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[CSSimplify] Further Restrict tuple splat behavior

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`isSingleParam` used to return `true` regardless of type of
the identified single parameter, but splat only makes sense
if such type is a tuple or a type variable which could later
be resolved to tuple. Otherwise it makes it hard to diagnose
missing arguments.
This commit is contained in:
Pavel Yaskevich
2019-02-22 14:31:56 -08:00
parent cca6fea65a
commit 12a65fffee
1 changed files with 23 additions and 3 deletions
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26
lib/Sema/CSSimplify.cpp
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@@ -1139,9 +1139,29 @@ ConstraintSystem::matchFunctionTypes(FunctionType *func1, FunctionType *func2,
// that expect a function that takes a single tuple (of the same
// arity).
auto isSingleParam = [&](ArrayRef<AnyFunctionType::Param> params) {
return (params.size() == 1 &&
params[0].getLabel().empty() &&
!params[0].isVariadic());
if (params.size() != 1)
return false;
const auto &param = params.front();
if (param.isVariadic() || param.isInOut())
return false;
auto paramType = param.getPlainType();
// Support following case which was allowed until 5:
// ``swift
// func bar(_: (Int, Int) -> Void) {}
// let foo: ((Int, Int)?) -> Void = { _ in }
//
// bar(foo) // Ok
// ```
if (!getASTContext().isSwiftVersionAtLeast(5))
paramType = paramType->lookThroughAllOptionalTypes();
// Parameter should have a label and be either a tuple tuple type,
// or a type variable which might later be assigned a tuple type,
// e.g. opened generic parameter.
return !param.hasLabel() &&
(paramType->is<TupleType>() || paramType->is<TypeVariableType>());
};
auto canImplodeParams = [&](ArrayRef<AnyFunctionType::Param> params) {