[compiler] FunctionExpression context locations point to first reference #33512
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This was referenced Jun 11, 2025
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This was referenced Jun 11, 2025
Squashed, review-friendly version of the stack from #33488. This is new version of our mutability and inference model, designed to replace the core algorithm for determining the sets of instructions involved in constructing a given value or set of values. The new model replaces InferReferenceEffects, InferMutableRanges (and all of its subcomponents), and parts of AnalyzeFunctions. The new model does not use per-Place effect values, but in order to make this drop-in the end _result_ of the inference adds these per-Place effects. I'll write up a larger document on the model, first i'm doing some housekeeping to rebase the PR.
AnalyzeFunctions had logic to reset the mutable ranges of context variables after visiting inner function expressions. However, there was a bug in that logic: InferReactiveScopeVariables makes all the identifiers in a scope point to the same mutable range instance. That meant that it was possible for a later function expression to indirectly cause an earlier function expressions' context variables to get a non-zero mutable range. The fix is to not just reset start/end of context var ranges, but assign a new range instance. Thanks for the help on debugging, @mofeiZ!
We're already tracking which variables are hoisted context variables, so if we see a mutation of a frozen value we can emit a custom error message to help users identify the problem.
This has always been awkward: `FunctionExpression.context` places have locations set to the declaration of the identifier, whereas other references have locations pointing to the reference itself. Here, we update context operands to have their location point to the first reference of that variable within the function.
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This has always been awkward:
FunctionExpression.contextplaces have locations set to the declaration of the identifier, whereas other references have locations pointing to the reference itself. Here, we update context operands to have their location point to the first reference of that variable within the function.Stack created with Sapling. Best reviewed with ReviewStack.