encoding: introduce tagging type for non-lossy non-ASCII string This fixes the weird behavior of toutf8b(), which would convert a local string back to UTF-8 *only if* it was lossy in the system encoding. Before b7b26e54e37a "encoding: avoid localstr when a string can be encoded losslessly (issue2763)", all local strings were wrapped by the localstr class. I think this would justify the round-trip behavior of toutf8b(). ASCII strings are special-cased, so the cost of wrapping with safelocalstr is negligible. (with mercurial repo) $ export HGRCPATH=/dev/null HGPLAIN= HGENCODING=latin-1 $ hg log --time --config experimental.evolution=all > /dev/null (original) time: real 11.340 secs (user 11.290+0.000 sys 0.060+0.000) time: real 11.390 secs (user 11.300+0.000 sys 0.080+0.000) time: real 11.430 secs (user 11.360+0.000 sys 0.070+0.000) (this patch) time: real 11.200 secs (user 11.100+0.000 sys 0.100+0.000) time: real 11.370 secs (user 11.300+0.000 sys 0.070+0.000) time: real 11.190 secs (user 11.130+0.000 sys 0.060+0.000)

--- a/tests/test-command-template.t	Sun Apr 22 11:38:53 2018 +0900
+++ b/tests/test-command-template.t	Sun Apr 23 13:15:30 2017 +0900
@@ -4691,6 +4691,13 @@
   $ HGENCODING=ascii hg log -T "{desc|json}\n" -r0
   "non-ascii branch: \u00e9"
 
+json filter should take input as utf-8 if it was converted from utf-8:
+
+  $ HGENCODING=latin-1 hg log -T "{branch|json}\n" -r0
+  "\u00e9"
+  $ HGENCODING=latin-1 hg log -T "{desc|json}\n" -r0
+  "non-ascii branch: \u00e9"
+
 json filter takes input as utf-8b:
 
   $ HGENCODING=ascii hg log -T "{'`cat utf-8`'|json}\n" -l1