Validate cpu_family (#3753)

* environment: validate cpu_family in cross file

* run_unittests: add unittest to ensure CPU family list in docs and environment matches

* run_unittests: skip compiler options test if not in a git repository

* environment: validate the detected cpu_family

* docs: add 32-bit PowerPC and 32/64-bit MIPS to CPU Families table

Names gathered by booting Linux in Qemu and running:

$ python3
import platform; platform.machine()

Partial fix for #3751

docs/markdown/Reference-tables.md

@@ -46,6 +46,9 @@ set in the cross file.
 | ia64                | Itanium processor     |
 | arm                 | 32 bit ARM processor  |
 | aarch64             | 64 bit ARM processor  |
+| mips                | 32 bit MIPS processor |
+| mips64              | 64 bit MIPS processor |
+| ppc                 | 32 bit PPC processors (Big Endian) |
 | ppc64               | 64 bit PPC processors (Big Endian) |
 | ppc64le             | 64 bit PPC processors (Little Endian) |
 | e2k                 | MCST Elbrus processor |

mesonbuild/environment.py

@@ -72,6 +72,22 @@ from .compilers import (
 
 build_filename = 'meson.build'
 
+known_cpu_families = (
+    'aarch64',
+    'arm',
+    'e2k',
+    'ia64',
+    'mips',
+    'mips64',
+    'parisc',
+    'ppc',
+    'ppc64',
+    'ppc64le',
+    'sparc64',
+    'x86',
+    'x86_64'
+)
+
 def detect_gcovr(version='3.1', log=False):
     gcovr_exe = 'gcovr'
     try:
@@ -209,6 +225,10 @@ def detect_cpu_family(compilers):
                 pass
         return 'x86_64'
     # Add fixes here as bugs are reported.
+
+    if trial not in known_cpu_families:
+        mlog.warning('Unknown CPU family %s, please report this at https://github.com/mesonbuild/meson/issues/new' % trial)
+
     return trial
 
 def detect_cpu(compilers):
@@ -953,6 +973,10 @@ class CrossBuildInfo:
                     res = eval(value, {'__builtins__': None}, {'true': True, 'false': False})
                 except Exception:
                     raise EnvironmentException('Malformed value in cross file variable %s.' % entry)
+
+                if entry == 'cpu_family' and res not in known_cpu_families:
+                    mlog.warning('Unknown CPU family %s, please report this at https://github.com/mesonbuild/meson/issues/new' % value)
+
                 if self.ok_type(res):
                     self.config[s][entry] = res
                 elif isinstance(res, list):

run_unittests.py

@@ -2206,6 +2206,7 @@ recommended as it is not supported on some platforms''')
             # they used to fail this test with Meson 0.46 an earlier versions.
             pass
 
+    @unittest.skipIf(not os.path.isdir('docs'), 'Doc dir not found, presumably because this is a tarball release.')
     def test_compiler_options_documented(self):
         '''
         Test that C and C++ compiler options and base options are documented in
@@ -2227,6 +2228,24 @@ recommended as it is not supported on some platforms''')
                 self.assertIn(opt, md)
         self.assertNotIn('b_unknown', md)
 
+    @unittest.skipIf(not os.path.isdir('docs'), 'Doc dir not found, presumably because this is a tarball release.')
+    def test_cpu_families_documented(self):
+        with open("docs/markdown/Reference-tables.md") as f:
+            md = f.read()
+        self.assertIsNotNone(md)
+
+        sections = list(re.finditer(r"^## (.+)$", md, re.MULTILINE))
+        for s1, s2 in zip(sections[::2], sections[1::2]):
+            if s1.group(1) == "CPU families":
+                # Extract the content for this section
+                content = md[s1.end():s2.start()]
+                # Find the list entries
+                arches = [m.group(1) for m in re.finditer(r"^\| (\w+) +\|", content, re.MULTILINE)]
+                # Drop the header
+                arches = set(arches[1:])
+                self.assertEqual(arches, set(mesonbuild.environment.known_cpu_families))
+
+
 class FailureTests(BasePlatformTests):
     '''
     Tests that test failure conditions. Build files here should be dynamically