[package] <zlib>/<1.2.12>: Can't link

[PolarStarWalker]

Package and Environment Details

• Package Name/Version: zlib/1.2.12
• Operating System+version: Windows 10
• Compiler+version: Clang 14
• Conan version: conan 1.51.3
• Python version: Python 3.10.6

Conan profile

[settings]
os=Windows
os.subsystem=msys2
os_build=Windows
arch=x86_64
arch_build=x86_64
compiler=clang
compiler.version=14
compiler.libcxx=libc++
compiler.cppstd=20
compiler.runtime=MTd
build_type=Debug
[options]
[conf]
[build_requires]
[env]
C=C:\msys64\clang64\bin\clang.exe
CXX=C:\msys64\clang64\bin\clang++.exe

Steps to reproduce

Linker expects the name libzlib.a
Actual name id directory is libz.a

I guess that the problem here
Name in package_info and actual name of library is different, because _is_clang_cl methond is wrong

my conan file conanfile.txt

[requires]
    zlib/1.2.12
[options]

[generators]
    cmake

[imports]

Logs

Click to expand log

lld: error: unable to find library -lzlib

[SpaceIm]

I don't have an elegant fix (except using conan.tools.files.collect_libs()), but this discussion might be of interest for you: conan-io/conan#10955

Basically during zlib build, the output name depends on https://cmake.org/cmake/help/latest/variable/MSVC.html, and this variable is TRUE if the compiler detected by CMake is cl (ie the compiler of Visual Studio), but also any "cl like" compilers.
In package_info() we deduce lib name from this condition, so we have to mimic this condition.
clang-cl is a cl like compiler, thus this _is_clang_cl in this recipe which has been added to handle some issues encoutered by @AndreyMlashkin, but it doesn't make the distinction between clang-cl and clang from MinGW (and actually it's not even clear how a canonical conan profile for clang-cl or even clang from MinGW should look like). clang from MinGW doesn't seem to be a cl like compiler for MSVC variable of CMake, so it breaks.

[calebgray]

I just ran in to a variation of this same issue with the latest version of zlib (1.2.13), thankfully there's an elegant fix for my issue.

I'm building using a version of mingw that was compiled using clang: https://github.com/mstorsjo/llvm-mingw

This line checks gcc but not clang which leads to an incorrect cpp_info.libs export: https://github.com/conan-io/conan-center-index/blob/master/recipes/zlib/all/conanfile.py#L32

I've forked the repo, and contributed a first pass solution: https://github.com/calebgray/conan-center-index

If/when I'm accepted as a contributor to the project, I'll create a PR for this and continue to follow the CONTRIBUTING guide.

[SpaceIm]

It would break clang-cl. There is PR already: #14644