STR: 1. Load attached testcase. EXPECTED RESULTS: No wrapping (I think). ACTUAL RESULTS: Wrapping. The testcase has a fixed-width <div> with: white-space: nowrap; -moz-hyphens: auto; word-break: break-all; I'd expect "white-space: nowrap" to prevent wrapping here. (see discussion below). However, when combined with *both* of the other two declarations, we end up wrapping at the right edge of the div. (You need *both* declarations, -moz-hyphens *and* word-break, to trigger this issue. If I only include one or the other of those, then I get EXPECTED RESULTS.) DISCUSSION: The CSS Text 3 spec says: > [...] like 'pre', it does not allow wrapping. http://dev.w3.org/csswg/css-text-3/#valdef-white-space-nowrap ...and the chunk of the 'pre' definition that it's referring to is (I think): > Lines only break at forced line breaks; content that > does not fit within the block container overflows it. http://dev.w3.org/csswg/css-text-3/#valdef-white-space-pre In that definition, "forced line breaks" is linkified to this chunk: http://dev.w3.org/csswg/css-text-3/#forced-line-break ...which explains that "forced lines breaks" are distinct from "soft line breaks". And the "word-break" & "hyphens" properties are each defined as creating "soft wrap opportunities". http://dev.w3.org/csswg/css-text-3/#word-break-property http://dev.w3.org/csswg/css-text-3/#hyphens-property So I don't think these properties should introduce any "forced breaks", which (per white-space:pre text quoted above definition) means there shouldn't be any breaks in this testcase, AFAICT. Neither IE nor Chrome have linebreaks in this testcase.

This bug seems to be responsible for text wrapping (instead of overflowing and ellipsisizing) at http://music.baidu.com/rings -- screencast attached, showing me disabling both "-moz-hyphens: auto" decls that affect the element. This fixes their layout and lets their desired ellipsizing happen. (Note: this site only loads if you have a mobile UA -- I'm using the User Agent Overrider extension's "Firefox 29 for Android" UA. With a desktop UA, I just get a 404.) This is our #2 fixlist site for mainland china, according to bug 1107378 comment 4.

(In reply to Daniel Holbert [:dholbert] from comment #1) > This is our #2 fixlist site for mainland china, according to bug 1107378 > comment 4. (Though I suspect the issues that got it on the fixlist may have been unrelated, worse problems that are now fixed [I think])

Here's a testcase with "white-space: pre" to show that that's affected, too. There are no forced linebreaks in the <div> here, and yet we wrap eagerly.

For thoroughness' sake: I'm using Nightly 38.0a1 (2015-01-28), and it goes back at least as far as Nightly 20.0a1 (2013-01-01) -- so it's not a recent regression. I'm betting it was introduced when bug 253317 added "-moz-hyphens" support. (I did confirm that a build before that -- Minefield 4.09b13pre (2011-03-18) gives EXPECTED RESULTS.) (I tried a few other intermediate builds just for fun, but a lot of old builds hit startup crashes these days, for some reason; probably a library mismatch or something.)

I think I see the problem: the equality test at [1] is broken due to the addition of the BREAK_USE_AUTO_HYPHENATION flag, which should be ignored there. I'll post a patch in a while, after testing whether it breaks other stuff....

(In reply to Jonathan Kew (:jfkthame) from comment #5) > I think I see the problem: the equality test at [1] is broken due to the > addition of the BREAK_USE_AUTO_HYPHENATION flag, which should be ignored > there. Oops.... [1] there was meant to refer to [1] http://mxr.mozilla.org/mozilla-central/source/dom/base/nsLineBreaker.cpp#197

Inspecting the code reveals that it's not only "-moz-hyphens:auto" that will trigger this incorrect wrapping. You can get a similar effect by applying "text-transform:capitalize": data:text/html,<div style="width:100px;white-space:nowrap;word-break:break-all; text-transform:capitalize">this text is not supposed to wrap Fixing this as well, without breaking the text-transform behavior, is going to add a few more lines to the necessary patch. Re-testing...

I believe reftests are all happy with the patch above, but I've started a try run to double-check: https://treeherder.mozilla.org/#/jobs?repo=try&revision=dd8e0a48d189

Comment on attachment 8556586 [details] [diff] [review] The presence of hyphens:auto and/or text-transform:capitalize should not affect no-wrap behavior Thanks for the quick action on this! >diff --git a/dom/base/nsLineBreaker.cpp b/dom/base/nsLineBreaker.cpp [...] > >+#define NO_BREAKS_NEEDED_FLAGS (BREAK_SUPPRESS_INITIAL | \ >+ BREAK_SUPPRESS_INSIDE | \ >+ BREAK_SKIP_SETTING_NO_BREAKS) Could you add a brief comment explaining the significance of this mask? e.g.... // If aFlags has *all* these bits set, then we don't need to worry about // finding break opportunities in the appended text. ...or something along those lines. >+ bool capitalizationNeeded = false; > nsTArray<bool> capitalizationState; > if (aSink && (aFlags & BREAK_NEED_CAPITALIZATION)) { > if (!capitalizationState.AppendElements(aLength)) > return NS_ERROR_OUT_OF_MEMORY; > memset(capitalizationState.Elements(), false, aLength*sizeof(bool)); >+ capitalizationNeeded = true; > } (Maybe this should be "noCapitalizationNeeded", with flipped polarity, so it matches "noBreaksNeeded" in all their combined or adjacent checks? Maybe that's more confusing, though. Whatever you prefer on this WFM.) >+ if (noBreaksNeeded && !capitalizationNeeded) { > // Skip to the space before the last word, since either the break data > // here is not needed, or no breaks are set in the sink and there cannot > // be any breaks in this chunk; all we need is the context for the next > // chunk (if any) It looks like this comment needs an update, to match its updated condition. (We're skipping because we don't need breaks *and we don't need capitalization* for this stretch.) r=me

https://hg.mozilla.org/integration/mozilla-inbound/rev/7d2762676005 https://hg.mozilla.org/integration/mozilla-inbound/rev/889db6ac72f0

https://hg.mozilla.org/mozilla-central/rev/7d2762676005 https://hg.mozilla.org/mozilla-central/rev/889db6ac72f0