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SVG: draw a <use> that references another <use>, or a later element - #2193
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A <use> was never registered under its own id, and a <use> in <defs> was skipped, so a clone of a clone, as Inkscape writes them, failed with ValueError: use ... references nonexistent ref id.
Outside <defs>, a <use> could only reference an element already built. Build a later element when it is first referenced, as for <defs>, so a clone that comes before the clone it references is drawn too.
andersonhc
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Nov 14, 2026
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I found one small edge case: when a references a hidden element, build_xref() returns before registering the clone’s own ID. Another referencing that clone then fails with “nonexistent ref id.”
<defs>
<rect id="hidden" display="none" width="10" height="10"/>
<use id="clone" href="#hidden"/>
</defs>
<use href="#clone"/>Could we register the empty clone before returning and add a regression test? This should render nothing without raising an error.
andersonhc
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Nov 14, 2026
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A
<use>that references another<use>fails withValueError: use ... references nonexistent ref id #use3396. Inkscape writes these for a clone of a clone, e.g. in the flags of the Vatican and the British Indian Ocean Territory in mledoze/countries, the cubemap figure of the WebGPU spec and the demo image of picnic.Two things were missing:
build_xref()never registered a<use>under its ownid, andhandle_defs()skipped a<use>in<defs>.<defs>, a<use>could only reference an element built before it. In the British Indian Ocean Territory flag,use3398referencesuse3396, which comes after it. Such an element is now built when it is first referenced, apart from its ancestors, as<defs>content already is.test_svg_use_of_usecovers a clone of a clone in the document, in<defs>, and one that references a later clone; all fail without the change. The five files above now convert.