Philip Taron
aade3eba23
afdko 5.0.1 regressed variable-font hinting: otfautohint aborts with an AssertionError in calcInstanceStems() when a high ghost stem is a glyph's first stem (e.g. small diagonal accents), which broke cantarell-fonts. Backport the upstream fix as a patch to afdko. https://github.com/adobe-type-tools/afdko/pull/1844 Closes #535887 Assisted-by: Claude Code (claude-opus-4-8)
39 lines
1.5 KiB
Diff
39 lines
1.5 KiB
Diff
From dc35a26c5b38bad40dd44d67609b6a89ee0d7774 Mon Sep 17 00:00:00 2001
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From: Philip Taron <philip.taron@gmail.com>
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Date: Mon, 29 Jun 2026 13:48:41 +0000
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Subject: [PATCH] Fix spurious assertion when a high ghost stem is a glyph's
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first stem
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In calcInstanceStems() the per-stem loop initializes lo = None and
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hi = None, then computes one or both locations per stem. For a 'high'
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ghost stem (a hint anchored only at the top edge) only hi is computed;
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lo is then unconditionally overwritten by hi on the next line, so its
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incoming value is dead.
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The 'high' branch nonetheless asserted lo is not None. When a high ghost
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is the glyph's first stem -- exactly the case for small diagonal accents
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-- lo is still None from its initialization, so the assertion fired and
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aborted hinting of the whole font.
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Drop the dead lo operand from the assertion, because hi is the only
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value actually read.
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---
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python/afdko/otfautohint/hinter.py | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/python/afdko/otfautohint/hinter.py b/python/afdko/otfautohint/hinter.py
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index 354d92f2f..1cea13a88 100644
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--- a/python/afdko/otfautohint/hinter.py
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+++ b/python/afdko/otfautohint/hinter.py
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@@ -2007,7 +2007,7 @@ def calcInstanceStems(self, glidx) -> None:
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lo = lo + 21
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hi = lo - 21
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elif isG == 'high':
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- assert lo is not None and hi is not None
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+ assert hi is not None
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lo = hi
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hi = lo - 20
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else:
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--
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2.49.0
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