libpng: version field in generated .pc file includes a "v" prefix, causing dependency resolution failures

[Doekin]

Xmake Version

xmake v3.0.0+HEAD.0db4fe610

Operating System Version and Architecture

Windows 10

Describe Bug

The libpng package generates a pkg-config file (.pc) with a Version field prefixed by a "v" (e.g., Version: v1.6.48).

This version string is not correctly parsed by other build systems, such as Meson. When a dependent package like cairo performs a version check (e.g., libpng >= 1.4.0), the check fails. Consequently, the build system ignores the existing xmake-installed libpng and attempts to download its own version, defeating the purpose of the package manager.

Expected Behavior

The Version field in the generated libpng.pc file should contain a standard, parsable version string without the "v" prefix, such as Version: 1.6.48.

Project Configuration

$ xrepo install -vD cairo

...
Dependency libpng found: NO. Found v1.6.48 but need: '>= 1.4.0'
Run-time dependency libpng found: NO (tried pkgconfig and cmake)
Looking for a fallback subproject for the dependency libpng
Downloading libpng source from https://github.com/glennrp/libpng/archive/v1.6.43.tar.gz
Downloading libpng patch from https://wrapdb.mesonbuild.com/v2/libpng_1.6.43-1/get_patch

Executing subproject libpng 

libpng| Project name: libpng
libpng| Project version: 1.6.43
libpng| C compiler for the host machine: /home/runner/work/_temp/cfdf5e8e-9c47-4d09-b13c-e3dbeb641388/emsdk-main/upstream/emscripten/emcc (emscripten 4.0.10 "emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 4.0.10 (b7dc6e5747465580df5984e723b9d1f10d8e804b)")
libpng| C linker for the host machine: /home/runner/work/_temp/cfdf5e8e-9c47-4d09-b13c-e3dbeb641388/emsdk-main/upstream/emscripten/emcc ld.wasm 21.0.0
libpng| C compiler for the build machine: cc (gcc 13.3.0 "cc (Ubuntu 13.3.0-6ubuntu2~24.04) 13.3.0")
libpng| C linker for the build machine: cc ld.bfd 2.42
libpng| Dependency zlib found: YES v1.3.1 (cached)
libpng| Library m found: YES
libpng| Fetching value of define "__ARM_NEON" : (undefined)
libpng| Configuring libpng16.pc using configuration
libpng| Configuring libpng.pc using configuration
libpng| Build targets in project: 2
libpng| Subproject libpng finished.

Dependency libpng from subproject subprojects/libpng-1.6.43 found: YES 1.6.43
...

Additional Information and Error Logs

Here is a comparison of different .pc files for context.

1. .pc file currently generated:

Name: libpng
Description: The official PNG reference library
Version: v1.6.48
Libs:  -L${libdir}/../../../../../z/zlib/v1.3.1/95786712bac941e795afa187a68143a4/lib -L${libdir} -lpng -lzlib
Libs.private: 
Cflags:  -I${includedir}/../../../../../z/zlib/v1.3.1/95786712bac941e795afa187a68143a4/include -I${includedir}

2. Output with pkgconfig_importfiles rule:
Strip the leading "v" from the version string obtained via package:version_str() and apply it using set_version().
Append add_rules("utils.install.pkgconfig_importfiles", {filename = "libpng.pc", links = {"z"}})

Name: png
Description: png
Version: 1.6.48
Libs: -L${libdir} -lz
Cflags: -I${includedir}

3. Reference .pc file from libpng's native build system:
For comparison, a .pc file generated by libpng's own build system provides a good reference for the expected format and content.

Name: libpng
Description: Loads and saves PNG files
Version: 1.6.49
Requires.private: zlib
Libs: -L${libdir} -lpng16
Libs.private: -lz 
Cflags: -I${includedir}