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[Constraint system] Clean up constraints associated with patterns. #30258

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Merged
merged 1 commit into from
Mar 6, 2020
Merged

[Constraint system] Clean up constraints associated with patterns. #30258

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41 changes: 29 additions & 12 deletions lib/Sema/CSGen.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2315,7 +2315,8 @@ namespace {
cast<TypedPattern>(pattern)->getSubPattern(), locator,
Type(), bindPatternVarsOneWay);
CS.addConstraint(
ConstraintKind::Conversion, subPatternType, openedType, locator);
ConstraintKind::Conversion, subPatternType, openedType,
locator.withPathElement(LocatorPathElt::PatternMatch(pattern)));
return setType(openedType);
}

Expand Down Expand Up @@ -2352,7 +2353,7 @@ namespace {

Type eltTy = getTypeForPattern(
tupleElt.getPattern(),
locator.withPathElement(LocatorPathElt::TupleElement(i)),
locator,
externalEltType,
bindPatternVarsOneWay);
tupleTypeElts.push_back(TupleTypeElt(eltTy, tupleElt.getLabel()));
Expand All @@ -2368,7 +2369,8 @@ namespace {
CS.getConstraintLocator(locator), TVO_CanBindToNoEscape);
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I think in this case we should have locator with points to pattern and ends with OptionalPayload.

CS.addConstraint(
ConstraintKind::OptionalObject, externalPatternType,
objVar, locator);
objVar,
locator.withPathElement(LocatorPathElt::PatternMatch(pattern)));

externalPatternType = objVar;
}
Expand All @@ -2386,7 +2388,9 @@ namespace {

Type castType =
resolveTypeReferenceInExpression(isPattern->getCastTypeLoc());
castType = CS.openUnboundGenericType(castType, locator);
castType = CS.openUnboundGenericType(
castType,
locator.withPathElement(LocatorPathElt::PatternMatch(pattern)));

Type subPatternType =
getTypeForPattern(isPattern->getSubPattern(), locator, castType,
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I think subPattern should have locator point to a sub-pattern used by a cast?

Expand All @@ -2395,7 +2399,8 @@ namespace {
// Make sure we can cast from the subpattern type to the type we're
// checking; if it's impossible, fail.
CS.addConstraint(
ConstraintKind::CheckedCast, subPatternType, castType, locator);
ConstraintKind::CheckedCast, subPatternType, castType,
locator.withPathElement(LocatorPathElt::PatternMatch(pattern)));

return setType(subPatternType);
}
Expand All @@ -2422,7 +2427,9 @@ namespace {
// Resolve the parent type.
Type parentType =
resolveTypeReferenceInExpression(enumPattern->getParentType());
parentType = CS.openUnboundGenericType(parentType, locator);
parentType = CS.openUnboundGenericType(
parentType,
locator.withPathElement(LocatorPathElt::PatternMatch(pattern)));
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I think we could use ParentType locator element for this transformation.

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Later one where we add a member constraint I think it should either end on regular Member locator or a new one specific for patterns...


// Perform member lookup into the parent's metatype.
Type parentMetaType = MetatypeType::get(parentType);
Expand All @@ -2433,8 +2440,9 @@ namespace {

// Parent type needs to be convertible to the pattern type; this
// accounts for cases where the pattern type is existential.
CS.addConstraint(ConstraintKind::Conversion, parentType, patternType,
locator);
CS.addConstraint(
ConstraintKind::Conversion, parentType, patternType,
locator.withPathElement(LocatorPathElt::PatternMatch(pattern)));

baseType = parentType;
} else {
Expand Down Expand Up @@ -2470,8 +2478,9 @@ namespace {
ConstraintKind::Equal, functionType, memberType,
locator.withPathElement(LocatorPathElt::PatternMatch(pattern)));

CS.addConstraint(ConstraintKind::Conversion, outputType, baseType,
locator);
CS.addConstraint(
ConstraintKind::Conversion, outputType, baseType,
locator.withPathElement(LocatorPathElt::PatternMatch(pattern)));
}

return setType(patternType);
Expand Down Expand Up @@ -4265,10 +4274,18 @@ bool ConstraintSystem::generateConstraints(
// For any pattern variable that has a parent variable (i.e., another
// pattern variable with the same name in the same case), require that
// the types be equivalent.
pattern->forEachVariable([&](VarDecl *var) {
pattern->forEachNode([&](Pattern *pattern) {
auto namedPattern = dyn_cast<NamedPattern>(pattern);
if (!namedPattern)
return;

auto var = namedPattern->getDecl();
if (auto parentVar = var->getParentVarDecl()) {
addConstraint(
ConstraintKind::Equal, getType(parentVar), getType(var), locator);
ConstraintKind::Equal, getType(parentVar), getType(var),
getConstraintLocator(
locator,
LocatorPathElt::PatternMatch(namedPattern)));
}
});
}
Expand Down
14 changes: 14 additions & 0 deletions test/Constraints/function_builder_diags.swift
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Expand Up @@ -466,3 +466,17 @@ func testCaseMutabilityMismatches(e: E3) {
}
}
}

// Check for type equivalence among different case variables with the same name.
func testCaseVarTypes(e: E3) {
// FIXME: Terrible diagnostic
tuplify(true) { c in // expected-error{{type of expression is ambiguous without more context}}
"testSwitch"
switch e {
case .a(let x, let y),
.c(let x, let y):
x
y + "a"
}
}
}