[PATCH v2 3/5] docs: sphinx-build-wrapper: prefer gmake

[Chen Miao <chenmiao.ku@gmail.com>]

Homebrew installs GNU Make as gmake on macOS, but the Sphinx build
wrapper invokes make directly when generating Info and Rust
documentation. This can make the dependency check succeed while those
documentation targets still use an incompatible make implementation.

Honor MAKE when it names a compatible GNU Make. Otherwise check gmake
and then make, selecting the first GNU Make 4.0 or newer. This keeps the
wrapper's selection consistent with sphinx-pre-install.

Signed-off-by: Chen Miao <chenmiao.ku@gmail.com>
---
 tools/docs/sphinx-build-wrapper | 55 ++++++++++++++++++++++++++++-----
 1 file changed, 48 insertions(+), 7 deletions(-)

diff --git a/tools/docs/sphinx-build-wrapper b/tools/docs/sphinx-build-wrapper
index 1bb962202..aa6a297db 100755
--- a/tools/docs/sphinx-build-wrapper
+++ b/tools/docs/sphinx-build-wrapper
@@ -71,6 +71,7 @@ from jobserver import JobserverExec         # pylint: disable=C0413,C0411,E0401
 #
 VENV_DEFAULT = "sphinx_latest"
 MIN_PYTHON_VERSION = PythonVersion("3.7").version
+MIN_MAKE_VERSION = PythonVersion("4.0").version
 PAPER = ["", "a4", "letter"]
 
 TARGETS = {
@@ -97,6 +98,46 @@ class SphinxBuilder:
     with the Kernel.
     """
 
+    @staticmethod
+    def get_make_version(cmd):
+        """Return the GNU Make version, or None for another make."""
+        if not cmd:
+            return None
+
+        try:
+            result = subprocess.run(
+                [cmd, "--version"],
+                stdout=subprocess.PIPE,
+                stderr=subprocess.PIPE,
+                text=True,
+                check=True,
+            )
+        except (OSError, subprocess.CalledProcessError):
+            return None
+
+        match = re.search(
+            r"^GNU Make\s+([0-9]+(?:\.[0-9]+)*)", result.stdout, re.MULTILINE
+        )
+        if not match:
+            return None
+
+        return PythonVersion.parse_version(match.group(1))
+
+    def get_make(self):
+        """Select the first GNU Make 4.0 or newer in preference order."""
+        candidates = [
+            self.env.get("MAKE"),
+            shutil.which("gmake"),
+            shutil.which("make"),
+        ]
+
+        for cmd in candidates:
+            version = self.get_make_version(cmd)
+            if version and version >= MIN_MAKE_VERSION:
+                return cmd
+
+        sys.exit("GNU Make 4.0 or newer is required")
+
     def get_path(self, path, use_cwd=False, abs_path=False):
         """
         Ancillary routine to handle patches the right way, as shell does.
@@ -569,9 +610,10 @@ class SphinxBuilder:
         texinfo directory.
         """
 
+        make = self.get_make()
         for output_dir in output_dirs:
             try:
-                subprocess.run(["make", "info"], cwd=output_dir, check=True)
+                subprocess.run([make, "info"], cwd=output_dir, check=True)
             except subprocess.CalledProcessError as e:
                 sys.exit(f"Error generating info docs: {e}")
 
@@ -787,12 +829,11 @@ class SphinxBuilder:
 
         if rustdoc and target in ["htmldocs", "epubdocs"]:
             print("Building rust docs")
-            if "MAKE" in self.env:
-                cmd = [self.env["MAKE"]]
-            else:
-                cmd = ["make", "LLVM=1"]
-
-            cmd += [ "rustdoc"]
+            make = self.get_make()
+            cmd = [make]
+            if make != self.env.get("MAKE"):
+                cmd.append("LLVM=1")
+            cmd.append("rustdoc")
             if self.verbose:
                 print(" ".join(cmd))
 
-- 
2.50.1 (Apple Git-155)