -Lbuild/linux/x86_64/release -Wl,-rpath=$ORIGIN -lxmake-test-lib
/usr/bin/ld: cannot find -lxmake-test-lib: No such file or directory
collect2: error: ld returned 1 exit status
error: @programdir/core/main.lua:306: @programdir/actions/build/main.lua:148: @programdir/modules/async/runjobs.lua:320: @programdir/actions/build/kinds/binary.lua:74: @programdir/core/sandbox/modules/os.lua:378: execv(/usr/bin/g++ -o build/linux/x86_64/release/xmake-test build/.objs/xmake-test/linux/x86_64/release/main.cpp.o -m64 -Lbuild/linux/x86_64/release -Wl,-rpath=$ORIGIN -lxmake-test-lib) failed(1)
stack traceback:
    [C]: in function 'error'
    [@programdir/core/base/os.lua:957]:
    [@programdir/core/sandbox/modules/os.lua:378]: in function 'execv'
    [@programdir/modules/core/tools/gcc.lua:527]:
    [C]: in function 'xpcall'
    [@programdir/core/base/utils.lua:280]:
    [@programdir/core/tool/linker.lua:221]: in function 'link'
    [@programdir/actions/build/kinds/binary.lua:74]: in function 'callback'
    [@programdir/modules/core/project/depend.lua:217]: in function 'on_changed'
    [@programdir/actions/build/kinds/binary.lua:55]: in function '_do_link_target'
    [@programdir/actions/build/kinds/binary.lua:105]:
    [@programdir/actions/build/kinds/binary.lua:132]: in function '_link_target'
    [@programdir/actions/build/kinds/binary.lua:160]: in function 'jobfunc'
    [@programdir/modules/async/runjobs.lua:237]:
    [C]: in function 'xpcall'
    [@programdir/core/base/utils.lua:280]: in function 'trycall'
    [@programdir/core/sandbox/modules/try.lua:117]: in function 'try'
    [@programdir/modules/async/runjobs.lua:220]: in function 'cotask'
    [@programdir/core/base/scheduler.lua:404]:

stack traceback:
	[C]: in function 'error'
	@programdir/core/base/os.lua:957: in function 'base/os.raiselevel'
	(...tail calls...)
	@programdir/core/main.lua:306: in upvalue 'cotask'
	@programdir/core/base/scheduler.lua:404: in function <@programdir/core/base/scheduler.lua:397>

The output directory contains xmake-test-lib.so library, but the linker is searching for a wrong name.
Shouldn't xmake provide different arguments to the linker in case when set_prefixname is used?

[waruqi]

xmake use -l to inherit dep link, it need lib prefix name, e.g. libxxx.so. if you want xxx.so, you can write after_build and copy it to xxx.so

target("foo")
    set_kind("shared")
    after_build(function (target)
        os.cp(target:targetfile(), path.join(target:targetdir(), "foo.so"))
    end)

[rws-git]

Hey @waruqi , thank you for explanation and the suggestion!
So, xmake always uses -l.

xmake use -l to inherit dep link, it need lib prefix name

I'd like to point out that there is a feature of ld -l option:

If namespec is of the form :filename, ld will search
the library path for a file called filename, otherwise it
will search the library path for a file called libnamespec.a.

Described here: https://www.man7.org/linux/man-pages/man1/ld.1.html
So when set_prefixname is used, xmake could pass the exact library name to ld with the colon.
This seems logical to me at least. May I suggest such functionality?

[waruqi]

I know about it, but it relies on a specific compiler and we need to deal with different compilers. But the implementation of dependent inheritance is currently a generic implementation, which would be complicated for us to change and not well maintained. So we won't consider supporting it for now.