fix: balance indent signals on multi-level jumps in embedded tagged templates#783
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dsherret merged 1 commit intoMay 20, 2026
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…emplates When the external formatter's output transitions by more than one indent level between adjacent lines, `maybe_gen_tagged_tpl_with_external_formatter` emitted only a single `StartIndent`/`FinishIndent` signal but jumped `current_indent_level` to the new level. The end-of-template cleanup then emitted one `FinishIndent` per level, leaving the IR unbalanced and panicking dprint-core's writer with "finish_indent was called without a corresponding start_indent". For example, `html\`<a><svg ...><path/></svg></a>\`` produces lines at indent levels 0 → 2 → 1: the old code pushed one StartIndent and one FinishIndent, but cleanup pushed two more FinishIndents at the end — three finishes against two starts. Replace the single-step `if`/`else if` with `while` loops so multi-level transitions emit one signal per level. Fixes denoland/deno#29963.
This was referenced May 20, 2026
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`deno fmt` panics with `finish_indent was called without a corresponding start_indent` when a tagged HTML/SVG template embeds content whose formatted output transitions by more than one indent level between adjacent lines. The minimal repro from #29963 is ```js console.log(html`<a><svg viewBox="0 0 16 16" width="20" height="20" fill="currentColor"> <path d="" /> </svg></a>`); ``` `markup_fmt` produces lines at indent levels 0 → 2 → 1, and `dprint-plugin-typescript`'s embedded-template path emitted only a single `StartIndent`/`FinishIndent` per transition while its end-of-template cleanup emitted one signal per remaining level, leaving the dprint IR unbalanced. The fix is in `dprint-plugin-typescript` (dprint/dprint-plugin-typescript#783) and is consumed here by bumping the pin to `=0.96.1`. A spec regression test in `tests/specs/fmt/embedded_html_multi_indent` covers the case using the exact input from the issue and asserts the expected formatted output. Closes #29963 Closes #33623 Closes #31820 Closes #30276 Closes #30980
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When the external formatter's output transitions by more than one indent
level between adjacent lines,
maybe_gen_tagged_tpl_with_external_formatteremitted only a single
StartIndent/FinishIndentsignal but jumpedcurrent_indent_leveldirectly to the new level. The end-of-templatecleanup (
while current_indent_level > 0 { FinishIndent }) then emittedone
FinishIndentper level, leaving the IR unbalanced and panickingdprint-core's writer with
finish_indent was called without a corresponding start_indent.For example, the input
produces lines at indent levels 0 → 2 → 1 from
markup_fmt. The old codepushed one StartIndent (for 0→2) and one FinishIndent (2→1), but cleanup
pushed two more FinishIndents (the 1→0 in the
whileloop plus thetrailing one closing the initial StartIndent) — three finishes against two
starts, which trips the assertion in
dprint-core.The fix replaces the single-step
if/else ifwithwhileloops somulti-level transitions emit one signal per level. Four regression specs
are added to
tests/specs/external_formatter/html.txtcovering theoriginal case, the same with an
${expr}placeholder, a three-levelsingle-line jump (
<a><b><svg>…), and a template with siblingmulti-level jumps. Each case panics on the existing code and passes on
the fix; the rest of the spec suite (648 tests) continues to pass.
Fixes denoland/deno#29963.