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Revert "Sema: Remove ConstraintKind::OneWayEqual"

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This reverts commit 385d66f24e.
This commit is contained in:
Slava Pestov
2025-02-01 23:55:25 -05:00
parent fa73be2415
commit 5b4218c38d
6 changed files with 109 additions and 1 deletions
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33
lib/Sema/ConstraintSystem.cpp
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@@ -1867,6 +1867,39 @@ Type Solution::simplifyTypeForCodeCompletion(Type Ty) const {
return typeVar;
});
// Logic to determine the contextual type inside buildBlock result builders:
//
// When completing inside a result builder, the result builder
// @ViewBuilder var body: some View {
// Text("Foo")
// #^COMPLETE^#
// }
// gets rewritten to
// @ViewBuilder var body: some View {
// let $__builder2: Text
// let $__builder0 = Text("Foo")
// let $__builder1 = #^COMPLETE^#
// $__builder2 = ViewBuilder.buildBlock($__builder0, $__builder1)
// return $__builder2
// }
// Inside the constraint system
// let $__builder1 = #^COMPLETE^#
// gets type checked without context, so we can't know the contextual type for
// the code completion token. But we know that $__builder1 (and thus the type
// of #^COMPLETE^#) is used as the second argument to ViewBuilder.buildBlock,
// so we can extract the contextual type from that call. To do this, figure
// out the type variable that is used for $__builder1 in the buildBlock call.
// This type variable is connected to the type variable of $__builder1's
// definition by a one-way constraint.
if (auto TV = Ty->getAs<TypeVariableType>()) {
for (auto constraint : CS.getConstraintGraph()[TV].getConstraints()) {
if (constraint->getKind() == ConstraintKind::OneWayEqual &&
constraint->getSecondType()->isEqual(TV)) {
return simplifyTypeForCodeCompletion(constraint->getFirstType());
}
}
}
// Remove any remaining type variables and placeholders
Ty = simplifyType(Ty);