Destructuring not recognized

[henry2004y]

Hi,

I've encountered a case where Polyester.jl does not know how to handle the destructuring syntax introduced in Julia 1.7:

using Polyester

struct A
   a
   b
end

x = A(1,2)

Threads.@threads for i in 1:2
   (; a, b) = x
end

@batch for i in 1:2
   (; a, b) = x
end

The @batch loop returns

ERROR: LoadError: "Don't know how to handle:\n \$(Expr(:parameters, :a, :b))"

[Moelf]

bump, do we need a pass in the macro to transform this into a bunch of getproperty?

[chriselrod]

bump, do we need a pass in the macro to transform this into a bunch of getproperty?

Yeah, that'd be a reasonable approach.
The alternative would be handling Expr(:parameters,...), where those parameters would be added to the symbols defined in the loop.

Want to take a stab at it?

[chriselrod]

Polyester.jl/src/closure.jl

Lines 18 to 30 in f49a308

	function define_tup!(arguments::Vector{Symbol}, defined::Dict{Symbol,Symbol}, ex::Expr, mod)
	for (i, a) ∈ enumerate(ex.args)
	if a isa Symbol
	ex.args[i] = getgensym!(defined, a)
	elseif Meta.isexpr(a, :tuple)
	define_tup!(defined, a)
	elseif Meta.isexpr(a, :ref)
	extractargs!(arguments, defined, a, mod)
	else
	throw("Don't know how to handle:\n $a")
	end
	end
	end

can handle

julia> y = (1,2);

julia> @batch for i in 1:2
          (a, b) = y
       end

so it should be straightforward to adapt to support (; a, b) = x.

Although preprocessing this into getproperty calls would work too, and not require as much looking into the internals, at the cost of requiring an extra pass over the Expr making macro expansion slower.

[Moelf]

where even is this signature defined

  define_tup!(defined, a) 

[Moelf]

also this doesn't quite work, this logic assumes each element in ex.args gets replaced by a gensym

but when a is a :parameters expression, it needs to inflate into multiple entries in ex.args

[chriselrod]

where even is this signature defined

  define_tup!(defined, a) 

That method does not exist. That is a bug.