python3.pc misses @LIBPYTHON@

[conversy]

Output of brew config

HOMEBREW_VERSION: 5.1.8-3-gab84fd7
ORIGIN: https://github.com/Homebrew/brew
HEAD: ab84fd761309e8f59e580ed0f881b5bdc4e1e7bf
Last commit: 2 weeks ago
Branch: main
Core tap JSON: 11 May 08:31 UTC
Core cask tap JSON: 11 May 08:31 UTC
HOMEBREW_PREFIX: /opt/homebrew
HOMEBREW_CASK_OPTS: []
HOMEBREW_DISPLAY: /var/run/com.apple.launchd.VPd7NHjkk1/org.xquartz:0
HOMEBREW_DOWNLOAD_CONCURRENCY: 20
HOMEBREW_FORBID_PACKAGES_FROM_PATHS: set
HOMEBREW_GITHUB_API_TOKEN: set
HOMEBREW_MAKE_JOBS: 10
HOMEBREW_SORBET_RUNTIME: set
Homebrew Ruby: 4.0.3 => /opt/homebrew/Library/Homebrew/vendor/portable-ruby/4.0.3/bin/ruby
CPU: deca-core 64-bit arm_firestorm_icestorm
Clang: 21.0.0 build 2100
Git: 2.53.0 => /opt/homebrew/bin/git
Curl: 8.7.1 => /usr/bin/curl
macOS: 26.4.1-arm64
CLT: 26.4.1.0.1775747724
Xcode: 26.4.1
Metal Toolchain: N/A
Rosetta 2: false

Output of brew doctor

Please note that these warnings are just used to help the Homebrew maintainers
with debugging if you file an issue. If everything you use Homebrew for is
working fine: please don't worry or file an issue; just ignore this. Thanks!

Warning: Unbrewed dylibs were found in /usr/local/lib.
If you didn't put them there on purpose they could cause problems when
building Homebrew formulae and may need to be deleted.

Unexpected dylibs:
  /usr/local/lib/libMoltenVK.dylib
  /usr/local/lib/libSPIRV-Tools-shared.dylib
  /usr/local/lib/libSPIRV.16.2.0.dylib
  /usr/local/lib/libSPIRV.16.dylib
  /usr/local/lib/libSPIRV.dylib
  /usr/local/lib/libVkLayer_api_dump.dylib
  /usr/local/lib/libVkLayer_gfxreconstruct.dylib
  /usr/local/lib/libVkLayer_khronos_profiles.dylib
  /usr/local/lib/libVkLayer_khronos_shader_object.dylib
  /usr/local/lib/libVkLayer_khronos_synchronization2.dylib
  /usr/local/lib/libVkLayer_khronos_validation.dylib
  /usr/local/lib/libVkLayer_screenshot.dylib
  /usr/local/lib/libdxcompiler.dylib
  /usr/local/lib/libgfx.0.2026.1.dylib
  /usr/local/lib/libglslang-default-resource-limits.16.2.0.dylib
  /usr/local/lib/libglslang-default-resource-limits.16.dylib
  /usr/local/lib/libglslang-default-resource-limits.dylib
  /usr/local/lib/libglslang.16.2.0.dylib
  /usr/local/lib/libglslang.16.dylib
  /usr/local/lib/libglslang.dylib
  /usr/local/lib/libshaderc_shared.1.dylib
  /usr/local/lib/libslang-compiler.0.2026.1.dylib
  /usr/local/lib/libslang-glsl-module-2026.1.dylib
  /usr/local/lib/libslang-glslang-2026.1.dylib
  /usr/local/lib/libslang-rt.0.2026.1.dylib
  /usr/local/lib/libspirv-cross-c-shared.0.68.0.dylib
  /usr/local/lib/libvulkan.1.4.341.dylib
  /usr/local/lib/libvulkan_kosmickrisp.dylib

Warning: Unbrewed header files were found in /usr/local/include.
If you didn't put them there on purpose they could cause problems when
building Homebrew formulae and may need to be deleted.

Unexpected header files:
  /usr/local/include/MoltenVK/*
  /usr/local/include/dxc/*
  /usr/local/include/glslang/*
  /usr/local/include/shaderc/*
  /usr/local/include/slang/*
  /usr/local/include/spirv-tools/*
  /usr/local/include/spirv/*
  /usr/local/include/spirv_cross/*
  /usr/local/include/vk_video/*
  /usr/local/include/vulkan/*

Warning: Unbrewed '.pc' files were found in /usr/local/lib/pkgconfig.
If you didn't put them there on purpose they could cause problems when
building Homebrew formulae and may need to be deleted.

Unexpected '.pc' files:
  /usr/local/lib/pkgconfig/SPIRV-Headers.pc
  /usr/local/lib/pkgconfig/SPIRV-Tools-shared.pc
  /usr/local/lib/pkgconfig/SPIRV-Tools.pc
  /usr/local/lib/pkgconfig/shaderc.pc
  /usr/local/lib/pkgconfig/spirv-cross-c-shared.pc
  /usr/local/lib/pkgconfig/spirv-cross-c.pc
  /usr/local/lib/pkgconfig/vulkan.pc

Warning: Unbrewed static libraries were found in /usr/local/lib.
If you didn't put them there on purpose they could cause problems when
building Homebrew formulae and may need to be deleted.

Unexpected static libraries:
  /usr/local/lib/libGenericCodeGen.a
  /usr/local/lib/libMachineIndependent.a
  /usr/local/lib/libOSDependent.a
  /usr/local/lib/libSPIRV-Tools-diff.a
  /usr/local/lib/libSPIRV-Tools-link.a
  /usr/local/lib/libSPIRV-Tools-lint.a
  /usr/local/lib/libSPIRV-Tools-opt.a
  /usr/local/lib/libSPIRV-Tools-reduce.a
  /usr/local/lib/libSPIRV-Tools.a
  /usr/local/lib/libSPIRV.a
  /usr/local/lib/libVulkanSafeStruct.a
  /usr/local/lib/libglslang-default-resource-limits.a
  /usr/local/lib/libglslang.a
  /usr/local/lib/libshaderc.a
  /usr/local/lib/libshaderc_combined.a
  /usr/local/lib/libshaderc_util.a
  /usr/local/lib/libspirv-cross-c.a
  /usr/local/lib/libspirv-cross-core.a
  /usr/local/lib/libspirv-cross-cpp.a
  /usr/local/lib/libspirv-cross-glsl.a
  /usr/local/lib/libspirv-cross-hlsl.a
  /usr/local/lib/libspirv-cross-msl.a
  /usr/local/lib/libspirv-cross-reflect.a
  /usr/local/lib/libspirv-cross-util.a
  /usr/local/lib/libspirv-reflect-static.a

Description of issue

When I try to use pkg-config to link a program with a python library installed with brew, I get the lib options like this:

$ PKG_CONFIG_PATH=`brew --prefix`/lib/pkgconfig pkg-config python3 --libs
-L/opt/homebrew/opt/python@3.14/Frameworks/Python.framework/Versions/3.14/lib

but shouldn't the results read:

-L/opt/homebrew/opt/python@3.14/Frameworks/Python.framework/Versions/3.14/lib -lpython3.14

?

It's as if python3.pc got an empty string as @LIBPYTHON@ when built.

Best.

[carlocab]

You need to use python3-embed if you want to link Python.framework/libpython.

❯ pkgconf --libs python3
-L/opt/homebrew/opt/python@3.14/Frameworks/Python.framework/Versions/3.14/lib
❯ pkgconf --libs python3-embed
-L/opt/homebrew/opt/python@3.14/Frameworks/Python.framework/Versions/3.14/lib -lpython3.14

[conversy]

got it, thank you!

It's too bad I missed this information, python-embed is not mentioned in
https://docs.brew.sh/Homebrew-and-Python and neither in
https://docs.brew.sh/Python-for-Formula-Authors

Have I overlooked it somewhere else?

[carlocab]

This isn't a Homebrew-specific question, so you should check the Python documentation for this. See, for example, https://docs.python.org/3/extending/embedding.html#compiling-and-linking-under-unix-like-systems.

[conversy]

thank you again.