klimek added inline comments.
================
Comment at: clang/unittests/Format/FormatTest.cpp:22584
+ Style.Macros.push_back("CALL(x)=f([] { x })");
+ Style.Macros.push_back("ASSIGN_OR_RETURN(a, b, c)=a = (b) || (c)");
+
----------------
sammccall wrote:
> klimek wrote:
> > sammccall wrote:
> > > If this is assign_or_return, the treatment of "c" is fairly strange. Also
> > > you are mostly calling this with only two args. Maybe drop C and use a
> > > different macro for the 3-arg case?
> > ASSIGN_OR_RETURN allows 3 args, though; this is basically the thing I'd
> > propose to configure for ASSIGN_OR_RETURN in general; is there anything
> > specific you don't like about this?
> OK, this is a bit sticky.
> - `ASSIGN_OR_RETURN` is almost always called with two args
> - some versions of `ASSIGN_OR_RETURN` support an optional third arg (there's
> no canonical public version)
> - these emulate overloading using variadic macro tricks
> - this patch doesn't claim to support either variadic macros or overloading
>
> So the principled options seem to be:
> - macros have fixed arity: clang-format can support the two-arg version of
> `ASSIGN_OR_RETURN` but not the three-arg version. (This is what I was
> assuming)
> - macros have variable arity: the public docs need to describe how passing
> too many/too few args is treated, because this isn't obvious and it sounds
> like we want people to rely on it. This feels like stretching "principled" to
> me - we're relying on the expansion still parsing correctly when args are
> missing, which basically seems like coincidence.
> - macros support overloading: instead of looking up macros by name, the key
> is `(string Name, optional<int> Arity)`
Chose option 3, as this is pretty straight-forward and I believe the best user
experience.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D144170/new/
https://reviews.llvm.org/D144170
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