Loop over bazel versions in build script.

.github/actions/set-up/action.yaml

@@ -16,9 +16,6 @@ name: Set up Bazel workspace
 description: Install necessary dependencies and load remote caches
 
 inputs:
-  bazel-version:
-    description: Bazel version to use
-    required: true
   github-token:
     description: GitHub authentication token from secrets.GITHUB_TOKEN
     required: true
@@ -84,10 +81,9 @@ runs:
       uses: actions/cache@v4
       with:
         path: ${{runner.temp}}/bazel-action-cache
-        key: bazel-actions-${{runner.os}}-${{inputs.bazel-version}}-${{inputs.cc}}-${{hashFiles('**')}}
+        key: bazel-actions-${{runner.os}}-${{inputs.cc}}-${{hashFiles('**')}}
         restore-keys: |
-          bazel-actions-${{runner.os}}-${{inputs.bazel-version}}-${{inputs.cc}}-
-          bazel-actions-${{runner.os}}-${{inputs.bazel-version}}-
+          bazel-actions-${{runner.os}}-${{inputs.cc}}-
           bazel-actions-${{runner.os}}-
     - name: Configure system (all platforms)
       shell: bash
@@ -116,7 +112,6 @@ runs:
         # Use the Unix toolchain only on Github to make coverage generation work
         # locally; see https://github.com/bazelbuild/bazel/issues/14970.
         cat >> "${GITHUB_ENV:?}" <<'EOF'
-        USE_BAZEL_VERSION=${{inputs.bazel-version}}
         BAZELISK_GITHUB_TOKEN=${{inputs.github-token}}
         BAZEL_USE_CPP_ONLY_TOOLCHAIN=1
         CC=${{inputs.cc}}
@@ -126,17 +121,3 @@ runs:
         # using git_override.
         git config --global core.autocrlf false
         git config --global core.eol lf
-    - name: Enable Build without the Bytes
-      shell: bash
-      run: >-
-        echo 'common --remote_download_minimal' >> github.bazelrc
-      # Don’t enable Build without the Bytes in Bazel versions affected by
-      # https://github.com/bazelbuild/bazel/issues/19143 and
-      # https://github.com/bazelbuild/bazel/issues/20408.  We can enable it
-      # unconditionally once we drop support for these versions.
-      if: >-
-        !startsWith(inputs.bazel-version, '6.') ||
-        !(
-        startsWith(inputs.bazel-version, '6.3.') ||
-        startsWith(inputs.bazel-version, '6.4.')
-        )

.github/workflows/bazel-test.yaml

@@ -27,9 +27,9 @@ jobs:
     name: Test
     strategy:
       matrix:
-        # We don’t use the GitHub matrix support for the Emacs toolchain to
-        # allow Bazel to cache intermediate results between the test runs.
-        bazel: [6.3.2, 6.5.0, 7.1.1, latest]
+        # We don’t use the GitHub matrix support for the Emacs toolchain and the
+        # Bazel version to allow Bazel to cache intermediate results between the
+        # test runs.
         os: [ubuntu-latest, macos-latest, windows-latest]
         cc: [gcc, clang, msvc]
         exclude:
@@ -54,27 +54,15 @@ jobs:
       - name: Set up workspace
         uses: ./.github/actions/set-up
         with:
-          bazel-version: ${{matrix.bazel}}
           cc: ${{matrix.cc}}
           github-token: ${{secrets.GITHUB_TOKEN}}
-      - name: Set lockfile mode
-        # The lockfile format differs between the Bazel versions, so only for
-        # one version --lockfile_mode=error can work.  --lockfile_mode=update
-        # would be useless since we never use the updated lockfiles, so switch
-        # lockfiles off entirely in other Bazel versions.
-        shell: bash
-        run: >-
-          echo common
-          --lockfile_mode=${{matrix.bazel == 'latest' && 'error' || 'off'}}>>
-          github.bazelrc
       - name: Run Bazel tests
         shell: pwsh
         run: python build.py --profiles='${{runner.temp}}/profiles' -- check
       - name: Upload profiles
         uses: actions/upload-artifact@v4
         with:
           name: >-
-            profiles for Bazel version ${{matrix.bazel}} on ${{runner.os}}
-            compiled with ${{matrix.cc}}
+            profiles on ${{runner.os}} compiled with ${{matrix.cc}}
           path: ${{runner.temp}}/profiles/*.json.gz
           if-no-files-found: ignore

.github/workflows/debug-cache.yaml

@@ -32,7 +32,6 @@ jobs:
       - name: Set up workspace
         uses: ./.github/actions/set-up
         with:
-          bazel-version: latest
           github-token: ${{secrets.GITHUB_TOKEN}}
       - name: Build Emacs
         shell: pwsh

.github/workflows/update-lockfiles.yaml

@@ -31,7 +31,6 @@ jobs:
       - name: Set up workspace
         uses: ./.github/actions/set-up
         with:
-          bazel-version: latest
           github-token: ${{secrets.GITHUB_TOKEN}}
       - name: Regenerate lockfiles
         shell: pwsh

build.py

@@ -19,11 +19,12 @@
 Mimics a trivial version of Make."""
 
 import argparse
-from collections.abc import Callable, Iterable, Sequence
+from collections.abc import Callable, Iterable, Mapping, Sequence
 import functools
 import io
 import os
 import pathlib
+import re
 import shlex
 import shutil
 import subprocess
@@ -46,21 +47,26 @@ def wrapper(self: 'Builder') -> None:
 
 
 def _run(args: Sequence[str | pathlib.Path], *,
-         cwd: Optional[pathlib.Path] = None) -> None:
+         cwd: Optional[pathlib.Path] = None,
+         env: Optional[Mapping[str, str]] = None) -> None:
     if cwd:
         print('cd', shlex.quote(str(cwd)), '&&', end=' ')
+    env = env or None
+    if env is not None:
+        print(*(f'{k}={shlex.quote(v)}' for k, v in env.items()), end=' ')
+        env = dict(os.environ, **env)
     print(_quote(args))
-    subprocess.run(args, check=True, cwd=cwd)
+    subprocess.run(args, check=True, cwd=cwd, env=env)
 
 
 class Builder:
     """Builds the project."""
 
     def __init__(self, *,
                  profiles: Optional[pathlib.Path]) -> None:
-        bazel = shutil.which('bazelisk') or shutil.which('bazel')
+        bazel = shutil.which('bazelisk')
         if not bazel:
-            raise FileNotFoundError('neither Bazelisk nor Bazel found')
+            raise FileNotFoundError('Bazelisk not found')
         self._bazel = pathlib.Path(bazel)
         self._profiles = profiles
         self._github = os.getenv('CI') == 'true'
@@ -91,6 +97,7 @@ def check(self) -> None:
         # Test both default toolchain and versioned toolchains.
         self.test()
         self.versions()
+        self.bazels()
         self.ext()
 
     @target
@@ -140,8 +147,35 @@ def versions(self) -> None:
             self._test(f'--extra_toolchains=//elisp:emacs_{version}_toolchain',
                        profile=version)
 
+    @target
+    def bazels(self) -> None:
+        """Runs the Bazel tests for all supported Bazel versions."""
+        for version in sorted(_BAZEL_VERSIONS):
+            self._test(profile=f'bazel-{version}', bazel_version=version)
+
     def _test(self, *args: str, profile: str,
-              cwd: Optional[pathlib.Path] = None) -> None:
+              cwd: Optional[pathlib.Path] = None,
+              bazel_version: str = 'latest') -> None:
+        # The lockfile format differs between the Bazel versions, so only for
+        # one version --lockfile_mode=error can work.  --lockfile_mode=update
+        # would be useless on GitHub since we never use the updated lockfiles,
+        # so switch lockfiles off entirely in other Bazel versions.
+        if bazel_version == 'latest':
+            # Assume Bazel that’s new enough.
+            bzlmod = True
+            bwtb = True
+            lockfile_mode = 'error'
+        else:
+            match = re.match(r'(\d+)\.(\d+)', bazel_version, re.ASCII)
+            if not match:
+                raise ValueError(f'invalid version string {bazel_version}')
+            version = (int(match[1]), int(match[2]))
+            # Don’t enable Build without the Bytes in Bazel versions affected by
+            # https://github.com/bazelbuild/bazel/issues/19143 and
+            # https://github.com/bazelbuild/bazel/issues/20408.  We can enable
+            # it unconditionally once we drop support for these versions.
+            bwtb = version >= (6, 5)
+            lockfile_mode = 'off'
         for bzlmod in (True, False):
             prefix = '' if bzlmod else 'no'
             options = [f'--{prefix}enable_bzlmod']
@@ -153,8 +187,13 @@ def _test(self, *args: str, profile: str,
                     '--experimental_announce_profile_path',
                     '--profile=' + str(profile_file),
                 ]
+            if bwtb and self._github:
+                options.append('--remote_download_minimal')
+            if self._github:
+                options.append(f'--lockfile_mode={lockfile_mode}')
             options.extend(args)
-            _run([self._bazel, 'test'] + options + ['--', '//...'], cwd=cwd)
+            _run([self._bazel, 'test'] + options + ['--', '//...'], cwd=cwd,
+                 env={'USE_BAZEL_VERSION': bazel_version})
 
     @target
     def ext(self) -> None:
@@ -176,6 +215,9 @@ def lock(self) -> None:
 # All potentially supported Emacs versions.
 _VERSIONS = frozenset({'28.1', '28.2', '29.1', '29.2', '29.3'})
 
+# Selection of supported Bazel versions.
+_BAZEL_VERSIONS = frozenset({'6.3.2', '6.5.0', '7.1.1', 'latest'})
+
 
 def main() -> None:
     """Builds the project."""