from F*cker Carlson's The Daily Caller, now that Jack Hunter has officially fallen out of my favor, be that as it may, how the writer wrote it, is acceptable, provided what follows "pro-" is a known word, or a phrase.
In modern diction, both "gun control" and "guncontrol" have been used interchangeably.
So, if the writer wants to allude that a term is 'for something,' and essentially make a transitory 'prefixed' word, anything "pro-___________" is fine, be that a single word, or a phrase.
I say "transitory" because while true, it's completely arbitrary when something culturally can 'acceptably' become a 'new' word, but it's become a common practice for one to add a dash before a word, as a descriptive prefix/adjective, for a word that has not been settled on widely, 'yet.'
So if the writer viewed "gun control" as a whole 'word,' it is grammatically correct to call it pro-gun control, as well as pro-guncontrol.
Though personally, I've rarely seen "gun-control," written in that manner, used widely. Of course, that doesn't mean you're wrong. It's just that I haven't seen it used that way, that much.
But, even IF one wants to add "pro-" prior to a two-word phrase connected via a dash like "gun-control" (if one accepts that version vs. say "gun control"), it still is a more widely accepted linguistic practice that one uses only one dash, not two, as the version you're asserting to be the correct one is really:
Thus, "pro-gun control," is still more preferable than "pro-gun-control."
Because if you say "pro gun-control," you're making the entire "pro gun" into a descriptor/adjective. As such, what you actually end up saying is that your "control" is "pro gun."
Think of say... a "reddish yellow-car."
In such case, because both "yellow" and "red" are colors, ie. same category, it's easier to distinguish; people automatically assume that you're referring to a car that's both red and yellow.
NOT, a "yellow car" (assuming that a car CAN be natively yellow, pre-paint) that's also a bit "red."
Now, if you wanted to say that your already "yellow car" has somewhat of "red" hue mixed in? Then, you would say "reddish-yellow car," which is kinda redundant as me merely stating "reddish" just made it an adjective for the color "yellow."
So in that case, with or without the dash, I'm already describing that particular "yellow" as having some "red" mixed in: thus, reddish yellow.
Suppose, one can argue that because you're describing variations in the same category, ie. color, trying to tie together "pro"+"gun"+"control," which are all separate items, into a working phrase, is comparing apples and oranges.
Well... true, kinda.
Which is why, ALL of my above stated reasons are PRECISELY why personally, I'm of the mind that one should write however one likes, as there is no real absolute right way of using any language, as it was never fiat; everyday-people used the language, verbally, before it were ever 'codified' into written structures.
Language has always developed that way, for the most part.
So, just because a bunch of hoity-toity self-proclaimed linguistic 'masters' meet annually to decide what is, or is not 'linguistically acceptable' as a modern vernacular, don't make it so.
Just in the same way that we won't accept fiat currency,
It's like, who the hell do they think they are?
Predictions in due Time...
"Let it not be said that no one cared, that no one objected once it's realized that our liberties and wealth are in jeopardy." - Dr. Ronald Ernest Paul
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