Closes#27596
The problem in this case was incorrect identification of which language
(layer) contains the selection.
Language layer selection incorrectly assumed that the deepest
`SyntaxLayer` containing a range was the most specific. This worked for
Markdown (base document + injected subtrees) but failed for PHP, where
`injection.combined` injections are used to make HTML logically function
as the base layer, despite being at a greater depth in the layer stack.
This caused HTML to be incorrectly identified as the most specific
language for PHP ranges.
The solution is to track included sub-ranges for syntax layers and
filter out layers that don't contain a sub-range covering the desired
range. The top-level layer is never filtered to ensure gaps between
sibling nodes always have a fallback language, as the top-level layer is
likely more correct than the default language settings.
Release Notes:
- Fixed an issue in PHP where PHP language settings would be
occasionally overridden by HTML language settings
Ben Kunkle
a40ee74a1f