[6.0] pkgconfig: Apply PKG_CONFIG_SYSROOTDIR when generating paths #7472
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SwiftPM's pkg-config implementation sets the `pc_sysrootdir` variable, but most `.pc` files do not use this variable directly. Instead, they rely on the pkg-config tool rewriting the generated paths to include the sysroot prefix when necessary. SwiftPM does not do this, so it does not generate the correct compiler flags to use libraries from a sysroot. This problem was reported in issue apple#7409 There are two major pkg-config implementations which handle sysroot differently: * `pkg-config` (the original https://pkg-config.freedesktop.org implementation) prepends sysroot after variable expansion, when it creates the compiler flag lists * `pkgconf` (the newer http://pkgconf.org implementation) prepends sysroot to variables when they are defined, so sysroot is included when they are expanded `pkg-config`'s method skips single character compiler flags, such as `-I` and `-L`, and has special cases for longer options. It does not handle spaces between the flags and their values properly, and prepends sysroot multiple times in some cases, such as when the .pc file uses the `sysroot_dir` variable directly or has been rewritten to hard-code the sysroot prefix. `pkgconf`'s method handles spaces correctly, although it also makes extra checks to ensure that sysroot is not applied more than once. In 2024 `pkg-config` is the more popular option according to Homebrew installation statistics, but the major Linux distributions have generally switched to `pkgconf`. We will use `pkgconf`'s method here as it seems more robust than `pkg-config`'s, and `pkgconf`'s greater popularity on Linux means libraries developed there may depend on the specific way it handles `.pc` files. SwiftPM will now apply the sysroot prefix to compiler flags, such as include (`-I`) and library (`-L`) search paths. This is a partial fix for apple#7409. The sysroot prefix is only applied when the `PKG_CONFIG_SYSROOT_DIR` environment variable is set. A future commit could apply an appropriate sysroot automatically when the `--experimental-swift-sdk` flag is used.
euanh
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@swift-ci test |
MaxDesiatov
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Apr 19, 2024
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LGTM, but might need @bnbarham's review as a PR on the 6.0 branch.
MaxDesiatov
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bnbarham
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Apr 19, 2024
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Cherry pick of #7461
SwiftPM's pkg-config implementation sets the
pc_sysrootdirvariable, but most.pcfiles do not use this variable directly. Instead, they rely onthe pkg-config tool rewriting the generated paths to include the sysroot prefix when necessary. SwiftPM does not do this, so it does not generate the correct compiler flags to use libraries from a sysroot.
This problem was reported in issue
#7409
There are two major pkg-config implementations which handle sysroot differently:
pkg-config(the original https://pkg-config.freedesktop.org implementation) prepends sysroot after variable expansion, when it creates the compiler flag listspkgconf(the newer http://pkgconf.org implementation) prepends sysroot to variables when they are defined, so sysroot is included when they are expandedpkg-config's method skips single character compiler flags, such as-Iand
-L, and has special cases for longer options. It does not handle spaces between the flags and their values properly, and prepends sysroot multiple times in some cases, such as when the .pc file uses thesysroot_dirvariable directly or has been rewritten to hard-code the sysroot prefix.pkgconf's method handles spaces correctly, although it also makes extra checks to ensure that sysroot is not applied more than once.In 2024
pkg-configis the more popular option according to Homebrew installation statistics, but the major Linux distributions have generallyswitched to
pkgconf.We will use
pkgconf's method here as it seems more robust thanpkg-config's, andpkgconf's greater popularity on Linux means librariesdeveloped there may depend on the specific way it handles
.pcfiles.SwiftPM will now apply the sysroot prefix to compiler flags, such as include (
-I) and library (-L) search paths.This is a partial fix for
#7409.
The sysroot prefix is only applied when the
PKG_CONFIG_SYSROOT_DIRenvironment variable is set. A future commit could apply an appropriate sysroot automatically when the--experimental-swift-sdkflag is used.Scope: Limited to packages relying on system libraries that utilize pkg-config.
Risk: Low, changes are isolated and the scope is limited to a small fraction of packages.
Testing: Automated with new test cases.
Issues: #7409
Reviewer: @MaxDesiatov.