fix: make fix-lints.py work on windows (leanprover-community#5055)

The `encoding='utf8'` fixes the crashes, the `with` statements are better WRT lifetime management of files.



Co-authored-by: Chris Hughes <[email protected]>

scripts/fix-lints.py

@@ -19,16 +19,17 @@ def getpos(line):
 # try to build
 log = subprocess.run(
     ['lake', 'build', leanmodule],
-    capture_output=True)
+    capture_output=True, encoding='utf8')
 if log.returncode == 0:
     print("no errors 🎉")
     exit(0)
 
 shutil.copyfile(leanfile, leanfile + '.bak')
 
+with open(leanfile + '.bak', encoding='utf8') as fp:
+    f = list(fp)
 count = 0
-f = list(open(leanfile + '.bak'))
-for l in reversed(log.stderr.decode().splitlines()):
+for l in reversed(log.stderr.splitlines()):
     if 'linter.unusedVariables' in l:
         line, col = getpos(l)
         f[line-1] = f[line-1][0:col] + '_' + f[line-1][col:]
@@ -42,5 +43,6 @@ def getpos(line):
 
 print(f'Fixed {count} warnings', file=sys.stderr)
 
-open(leanfile, 'w').write(''.join(f))
+with open(leanfile, 'w', encoding='utf8') as fp:
+    fp.write(''.join(f))
 os.remove(leanfile + '.bak')