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[ConstraintSystem] Diagnose conformance failure with base of a static member lookup

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Produce a tailored diagnostic when it has been established that
base type of a static member reference on protocol metatype doesn't
conform to a required protocol.
This commit is contained in:
Pavel Yaskevich
2020-10-30 13:46:30 -07:00
parent 5758ae2bcc
commit d1ab178471
2 changed files with 70 additions and 44 deletions
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90
lib/Sema/CSSimplify.cpp
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@@ -5787,20 +5787,27 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyConformsToConstraint(
return SolutionKind::Solved;
}
// If we hit a type variable without a fixed type, we can't
// solve this yet.
if (type->isTypeVariableOrMember()) {
auto formUnsolved = [&](bool activate = false) {
// If we're supposed to generate constraints, do so.
if (flags.contains(TMF_GenerateConstraints)) {
addUnsolvedConstraint(
Constraint::create(*this, kind, type,
protocol->getDeclaredInterfaceType(),
getConstraintLocator(locator)));
auto *conformance = Constraint::create(
*this, kind, type, protocol->getDeclaredInterfaceType(),
getConstraintLocator(locator));
addUnsolvedConstraint(conformance);
if (activate)
activateConstraint(conformance);
return SolutionKind::Solved;
}
return SolutionKind::Unsolved;
}
};
// If we hit a type variable without a fixed type, we can't
// solve this yet.
if (type->isTypeVariableOrMember())
return formUnsolved();
auto *loc = getConstraintLocator(locator);
@@ -5922,7 +5929,7 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyConformsToConstraint(
return recordFix(fix) ? SolutionKind::Error : SolutionKind::Solved;
}
if (path.back().is<LocatorPathElt::AnyRequirement>()) {
if (auto req = path.back().getAs<LocatorPathElt::AnyRequirement>()) {
// If this is a requirement associated with `Self` which is bound
// to `Any`, let's consider this "too incorrect" to continue.
//
@@ -5941,6 +5948,39 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyConformsToConstraint(
}
}
auto anchor = locator.getAnchor();
if ((isExpr<UnresolvedDotExpr>(anchor) ||
isExpr<UnresolvedMemberExpr>(anchor)) &&
req->is<LocatorPathElt::TypeParameterRequirement>()) {
auto signature = path[path.size() - 2]
.castTo<LocatorPathElt::OpenedGeneric>()
.getSignature();
auto requirement = signature->getRequirements()[req->getIndex()];
auto *memberLoc = getConstraintLocator(anchor, path.front());
auto *memberRef = findResolvedMemberRef(memberLoc);
// To figure out what is going on here we need to wait until
// member overload is set in the constraint system.
if (!memberRef)
return formUnsolved(/*activate=*/true);
// If this is a `Self` conformance requirement from a static member
// reference on a protocol metatype, let's produce a tailored diagnostic.
if (memberRef->isStatic()) {
if (auto *protocolDecl =
memberRef->getDeclContext()->getSelfProtocolDecl()) {
auto selfTy = protocolDecl->getProtocolSelfType();
if (selfTy->isEqual(requirement.getFirstType())) {
auto *fix = AllowInvalidStaticMemberRefOnProtocolMetatype::create(
*this, memberLoc);
return recordFix(fix) ? SolutionKind::Error : SolutionKind::Solved;
}
}
}
}
if (auto *fix =
fixRequirementFailure(*this, type, protocolTy, anchor, path)) {
auto impact = assessRequirementFailureImpact(*this, rawType, locator);
@@ -5953,27 +5993,6 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyConformsToConstraint(
}
}
if (path.back().is<LocatorPathElt::MemberRefBase>()) {
path.pop_back();
auto *memberLoc = getConstraintLocator(anchor, path);
if (auto overload = findSelectedOverloadFor(memberLoc)) {
const auto &choice = overload->choice;
assert(choice.isDecl());
auto *decl = choice.getDecl();
auto nameRef = choice.getFunctionRefKind() == FunctionRefKind::Compound
? decl->createNameRef()
: DeclNameRef(decl->getBaseName());
auto *fix = AllowTypeOrInstanceMember::create(
*this, MetatypeType::get(protocolTy, getASTContext()), decl,
nameRef, memberLoc);
return recordFix(fix) ? SolutionKind::Error : SolutionKind::Solved;
}
}
// If this is an implicit Hashable conformance check generated for each
// index argument of the keypath subscript component, we could just treat
// it as though it conforms.
@@ -6833,8 +6852,6 @@ performMemberLookup(ConstraintKind constraintKind, DeclNameRef memberName,
// referred from.
assert(hasStaticMembers);
Type resultTy;
// Cannot instantiate a protocol or reference a member on
// protocol composition type.
if (isa<ConstructorDecl>(decl) ||
@@ -6844,6 +6861,8 @@ performMemberLookup(ConstraintKind constraintKind, DeclNameRef memberName,
return;
}
Type resultTy;
if (isa<AbstractFunctionDecl>(decl)) {
auto refTy =
decl->getInterfaceType()->castTo<AnyFunctionType>()->getResult();
@@ -8017,10 +8036,11 @@ ConstraintSystem::simplifyUnresolvedMemberChainBaseConstraint(
auto *memberLoc =
getConstraintLocator(baseExpr, ConstraintLocator::UnresolvedMember);
auto *memberRef = findResolvedMemberRef(memberLoc);
assert(memberRef);
if (shouldAttemptFixes() && hasFixFor(memberLoc))
return SolutionKind::Solved;
if (memberRef->isStatic()) {
auto *memberRef = findResolvedMemberRef(memberLoc);
if (memberRef && memberRef->isStatic()) {
return simplifyConformsToConstraint(
resultTy, baseTy, ConstraintKind::ConformsTo,
getConstraintLocator(memberLoc, ConstraintLocator::MemberRefBase),