Merge branch 'lint-followup' into 'main'

Improve maint/add_warning

Closes #494

See merge request tpo/core/arti!560

maint/add_warning

@@ -1,5 +1,6 @@
 #!/usr/bin/python3
 
+import argparse
 import sys
 import os
 import re
@@ -66,15 +67,23 @@ DECIDED_NOT = """
 
 PAT = re.compile(r'^#!\[(allow|deny|warn)')
 
-opt_check = False
+opts = None
 deferred_errors = []
 
+class ImproperFile(Exception):
+    def __init__(self, lno, message):
+        self.lno = lno
+        self.message = message
+
 def filter_file(lints, inp, outp):
     in_lint_list = False
     found_lint_list = False
+    lno = 0
     for line in inp.readlines():
+        lno += 1
         if line.startswith("// @@ begin lint list"):
-            assert not in_lint_list
+            if in_lint_list:
+                raise ImproperFile(lno, 'found "@@ begin lint list" but inside lint list')
             found_lint_list = True
             in_lint_list = True
         elif line.startswith("//! <!-- @@ end lint list"):
@@ -82,27 +91,39 @@ def filter_file(lints, inp, outp):
             # *really really* hates comments that come after things.
             # Finishing the automaintained block with just a blank line is too much of a hazard.
             # It does end up in the output HTML from Rustdoc, but it is harmless there.
-            assert in_lint_list
+            if not in_lint_list:
+                raise ImproperFile(lno, 'found "@@ end lint list" but not inside lint list')
             in_lint_list = False
             outp.write(WANT_LINTS.strip())
             outp.write("\n")
         elif in_lint_list:
-            assert PAT.match(line)
+            if not PAT.match(line):
+                raise ImproperFile(lno, 'entry in lint list does not look like a lint')
             # do not send to output
             continue
         outp.write(line)
-    assert not in_lint_list
-    assert found_lint_list
+    if in_lint_list:
+        raise ImproperFile(lno, 'missing "@@ lint list" delimiter, still in lint list at EOF')
+    if not found_lint_list:
+        raise ImproperFile(lno, 'standard lint list block seems to be missing (wrong delimiters?)')
 
 def process(lints, fn):
     print("{}...".format(fn))
     tmp_name = fn+".tmp~"
     outp = open(tmp_name,'w')
     inp = open(fn,'r')
-    filter_file(lints, inp, outp)
+    try:
+        filter_file(lints, inp, outp)
+    except ImproperFile as e:
+        print('%s:%d: %s' % (fn, e.lno, e.message), file=sys.stderr)
+        deferred_errors.append(fn)
+        os.remove(tmp_name) # this tmp file is probably partial
+        return
+
     inp.close()
     outp.close()
-    if opt_check:
+
+    if opts.check:
         if subprocess.run(['diff', '-u', '--', fn, tmp_name]).returncode != 0:
             deferred_errors.append(fn)
     else:
@@ -127,12 +148,9 @@ def main(lints,files):
         sys.exit(1)
 
 if __name__ == '__main__':
-    args = sys.argv[1:]
-    while len(args) > 0 and args[0].startswith('-'):
-        arg = args.pop(0)
-        if arg == '--check':
-            opt_check = True
-        else:
-            raise(Exception('unknown option '+arg))
+    parser = argparse.ArgumentParser('standardise Rust lint blocks')
+    parser.add_argument('--check')
+    parser.add_argument('file', nargs='+')
+    opts = parser.parse_args()
 
-    main(WANT_LINTS, args)
+    main(WANT_LINTS, opts.file)