` ` triggers "hidden Unicode characters" warning

[silverwind]

Description

https://try.gitea.io/silverwind/symlink-test/src/branch/master/bidi.md
https://github.com/silverwind/symlink-test/blob/master/bidi.md

The file contains a b and triggers the "hidden Unicode characters" warning on Gitea while it doesn't on GitHub. I think this character may need to be excluded from the warning as it's pretty commonly used in Markdown for non-nefarious purposes.

[wxiaoguang]

U+0020	SPACE	foo bar	Depends on font, typically 1/4 em, often adjusted
U+00A0	NO-BREAK SPACE	foo bar	As a space, but often not adjusted
U+1680	OGHAM SPACE MARK	foo bar	Unspecified; usually not really a space but a dash
U+180E	MONGOLIAN VOWEL SEPARATOR	foo᠎bar	0
U+2000	EN QUAD	foo bar	1 en (= 1/2 em)
U+2001	EM QUAD	foo bar	1 em (nominally, the height of the font)
U+2002	EN SPACE (nut)	foo bar	1 en (= 1/2 em)
U+2003	EM SPACE (mutton)	foo bar	1 em
U+2004	THREE-PER-EM SPACE (thick space)	foo bar	1/3 em
U+2005	FOUR-PER-EM SPACE (mid space)	foo bar	1/4 em
U+2006	SIX-PER-EM SPACE	foo bar	1/6 em
U+2007	FIGURE SPACE	foo bar	“Tabular width”, the width of digits
U+2008	PUNCTUATION SPACE	foo bar	The width of a period “.”
U+2009	THIN SPACE	foo bar	1/5 em (or sometimes 1/6 em)
U+200A	HAIR SPACE	foo bar	Narrower than THIN SPACE
U+200B	ZERO WIDTH SPACE	foo​bar	0
U+202F	NARROW NO-BREAK SPACE	foo bar	Narrower than NO-BREAK SPACE (or SPACE), “typically the width of a thin space or a mid space”
U+205F	MEDIUM MATHEMATICAL SPACE	foo bar	4/18 em
U+3000	IDEOGRAPHIC SPACE	foo　bar	The width of ideographic (CJK) characters.
U+FEFF	ZERO WIDTH NO-BREAK SPACE	foobar	0

[zeripath]

th‍is is not the same as thi‍s.

nor is ä the same as ä!

[wxiaoguang]

Yep, unicode is very tricky. The question is what should we do or should we be too strict?

	s := string([]byte{0xE2, 0x84, 0xAA})
	log.Print(s)
	log.Print("K" == s)
	log.Print(strings.EqualFold("K", s))

2022/01/19 17:31:11 K
2022/01/19 17:31:11 false
2022/01/19 17:31:11 true

[zeripath]

I tried to just warn for bad bidi and was forced to add warning for every use of bidi. At that point I simply added escaping for every non-visible character. Genuine homoglyph detection stalled because the original PR completely stalled.

The code has the ability to mark the escape with the type of character that is escaping. We can tune where and when the warning occurs instead of just for any escaping. Adding in a classifier to the type of escaping would also be easy and so would then be escaping only for certain types of characters etc.

[silverwind]

Isn't it sufficient to only highlight the bidi characters?

What's the purpose of the "invisible characters" warning? I mean any space-type character is "invisible" by definition and not really a concern, or is it?

[zeripath]

th‍is is not the same as thi‍s.

nor is ä the same as ä!

[zeripath]

diff --git a/options/locale/locale_en-US.ini b/options/locale/locale_en-US.ini
index d8398f6d9..036a1a983 100644
--- a/options/locale/locale_en-US.ini
+++ b/options/locale/locale_en-US.ini
@@ -1015,6 +1015,9 @@ bidi_bad_description_escaped = `This file contains unexpected Bidirectional Unic
 unicode_header = `This file contains hidden Unicode characters!`
 unicode_description = `This file contains hidden Unicode characters that may be processed differently from what appears below. If your use case is intentional and legitimate, you can safely ignore this warning. Use the Escape button to reveal hidden characters.`
 unicode_description_escaped = `This file contains hidden Unicode characters. Hidden unicode characters are escaped below. Use the Unescape button to show how they render.`
+bidi_header = `This file contains Bidirectional Unicode characters!`
+bidi_description = `This file contains Bidirectional Unicode characters that may be processed differently from what appears below. If your use case is intentional and legitimate, you can safely ignore this warning. Use the Escape button to reveal hidden characters.`
+bidi_description_escaped = `This file contains Bidirectional Unicode characters. Hidden unicode characters are escaped below. Use the Unescape button to show how they render.`
 line_unicode = `This line has hidden unicode characters`
 
 escape_control_characters = Escape
diff --git a/templates/repo/unicode_escape_prompt.tmpl b/templates/repo/unicode_escape_prompt.tmpl
index 855d7866a..171752498 100644
--- a/templates/repo/unicode_escape_prompt.tmpl
+++ b/templates/repo/unicode_escape_prompt.tmpl
@@ -7,13 +7,13 @@
 			</div>
 			<p>{{$.root.i18n.Tr "repo.bidi_bad_description" | Str2html}}</p>
 		</div>
-	{{else if .EscapeStatus.Escaped}}
+	{{else if .EscapeStatus.HasBIDI}}
 		<div class="ui warning message unicode-escape-prompt">
 			<span class="close icon hide-panel button" data-panel-closest=".message">{{svg "octicon-x" 16 "close inside"}}</span>
 			<div class="header">
-				{{$.root.i18n.Tr "repo.unicode_header"}}
+				{{$.root.i18n.Tr "repo.bidi_header"}}
 			</div>
-			<p>{{$.root.i18n.Tr "repo.unicode_description" | Str2html}}</p>
+			<p>{{$.root.i18n.Tr "repo.bidi_description" | Str2html}}</p>
 		</div>
 	{{end}}
 {{end}}

Would simply drop the header and only show it if there are bidi characters.

The ⚠️ indicators would still be present on the lines that had unicode spaces etc. on them - I'd note that monaco has highlights nbsp characters.

[silverwind]

Yes, non-ASCII spaces could still be highlighted, they are usually an error in code. But I'd certainly get rid of the obnoxious yellow box unless there are BIDI characters.

  in rendered markdown should also not show a ⚠️, as an exception.

[zeripath]

  in rendered markdown should also not show a ⚠️, as an exception.

Without the "obnoxious" box there is nothing shown in rendered markdown except that the "escape" button is present.