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Fix InexactError in peek_behind_pos when skipping nested trivia nodes #604

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Merged
merged 1 commit into from
Nov 9, 2025
Merged

Fix InexactError in peek_behind_pos when skipping nested trivia nodes #604

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8 changes: 7 additions & 1 deletion src/core/parse_stream.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -635,8 +635,14 @@ function peek_behind_pos(stream::ParseStream; skip_trivia::Bool=true,
while node_idx > 0
node = stream.output[node_idx]
if kind(node) == K"TOMBSTONE" || (skip_trivia && is_trivia(node))
node_idx -= 1
byte_idx -= node.byte_span
# If this is a non-terminal node, skip its children without
# subtracting their byte_spans, as they're already included in the parent
if is_non_terminal(node)
node_idx -= (1 + node.node_span)
else
node_idx -= 1
end
else
break
end
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10 changes: 10 additions & 0 deletions test/parse_stream.jl
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Expand Up @@ -156,3 +156,13 @@ end
@test ParseStream(y) isa ParseStream
@test parsestmt(Expr, y) == parsestmt(Expr, "1")
end

@testset "peek_behind_pos with negative byte index" begin
# Test that peek_behind_pos doesn't cause InexactError when byte_idx goes negative
# This can happen when parsing certain incomplete keywords like "do"
# where trivia skipping walks back past the beginning of the stream
@test_throws JuliaSyntax.ParseError parseall(GreenNode, "do")
@test_throws JuliaSyntax.ParseError parseall(GreenNode, "do ")
@test_throws JuliaSyntax.ParseError parseall(GreenNode, " do")
@test_throws JuliaSyntax.ParseError parseall(GreenNode, "do\n")
end
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