[JuliaLowering] Remove use of @SyntaxTree in ccall

[mlechu]

I'm assuming this macro (which is defined as "go find the file or REPL history
entry this Expr came from and re-parse the text to SyntaxTree") is mostly
for convenience in interactive environments. It's also breakable at
precompile time with changes in the way we expand quote, and it takes a
noticable amount of time in inference. This change just uses the
less-convenient @ast form like the rest of the project.

[topolarity]

It's also breakable at precompile time with changes in the way we expand quote

Can you elaborate?

This change just uses the less-convenient @ast form like the rest of the project.

The @ast form is probably fine for now, but it's worth mentioning that having proper non-hacky SyntaxTree quoting is probably required for "new style" macros eventually. The current implementation (

julia/JuliaLowering/src/syntax_graph.jl

Lines 679 to 713 in fd419bd

	macro SyntaxTree(ex_old)
	# The implementation here is hilarious and arguably very janky: we
	# 1. Briefly check but throw away the Expr-AST
	if !(Meta.isexpr(ex_old, :quote) || ex_old isa QuoteNode)
	throw(ArgumentError("@SyntaxTree expects a `quote` block or `:`-quoted expression"))
	end
	# 2. Re-parse the current source file as SyntaxTree instead
	fname = isnothing(__source__.file) ? error("No current file") : String(__source__.file)
	if occursin(r"REPL\[\d+\]", fname)
	# Assume we should look at last history entry in REPL
	try
	# Wow digging in like this is an awful hack but `@SyntaxTree` is
	# already a hack so let's go for it I guess 😆
	text = Base.active_repl.mistate.interface.modes[1].hist.history[end]
	if !occursin("@SyntaxTree", text)
	error("Text not found in last REPL history line")
	end
	catch
	error("Text not found in REPL history")
	end
	else
	text = read(fname, String)
	end
	full_ex = parseall(SyntaxTree, text)
	# 3. Using the current file and line number, dig into the re-parsed tree and
	# discover the piece of AST which should be returned.
	ex = _find_SyntaxTree_macro(full_ex, __source__.line)
	isnothing(ex) && error("_find_SyntaxTree_macro failed")
	# 4. Do the first step of JuliaLowering's syntax lowering to get
	# syntax interpolations to work
	_, ex1 = expand_forms_1(__module__, ex, false, Base.tls_world_age())
	@assert kind(ex1) == K"call" && ex1[1].value == interpolate_ast
	Expr(:call, :interpolate_ast, SyntaxTree, ex1[3][1],
	map(e->_scope_layer_1_to_esc!(Expr(e)), ex1[4:end])...)
	end

) seems too hacky to rely on as-is though, I agree.