Rollup merge of #125590 - ChrisDenton:mingw-ci-3, r=Kobzol

Add a "Setup Python" action for github-hosted runners and remove unnecessary `CUSTOM_MINGW` environment variable

The Setup Python action isn't strictly necessary ([even on Windows](https://github.com/rust-lang/rust/pull/125584)) but it is [recommend by GitHub](https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-python#specifying-a-python-version).

The `CUSTOM_MINGW` environment variable is redundant now as it's always set for mingw and always unset otherwise.

try-job: x86_64-mingw
try-job: x86_64-mingw
try-job: dist-x86_64-msvc
try-job: dist-x86_64-mingw

.github/workflows/ci.yml

@@ -154,9 +154,12 @@ jobs:
 
       - name: checkout submodules
         run: src/ci/scripts/checkout-submodules.sh
-
-      - name: install MSYS2
-        run: src/ci/scripts/install-msys2.sh
+      
+      - name: Setup Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.x'
+        if: runner.environment == 'github-hosted'
 
       - name: install MinGW
         run: src/ci/scripts/install-mingw.sh

src/ci/github-actions/jobs.yml

@@ -378,7 +378,6 @@ auto:
       # We are intentionally allowing an old toolchain on this builder (and that's
       # incompatible with LLVM downloads today).
       NO_DOWNLOAD_CI_LLVM: 1
-      CUSTOM_MINGW: 1
     <<: *job-windows-8c
 
   - image: x86_64-mingw
@@ -390,7 +389,6 @@ auto:
       # We are intentionally allowing an old toolchain on this builder (and that's
       # incompatible with LLVM downloads today).
       NO_DOWNLOAD_CI_LLVM: 1
-      CUSTOM_MINGW: 1
     <<: *job-windows-8c
 
   - image: dist-x86_64-msvc
@@ -439,7 +437,6 @@ auto:
       # incompatible with LLVM downloads today).
       NO_DOWNLOAD_CI_LLVM: 1
       SCRIPT: python x.py dist bootstrap --include-default-paths
-      CUSTOM_MINGW: 1
       DIST_REQUIRE_ALL_TOOLS: 1
     <<: *job-windows-8c
 
@@ -453,7 +450,6 @@ auto:
       # We are intentionally allowing an old toolchain on this builder (and that's
       # incompatible with LLVM downloads today).
       NO_DOWNLOAD_CI_LLVM: 1
-      CUSTOM_MINGW: 1
       DIST_REQUIRE_ALL_TOOLS: 1
     <<: *job-windows-8c
 

src/ci/scripts/install-mingw.sh

@@ -1,8 +1,5 @@
 #!/bin/bash
-# If we need to download a custom MinGW, do so here and set the path
-# appropriately.
-#
-# Otherwise install MinGW through `pacman`
+# For mingw builds use a vendored mingw.
 
 set -euo pipefail
 IFS=$'\n\t'
@@ -16,19 +13,16 @@ if isWindows && isKnownToBeMingwBuild; then
     case "${CI_JOB_NAME}" in
         *i686*)
             bits=32
-            arch=i686
             mingw_archive="${MINGW_ARCHIVE_32}"
             ;;
         *x86_64*)
             bits=64
-            arch=x86_64
             mingw_archive="${MINGW_ARCHIVE_64}"
             ;;
         *aarch64*)
             # aarch64 is a cross-compiled target. Use the x86_64
             # mingw, since that's the host architecture.
             bits=64
-            arch=x86_64
             mingw_archive="${MINGW_ARCHIVE_64}"
             ;;
         *)
@@ -38,13 +32,9 @@ if isWindows && isKnownToBeMingwBuild; then
             ;;
     esac
 
-    if [[ "${CUSTOM_MINGW:-0}" == 0 ]]; then
-        pacman -S --noconfirm --needed mingw-w64-$arch-toolchain
-    else
-        mingw_dir="mingw${bits}"
+    mingw_dir="mingw${bits}"
 
-        curl -o mingw.7z "${MIRRORS_BASE}/${mingw_archive}"
-        7z x -y mingw.7z > /dev/null
-        ciCommandAddPath "$(pwd)/${mingw_dir}/bin"
-    fi
+    curl -o mingw.7z "${MIRRORS_BASE}/${mingw_archive}"
+    7z x -y mingw.7z > /dev/null
+    ciCommandAddPath "$(pwd)/${mingw_dir}/bin"
 fi

src/ci/scripts/install-msys2.sh

@@ -1,27 +0,0 @@
-#!/bin/bash
-# Clean up and prepare the MSYS2 installation.
-# MSYS2 is used by the MinGW toolchain for assembling things.
-
-set -euo pipefail
-IFS=$'\n\t'
-
-source "$(cd "$(dirname "$0")" && pwd)/../shared.sh"
-if isWindows; then
-    # Detect the native Python version installed on the agent. On GitHub
-    # Actions, the C:\hostedtoolcache\windows\Python directory contains a
-    # subdirectory for each installed Python version.
-    #
-    # The -V flag of the sort command sorts the input by version number.
-    native_python_version="$(ls /c/hostedtoolcache/windows/Python | sort -Vr | head -n 1)"
-
-    # Make sure we use the native python interpreter instead of some msys equivalent
-    # one way or another. The msys interpreters seem to have weird path conversions
-    # baked in which break LLVM's build system one way or another, so let's use the
-    # native version which keeps everything as native as possible.
-    python_home="/c/hostedtoolcache/windows/Python/${native_python_version}/x64"
-    if ! [[ -f "${python_home}/python3.exe" ]]; then
-        cp "${python_home}/python.exe" "${python_home}/python3.exe"
-    fi
-    ciCommandAddPath "C:\\hostedtoolcache\\windows\\Python\\${native_python_version}\\x64"
-    ciCommandAddPath "C:\\hostedtoolcache\\windows\\Python\\${native_python_version}\\x64\\Scripts"
-fi