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[prism] Don't panic on invalid UTF-8 strings in heredocs #758

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Merged
reese merged 1 commit into from
Jan 5, 2026
Merged

[prism] Don't panic on invalid UTF-8 strings in heredocs #758

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4 changes: 4 additions & 0 deletions fixtures/small/prism/heredoc_invalid_utf8_escape_actual.rb
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Original file line number Diff line number Diff line change
@@ -0,0 +1,4 @@
<<~EOF
line with \xFF escape
foo
EOF
4 changes: 4 additions & 0 deletions fixtures/small/prism/heredoc_invalid_utf8_escape_expected.rb
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Original file line number Diff line number Diff line change
@@ -0,0 +1,4 @@
<<~EOF
line with \xFF escape
foo
EOF
14 changes: 8 additions & 6 deletions librubyfmt/src/format_prism.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@ use crate::{
parser_state::{FormattingContext, HashType, ParserState},
render_targets::MultilineHandling,
types::SourceOffset,
util::{const_to_str, loc_to_str, loc_to_string, u8_to_str},
util::{const_to_str, loc_to_str, loc_to_string},
};

pub fn format_node<'src>(ps: &mut ParserState<'src>, node: prism::Node<'src>) {
Expand Down Expand Up @@ -909,12 +909,14 @@ fn format_inner_string<'src>(
.iter()
.filter_map(|part| {
if let Some(node) = part.as_string_node() {
let raw = loc_to_str(node.content_loc());
let unescaped = u8_to_str(node.unescaped());
let raw = node.content_loc().as_slice();
let unescaped = node.unescaped();

// Count leading whitespace in each
let raw_leading = raw.len() - raw.trim_start().len();
let unescaped_leading = unescaped.len() - unescaped.trim_start().len();
let raw_leading = raw.iter().take_while(|&&b| b == b' ' || b == b'\t').count();
let unescaped_leading = unescaped
.iter()
.take_while(|&&b| b == b' ' || b == b'\t')
Comment on lines +915 to +918
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@froydnj froydnj Jan 5, 2026

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I know that Sorbet's heredoc bits in the parser have to take into account a tab being 8 spaces. Do we have to do that same accounting here as well?

Answering my own question, I guess not, because the number of spaces and tabs in the raw and unescaped are essentially coming from the same source, so things should just match up?

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@reese reese Jan 5, 2026

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Yeah I think in this case since they're the same source, it doesn't really matter, and I think if you had a tab that was beyond the common indent, it would be a part of the string contents and just get rendered anyways.

.count();

// The difference is the common indent (if raw has more leading whitespace)
if raw_leading > unescaped_leading {
Expand Down