bug#8576: 23.2; js-mode doesn't support multi-line variable declarations

[Daniel Colascione]

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Hi Felix,

Thanks for the bug report.

On 4/28/11 12:22 AM, Felix H. Dahlke wrote:
> The problem can be reproduced as follows:
> 
> 1. Open a JavaScript file or load js-mode
> 2. Insert the following code:
>    var i = 1,
>        j = 2;
> 3. Observe that "j" is not highlighted and that pressing TAB on the
> second line doesn't indent it correctly.
> 
> Highlighting works correctly if both variables are declared on the
> same line:
>     var i = 1, j = 2;
> 

After looking at what would be required to address this bug, I'd like to
leave it unfixed for now:

The machinery required to implement the tracking necessary to handle
this construct in a generic way would be quite complex. Simple cases
could perhaps be recognized more quickly, but such a solution would fail
in hard to predict ways. Long-range effects are notoriously difficult to
recognize in font-lock, and reliably rehighlighting them after a change
is even trickier.

Additionally, this construct is relatively rare; if you're going to
split variable declarations across several lines, you might as well use
another "var". Also, the existing highlighting has no ill effects: the
second declaration is just interpreted as an assignment, and the worst
part is a lack of font-lock-variable-name-face, not syntactic incoherence.

I'll take patches, but for now, I think we should defer a solution to
this issue until we have a more sophisticated and general highlighting
scheme.
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