I am not a PHP expert and i don't have an environment to test it, but it looks like it's really easy to change.

Just change the line

return syntaxHighlightHelp( wfMsgHtml( 'syntaxhighlight-err-language' ) );

into

return $text . syntaxHighlightHelp( wfMsgHtml( 'syntaxhighlight-err-language' ) );

And make syntaxHighlightHelp() and syntaxHighlightError() return more modest error messages.

I hope it helps.

robchur wrote:

Not a viable patch, includes cross-site scripting injection vector.

It probably wouldn't be a bad idea to go ahead and show the input (properly escaped and <pre>d of course), but I'm not sure about making the warning smaller... listing the supported languages is probably the only way to figure out wtf is going on. :)

[Though in theory that could be moved to a special help page or something and that could be linked.... shrug]

ayg wrote:

Why not pass the list of supported languages and escaped properly formatted code as $1 and $2 to the error message so this can be decided on a site-by-site basis? I'd say the default should be to display it, yes, that's a much better failure mode, but with a list of supported languages too.

Nod, go ahead and try that.

So how about this ?

<source lang="something">
Code
</source>
still only shows an error message.

Or was something else meant (which may or may not be fixed in the mean time)

No, this isn't fixed. Haskell seems to be supported now, but for unsupported language only an error message is shown.

Done on trunk in r87976