Build libpng manually to create fat macOS binaries

The lib Brew distributes only contains code for the host arch.
(Which makes sense, not gonna blame them.)

.github/scripts/build_libpng.sh

@@ -0,0 +1,27 @@
+#!/bin/sh
+set -e
+
+pngver=1.6.43
+
+## Grab sources and check them
+
+curl -LOJ "http://prdownloads.sourceforge.net/libpng/libpng-$pngver.tar.xz?download"
+# Brew doesn't provide any sha256sum, so we're making do with `sha2` instead.
+if [ "$(sha2 -q -256 libpng-$pngver.tar.xz)" != 6a5ca0652392a2d7c9db2ae5b40210843c0bbc081cbd410825ab00cc59f14a6c ]; then
+	sha2 -256 libpng-$pngver.tar.xz
+	echo Checksum mismatch! Aborting. >&2
+	exit 1
+fi
+
+## Extract sources and patch them
+
+tar -xvf libpng-$pngver.tar.xz
+
+## Start building!
+
+mkdir -p build
+cd build
+../libpng-$pngver/configure --disable-shared --enable-static \
+	CFLAGS="-O3 -flto -DNDEBUG -mmacosx-version-min=10.9 -arch x86_64 -arch arm64 -fno-exceptions"
+make -kj
+make install prefix="$PWD/../libpng-staging"

.github/scripts/install_deps.sh

@@ -7,11 +7,21 @@ case "${1%-*}" in
 		sudo apt-get install -yq bison libpng-dev pkg-config
 		;;
 	macos)
+<<<<<<< HEAD
 		brew install bison libpng pkg-config md5sha1sum
 		# Export `bison` to allow using the version we install from Homebrew,
 		# instead of the outdated one preinstalled on macOS (which doesn't even support `-Wall`...)
 		export PATH="/opt/homebrew/opt/bison/bin:$PATH"
 		printf 'PATH=%s\n' "$PATH" >>"$GITHUB_ENV" # Make it available to later CI steps tpp
+||||||| parent of f9e1ce51 (Build libpng manually to create fat macOS binaries)
+		brew install bison libpng pkg-config md5sha1sum
+		# For the version check below exclusively, re-do this before building
+		export PATH="/opt/homebrew/opt/bison/bin:/usr/local/opt/bison/bin:$PATH"
+=======
+		brew install bison sha2 md5sha1sum # pret projects use sha1sum, we use SHA-256
+		# For the version check below exclusively, re-do this before building
+		export PATH="/opt/homebrew/opt/bison/bin:/usr/local/opt/bison/bin:$PATH"
+>>>>>>> f9e1ce51 (Build libpng manually to create fat macOS binaries)
 		;;
 	*)
 		echo "WARNING: Cannot install deps for OS '$1'"

.github/workflows/create-release-artifacts.yml

@@ -79,10 +79,13 @@ jobs:
         shell: bash
         run: |
           ./.github/scripts/install_deps.sh macos
+      - name: Build libpng
+        run: |
+          ./.github/scripts/build_libpng.sh
       # We force linking libpng statically; the other libs are provided by macOS itself
       - name: Build binaries
         run: |
-          make -kj CXXFLAGS="-O3 -flto -DNDEBUG -mmacosx-version-min=10.9 -arch x86_64 -arch arm64" PKG_CONFIG="pkg-config --static" PNGLDLIBS="$(pkg-config --static --libs-only-L libpng | cut -c 3-)/libpng.a $(pkg-config --static --libs-only-l libpng | sed s/-lpng[0-9]*//g)" Q=
+          make -kj CXXFLAGS="-O3 -flto -DNDEBUG -mmacosx-version-min=10.9 -arch x86_64 -arch arm64" PNGCFLAGS="-I libpng-staging/include" PNGLDLIBS="libpng-staging/lib/libpng.a -lz" Q=
           strip rgb{asm,link,fix,gfx}
       - name: Package binaries
         run: |

.github/workflows/testing.yml

@@ -80,9 +80,12 @@ jobs:
         shell: bash
         run: |
           ./.github/scripts/install_deps.sh macos
+      - name: Build libpng
+        run: |
+          ./.github/scripts/build_libpng.sh
       - name: Build & install
         run: |
-          make -kj CXXFLAGS="-O3 -flto -DNDEBUG -mmacosx-version-min=10.9 -arch x86_64 -arch arm64" PKG_CONFIG="pkg-config --static" PNGLDLIBS="$(pkg-config --static --libs-only-L libpng | cut -c 3-)/libpng.a $(pkg-config --static --libs-only-l libpng | sed s/-lpng[0-9]*//g)" Q=
+          make -kj CXXFLAGS="-O3 -flto -DNDEBUG -mmacosx-version-min=10.9 -arch x86_64 -arch arm64" PNGCFLAGS="-I libpng-staging/include" PNGLDLIBS="libpng-staging/lib/libpng.a -lz" Q=
       - name: Package binaries
         run: |
           mkdir bins