[swift-evolution] [Discussion]: Renaming #line, the line control statement

Dave Abrahams dabrahams at apple.com
Thu Feb 4 13:54:08 CST 2016

on Thu Feb 04 2016, Chris Lattner <swift-evolution at swift.org> wrote:

>> On Feb 3, 2016, at 7:29 PM, Brent Royal-Gordon via swift-evolution
>> <swift-evolution at swift.org> wrote:
>>> line-control-statement → #line­
>>> line-control-statement → #line­line-number­file-name­
>>> line-number → A decimal integer greater than zero
>>> file-name → static-string-literal­
>>> The accepted implementation of SE-0028 disambiguates the two by
>>> requiring #line (the control statement) to appear at the first
>>> column for the time being. This is a stop-gap solution best
>>> remedied by renaming #line.
>>> Chris Lattner writes, "The core team isn’t thrilled with the magic
>>> “first token on a line” whitespace behavior that #line will be
>>> getting, and would like someone to start a discussion about
>>> renaming the old #line directive to something more specific and
>>> tailored to its purpose.  Once that name and syntax is settled, we
>>> can rename the directive and remove the whitespace rule."
>>> I'd recommend #setline or #linenumber. Starting this thread to solicit other suggestions.
>> I don't love the way the current format has two unlabeled parameters
>> in an arbitrary order. Maybe something more like this?
>> 	#reset line=50, file="foo.swift"
>> (I have a soft preference for "reset" over "set" because these are
>> things the compiler changes automatically, but that might be a silly
>> reason.)
>> Perhaps this could even let you set any combination of the #whatever
>> parameters, so if, for instance, you were writing a parser
>> generator, you could set #function to the name of the rule a
>> particular piece of code came from.
> Using something like this as the grammar structure makes sense to me,
> but I’d suggest something more specific (and longer) for this,
> perhaps:
> #setsyntacticsourcelocation
> or something. :-)

What does “syntactic” communicate that isn't already in 



ommitting-needless-words-ly y'rs,

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