[PATCH v3 4/6] 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. Use the common kdoc
detector to keep this selection consistent with sphinx-pre-install.

Signed-off-by: Chen Miao <chenmiao.ku@gmail.com>
---
 tools/docs/sphinx-build-wrapper | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/tools/docs/sphinx-build-wrapper b/tools/docs/sphinx-build-wrapper
index 1bb962202..15c7e0938 100755
--- a/tools/docs/sphinx-build-wrapper
+++ b/tools/docs/sphinx-build-wrapper
@@ -63,6 +63,7 @@ SRC_DIR = os.path.dirname(os.path.realpath(__file__))
 sys.path.insert(0, os.path.join(SRC_DIR, LIB_DIR))
 
 from kdoc.python_version import PythonVersion
+from kdoc.gmake_detect import find_gmake
 from kdoc.latex_fonts import LatexFontChecker
 from jobserver import JobserverExec         # pylint: disable=C0413,C0411,E0401
 
@@ -97,6 +98,14 @@ class SphinxBuilder:
     with the Kernel.
     """
 
+    def get_make(self):
+        """Select the first GNU Make 4.0 or newer in preference order."""
+        make = find_gmake(self.env.get("MAKE"))
+        if make:
+            return make
+
+        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 +578,10 @@ 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 +797,11 @@ 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)