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fix type inference

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This commit is contained in:
nora 2023-07-29 17:55:36 +02:00
parent 162d71c8b8
commit e88d0f8782
2 changed files with 37 additions and 8 deletions
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25
src/typeck.ts
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@ -283,21 +283,32 @@ export class InferContext {
}
}
private findRoot(variable: number): number {
let root = variable;
let nextVar;
while ((nextVar = this.tyVars[root]).kind === "unified") {
root = nextVar.index;
}
return root;
}
/**
* Try to constrain a type variable to be of a specific type.
* INVARIANT: Both sides must not be of res "final", use resolveIfPossible
* before calling this.
*/
private constrainVar(variable: number, ty: Ty) {
let root = variable;
let nextVar;
while ((nextVar = this.tyVars[root]).kind === "unified") {
root = nextVar.index;
}
let root = this.findRoot(variable);
if (ty.kind === "var") {
// Point the lhs to the rhs.
this.tyVars[root] = { kind: "unified", index: ty.index };
// Now we point our root to the other root to unify the two graphs.
const otherRoot = this.findRoot(ty.index);
// If both types have the same root, we don't need to do anything
// as they're already part of the same graph.
if (root != otherRoot) {
this.tyVars[root] = { kind: "unified", index: otherRoot };
}
} else {
this.tyVars[root] = { kind: "final", ty };
}