add check.py to perform syntax-checking of generated cpp

it would be nice to run this in ci. note llvm 17 dependency

offlineASL-cpp/check.py

@@ -0,0 +1,52 @@
+#!/usr/bin/env python3
+
+"""
+Configures a meson build for syntax-checking only.
+To use, run `meson compile -C build` after this script.
+
+This script works by manually editing the meson-generated
+ninja files. This is obviously a bit hacky, but meson does
+not yet properly support -fsyntax-only.
+"""
+
+import os
+import shutil
+import subprocess
+
+clangpp = shutil.which('clang++')
+true = shutil.which('true')
+assert clangpp
+assert true
+
+def main():
+  os.environ['CXX'] = str(clangpp)
+
+  subprocess.check_call('meson setup --reconfigure build'.split())
+
+  with open('build/build.ninja', 'rb') as f:
+    build = f.readlines()
+
+  bstr = lambda x: str(x).encode('utf-8')
+
+  # replacement rules, keyed by sentinel line, and values are
+  # replacements to perform on the NEXT line.
+  repls = {
+    b'rule cpp_COMPILER\n': (b' $ARGS ', b' $ARGS -fsyntax-only '),
+    b'rule cpp_LINKER\n': (bstr(clangpp), bstr(true)),
+    b'rule cpp_LINKER_RSP\n': (bstr(clangpp), bstr(true)),
+  }
+
+  with open('build/build.ninja', 'wb') as f:
+    repl = None
+    for l in build:
+      if repl is not None:
+        assert repl[0] in l, f'replacement failed {repl} in {l!r}'
+        f.write(l.replace(repl[0], repl[1]))
+        repl = None
+      else:
+        repl = repls.get(l) # must match exactly
+        f.write(l)
+
+if __name__ == '__main__':
+  main()
+