[NFC] Fix note about manually generated test output (#7221)

The note mentioned update_lit_checks.py in the first line, which made
update_lit_checks.py think that it _should_ update the test output, even
though the comment was explicitly about how it should not update the
test output. Reword the comment to avoid the problem.

Also make the check in the update script stricter for good measure.

Author: tlively

scripts/update_lit_checks.py

@@ -30,8 +30,8 @@
 script_dir = os.path.dirname(__file__)
 script_name = os.path.basename(__file__)
 
-NOTICE = (';; NOTE: Assertions have been generated by {script} and should not' +
-          ' be edited.')
+NOTICE_PREFIX = f';; NOTE: Assertions have been generated by {script_name}'
+NOTICE = NOTICE_PREFIX + '{args} and should not be edited.'
 
 RUN_LINE_RE = re.compile(r'^\s*;;\s*RUN:\s*(.*)$')
 CHECK_PREFIX_RE = re.compile(r'.*--check-prefix[= ](\S+).*')
@@ -80,7 +80,7 @@ def itertests(args):
             with open(test) as f:
                 lines = [line.rstrip() for line in f]
             first_line = lines[0] if lines else ''
-            if script_name not in first_line and not args.force:
+            if NOTICE_PREFIX not in first_line and not args.force:
                 warn(f'Skipping test {test} which was not generated by '
                      f'{script_name}. Use -f to override.')
                 continue
@@ -258,12 +258,12 @@ def update_test(args, test, lines, tmp):
             _, kind, name = indentKindName(match)
             named_items.append((kind, name))
 
-    script = script_name
+    notice_args = ''
     if all_items:
-        script += ' --all-items'
+        notice_args += ' --all-items'
     if output_kind != 'wat':
-        script += f' --output={output_kind}'
-    output_lines = [NOTICE.format(script=script)]
+        notice_args += f' --output={output_kind}'
+    output_lines = [NOTICE.format(args=notice_args)]
 
     def emit_checks(indent, prefix, lines):
         def pad(line):

test/lit/passes/memory-copy-fill-lowering.wast

@@ -1,5 +1,5 @@
-;; NOTE: These assertions have been manually generated, and cannot be updated by update_lit_checks.py
-;; because of the assertion at the end (update_lit_checks.py ignores the features section because it's
+;; NOTE: These assertions have been manually generated because of the assertion
+;; at the end (update_lit_checks.py ignores the features section because it's
 ;; not semantically part of the module.)
 
 ;; RUN: wasm-opt --enable-bulk-memory %s --llvm-memory-copy-fill-lowering --emit-target-features -S -o - | filecheck %s