For `Assign` and `ReturnExpression`, this field wasn't used for
anything. For `StructTypeField`, we stored the type of the field here,
and now store it as an argument of the node instead.
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Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
This started with cleaning up the remaining Name/expression type punning
in the node stack, and grew. I'm factoring out a class because we've
previously expressed the desire to factor logic out of SemanticsContext
where possible, and this seemed like a reasonable cut.
NameExpression as the first node as a QualifiedExpression allows the
qualifier handling to consider Name in one less spot, an incremental
simplification. However, the additional complexity caused by this makes
me split ApplyNameQualifier/ApplyExpressionQualifier in order to avoid
repeat checks of the parse node's kind. The logic is still largely
shared, thus a couple helper functions. I think this is all fairly well
structured in the isolated class.
I can see that we may want to avoid passing SemanticsContext as an
argument in the future if it elides a step of lookup.
This adds a distinction between Unused and SoloParseNode, rather than
equating the two. This is intended to help identify nodes which are
getting pushed but maybe don't need to be.
Not totally done because I want to adjust declaration name handling due
to a quirk with how it mixes Name with Expression, but almost done. Once
that's done the type punning will be completely gone.
I think there's more we can do here, but this seemed like a good
checkpoint to make sure the path I'm going down is roughly what you
expected. There's one actual edit in if expression structure to match
the increased enforcement.
Richard SmithandJon Ross-Perkins