052bb41410
without stable ids on headings we cannot generate stable links to these headings. nrd complains about this, but the current docbook workflow does not. a few generated ids remain, mostly in examples and footnotes. most of the examples are generated by nixdoc (which has since gained MD export functions, and the MD export does generate IDs).
51 lines
1.9 KiB
Markdown
51 lines
1.9 KiB
Markdown
# pkg-config {#sec-pkg-config}
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*pkg-config* is a unified interface for declaring and querying built C/C++ libraries.
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Nixpkgs provides a couple of facilities for working with this tool.
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## Writing packages providing pkg-config modules {#pkg-config-writing-packages}
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Packages should set `meta.pkgConfigModules` with the list of package config modules they provide.
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They should also use `testers.testMetaPkgConfig` to check that the final built package matches that list.
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Additionally, the [`validatePkgConfig` setup hook](https://nixos.org/manual/nixpkgs/stable/#validatepkgconfig), will do extra checks on to-be-installed pkg-config modules.
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A good example of all these things is zlib:
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```
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{ pkg-config, testers, ... }:
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stdenv.mkDerivation (finalAttrs: {
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...
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nativeBuildInputs = [ pkg-config validatePkgConfig ];
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passthru.tests.pkg-config = testers.testMetaPkgConfig finalAttrs.finalPackage;
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meta = {
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...
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pkgConfigModules = [ "zlib" ];
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};
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})
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```
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## Accessing packages via pkg-config module name {#sec-pkg-config-usage}
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### Within Nixpkgs {#sec-pkg-config-usage-internal}
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A [setup hook](#setup-hook-pkg-config) is bundled in the `pkg-config` package to bring a derivation's declared build inputs into the environment.
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This will populate environment variables like `PKG_CONFIG_PATH`, `PKG_CONFIG_PATH_FOR_BUILD`, and `PKG_CONFIG_PATH_HOST` based on:
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- how `pkg-config` itself is depended upon
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- how other dependencies are depended upon
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For more details see the section on [specifying dependencies in general](#ssec-stdenv-dependencies).
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Normal pkg-config commands to look up dependencies by name will then work with those environment variables defined by the hook.
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### Externally {#sec-pkg-config-usage-external}
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The `defaultPkgConfigPackages` package set is a set of aliases, named after the modules they provide.
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This is meant to be used by language-to-nix integrations.
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Hand-written packages should use the normal Nixpkgs attribute name instead.
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