[[FIX]] Support y RegExp flag in ES2015 code
#2999
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| }); | ||
| } | ||
| if (value.indexOf("y") > -1) { | ||
| malformedDesc = "Duplicate RegExp flag"; |
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Is this necessary? Duplicate flags produce syntax errors
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This is a bit tricky. We're maintaining two variables for the flags: a string
named value and an array named flags. The flags array is eventually used
to create a RegExp instance in order to off-load the difficult work of RegExp
validation to whatever engine happens to be running JSHint itself.
If we include the y flag in this array, then running JSHint with esversion: 6 would produce different results according to whether the current engine
supported "sticky" RegExps. So instead, this patch "skips" the y flag when it
is encountered.
This could be an invalid transformation for other flags. For example, /{/ is
valid JavaScript but /{/u is not. Indiscriminately removing u would
therefor effect parsing correctness.
As far as I know, the only time the y flag could impact parsing is if it were
duplicated. (Runtime behavior is another matter, of course.) So this patch
explicitly verifies that the flag is not duplicated (using the separate
value string mentioned earlier) and otherwise parses y-containing RegExps
as though they did not have the y flag at all.
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@rwaldron This should be good to go. |
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Thanks for the explanation! LGTM |
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