Rework Darwin jobs

* Use `arch` explicitly in both jobs. I don't know why x86_64 is the
  default, and I don't like it.

* Stop using brew. This means a toolchain needs to already be installed
  where CI is run. This is the case today, although it's a bit fragile
  and I'll probably revisit it.

* Use a matrix build to clean up the yml.

* Use GHC 9.8.2 to work around GHC#24050

Author: chreekat

.gitlab-ci.yml

@@ -91,48 +91,26 @@ alpine-linux:
     TARBALL_EXT: tar.xz
     ADD_CABAL_ARGS: "--enable-split-sections --enable-executable-static"
 
-build-x86_64-darwin:
+darwin:
   extends: .build
+  parallel:
+    matrix:
+      # Help me with names pls
+      - ARCH: x86_64
+        ARCHARCH: x86_64
+      - ARCH: aarch64
+        ARCHARCH: arm64
   tags:
-    - x86_64-darwin
-  variables:
-    TARBALL_ARCHIVE_SUFFIX: x86_64-darwin
-    TARBALL_EXT: tar.xz
-    ADD_CABAL_ARGS: ""
-
-build-aarch64-darwin:
-  stage: build
-  tags:
-    - aarch64-darwin-m1
-  before_script:
-    - export HOMEBREW_CHANGE_ARCH_TO_ARM=1
-    - arch -arm64 /bin/bash ./.gitlab/brew.sh llvm autoconf automake coreutils make tree
-  # C_INCLUDE_PATH: https://gitlab.haskell.org/ghc/ghc/-/issues/20592
-  script: |
-    export PATH="$CI_PROJECT_DIR/.brew/opt/llvm/bin:$CI_PROJECT_DIR/.brew/bin:$CI_PROJECT_DIR/.brew/sbin:$PATH"
-    export CC=$CI_PROJECT_DIR/.brew/opt/llvm/bin/clang
-    export CXX=$CI_PROJECT_DIR/.brew/opt/llvm/bin/clang++
-    export LD=ld
-    export AR=$CI_PROJECT_DIR/.brew/opt/llvm/bin/llvm-ar
-    export RANLIB=$CI_PROJECT_DIR/.brew/opt/llvm/bin/llvm-ranlib
-    export C_INCLUDE_PATH="`xcrun --show-sdk-path`/usr/include/ffi"
-    arch -arm64 /bin/bash ./.gitlab/ci.sh
-  after_script:
-    - rm -Rf /private/tmp/.brew_tmp
+    - ${ARCH}-darwin-m1
   variables:
-    MACOSX_DEPLOYMENT_TARGET: "10.7"
-    TARBALL_ARCHIVE_SUFFIX: aarch64-darwin
+    # Using 9.8.2 to work around
+    # https://gitlab.haskell.org/ghc/ghc/-/issues/24050
+    GHC_VERSION: 9.8.2
+    TARBALL_ARCHIVE_SUFFIX: ${ARCH}-darwin
     TARBALL_EXT: tar.xz
     ADD_CABAL_ARGS: ""
-    # Update periodically.
-    BREW_VERSION: 4.0.5
-  artifacts:
-    expire_in: 2 week
-    paths:
-      - out/*
-  cache:
-    paths:
-      - .brew
+  script:
+    - arch -${ARCHARCH} /bin/bash .gitlab/ci.sh
 
 x86_64-windows:
   extends: .build