fix(make): distinguish native Windows shell bootstrap (#4948) (#4949)

Bootstrap Git Bash only for native GNU Make host identities. Neutralize startup overrides, validate the required Git tools, preserve MSYS2 and Cygwin POSIX semantics, and feed real native, MSYS2, and Cygwin smoke lanes into the required PR aggregate.

Agent-Signature: codex-tui-gpt-5.6-sol-ultra on behalf of Ewen Cuthiell

.github/workflows/pr.yml

@@ -534,6 +534,188 @@ jobs:
           version: latest
           args: --timeout=5m --build-tags=gms_pure_go
 
+  windows-make-shell:
+    name: Windows Make shell (${{ matrix.host }})
+    runs-on: windows-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        host:
+          - native
+          - msys2
+          - cygwin
+    steps:
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v6
+
+      - name: Install native GNU Make
+        if: matrix.host == 'native'
+        shell: pwsh
+        run: choco install make --version=4.4.1 --yes --no-progress
+
+      - name: Set up MSYS2 GNU Make
+        if: matrix.host == 'msys2'
+        uses: msys2/setup-msys2@66cd2cce69caa17b53920067426061ca1de3a884 # v2.32.0
+        with:
+          msystem: MSYS
+          install: git make
+          path-type: minimal
+
+      - name: Set up Cygwin GNU Make
+        if: matrix.host == 'cygwin'
+        id: cygwin
+        uses: cygwin/cygwin-install-action@3f0a3f9f988f7e96b8c18098ae05eaec175f5b52 # v6
+        with:
+          packages: git make
+          add-to-path: 'false'
+
+      - name: Exercise native Windows Make
+        if: matrix.host == 'native'
+        shell: pwsh
+        run: |
+          $ErrorActionPreference = 'Stop'
+          $make = (Get-Command make.exe -ErrorAction Stop).Source
+          $hostOutput = & $make --no-print-directory -f NUL --eval '$(info MAKE_HOST=$(MAKE_HOST))' --eval 'noop:;' noop
+          $makeHost = (($hostOutput | Where-Object { $_ -like 'MAKE_HOST=*' }) -replace '^MAKE_HOST=', '').Trim()
+          if ($LASTEXITCODE -ne 0 -or ($makeHost -ne 'Windows32' -and $makeHost -notmatch '-mingw32$')) {
+            throw "Expected native Windows GNU Make, found '$makeHost' at '$make'"
+          }
+
+          $git = (Get-Command git.exe -ErrorAction Stop).Source
+          if ($git -notmatch ' ') {
+            throw "Expected the hosted Git for Windows path to contain a space, found '$git'"
+          }
+
+          $profile = Join-Path $env:RUNNER_TEMP 'profile with spaces'
+          New-Item -ItemType Directory -Force -Path $profile | Out-Null
+          $poison = Join-Path $profile 'poison bash env.sh'
+          Set-Content -LiteralPath $poison -Encoding utf8 -Value 'exit 97'
+
+          $env:USERPROFILE = $profile
+          $env:BASH_ENV = $poison
+          $env:BASHOPTS = 'failglob'
+          $env:SHELLOPTS = 'nounset'
+          $env:GIT_EXEC_PATH = Join-Path $profile 'missing git exec path'
+          $env:PATH = "$(Split-Path $git);$env:SystemRoot\System32"
+
+          & $make --no-print-directory help | Out-Null
+          if ($LASTEXITCODE -ne 0) {
+            throw 'Native Make failed while parsing or running help'
+          }
+
+          @'
+          include Makefile
+          .RECIPEPREFIX := >
+          .PHONY: windows-make-shell-smoke
+          windows-make-shell-smoke:
+          >@case "$(SHELL)" in */bin/bash.exe) ;; *) exit 1;; esac
+          >@test -n "$$BASH_VERSION"
+          >@test "$$(command -v sed)" = /usr/bin/sed
+          >@test "$$(command -v env)" = /usr/bin/env
+          >@test -z "$${BASH_ENV+x}"
+          >@case "$$-" in *u*) exit 1;; esac
+          >@shopt -q failglob && exit 1 || :
+          >@test -z "$${GIT_EXEC_PATH+x}"
+          >@env printf '%s\n' 'native Windows Make shell smoke passed'
+          '@ | & $make --no-print-directory -f - windows-make-shell-smoke
+          if ($LASTEXITCODE -ne 0) {
+            throw 'Native Make shell smoke failed'
+          }
+
+      - name: Exercise MSYS2-hosted Make
+        if: matrix.host == 'msys2'
+        shell: msys2 {0}
+        run: |
+          set -euo pipefail
+          make_host="$(
+            make --no-print-directory -f /dev/null \
+              --eval '$(info $(MAKE_HOST))' \
+              --eval 'noop:;' noop |
+              sed -n '1p'
+          )"
+          case "$make_host" in
+            *-msys|*-cygwin) ;;
+            *) echo "Expected a POSIX-hosted MSYS2 GNU Make, found '$make_host'" >&2; exit 1 ;;
+          esac
+
+          profile="$(cygpath -u "$RUNNER_TEMP")/profile with spaces"
+          mkdir -p "$profile"
+          bash_env="$profile/compat bash env.sh"
+          printf '%s\n' 'exit 97' > "$bash_env"
+          export BASH_ENV="$bash_env"
+          export GIT_EXEC_PATH="$profile/missing git exec path"
+          export PATH=/usr/bin
+
+          make --no-print-directory help >/dev/null
+          cat > "$profile/smoke.mk" <<'MAKE_EOF'
+          include Makefile
+          .RECIPEPREFIX := >
+          .PHONY: windows-make-shell-smoke
+          windows-make-shell-smoke:
+          >@case "$(SHELL)" in */sh) ;; *) exit 1;; esac
+          >@test -n "$$BASH_VERSION"
+          >@test "$$(command -v sed)" = /usr/bin/sed
+          >@test "$$(command -v env)" = /usr/bin/env
+          >@test -f "$$BASH_ENV"
+          >@test -n "$$GIT_EXEC_PATH"
+          >@case "$$PATH" in *';'*) exit 1;; esac
+          >@env printf '%s\n' 'MSYS2 Make shell smoke passed'
+          MAKE_EOF
+          make --no-print-directory -f "$profile/smoke.mk" windows-make-shell-smoke
+
+      - name: Exercise Cygwin-hosted Make
+        if: matrix.host == 'cygwin'
+        shell: pwsh
+        env:
+          CYGWIN_ROOT: ${{ steps.cygwin.outputs.root }}
+        run: |
+          $ErrorActionPreference = 'Stop'
+          $bash = Join-Path $env:CYGWIN_ROOT 'bin\bash.exe'
+          $script = @'
+          set -euo pipefail
+          export PATH=/usr/bin
+          cd "$(cygpath -u "$GITHUB_WORKSPACE")"
+
+          make_host="$(
+            make --no-print-directory -f /dev/null \
+              --eval '$(info $(MAKE_HOST))' \
+              --eval 'noop:;' noop |
+              sed -n '1p'
+          )"
+          case "$make_host" in
+            *-cygwin) ;;
+            *) echo "Expected Cygwin GNU Make, found '$make_host'" >&2; exit 1 ;;
+          esac
+
+          profile="$(mktemp -d)"
+          trap 'rm -rf -- "$profile"' EXIT
+          bash_env="$profile/cygwin bash env.sh"
+          printf '%s\n' 'exit 97' > "$bash_env"
+          export BASH_ENV="$bash_env"
+          export GIT_EXEC_PATH="$profile/missing git exec path"
+
+          make --no-print-directory help >/dev/null
+          cat > "$profile/smoke.mk" <<'MAKE_EOF'
+          include Makefile
+          .RECIPEPREFIX := >
+          .PHONY: windows-make-shell-smoke
+          windows-make-shell-smoke:
+          >@case "$(SHELL)" in */sh) ;; *) exit 1;; esac
+          >@test -n "$$BASH_VERSION"
+          >@test "$$(command -v sed)" = /usr/bin/sed
+          >@test "$$(command -v env)" = /usr/bin/env
+          >@test -f "$$BASH_ENV"
+          >@test -n "$$GIT_EXEC_PATH"
+          >@case "$$PATH" in *';'*) exit 1;; esac
+          >@env printf '%s\n' 'Cygwin Make shell smoke passed'
+          MAKE_EOF
+          make --no-print-directory -f "$profile/smoke.mk" windows-make-shell-smoke
+          '@
+          $script = $script.Replace("`r`n", "`n")
+          & $bash --noprofile --norc -c $script
+          if ($LASTEXITCODE -ne 0) {
+            throw 'Cygwin Make shell smoke failed'
+          }
+
   ci-gate:
     name: CI Gate / Required
     runs-on: ubuntu-latest
@@ -555,6 +737,7 @@ jobs:
       - contract-corpus
       - fmt-check
       - lint
+      - windows-make-shell
     if: ${{ always() }}
     steps:
       - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v6
@@ -580,6 +763,7 @@ jobs:
             CONTRACT_CORPUS
             FMT_CHECK
             LINT
+            WINDOWS_MAKE_SHELL
           BUILD_ARTIFACTS: ${{ needs.build-artifacts.result }}
           CHECK_BUILD_TAGS: ${{ needs.check-build-tags.result }}
           CHECK_CMD_BD_PUREGEO_TESTS: ${{ needs.check-cmd-bd-puregeo-tests.result }}
@@ -597,6 +781,7 @@ jobs:
           CONTRACT_CORPUS: ${{ needs.contract-corpus.result }}
           FMT_CHECK: ${{ needs.fmt-check.result }}
           LINT: ${{ needs.lint.result }}
+          WINDOWS_MAKE_SHELL: ${{ needs.windows-make-shell.result }}
         run: |
           skipped_ok=""
           if [[ "$GITHUB_EVENT_NAME" == "merge_group" ]]; then

Makefile

@@ -1,11 +1,45 @@
 # Makefile for beads project
 
-# On Windows, GNU Make defaults to cmd.exe which doesn't support POSIX
-# shell syntax used throughout this Makefile. Use Git for Windows' bash.
+# Native Windows GNU Make needs Git for Windows' bash for the POSIX shell
+# syntax used throughout this Makefile. MSYS2 and Cygwin Make already provide
+# POSIX shell semantics, despite inheriting OS=Windows_NT, so leave them alone.
 ifeq ($(OS),Windows_NT)
-GIT_BASH := $(shell where git 2>/dev/null)
-ifneq ($(GIT_BASH),)
-SHELL := $(subst cmd,bin,$(subst git.exe,bash.exe,$(GIT_BASH)))
+ifneq ($(filter Windows32 mingw32 %-mingw32,$(MAKE_HOST)),)
+override BASH_ENV :=
+unexport BASH_ENV
+unexport GIT_EXEC_PATH
+unexport BASHOPTS
+unexport SHELLOPTS
+SHELL := cmd.exe
+.SHELLFLAGS := /d /c
+GIT_WINDOWS_EXEC_PATH := $(strip $(shell set "GIT_EXEC_PATH=" && git.exe --exec-path))
+ifeq ($(GIT_WINDOWS_EXEC_PATH),)
+$(error Git for Windows is required to run this Makefile)
+endif
+GIT_WINDOWS_ROOT := $(strip $(shell cd /d "$(GIT_WINDOWS_EXEC_PATH)/../../.." && cd))
+ifeq ($(GIT_WINDOWS_ROOT),)
+$(error Could not resolve the Git for Windows installation from $(GIT_WINDOWS_EXEC_PATH))
+endif
+GIT_WINDOWS_BASH := $(GIT_WINDOWS_ROOT)/bin/bash.exe
+GIT_WINDOWS_SED := $(GIT_WINDOWS_ROOT)/usr/bin/sed.exe
+GIT_WINDOWS_ENV := $(GIT_WINDOWS_ROOT)/usr/bin/env.exe
+ifneq ($(strip $(shell if exist "$(GIT_WINDOWS_BASH)" echo ready)),ready)
+$(error Could not find Git for Windows' bash at $(GIT_WINDOWS_BASH))
+endif
+ifneq ($(strip $(shell if exist "$(GIT_WINDOWS_SED)" echo ready)),ready)
+$(error Could not find Git for Windows' sed at $(GIT_WINDOWS_SED))
+endif
+ifneq ($(strip $(shell if exist "$(GIT_WINDOWS_ENV)" echo ready)),ready)
+$(error Could not find Git for Windows' env at $(GIT_WINDOWS_ENV))
+endif
+SHELL := $(GIT_WINDOWS_BASH)
+.SHELLFLAGS := -c
+ifneq ($(strip $(shell printf '%s' ready;)),ready)
+$(error Could not start Git for Windows' bash at $(SHELL))
+endif
+# GNU Make may launch simple commands and shebang interpreters directly instead
+# of through SHELL, so expose Git's POSIX tools to those process lookups too.
+export PATH := $(GIT_WINDOWS_ROOT)/usr/bin;$(PATH)
 endif
 endif