ci: drone: use zig-bootstrap tarball instead of system toolchain

Author: andrewrk

ci/drone/drone.yml

@@ -7,28 +7,28 @@ platform:
 
 steps:
 - name: build
-  image: ziglang/static-base:llvm12-aarch64-3
+  image: ziglang/static-base:llvm12-aarch64-5
   commands:
   - ./ci/drone/linux_script_build
 
 - name: test-1
   depends_on:
   - build
-  image: ziglang/static-base:llvm12-aarch64-3
+  image: ziglang/static-base:llvm12-aarch64-5
   commands:
   - ./ci/drone/linux_script_test 1
 
 - name: test-2
   depends_on:
   - build
-  image: ziglang/static-base:llvm12-aarch64-3
+  image: ziglang/static-base:llvm12-aarch64-5
   commands:
   - ./ci/drone/linux_script_test 2
 
 - name: test-3
   depends_on:
   - build
-  image: ziglang/static-base:llvm12-aarch64-3
+  image: ziglang/static-base:llvm12-aarch64-5
   commands:
   - ./ci/drone/linux_script_test 3
 
@@ -38,7 +38,7 @@ steps:
   - test-1
   - test-2
   - test-3
-  image: ziglang/static-base:llvm12-aarch64-3
+  image: ziglang/static-base:llvm12-aarch64-5
   environment:
     SRHT_OAUTH_TOKEN:
       from_secret: SRHT_OAUTH_TOKEN

ci/drone/linux_script_build

@@ -2,8 +2,15 @@
 
 . ./ci/drone/linux_script_base
 
-apk update
-apk add samurai
+PREFIX="/deps/local"
+ZIG="$PREFIX/bin/zig"
+TARGET="$TRIPLEARCH-linux-musl"
+MCPU="baseline"
+
+export CC="$ZIG cc -target $TARGET -mcpu=$MCPU"
+export CXX="$ZIG c++ -target $TARGET -mcpu=$MCPU"
+export AR="$ZIG ar"
+export RANLIB="$ZIG ranlib"
 
 # Make the `zig version` number consistent.
 # This will affect the cmake command below.
@@ -13,6 +20,25 @@ git fetch --tags
 
 mkdir build
 cd build
-cmake .. -DCMAKE_BUILD_TYPE=Release "-DCMAKE_INSTALL_PREFIX=$DISTDIR" -DZIG_STATIC=ON -DCMAKE_PREFIX_PATH=/deps/local -GNinja
+cmake .. \
+  -DCMAKE_INSTALL_PREFIX="$DISTDIR" \
+  -DCMAKE_PREFIX_PATH="$PREFIX" \
+  -DCMAKE_BUILD_TYPE=Release \
+  -DZIG_TARGET_TRIPLE="$TARGET" \
+  -DZIG_TARGET_MCPU="$MCPU" \
+  -DZIG_STATIC=ON \
+  -DCMAKE_CROSSCOMPILING=True \
+  -DCMAKE_SYSTEM_NAME=Linux \
+  -GNinja
+
+# Now CMake will use Zig as the C/C++ compiler. We reset the environment variables
+# so that installation and testing do not get affected by them.
+unset CC
+unset CXX
+samu install
 
+# Here we rebuild Zig but this time using the Zig binary we just now produced to
+# build zig1.o rather than relying on the one built with stage0. See
+# https://github.com/ziglang/zig/issues/6830 for more details.
+cmake .. -DZIG_EXECUTABLE="$DISTDIR/bin/zig"
 samu install

ci/drone/linux_script_finalize

@@ -7,7 +7,7 @@ if [ -n "$DRONE_PULL_REQUEST" ]; then
 fi
 
 apk update
-apk add py3-pip xz perl-utils jq curl samurai
+apk add py3-pip perl-utils jq curl
 pip3 install s3cmd
 
 cd build