[tausbn]

These are needed for Python, where expression contexts (Store/Load/Param/Del) are AST nodes that are explicitly locationless. Thus, for these the default heuristic of giving them an empty range at the start of the enclosing node is not that useful (and the subsequent unioning of child ranges is quite detrimental).

We therefore need a way to specify that some nodes are locationless, and I ended up with the syntax location: none. I briefly considered writing this as location: {None} instead, but unfortunately rustc does not accept this as the type of None is not fully specified. It would have to be written as None::<OutputId> which is quite ugly.

Finally, having explicit location overrides and location: none at the same time is an error (that we discover during parsing).

[Copilot]

🟡 Changes recommended

Remaining findings identify incomplete documentation of none restrictions and missing nested-node tests confirming that locationless children retain None without widening parent ranges.

2 open issues

• Clarify locationless syntax and parent range behavior · New
• Test nested locationless nodes preserve parent range · New

What changed in this PR

Adds explicit locationless synthetic nodes to YEAST, supporting cases such as Python expression-context nodes where inferred source ranges are inappropriate.

Changes:

• Introduces location: none and rejects combinations with other location overrides.
• Clears inferred ranges and prevents locationless rule results from inheriting the matched input range.
• Documents the syntax and adds parser and root-location tests.

File	Description
shared/​yeast/​tests/​test.rs	Tests that a returned node remains locationless.
shared/​yeast/​src/​lib.rs	Adds source-range clearing for synthetic nodes.
shared/​yeast/​src/​build.rs	Prevents explicitly locationless nodes from inheriting ranges.
shared/​yeast/​doc/​yeast.md	Documents location: none.
shared/​yeast-macros/​src/​template_parse.rs	Parses the syntax, rejects conflicting fields, and adds tests.
shared/​yeast-macros/​src/​lower.rs	Generates locationless-node construction calls.
shared/​yeast-macros/​src/​lib.rs	Adds the syntax to macro documentation.
shared/​yeast-macros/​src/​ast.rs	Represents locationless metadata in the macro AST.

_{Review effort: Max}