pkg-config: split out pkg.m4

Formula/p/pkg-config.rb

@@ -1,12 +1,12 @@
 class PkgConfig < Formula
   desc "Manage compile and link flags for libraries"
-  homepage "https://freedesktop.org/wiki/Software/pkg-config/"
+  homepage "https://www.freedesktop.org/wiki/Software/pkg-config/"
   url "https://pkgconfig.freedesktop.org/releases/pkg-config-0.29.2.tar.gz"
   mirror "http://fresh-center.net/linux/misc/pkg-config-0.29.2.tar.gz"
   mirror "http://fresh-center.net/linux/misc/legacy/pkg-config-0.29.2.tar.gz"
   sha256 "6fc69c01688c9458a57eb9a1664c9aba372ccda420a02bf4429fe610e7e7d591"
   license "GPL-2.0-or-later"
-  revision 3
+  revision 4
 
   livecheck do
     url "https://pkg-config.freedesktop.org/releases/"
@@ -28,12 +28,12 @@ class PkgConfig < Formula
     sha256 cellar: :any_skip_relocation, x86_64_linux:   "3d9b8bf9b7b4bd08086be1104e3e18afb1c437dfaca03e6e7df8f2710b9c1c1a"
   end
 
-  conflicts_with "pkgconf", because: "both install `pkg.m4` file"
-
   # FIXME: The bottle is mistakenly considered relocatable on Linux.
   # See https://github.com/Homebrew/homebrew-core/pull/85032.
   pour_bottle? only_if: :default_prefix
 
+  depends_on "pkg.m4"
+
   def install
     pc_path = %W[
       #{HOMEBREW_PREFIX}/lib/pkgconfig
@@ -65,6 +65,9 @@ def install
                           "--with-system-include-path=#{system_include_path}"
     system "make"
     system "make", "install"
+
+    # Move `pkg.m4` into libexec as using copy from formula. Keep to make sure identical.
+    libexec.install share/"aclocal/pkg.m4"
   end
 
   test do
@@ -86,5 +89,6 @@ def install
     assert_equal "1.0.0\n", shell_output("#{bin}/pkg-config --modversion foo")
     assert_equal "-lfoo\n", shell_output("#{bin}/pkg-config --libs foo")
     assert_equal "-I/usr/include/foo\n", shell_output("#{bin}/pkg-config --cflags foo")
+    assert_equal (Formula["pkg.m4"].share/"aclocal/pkg.m4").read, (libexec/"pkg.m4").read
   end
 end

Formula/p/pkg.m4.rb

@@ -0,0 +1,31 @@
+class PkgM4 < Formula
+  # TODO: Switch to pkgconf source or merge back into pkgconf formula once migration is done
+  desc "Macros to locate and use pkg-config"
+  homepage "https://www.freedesktop.org/wiki/Software/pkg-config/"
+  url "https://pkgconfig.freedesktop.org/releases/pkg-config-0.29.2.tar.gz"
+  mirror "http://fresh-center.net/linux/misc/pkg-config-0.29.2.tar.gz"
+  sha256 "6fc69c01688c9458a57eb9a1664c9aba372ccda420a02bf4429fe610e7e7d591"
+  license "GPL-2.0-or-later"
+
+  livecheck do
+    formula "pkg-config"
+  end
+
+  uses_from_macos "m4" => :test
+
+  def install
+    system "./configure", "--disable-host-tool",
+                          "--disable-silent-rules",
+                          "--with-internal-glib",
+                          *std_configure_args
+    system "make", "install-m4DATA"
+  end
+
+  test do
+    (testpath/"test.m4").write <<~EOS
+      changequote([,])
+      include([#{share}/aclocal/pkg.m4])
+    EOS
+    assert_match "AC_DEFUN(PKG_CHECK_MODULES", shell_output("m4 --fatal-warnings test.m4")
+  end
+end

Formula/p/pkgconf.rb

@@ -4,6 +4,7 @@ class Pkgconf < Formula
   url "https://distfiles.ariadne.space/pkgconf/pkgconf-2.3.0.tar.xz"
   sha256 "3a9080ac51d03615e7c1910a0a2a8df08424892b5f13b0628a204d3fcce0ea8b"
   license "ISC"
+  revision 1
 
   livecheck do
     url "https://distfiles.ariadne.space/pkgconf/"
@@ -28,35 +29,61 @@ class Pkgconf < Formula
     depends_on "libtool" => :build
   end
 
-  conflicts_with "pkg-config", because: "both install `pkg.m4` file"
+  depends_on "pkg.m4"
 
   def install
     if build.head?
       ENV["LIBTOOLIZE"] = "glibtoolize"
       system "./autogen.sh"
     end
 
+    system_prefix = "/usr"
     pc_path = %W[
       #{HOMEBREW_PREFIX}/lib/pkgconfig
       #{HOMEBREW_PREFIX}/share/pkgconfig
     ]
     pc_path << if OS.mac?
-      pc_path << "/usr/local/lib/pkgconfig"
+      system_prefix = "#{MacOS.sdk_path_if_needed}/usr"
+
+      pc_path << "/usr/local/lib/pkgconfig" if HOMEBREW_PREFIX.to_s != "/usr/local"
       pc_path << "/usr/lib/pkgconfig"
       "#{HOMEBREW_LIBRARY}/Homebrew/os/mac/pkgconfig/#{MacOS.version}"
     else
       "#{HOMEBREW_LIBRARY}/Homebrew/os/linux/pkgconfig"
     end
 
-    pc_path = pc_path.uniq.join(File::PATH_SEPARATOR)
-
-    configure_args = std_configure_args + %W[
-      --with-pkg-config-dir=#{pc_path}
+    args = %W[
+      --with-pkg-config-dir=#{pc_path.uniq.join(File::PATH_SEPARATOR)}
+      --with-personality-dir=#{HOMEBREW_PREFIX}/share/pkgconfig/personality.d:#{etc}/pkgconfig/personality.d
+      --with-system-includedir=#{HOMEBREW_PREFIX}/include:#{system_prefix}/include
+      --with-system-libdir=#{HOMEBREW_PREFIX}/lib:#{system_prefix}/lib
+      --disable-silent-rules
     ]
 
-    system "./configure", *configure_args
+    system "./configure", *args, *std_configure_args
     system "make"
     system "make", "install"
+
+    # Move `pkg.m4` into libexec to make it easier for migration to `pkgconf`
+    libexec.install share/"aclocal/pkg.m4"
+
+    # TODO: Consider making `pkgconf` a drop-in replacement to `pkg-config` by adding
+    # symlink and restoring conflicts. Similar to Debian, Fedora, ArchLinux and MacPorts.
+    # Alternatively can keep separate non-conflicting commands and update `pkg.m4` to use
+    # `pkgconf` copy after sufficiently migrated.
+    # Ref: https://github.com/pkgconf/pkgconf/#pkg-config-symlink
+    # Ref: https://salsa.debian.org/debian/pkgconf/-/blob/debian/unstable/debian/pkgconf.links?ref_type=heads
+    #
+    # bin.install_symlink "pkgconf" => "pkg-config"
+    # man1.install_symlink "pkgconf.1" => "pkg-config.1"
+  end
+
+  def caveats
+    <<~EOS
+      To allow easier migration from `pkg-config` to `pkgconf`, the `pkgconf` formula
+      uses `pkg-config`'s pkg.m4 to avoid conflict. If you need the copy from `pkgconf`,
+      then it is available at #{libexec}/pkg.m4
+    EOS
   end
 
   test do