931401 - Firefox page info says windows-1252 but it's really US-ASCII

Status: RESOLVED DUPLICATE of bug 890478

(Core :: DOM: Core & HTML, defect)

Description

[Paul Eggert]

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:24.0) Gecko/20100101 Firefox/24.0 (Beta/Release)
Build ID: 20130917154415

Steps to reproduce:

Start up Firefox and cut and paste this URL:

http://www.cs.ucla.edu/~eggert/tz/tz-link.htm

to visit the page. Then type Control-I to get Page Info.


Actual results:

It reports "Encoding: windows-1252".


Expected results:

It should report "Encoding: US-ASCII", since that's what's in the HTTP header and in the
contents, which say "<meta http-equiv="Content-type" content='text/html; charset="US-ASCII"'>".

Comment 1

[Alice0775 White]

Pushlog
http://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=539bb6ca633a&tochange=3267977b0f8a

Comment 2

[:Ms2ger (he/him; ⌚ UTC+1/+2)]

us-ascii is a label for windows-1252, per <http://encoding.spec.whatwg.org/>.

Comment 3

[Paul Eggert]

<http://encoding.spec.whatwg.org/> is incorrect.  US-ASCII is not an alias for Windows-1252.  Windows-1252 is an 8-bit encoding and has assignments for most characters 128-255.  US-ASCII has assignments only for characters 0-127.  If you look at the IANA assignments for character sets <http://www.iana.org/assignments/character-sets/character-sets.xhtml>, which is the official registry for encodings, you'll see that they are distinct.

Comment 4

[Simon Montagu :smontagu]

Comment 2 and comment 3 are at cross purposes: <http://encoding.spec.whatwg.org/> is aware that US-ASCII and Windows-1252 are distinct encodings; what it is saying is that user agents must interpret web content labeled as US-ASCII as if it were labeled as Windows-1252.

Comment 5

[Henri Sivonen (:hsivonen)]

(In reply to Paul Eggert from comment #3)
> <http://www.iana.org/assignments/character-sets/character-sets.xhtml>, which
> is the official registry for encodings, you'll see that they are distinct.

The Gecko implementation doesn't treat the IANA registry as authoritative, because treating http://encoding.spec.whatwg.org/ as authoritative is better for compatibility with Web content and other browsers. This results in some political friction, sure, but it also results in more useful software.