meson: add sparse support

Do not use cgcc; instead, extract compilation commands from compile_commands.json
and invoke sparse directly.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

scripts/check_sparse.py

@@ -0,0 +1,25 @@
+#! /usr/bin/env python3
+
+# Invoke sparse based on the contents of compile_commands.json
+
+import json
+import subprocess
+import sys
+import shlex
+
+def extract_cflags(shcmd):
+    cflags = shlex.split(shcmd)
+    return [x for x in cflags
+            if x.startswith('-D') or x.startswith('-I') or x.startswith('-W')
+               or x.startswith('-std=')]
+
+cflags = sys.argv[1:-1]
+with open(sys.argv[-1], 'r') as fd:
+    compile_commands = json.load(fd)
+
+for cmd in compile_commands:
+    cmd = ['sparse'] + cflags + extract_cflags(cmd['command']) + [cmd['file']]
+    print(' '.join((shlex.quote(x) for x in cmd)))
+    r = subprocess.run(cmd)
+    if r.returncode != 0:
+        sys.exit(r.returncode)