+++ This bug was initially created as a clone of Bug #1739784 +++

See bug 1739784 comment #17 and below.

We'll follow up with a patch to change some of the interfaces to reduce the conversions. For the
const nsPromiseFlatCString& flat = PromiseFlatCString(aSpec); see M-C examples here:
https://searchfox.org/comm-central/search?q=nsPromiseFlatCString&path=netwerk&case=false&regexp=false

Follow-up in bug 1741619, this is rippling out terribly.

Pushed by mkmelin@iki.fi:
https://hg.mozilla.org/comm-central/rev/f1a7bcd6d770
Replace use of nsCString().get() with PromiseFlatCString().get() in mailnews. r=mkmelin

Comment on attachment 9251108 [details] [diff] [review]
1741559-replace-nsCString-get.patch

[Approval Request Comment]
Regression caused by (bug #): bug 1571672
User impact if declined: Various things don't work on folders with non-ASCII names: Saves multiple drafts, virtual folders don't work, etc.
Testing completed (on c-c, etc.): Yes.
Risk to taking this patch (and alternatives if risky):
Not risky, mostly mechanical change of raw string API to "smart" string API allowing for non-ASCII strings to be correctly passed around.
Part of a pack of four bugs which need to be uplifted in this order:
Bug 1741559, bug 1741619, bug 1739814, bug 1739903. Bug 1739784 was the first one in the series and that's already on ESR.

Comment on attachment 9251108 [details] [diff] [review]
1741559-replace-nsCString-get.patch

[Triage Comment]
Approved for beta

Thunderbird 95.0b5:
https://hg.mozilla.org/releases/comm-beta/rev/1a32d92a0836

Comment on attachment 9251108 [details] [diff] [review]
1741559-replace-nsCString-get.patch

[Triage Comment]
Approved for esr91

Thunderbird 91.4.1:
https://hg.mozilla.org/releases/comm-esr91/rev/b4c26539b451