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JuliaSyntax: fix anonymous function parsing #60221

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JuliaSyntax: fix anonymous function parsing #60221

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82e4fa2
fix anonymous function parsing
IanButterworth Nov 24, 2025
e5769e5
tryfix
IanButterworth Nov 24, 2025
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9 changes: 5 additions & 4 deletions JuliaSyntax/src/julia/parser.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -2200,10 +2200,11 @@ function parse_function_signature(ps::ParseState, is_function::Bool)
opts = parse_brackets(ps, K")") do had_commas, had_splat, num_semis, num_subexprs
_parsed_call = was_eventually_call(ps)
_maybe_grouping_parens = !had_commas && !had_splat && num_semis == 0 && num_subexprs == 1
# Skip intervening newlines only when the parentheses hold a single
# expression, which is the ambiguous case between a name like (::T)
# and an anonymous function parameter list.
next_kind = peek(ps, 2, skip_newlines=_maybe_grouping_parens)
# Check if there's a newline right after the closing paren
has_newline_after = peek(ps) == K"NewlineWs"
# Skip newlines when looking ahead only if there's no newline immediately after )
# This prevents treating `function (x)\n(body)` as a named function
next_kind = peek(ps, 2, skip_newlines=_maybe_grouping_parens && !has_newline_after)
_needs_parse_call = next_kind ∈ KSet"( ."
_is_anon_func = (!_needs_parse_call && !_parsed_call) || had_commas
return (needs_parameters = _is_anon_func,
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1 change: 1 addition & 0 deletions JuliaSyntax/test/parser.jl
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Expand Up @@ -603,6 +603,7 @@ tests = [
"macro \$f() end" => "(macro (call (\$ f)) (block))"
"macro (\$f)() end" => "(macro (call (parens (\$ f))) (block))"
"function (x) body end"=> "(function (tuple-p x) (block body))"
"function (x)\n body\nend"=> "(function (tuple-p x) (block body))"
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@fingolfin fingolfin Nov 24, 2025

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Maybe also insert a involving explicitly a tuple () as the body?

E.g. near line 622-628, where in JuliaLang/JuliaSyntax.jl#580 this test was inserted:

        "function (\n        f\n        )() end" =>  "(function (call (parens f)) (block))"

well now we want to test something like this (not sure if I got it quite right)

        "function (\n        x\n        )\n() end" =>  "(function (tuple-p x) (block (tuple-p)))"

Because for me, on master, this parses:

function(y)
  body
end

but this does not:

function(y)
  ()
end

"function (x,y) end" => "(function (tuple-p x y) (block))"
"function (x,y,) end" => "(function (tuple-p-, x y) (block))"
"function (x=1) end" => "(function (tuple-p (= x 1)) (block))"
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