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[ConstraintSystem] Diagnose conditional requirement failures via fixes

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Extend existing `RequirementFailure` functionality to support
conditional requirement failures. Such fixes are introduced
only if the parent type requirement has been matched successfully.

Resolves: rdar://problem/47871590
This commit is contained in:
Pavel Yaskevich
2019-02-08 11:16:54 -08:00
parent dfac0d8323
commit 6fd1600534
7 changed files with 127 additions and 118 deletions
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60
lib/Sema/CSSimplify.cpp
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@@ -1602,7 +1602,7 @@ ConstraintSystem::matchTypesBindTypeVar(
static ConstraintFix *fixRequirementFailure(ConstraintSystem &cs, Type type1,
Type type2, Expr *anchor,
LocatorPathElt &req) {
ArrayRef<LocatorPathElt> path) {
// Can't fix not yet properly resolved types.
if (type1->hasTypeVariable() || type2->hasTypeVariable())
return nullptr;
@@ -1612,9 +1612,21 @@ static ConstraintFix *fixRequirementFailure(ConstraintSystem &cs, Type type1,
if (type1->hasDependentMember() || type2->hasDependentMember())
return nullptr;
// Build simplified locator which only contains anchor and requirement info.
ConstraintLocatorBuilder requirement(cs.getConstraintLocator(anchor));
auto *reqLoc = cs.getConstraintLocator(requirement.withPathElement(req));
auto req = path.back();
ConstraintLocator *reqLoc = nullptr;
if (req.getKind() == ConstraintLocator::ConditionalRequirement) {
// If underlaying conformance requirement has been fixed as
// we there is no reason to fix up conditional requirements.
if (cs.hasFixFor(cs.getConstraintLocator(anchor, req)))
return nullptr;
// For conditional requirements we need a full path.
reqLoc = cs.getConstraintLocator(anchor, path, /*summaryFlags=*/0);
} else {
// Build simplified locator which only contains anchor and requirement info.
reqLoc = cs.getConstraintLocator(anchor, req);
}
auto reqKind = static_cast<RequirementKind>(req.getValue2());
switch (reqKind) {
@@ -1644,8 +1656,9 @@ repairFailures(ConstraintSystem &cs, Type lhs, Type rhs,
auto &elt = path.back();
switch (elt.getKind()) {
case ConstraintLocator::TypeParameterRequirement: {
if (auto *fix = fixRequirementFailure(cs, lhs, rhs, anchor, elt))
case ConstraintLocator::TypeParameterRequirement:
case ConstraintLocator::ConditionalRequirement: {
if (auto *fix = fixRequirementFailure(cs, lhs, rhs, anchor, path))
conversionsOrFixes.push_back(fix);
break;
}
@@ -2764,15 +2777,25 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyConformsToConstraint(
SmallVector<LocatorPathElt, 4> path;
auto *anchor = locator.getLocatorParts(path);
if (!path.empty() && path.back().getKind() ==
ConstraintLocator::PathElementKind::TypeParameterRequirement) {
auto typeRequirement = path.back();
// Let's strip all of the unnecessary information from locator,
// diagnostics only care about anchor - to lookup type,
// and what was the requirement# which is not satisfied.
ConstraintLocatorBuilder requirement(getConstraintLocator(anchor));
auto *reqLoc =
getConstraintLocator(requirement.withPathElement(typeRequirement));
if (!path.empty() &&
(path.back().getKind() == ConstraintLocator::TypeParameterRequirement ||
path.back().getKind() == ConstraintLocator::ConditionalRequirement)) {
ConstraintLocator *reqLoc = nullptr;
if (path.back().getKind() == ConstraintLocator::ConditionalRequirement) {
// Underlying conformance requirement is itself fixed,
// this wouldn't lead to right solution.
if (hasFixFor(getConstraintLocator(anchor, path.back())))
return SolutionKind::Error;
// For conditional requirements we need complete path, which includes
// type requirement position, to be able to fetch conformance later.
reqLoc = getConstraintLocator(locator);
} else {
// Let's strip all of the unnecessary information from locator,
// diagnostics only care about anchor - to lookup type,
// and what was the requirement# which is not satisfied.
reqLoc = getConstraintLocator(anchor, path.back());
}
auto *fix = MissingConformance::create(*this, type, protocol, reqLoc);
if (!recordFix(fix))
@@ -5417,12 +5440,7 @@ bool ConstraintSystem::recordFix(ConstraintFix *fix) {
// Always useful, unless duplicate of exactly the same fix and location.
// This situation might happen when the same fix kind is applicable to
// different overload choices.
auto *loc = fix->getLocator();
auto existingFix = llvm::find_if(Fixes, [&](const ConstraintFix *e) {
// If we already have a fix like this recorded, let's not do it again,
return e->getKind() == fix->getKind() && e->getLocator() == loc;
});
if (existingFix == Fixes.end())
if (!hasFixFor(fix->getLocator()))
Fixes.push_back(fix);
} else {
// Only useful to record if no pre-existing fix in the subexpr tree.