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SILGen: Don't pretend to handle ObjC APIs that "lie" about block return optionality. #4281

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Merged
merged 1 commit into from
Aug 13, 2016
Merged

SILGen: Don't pretend to handle ObjC APIs that "lie" about block return optionality. #4281

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38 changes: 27 additions & 11 deletions lib/SILGen/SILGenExpr.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2274,12 +2274,28 @@ RValue RValueEmitter::visitRebindSelfInConstructorExpr(
return SGF.emitEmptyTupleRValue(E, C);
}

static bool isNullableTypeInC(SILModule &M, Type ty) {
static bool isVerbatimNullableTypeInC(SILModule &M, Type ty) {
ty = ty->getLValueOrInOutObjectType()->getReferenceStorageReferent();

// Functions, class instances, and @objc existentials are all nullable.
if (ty->hasReferenceSemantics())
// Class instances, and @objc existentials are all nullable.
if (ty->hasReferenceSemantics()) {
// So are blocks, but we usually bridge them to Swift closures before we get
// a chance to check for optional promotion, so we're already screwed if
// an API lies about nullability.
if (auto fnTy = ty->getAs<AnyFunctionType>()) {
switch (fnTy->getRepresentation()) {
// Carried verbatim from C.
case FunctionTypeRepresentation::Block:
case FunctionTypeRepresentation::CFunctionPointer:
return true;
// Was already bridged.
case FunctionTypeRepresentation::Swift:
case FunctionTypeRepresentation::Thin:
return false;
}
}
return true;
}

// Other types like UnsafePointer can also be nullable.
const DeclContext *DC = M.getAssociatedContext();
Expand Down Expand Up @@ -2310,7 +2326,7 @@ static bool mayLieAboutNonOptionalReturn(SILModule &M,
// Functions that return non-optional reference type and were imported from
// Objective-C.
if (auto func = dyn_cast<FuncDecl>(decl)) {
assert((isNullableTypeInC(M, func->getResultType())
assert((isVerbatimNullableTypeInC(M, func->getResultType())
|| func->getResultType()->hasArchetype())
&& "func's result type is not nullable?!");
return func->hasClangNode();
Expand All @@ -2319,7 +2335,7 @@ static bool mayLieAboutNonOptionalReturn(SILModule &M,
// Computed properties of non-optional reference type that were imported from
// Objective-C.
if (auto var = dyn_cast<VarDecl>(decl)) {
assert((isNullableTypeInC(M, var->getType()->getReferenceStorageReferent())
assert((isVerbatimNullableTypeInC(M, var->getType()->getReferenceStorageReferent())
|| var->getType()->getReferenceStorageReferent()->hasArchetype())
&& "property's result type is not nullable?!");
return var->hasClangNode();
Expand All @@ -2328,7 +2344,7 @@ static bool mayLieAboutNonOptionalReturn(SILModule &M,
// Subscripts of non-optional reference type that were imported from
// Objective-C.
if (auto subscript = dyn_cast<SubscriptDecl>(decl)) {
assert((isNullableTypeInC(M, subscript->getElementType())
assert((isVerbatimNullableTypeInC(M, subscript->getElementType())
|| subscript->getElementType()->hasArchetype())
&& "subscript's result type is not nullable?!");
return subscript->hasClangNode();
Expand All @@ -2352,7 +2368,7 @@ static bool mayLieAboutNonOptionalReturn(SILModule &M, Expr *expr) {
// get the function we're calling.
if (auto apply = dyn_cast<ApplyExpr>(expr)) {
// The result has to be a nullable type.
if (!isNullableTypeInC(M, apply->getType()))
if (!isVerbatimNullableTypeInC(M, apply->getType()))
return false;

auto getFuncDeclFromDynamicMemberLookup = [&](Expr *expr) -> FuncDecl * {
Expand Down Expand Up @@ -2405,25 +2421,25 @@ static bool mayLieAboutNonOptionalReturn(SILModule &M, Expr *expr) {

// A reference to a member property.
if (auto member = dyn_cast<MemberRefExpr>(expr)) {
return isNullableTypeInC(M, member->getType()) &&
return isVerbatimNullableTypeInC(M, member->getType()) &&
mayLieAboutNonOptionalReturn(M, member->getMember().getDecl());
}

// A reference to a subscript.
if (auto subscript = dyn_cast<SubscriptExpr>(expr)) {
return isNullableTypeInC(M, subscript->getType()) &&
return isVerbatimNullableTypeInC(M, subscript->getType()) &&
mayLieAboutNonOptionalReturn(M, subscript->getDecl().getDecl());
}

// A reference to a member property found via dynamic lookup.
if (auto member = dyn_cast<DynamicMemberRefExpr>(expr)) {
return isNullableTypeInC(M, member->getType()) &&
return isVerbatimNullableTypeInC(M, member->getType()) &&
mayLieAboutNonOptionalReturn(M, member->getMember().getDecl());
}

// A reference to a subscript found via dynamic lookup.
if (auto subscript = dyn_cast<DynamicSubscriptExpr>(expr)) {
return isNullableTypeInC(M, subscript->getType()) &&
return isVerbatimNullableTypeInC(M, subscript->getType()) &&
mayLieAboutNonOptionalReturn(M, subscript->getMember().getDecl());
}

Expand Down
4 changes: 2 additions & 2 deletions test/SILGen/lying_about_optional_return_objc.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -6,13 +6,13 @@ func optionalChainingForeignFunctionTypeProperties(b: BlockProperty?) {
// CHECK: enum $Optional<()>, #Optional.some!enumelt.1, {{%.*}} : $()
b?.readWriteBlock()

// CHECK: unchecked_bitwise_cast
// CHECK: enum $Optional
_ = b?.readWriteBlock

// CHECK: enum $Optional<()>, #Optional.some!enumelt.1, {{%.*}} : $()
b?.readOnlyBlock()

// CHECK: unchecked_bitwise_cast
// CHECK: enum $Optional
_ = b?.readOnlyBlock

// CHECK: unchecked_trivial_bit_cast
Expand Down