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[CS] Adjust assessRequirementFailureImpact

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- In `simplifyConformsToConstraint`, pass the LHS
type regardless of whether it is a type variable.

- Add the `choiceImpact` onto the impact for
adding a stdlib conformance.

- Treat Any and AnyObject as standard library
types.
This commit is contained in:
Hamish Knight
2020-03-20 13:32:43 -07:00
parent dc4b089b9f
commit b4c13c2c55
4 changed files with 71 additions and 38 deletions
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78
lib/Sema/CSSimplify.cpp
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@@ -1369,37 +1369,12 @@ static ConstraintFix *fixRequirementFailure(ConstraintSystem &cs, Type type1,
static unsigned
assessRequirementFailureImpact(ConstraintSystem &cs, Type requirementType,
ConstraintLocatorBuilder locator) {
assert(requirementType);
unsigned impact = 1;
auto *anchor = locator.getAnchor();
if (!anchor)
return 1;
if (requirementType && cs.simplifyType(requirementType)->isStdlibType()) {
if (auto last = locator.last()) {
if (auto requirement = last->getAs<LocatorPathElt::AnyRequirement>()) {
auto kind = requirement->getRequirementKind();
if (kind == RequirementKind::Conformance)
return 3;
}
}
}
// If this requirement is associated with an overload choice let's
// tie impact to how many times this requirement type is mentioned.
if (auto *ODRE = dyn_cast<OverloadedDeclRefExpr>(anchor)) {
if (!(requirementType && requirementType->is<TypeVariableType>()))
return 1;
unsigned choiceImpact = 0;
if (auto choice = cs.findSelectedOverloadFor(ODRE)) {
auto *typeVar = requirementType->castTo<TypeVariableType>();
choice->openedType.visit([&](Type type) {
if (type->isEqual(typeVar))
++choiceImpact;
});
}
return choiceImpact == 0 ? 1 : choiceImpact;
}
return impact;
// If this requirement is associated with a member reference and it
// was possible to check it before overload choice is bound, that means
@@ -1417,13 +1392,53 @@ assessRequirementFailureImpact(ConstraintSystem &cs, Type requirementType,
// fix for same-type requirement higher impact vs. requirement associated
// with method itself e.g. `func foo<U>() -> U where U : P {}` because
// `foo` is accessible from any `S` regardless of what `T` is.
//
// Don't add this impact with the others, as we want to keep it consistent
// across requirement failures to present the user with a choice.
if (isa<UnresolvedDotExpr>(anchor) || isa<UnresolvedMemberExpr>(anchor)) {
auto *calleeLoc = cs.getCalleeLocator(cs.getConstraintLocator(locator));
if (!cs.findSelectedOverloadFor(calleeLoc))
return 10;
}
return 1;
// Increase the impact of a conformance fix for a standard library type,
// as it's unlikely to be a good suggestion. Also do the same for the builtin
// compiler types Any and AnyObject, which cannot conform to protocols.
// FIXME: We ought not to have the is<TypeVariableType>() condition here, but
// removing it currently regresses the diagnostic for the test case for
// rdar://60727310. Once we better handle the separation of conformance fixes
// from argument mismatches in cases like SR-12438, we should be able to
// remove it from the condition.
auto resolvedTy = cs.simplifyType(requirementType);
if ((requirementType->is<TypeVariableType>() && resolvedTy->isStdlibType()) ||
resolvedTy->isAny() || resolvedTy->isAnyObject()) {
if (auto last = locator.last()) {
if (auto requirement = last->getAs<LocatorPathElt::AnyRequirement>()) {
auto kind = requirement->getRequirementKind();
if (kind == RequirementKind::Conformance)
impact += 2;
}
}
}
// If this requirement is associated with an overload choice let's
// tie impact to how many times this requirement type is mentioned.
if (auto *ODRE = dyn_cast<OverloadedDeclRefExpr>(anchor)) {
if (auto *typeVar = requirementType->getAs<TypeVariableType>()) {
unsigned choiceImpact = 0;
if (auto choice = cs.findSelectedOverloadFor(ODRE)) {
choice->openedType.visit([&](Type type) {
if (type->isEqual(typeVar))
++choiceImpact;
});
}
// If the type is used multiple times in the signature, increase the
// impact for every additional use.
if (choiceImpact > 1)
impact += choiceImpact - 1;
}
}
return impact;
}
/// Attempt to fix missing arguments by introducing type variables
@@ -5072,6 +5087,7 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyConformsToConstraint(
ConstraintKind kind,
ConstraintLocatorBuilder locator,
TypeMatchOptions flags) {
const auto rawType = type;
auto *typeVar = type->getAs<TypeVariableType>();
// Dig out the fixed type to which this type refers.
@@ -5243,7 +5259,7 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyConformsToConstraint(
if (auto *fix =
fixRequirementFailure(*this, type, protocolTy, anchor, path)) {
auto impact = assessRequirementFailureImpact(*this, typeVar, locator);
auto impact = assessRequirementFailureImpact(*this, rawType, locator);
if (!recordFix(fix, impact)) {
// Record this conformance requirement as "fixed".
recordFixedRequirement(type, RequirementKind::Conformance,