Do less reinstalling in mingw CI

src/ci/scripts/install-mingw.sh

@@ -39,10 +39,10 @@ if isWindows; then
     esac
 
     if [[ "${CUSTOM_MINGW:-0}" == 0 ]]; then
-        pacboy -S --noconfirm toolchain:p
-        # According to the comment in the Windows part of install-clang.sh, in the future we might
-        # want to do this instead:
-        # pacboy -S --noconfirm clang:p ...
+        pacman -S --noconfirm --needed mingw-w64-$arch-toolchain mingw-w64-$arch-cmake \
+            mingw-w64-$arch-gcc \
+            mingw-w64-$arch-python # the python package is actually for python3
+        ciCommandAddPath "$(ciCheckoutPath)/msys2/mingw${bits}/bin"
     else
         mingw_dir="mingw${bits}"
 

src/ci/scripts/install-msys2.sh

@@ -7,6 +7,8 @@ IFS=$'\n\t'
 
 source "$(cd "$(dirname "$0")" && pwd)/../shared.sh"
 if isWindows; then
+    ciCommandAddPath "c:/msys64/usr/bin"
+
     # Detect the native Python version installed on the agent. On GitHub
     # Actions, the C:\hostedtoolcache\windows\Python directory contains a
     # subdirectory for each installed Python version.
@@ -24,38 +26,4 @@ if isWindows; then
     fi
     ciCommandAddPath "C:\\hostedtoolcache\\windows\\Python\\${native_python_version}\\x64"
     ciCommandAddPath "C:\\hostedtoolcache\\windows\\Python\\${native_python_version}\\x64\\Scripts"
-
-    # Install pacboy for easily installing packages
-    pacman -S --noconfirm pactoys
-
-    # Remove these pre-installed tools so we can't accidentally use them, because we are using the
-    # MSYS2 setup action versions instead. Because `rm -r`-ing them is slow, we mv them off path
-    # instead.
-    # Remove pre-installed version of MSYS2
-    echo "Cleaning up existing tools in PATH"
-    notpath="/c/NOT/ON/PATH/"
-    mkdir --parents "$notpath"
-    mv -t "$notpath" "/c/msys64/"
-    # Remove Strawberry Perl, which contains a version of mingw
-    mv -t "$notpath" "/c/Strawberry/"
-    # Remove these other copies of mingw, I don't even know where they come from.
-    mv -t "$notpath" "/c/mingw64/"
-    mv -t "$notpath" "/c/mingw32/"
-    echo "Finished cleaning up tools in PATH"
-
-    if isKnownToBeMingwBuild; then
-        # Use the mingw version of CMake for mingw builds.
-        # However, the MSVC build needs native CMake, as it fails with the mingw one.
-        # Delete native CMake
-        rm -r "/c/Program Files/CMake/"
-        # Install mingw-w64-$arch-cmake
-        pacboy -S --noconfirm cmake:p
-
-        # It would be nice to use MSYS's git in MinGW builds so that it's tested and known to
-        # work. But it makes everything extremely slow, so it's commented out for now.
-        # # Delete Windows-Git
-        # rm -r "/c/Program Files/Git/"
-        # # Install MSYS2 git
-        # pacman -S --noconfirm git
-    fi
 fi