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MiscDiagnostics.cpp
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//===--- MiscDiagnostics.cpp - AST-Level Diagnostics ----------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
//
// This file implements AST-level diagnostics.
//
//===----------------------------------------------------------------------===//
#include "MiscDiagnostics.h"
#include "TypeCheckAvailability.h"
#include "TypeCheckConcurrency.h"
#include "TypeCheckInvertible.h"
#include "TypeChecker.h"
#include "swift/AST/ASTBridging.h"
#include "swift/AST/ASTWalker.h"
#include "swift/AST/AvailabilitySpec.h"
#include "swift/AST/ConformanceLookup.h"
#include "swift/AST/DiagnosticsParse.h"
#include "swift/AST/DiagnosticsSema.h"
#include "swift/AST/ExistentialLayout.h"
#include "swift/AST/Expr.h"
#include "swift/AST/NameLookup.h"
#include "swift/AST/NameLookupRequests.h"
#include "swift/AST/Pattern.h"
#include "swift/AST/SemanticAttrs.h"
#include "swift/AST/SourceFile.h"
#include "swift/AST/Stmt.h"
#include "swift/AST/TypeCheckRequests.h"
#include "swift/AST/Types.h"
#include "swift/Basic/Assertions.h"
#include "swift/Basic/Defer.h"
#include "swift/Basic/SourceManager.h"
#include "swift/Basic/Statistic.h"
#include "swift/Basic/StringExtras.h"
#include "swift/Parse/Lexer.h"
#include "swift/Sema/ConstraintSystem.h"
#include "swift/Sema/IDETypeChecking.h"
#include "clang/AST/DeclObjC.h"
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/Support/SaveAndRestore.h"
#define DEBUG_TYPE "Sema"
using namespace swift;
using namespace constraints;
/// Return true if this expression is an implicit promotion from T to T?.
static Expr *isImplicitPromotionToOptional(Expr *E) {
if (E->isImplicit())
if (auto IIOE = dyn_cast<InjectIntoOptionalExpr>(
E->getSemanticsProvidingExpr()))
return IIOE->getSubExpr();
return nullptr;
}
/// Diagnose syntactic restrictions of expressions.
///
/// - Module values may only occur as part of qualification.
/// - Metatype names cannot generally be used as values: they need a "T.self"
/// qualification unless used in narrow case (e.g. T() for construction).
/// - '_' may only exist on the LHS of an assignment expression.
/// - warn_unqualified_access values must not be accessed except via qualified
/// lookup.
/// - Partial application of some decls isn't allowed due to implementation
/// limitations.
/// - "&" (aka InOutExpressions) may only exist directly in function call
/// argument lists.
/// - 'self.init' and 'super.init' cannot be wrapped in a larger expression
/// or statement.
/// - Warn about promotions to optional in specific syntactic forms.
/// - Error about collection literals that default to Any collections in
/// invalid positions.
/// - Marker protocols cannot occur as the type of an as? or is expression.
/// - KeyPath expressions cannot refer to effectful properties / subscripts
/// - SingleValueStmtExprs may only appear in certain places and has
/// restrictions on the control flow allowed.
/// - Move expressions must have a declref expr subvalue.
///
static void diagSyntacticUseRestrictions(const Expr *E, const DeclContext *DC,
bool isExprStmt) {
class DiagnoseWalker : public BaseDiagnosticWalker {
SmallPtrSet<Expr*, 4> AlreadyDiagnosedMetatypes;
SmallPtrSet<DeclRefExpr*, 4> AlreadyDiagnosedBitCasts;
bool IsExprStmt;
ASTContext &Ctx;
const DeclContext *DC;
public:
DiagnoseWalker(const DeclContext *DC, bool isExprStmt)
: IsExprStmt(isExprStmt), Ctx(DC->getASTContext()), DC(DC) {}
PreWalkAction walkToTypeReprPre(TypeRepr *T) override {
return Action::Continue();
}
PreWalkResult<Expr *> walkToExprPre(Expr *E) override {
// See through implicit conversions of the expression. We want to be able
// to associate the parent of this expression with the ultimate callee.
auto Base = E;
while (auto Conv = dyn_cast<ImplicitConversionExpr>(Base))
Base = Conv->getSubExpr();
if (auto *DRE = dyn_cast<DeclRefExpr>(Base)) {
// Verify metatype uses.
if (isa<TypeDecl>(DRE->getDecl())) {
if (isa<ModuleDecl>(DRE->getDecl()))
checkUseOfModule(DRE);
else
checkUseOfMetaTypeName(Base);
}
// Verify warn_unqualified_access uses.
checkUnqualifiedAccessUse(DRE);
// Verify that special decls are eliminated.
checkForDeclWithSpecialTypeCheckingSemantics(DRE);
// Verify that `unsafeBitCast` isn't misused.
checkForSuspiciousBitCasts(DRE, nullptr);
}
if (auto *MRE = dyn_cast<MemberRefExpr>(Base)) {
if (isa<TypeDecl>(MRE->getMember().getDecl()))
checkUseOfMetaTypeName(Base);
}
// Don't diagnose a missing '.self' for type value expressions.
if (isa<TypeExpr>(Base) && !isa<TypeValueExpr>(E))
checkUseOfMetaTypeName(Base);
if (auto *KPE = dyn_cast<KeyPathExpr>(E))
checkForInvalidKeyPath(KPE);
// Check function calls, looking through implicit conversions on the
// function and inspecting the arguments directly.
if (auto *Call = dyn_cast<ApplyExpr>(E)) {
// Warn about surprising implicit optional promotions.
checkOptionalPromotions(Call);
// Check the callee, looking through implicit conversions.
auto base = Call->getFn();
unsigned uncurryLevel = 0;
while (auto conv = dyn_cast<ImplicitConversionExpr>(base))
base = conv->getSubExpr();
const auto findDynamicMemberRefExpr =
[](Expr *e) -> DynamicMemberRefExpr* {
if (auto open = dyn_cast<OpenExistentialExpr>(e)) {
return dyn_cast<DynamicMemberRefExpr>(open->getSubExpr());
}
return nullptr;
};
if (auto force = dyn_cast<ForceValueExpr>(base)) {
if (auto ref = findDynamicMemberRefExpr(force->getSubExpr()))
base = ref;
} else if (auto bind = dyn_cast<BindOptionalExpr>(base)) {
if (auto ref = findDynamicMemberRefExpr(bind->getSubExpr()))
base = ref;
}
while (auto ignoredBase = dyn_cast<DotSyntaxBaseIgnoredExpr>(base))
base = ignoredBase->getRHS();
ConcreteDeclRef callee;
if (auto *calleeDRE = dyn_cast<DeclRefExpr>(base)) {
checkForSuspiciousBitCasts(calleeDRE, Call);
callee = calleeDRE->getDeclRef();
// Otherwise, try to drill down through member calls for the purposes
// of argument-matching code below.
} else if (auto selfApply = dyn_cast<SelfApplyExpr>(base)) {
++uncurryLevel;
base = selfApply->getSemanticFn();
if (auto calleeDRE = dyn_cast<DeclRefExpr>(base))
callee = calleeDRE->getDeclRef();
// Otherwise, check for a dynamic member.
} else if (auto dynamicMRE = dyn_cast<DynamicMemberRefExpr>(base)) {
++uncurryLevel;
callee = dynamicMRE->getMember();
}
if (callee) {
auto *args = Call->getArgs();
for (auto idx : indices(*args)) {
auto *arg = args->getExpr(idx);
checkMagicIdentifierMismatch(callee, uncurryLevel, idx, arg);
// InOutExprs can be wrapped in some implicit casts.
Expr *unwrapped = arg;
if (auto *IIO = dyn_cast<InjectIntoOptionalExpr>(arg))
unwrapped = IIO->getSubExpr();
if (isa<InOutToPointerExpr>(unwrapped) ||
isa<ArrayToPointerExpr>(unwrapped) ||
isa<ErasureExpr>(unwrapped)) {
auto operand =
cast<ImplicitConversionExpr>(unwrapped)->getSubExpr();
if (auto *IOE = dyn_cast<InOutExpr>(operand))
operand = IOE->getSubExpr();
// Also do some additional work based on how the function uses
// the argument.
checkConvertedPointerArgument(callee, uncurryLevel, idx,
unwrapped, operand);
}
}
}
}
// If we have an assignment expression, scout ahead for acceptable _'s.
if (auto *AE = dyn_cast<AssignExpr>(E)) {
auto destExpr = AE->getDest();
// If the user is assigning the result of a function that returns
// Void to _ then warn, because that is redundant.
if (auto DAE = dyn_cast<DiscardAssignmentExpr>(destExpr)) {
if (auto CE = dyn_cast<CallExpr>(AE->getSrc())) {
if (getAsDecl<FuncDecl>(
CE->getCalledValue(/*skipFunctionConversions=*/true)) &&
CE->getType()->isVoid()) {
Ctx.Diags
.diagnose(DAE->getLoc(),
diag::discard_expr_void_result_redundant)
.fixItRemoveChars(DAE->getStartLoc(),
AE->getSrc()->getStartLoc());
}
}
}
}
// Diagnose 'self.init' or 'super.init' nested in another expression
// or closure.
if (auto *rebindSelfExpr = dyn_cast<RebindSelfInConstructorExpr>(E)) {
if (!Parent.isNull() || !IsExprStmt || DC->getParent()->isLocalContext()) {
bool isChainToSuper;
(void)rebindSelfExpr->getCalledConstructor(isChainToSuper);
Ctx.Diags.diagnose(E->getLoc(), diag::init_delegation_nested,
isChainToSuper, !IsExprStmt);
}
}
// Diagnose single-element tuple expressions.
if (auto *tupleExpr = dyn_cast<TupleExpr>(E)) {
if (tupleExpr->getNumElements() == 1 &&
!isa<PackExpansionExpr>(tupleExpr->getElement(0))) {
Ctx.Diags.diagnose(tupleExpr->getElementNameLoc(0),
diag::tuple_single_element)
.fixItRemoveChars(tupleExpr->getElementNameLoc(0),
tupleExpr->getElement(0)->getStartLoc());
}
}
auto diagnoseDuplicateLabels = [&](SourceLoc loc,
ArrayRef<Identifier> labels) {
llvm::SmallDenseSet<Identifier> names;
names.reserve(labels.size());
for (auto name : labels) {
if (name.empty())
continue;
auto inserted = names.insert(name).second;
if (!inserted) {
Ctx.Diags.diagnose(loc, diag::tuple_duplicate_label);
return;
}
}
};
// FIXME: Duplicate labels on enum payloads should be diagnosed
// when declared, not when called.
if (auto *CE = dyn_cast_or_null<CallExpr>(E)) {
auto calledValue = CE->getCalledValue(/*skipFunctionConversions=*/true);
if (calledValue && isa<EnumElementDecl>(calledValue)) {
auto *args = CE->getArgs();
SmallVector<Identifier, 4> scratch;
diagnoseDuplicateLabels(args->getLoc(),
args->getArgumentLabels(scratch));
}
}
if (auto *tupleExpr = dyn_cast<TupleExpr>(E)) {
// Diagnose tuple expressions with duplicate element label.
diagnoseDuplicateLabels(tupleExpr->getLoc(),
tupleExpr->getElementNames());
// Diagnose attempts to form a tuple with any noncopyable elements.
if (E->getType()->isNoncopyable()
&& !Ctx.LangOpts.hasFeature(Feature::MoveOnlyTuples)) {
auto noncopyableTy = E->getType();
assert(noncopyableTy->is<TupleType>() && "will use poor wording");
Ctx.Diags.diagnose(E->getLoc(),
diag::tuple_containing_move_only_not_supported,
noncopyableTy);
}
}
// Specially diagnose some checked casts that are illegal.
if (auto cast = dyn_cast<CheckedCastExpr>(E)) {
checkCheckedCastExpr(cast);
}
// Diagnose move expression uses where the sub expression is not a declref
// expr.
if (auto *consumeExpr = dyn_cast<ConsumeExpr>(E)) {
checkConsumeExpr(consumeExpr);
}
// Diagnose copy expression uses where the sub expression is not a declref
// expr.
if (auto *copyExpr = dyn_cast<CopyExpr>(E)) {
checkCopyExpr(copyExpr);
}
// Diagnose move expression uses where the sub expression is not a declref expr
if (auto *borrowExpr = dyn_cast<BorrowExpr>(E)) {
checkBorrowExpr(borrowExpr);
}
return Action::Continue(E);
}
/// Visit each component of the keypath and emit a diagnostic if they
/// refer to a member that meets any of the following:
/// - has effects.
/// - is a noncopyable type.
void checkForInvalidKeyPath(KeyPathExpr *keyPath) {
for (const auto &component : keyPath->getComponents()) {
if (component.hasDeclRef()) {
auto decl = component.getDeclRef().getDecl();
// Check for effects
if (auto asd = dyn_cast<AbstractStorageDecl>(decl)) {
if (asd->getEffectfulGetAccessor()) {
Ctx.Diags.diagnose(component.getLoc(),
diag::effectful_keypath_component,
asd->getDescriptiveKind(),
/*dynamic member lookup*/ false);
Ctx.Diags.diagnose(asd->getLoc(), diag::kind_declared_here,
asd->getDescriptiveKind());
}
}
// Check for the ability to copy.
if (component.getComponentType()->isNoncopyable()) {
Ctx.Diags.diagnose(component.getLoc(),
diag::expr_keypath_noncopyable_type,
component.getComponentType()->getRValueType());
}
}
}
}
void checkCheckedCastExpr(CheckedCastExpr *cast) {
Type castType = cast->getCastType();
if (!castType)
return;
if (castType->isNoncopyable()) {
// can't cast anything to move-only; there should be no valid ones.
Ctx.Diags.diagnose(cast->getLoc(), diag::noncopyable_cast);
return;
}
// no support for runtime casts from move-only types.
// as of now there is no type it could be cast to except itself, so
// there's no reason for it to happen at runtime.
if (auto fromType = cast->getSubExpr()->getType()) {
if (fromType->isNoncopyable()) {
// can't cast move-only to anything.
Ctx.Diags.diagnose(cast->getLoc(), diag::noncopyable_cast);
return;
}
}
// now, look for conditional casts to marker protocols.
if (!isa<ConditionalCheckedCastExpr>(cast) && !isa<IsExpr>(cast))
return;
if(!castType->isExistentialType())
return;
auto layout = castType->getExistentialLayout();
for (auto proto : layout.getProtocols()) {
if (proto->isMarkerProtocol() && !proto->getInvertibleProtocolKind()) {
// can't conditionally cast to a marker protocol
Ctx.Diags.diagnose(cast->getLoc(), diag::marker_protocol_cast,
proto->getName());
}
}
}
void checkConsumeExpr(ConsumeExpr *consumeExpr) {
auto diags = findSyntacticErrorForConsume(DC->getParentModule(),
consumeExpr->getLoc(),
consumeExpr->getSubExpr());
for (auto &diag : diags)
diag.emit(Ctx);
// As of now, SE-366 is not correctly implemented (rdar://102780553),
// so warn about certain consume's being no-ops today that will no longer
// be a no-op in the future once we fix this.
if (auto ty = consumeExpr->getType()) {
bool shouldWarn = true;
// Look through any load.
auto *expr = consumeExpr->getSubExpr();
if (auto *load = dyn_cast<LoadExpr>(expr))
expr = load->getSubExpr();
// Don't warn if explicit ownership was provided on a parameter.
// Those seem to be checked just fine in SIL.
if (auto *declRef = dyn_cast<DeclRefExpr>(expr)) {
if (auto *decl = declRef->getDecl()) {
if (auto *paramDecl = dyn_cast<ParamDecl>(decl)) {
switch (paramDecl->getSpecifier()) {
case ParamSpecifier::InOut:
case ParamSpecifier::Borrowing:
case ParamSpecifier::Consuming:
case ParamSpecifier::ImplicitlyCopyableConsuming:
shouldWarn = false;
break;
case ParamSpecifier::Default:
case ParamSpecifier::LegacyShared:
case ParamSpecifier::LegacyOwned:
break; // warn
}
}
}
}
// Only warn about obviously concrete BitwiseCopyable types, since we
// know those won't get checked for consumption.
if (diags.empty() &&
shouldWarn &&
!ty->hasError() &&
!ty->hasTypeParameter() &&
!ty->hasUnboundGenericType() &&
!ty->hasArchetype()) {
auto bitCopy = Ctx.getProtocol(KnownProtocolKind::BitwiseCopyable);
if (checkConformance(ty, bitCopy)) {
Ctx.Diags.diagnose(consumeExpr->getLoc(),
diag::consume_of_bitwisecopyable_noop, ty)
.fixItRemoveChars(consumeExpr->getStartLoc(),
consumeExpr->getSubExpr()->getStartLoc());
}
}
}
}
void checkCopyExpr(CopyExpr *copyExpr) {
// Do not allow for copy_expr to be used with pure move only types. We
// /do/ allow it to be used with no implicit copy types though.
if (copyExpr->getType()->isNoncopyable()) {
Ctx.Diags.diagnose(
copyExpr->getLoc(),
diag::copy_expression_cannot_be_used_with_noncopyable_types);
}
// We only allow for copy_expr to be applied directly to lvalues. We do
// not allow currently for it to be applied to fields.
auto *subExpr = copyExpr->getSubExpr();
if (auto *li = dyn_cast<LoadExpr>(subExpr))
subExpr = li->getSubExpr();
if (!isa<DeclRefExpr>(subExpr)) {
Ctx.Diags.diagnose(copyExpr->getLoc(),
diag::copy_expression_not_passed_lvalue);
}
}
void checkBorrowExpr(BorrowExpr *borrowExpr) {
// Allow for a chain of member_ref exprs that end in a decl_ref expr.
auto *subExpr = borrowExpr->getSubExpr();
while (auto *memberRef = dyn_cast<MemberRefExpr>(subExpr))
subExpr = memberRef->getBase();
if (!isa<DeclRefExpr>(subExpr)) {
Ctx.Diags.diagnose(borrowExpr->getLoc(),
diag::borrow_expression_not_passed_lvalue);
}
}
static Expr *lookThroughArgument(Expr *arg) {
while (1) {
if (auto conv = dyn_cast<ImplicitConversionExpr>(arg))
arg = conv->getSubExpr();
else if (auto *PE = dyn_cast<ParenExpr>(arg))
arg = PE->getSubExpr();
else
break;
}
return arg;
}
void checkConvertedPointerArgument(ConcreteDeclRef callee,
unsigned uncurryLevel,
unsigned argIndex,
Expr *pointerExpr,
Expr *storage) {
if (!isPointerIdentityArgument(callee, uncurryLevel, argIndex))
return;
// Flag that the argument is non-accessing.
if (auto inout = dyn_cast<InOutToPointerExpr>(pointerExpr)) {
inout->setNonAccessing(true);
} else if (auto array = dyn_cast<ArrayToPointerExpr>(pointerExpr)) {
array->setNonAccessing(true);
}
// TODO: warn if taking the address of 'storage' will definitely
// yield a temporary address.
}
/// Is the given call argument, known to be of pointer type, just used
/// for its pointer identity?
bool isPointerIdentityArgument(ConcreteDeclRef ref, unsigned uncurryLevel,
unsigned argIndex) {
// FIXME: derive this from an attribute instead of hacking it based
// on the target name!
auto decl = ref.getDecl();
// Assume that == and != are non-accessing uses.
if (decl->isOperator()) {
auto op = decl->getBaseName();
if (op == "==" || op == "!=")
return true;
return false;
}
// NSObject.addObserver(_:forKeyPath:options:context:)
if (uncurryLevel == 1 && argIndex == 3) {
return decl->getName().isCompoundName("addObserver",
{ "", "forKeyPath",
"options", "context" });
}
// NSObject.removeObserver(_:forKeyPath:context:)
if (uncurryLevel == 1 && argIndex == 2) {
return decl->getName().isCompoundName("removeObserver",
{ "", "forKeyPath", "context" });
}
return false;
}
/// We have a collection literal with a defaulted type, e.g. of [Any]. Emit
/// an error if it was inferred to this type in an invalid context, which is
/// one in which the parent expression is not itself a collection literal.
void checkTypeDefaultedCollectionExpr(CollectionExpr *c) {
// If the parent is a non-expression, or is not itself a literal, then
// produce an error with a fixit to add the type as an explicit
// annotation.
if (c->getNumElements() == 0)
Ctx.Diags.diagnose(c->getLoc(), diag::collection_literal_empty)
.highlight(c->getSourceRange());
else {
assert(c->getType()->hasTypeRepr() &&
"a defaulted type should always be printable");
Ctx.Diags
.diagnose(c->getLoc(), diag::collection_literal_heterogeneous,
c->getType())
.highlight(c->getSourceRange())
.fixItInsertAfter(c->getEndLoc(),
" as " + c->getType()->getString());
}
}
void checkMagicIdentifierMismatch(ConcreteDeclRef callee,
unsigned uncurryLevel,
unsigned argIndex,
Expr *arg) {
// We only care about args in the arg list.
if (uncurryLevel != (callee.getDecl()->hasCurriedSelf() ? 1 : 0))
return;
// Get underlying params for both callee and caller, if declared.
auto *calleeParam = getParameterAt(callee, argIndex);
auto *callerParam = dyn_cast_or_null<ParamDecl>(
arg->getReferencedDecl(/*stopAtParenExpr=*/true).getDecl()
);
// (Otherwise, we don't need to do anything.)
if (!calleeParam || !callerParam)
return;
auto calleeDefaultArg = getMagicIdentifierDefaultArgKind(calleeParam);
auto callerDefaultArg = getMagicIdentifierDefaultArgKind(callerParam);
// If one of the parameters doesn't have a default arg, or they're both
// compatible, everything's fine.
if (!calleeDefaultArg || !callerDefaultArg ||
areMagicIdentifiersCompatible(*calleeDefaultArg, *callerDefaultArg))
return;
StringRef calleeDefaultArgString =
MagicIdentifierLiteralExpr::getKindString(*calleeDefaultArg);
StringRef callerDefaultArgString =
MagicIdentifierLiteralExpr::getKindString(*callerDefaultArg);
// Emit main warning
Ctx.Diags.diagnose(arg->getLoc(), diag::default_magic_identifier_mismatch,
callerParam->getName(), callerDefaultArgString,
calleeParam->getName(), calleeDefaultArgString);
// Add "change caller default arg" fixit
SourceLoc callerDefaultArgLoc =
callerParam->getStructuralDefaultExpr()->getLoc();
Ctx.Diags.diagnose(callerDefaultArgLoc,
diag::change_caller_default_to_match_callee,
callerParam->getName(), calleeDefaultArgString)
.fixItReplace(callerDefaultArgLoc, calleeDefaultArgString);
// Add "silence with parens" fixit
Ctx.Diags.diagnose(arg->getLoc(),
diag::silence_default_magic_identifier_mismatch)
.fixItInsert(arg->getStartLoc(), "(")
.fixItInsertAfter(arg->getEndLoc(), ")");
// Point to callee parameter
Ctx.Diags.diagnose(calleeParam, diag::decl_declared_here, calleeParam);
}
std::optional<MagicIdentifierLiteralExpr::Kind>
getMagicIdentifierDefaultArgKind(const ParamDecl *param) {
switch (param->getDefaultArgumentKind()) {
#define MAGIC_IDENTIFIER(NAME, STRING) \
case DefaultArgumentKind::NAME: \
return MagicIdentifierLiteralExpr::Kind::NAME;
#include "swift/AST/MagicIdentifierKinds.def"
case DefaultArgumentKind::None:
case DefaultArgumentKind::Normal:
case DefaultArgumentKind::Inherited:
case DefaultArgumentKind::NilLiteral:
case DefaultArgumentKind::EmptyArray:
case DefaultArgumentKind::EmptyDictionary:
case DefaultArgumentKind::StoredProperty:
case DefaultArgumentKind::ExpressionMacro:
return std::nullopt;
}
llvm_unreachable("Unhandled DefaultArgumentKind in "
"getMagicIdentifierDefaultArgKind");
}
static bool
areMagicIdentifiersCompatible(MagicIdentifierLiteralExpr::Kind a,
MagicIdentifierLiteralExpr::Kind b) {
if (a == b)
return true;
// The rest of this handles special compatibility rules between the
// `*SpelledAsFile` cases and various other File-related cases.
//
// The way we're going to do this is a bit magical. We will arrange the
// cases in MagicIdentifierLiteralExpr::Kind so that they sort in
// this order:
//
// #fileID < Swift 6 #file < #filePath < Swift 5 #file < others
//
// Before we continue, let's verify that this holds.
using Kind = MagicIdentifierLiteralExpr::Kind;
static_assert(Kind::FileID < Kind::FileIDSpelledAsFile,
"#fileID < Swift 6 #file");
static_assert(Kind::FileIDSpelledAsFile < Kind::FilePath,
"Swift 6 #file < #filePath");
static_assert(Kind::FilePath < Kind::FilePathSpelledAsFile,
"#filePath < Swift 5 #file");
static_assert(Kind::FilePathSpelledAsFile < Kind::Line,
"Swift 5 #file < #line");
static_assert(Kind::FilePathSpelledAsFile < Kind::Column,
"Swift 5 #file < #column");
static_assert(Kind::FilePathSpelledAsFile < Kind::Function,
"Swift 5 #file < #function");
static_assert(Kind::FilePathSpelledAsFile < Kind::DSOHandle,
"Swift 5 #file < #dsohandle");
// The rules are all commutative, so we will take the greater of the two
// kinds.
auto maxKind = std::max(a, b);
// Both Swift 6 #file and Swift 5 #file are greater than all of the cases
// they're compatible with. So if `maxCase` is one of those two, the other
// case must have been compatible with it!
return maxKind == Kind::FileIDSpelledAsFile ||
maxKind == Kind::FilePathSpelledAsFile;
}
void checkUseOfModule(DeclRefExpr *E) {
// Allow module values as a part of:
// - ignored base expressions;
// - expressions that failed to type check.
if (auto *ParentExpr = Parent.getAsExpr()) {
if (isa<DotSyntaxBaseIgnoredExpr>(ParentExpr) ||
isa<UnresolvedDotExpr>(ParentExpr))
return;
}
Ctx.Diags.diagnose(E->getStartLoc(), diag::value_of_module_type);
}
// Diagnose metatype values that don't appear as part of a property,
// method, or constructor reference.
void checkUseOfMetaTypeName(Expr *E) {
// If we've already checked this at a higher level, we're done.
if (!AlreadyDiagnosedMetatypes.insert(E).second)
return;
DiagnosticBehavior behavior = DiagnosticBehavior::Error;
if (auto *ParentExpr = Parent.getAsExpr()) {
if (ParentExpr->isValidParentOfTypeExpr(E))
return;
// In Swift < 6 warn about
// - plain type name passed as an argument to a subscript, dynamic
// subscript, or ObjC literal since it used to be accepted.
// - member type expressions rooted on non-identifier types, e.g.
// '[X].Y' since they used to be accepted without the '.self'.
if (!Ctx.LangOpts.isSwiftVersionAtLeast(6)) {
if (isa<SubscriptExpr>(ParentExpr) ||
isa<DynamicSubscriptExpr>(ParentExpr) ||
isa<ObjectLiteralExpr>(ParentExpr)) {
auto *argList = ParentExpr->getArgs();
assert(argList);
if (argList->isUnlabeledUnary())
behavior = DiagnosticBehavior::Warning;
} else if (auto *TE = dyn_cast<TypeExpr>(E)) {
if (auto *QualIdentTR = dyn_cast_or_null<QualifiedIdentTypeRepr>(
TE->getTypeRepr())) {
if (!isa<UnqualifiedIdentTypeRepr>(QualIdentTR->getRoot())) {
behavior = DiagnosticBehavior::Warning;
}
}
}
}
}
// Is this a protocol metatype?
Ctx.Diags
.diagnose(E->getStartLoc(), diag::value_of_metatype_type,
behavior == DiagnosticBehavior::Warning)
.limitBehavior(behavior);
// Add fix-it to insert '()', only if this is a metatype of
// non-existential type and has any initializers.
bool isExistential = false;
if (auto metaTy = E->getType()->getAs<MetatypeType>()) {
auto instanceTy = metaTy->getInstanceType();
isExistential = instanceTy->isExistentialType();
if (!isExistential &&
instanceTy->mayHaveMembers() &&
!TypeChecker::lookupMember(const_cast<DeclContext *>(DC), instanceTy,
DeclNameRef::createConstructor()).empty()) {
Ctx.Diags.diagnose(E->getEndLoc(), diag::add_parens_to_type)
.fixItInsertAfter(E->getEndLoc(), "()");
}
}
// Add fix-it to insert ".self".
auto diag = Ctx.Diags.diagnose(E->getEndLoc(), diag::add_self_to_type);
if (E->canAppendPostfixExpression()) {
diag.fixItInsertAfter(E->getEndLoc(), ".self");
} else {
diag.fixItInsert(E->getStartLoc(), "(");
diag.fixItInsertAfter(E->getEndLoc(), ").self");
}
}
void checkUnqualifiedAccessUse(const DeclRefExpr *DRE) {
const Decl *D = DRE->getDecl();
if (!D->getAttrs().hasAttribute<WarnUnqualifiedAccessAttr>())
return;
if (auto *parentExpr = Parent.getAsExpr()) {
if (auto *ignoredBase = dyn_cast<DotSyntaxBaseIgnoredExpr>(parentExpr)){
if (!ignoredBase->isImplicit())
return;
}
if (auto *calledBase = dyn_cast<DotSyntaxCallExpr>(parentExpr)) {
if (!calledBase->isImplicit())
return;
}
}
const auto *VD = cast<ValueDecl>(D);
const TypeDecl *declParent =
VD->getDeclContext()->getSelfNominalTypeDecl();
if (!declParent) {
// If the declaration has been validated but not fully type-checked,
// the attribute might be applied to something invalid.
if (!VD->getDeclContext()->isModuleScopeContext())
return;
declParent = VD->getDeclContext()->getParentModule();
}
Ctx.Diags.diagnose(DRE->getLoc(), diag::warn_unqualified_access,
VD->getBaseIdentifier(),
VD->getDescriptiveKind(),
declParent);
Ctx.Diags.diagnose(VD, diag::decl_declared_here, VD);
if (VD->getDeclContext()->isTypeContext()) {
Ctx.Diags.diagnose(DRE->getLoc(), diag::fix_unqualified_access_member)
.fixItInsert(DRE->getStartLoc(), "self.");
}
DeclContext *topLevelSubcontext = DC->getModuleScopeContext();
auto descriptor = UnqualifiedLookupDescriptor(
DeclNameRef(VD->getBaseName()), topLevelSubcontext, SourceLoc());
auto lookup = evaluateOrDefault(Ctx.evaluator,
UnqualifiedLookupRequest{descriptor}, {});
// Group results by module. Pick an arbitrary result from each module.
llvm::SmallDenseMap<const ModuleDecl*,const ValueDecl*,4> resultsByModule;
for (auto &result : lookup) {
const ValueDecl *value = result.getValueDecl();
resultsByModule.insert(std::make_pair(value->getModuleContext(),value));
}
// Sort by module name.
using ModuleValuePair = std::pair<const ModuleDecl *, const ValueDecl *>;
SmallVector<ModuleValuePair, 4> sortedResults{
resultsByModule.begin(), resultsByModule.end()
};
llvm::array_pod_sort(sortedResults.begin(), sortedResults.end(),
[](const ModuleValuePair *lhs,
const ModuleValuePair *rhs) {
return lhs->first->getName().compare(rhs->first->getName());
});
auto topLevelDiag = diag::fix_unqualified_access_top_level;
if (sortedResults.size() > 1)
topLevelDiag = diag::fix_unqualified_access_top_level_multi;
for (const ModuleValuePair &pair : sortedResults) {
DescriptiveDeclKind k = pair.second->getDescriptiveKind();
SmallString<32> namePlusDot = pair.first->getName().str();
namePlusDot.push_back('.');
Ctx.Diags.diagnose(DRE->getLoc(), topLevelDiag,
namePlusDot, k, pair.first->getName())
.fixItInsert(DRE->getStartLoc(), namePlusDot);
}
}
void checkForDeclWithSpecialTypeCheckingSemantics(const DeclRefExpr *DRE) {
// Referencing type(of:) and other decls with special type-checking
// behavior as functions is not implemented. Maybe we could wrap up the
// special-case behavior in a closure someday...
if (TypeChecker::getDeclTypeCheckingSemantics(DRE->getDecl())
!= DeclTypeCheckingSemantics::Normal) {
Ctx.Diags.diagnose(DRE->getLoc(), diag::unsupported_special_decl_ref,
DRE->getDecl()->getBaseIdentifier());
}
}
enum BitcastableNumberKind {
BNK_None = 0,
BNK_Int8,
BNK_Int16,
BNK_Int32,
BNK_Int64,
BNK_Int,
BNK_UInt8,
BNK_UInt16,
BNK_UInt32,
BNK_UInt64,
BNK_UInt,
BNK_Float,
BNK_Double,
};
BitcastableNumberKind getBitcastableNumberKind(Type t) const {
auto decl = t->getNominalOrBoundGenericNominal();
#define MATCH_DECL(type) \
if (decl == Ctx.get##type##Decl()) \
return BNK_##type;
MATCH_DECL(Int8)
MATCH_DECL(Int16)
MATCH_DECL(Int32)
MATCH_DECL(Int64)
MATCH_DECL(Int)
MATCH_DECL(UInt8)
MATCH_DECL(UInt16)
MATCH_DECL(UInt32)
MATCH_DECL(UInt64)
MATCH_DECL(UInt)
MATCH_DECL(Float)
MATCH_DECL(Double)
#undef MATCH_DECL
return BNK_None;
}
static constexpr unsigned BNKPair(BitcastableNumberKind a,
BitcastableNumberKind b) {
return (a << 8) | b;
}
void checkForSuspiciousBitCasts(DeclRefExpr *DRE,
Expr *Parent = nullptr) {
if (DRE->getDecl() != Ctx.getUnsafeBitCast())
return;
if (DRE->getDeclRef().getSubstitutions().empty())
return;
// Don't check the same use of unsafeBitCast twice.
if (!AlreadyDiagnosedBitCasts.insert(DRE).second)
return;
auto subMap = DRE->getDeclRef().getSubstitutions();
auto fromTy = subMap.getReplacementTypes()[0];
auto toTy = subMap.getReplacementTypes()[1];
// Warn about `unsafeBitCast` formulations that are undefined behavior
// or have better-defined alternative APIs that can be used instead.
// If we have a parent ApplyExpr that calls bitcast, extract the argument
// for fixits.
Expr *subExpr = nullptr;
CharSourceRange removeBeforeRange, removeAfterRange;
if (auto apply = dyn_cast_or_null<ApplyExpr>(Parent)) {
subExpr = apply->getArgs()->getExpr(0);
// Determine the fixit range from the start of the application to
// the first argument, `unsafeBitCast(`
removeBeforeRange = CharSourceRange(Ctx.SourceMgr, DRE->getLoc(),
subExpr->getStartLoc());
// Determine the fixit range from the end of the first argument to
// the end of the application, `, to: T.self)`
removeAfterRange = CharSourceRange(Ctx.SourceMgr,
Lexer::getLocForEndOfToken(Ctx.SourceMgr,
subExpr->getEndLoc()),
Lexer::getLocForEndOfToken(Ctx.SourceMgr,
apply->getEndLoc()));
}
// Casting to the same type or a superclass is a no-op.
if (toTy->isEqual(fromTy) ||
toTy->isExactSuperclassOf(fromTy)) {
auto d = Ctx.Diags.diagnose(DRE->getLoc(), diag::bitcasting_is_no_op,
fromTy, toTy);
if (subExpr) {
d.fixItRemoveChars(removeBeforeRange.getStart(),
removeBeforeRange.getEnd())
.fixItRemoveChars(removeAfterRange.getStart(),
removeAfterRange.getEnd());
}
return;
}
if (auto fromFnTy = fromTy->getAs<FunctionType>()) {
if (auto toFnTy = toTy->getAs<FunctionType>()) {
// Casting a nonescaping function to escaping is UB.
// `withoutActuallyEscaping` ought to be used instead.
if (fromFnTy->isNoEscape() && !toFnTy->isNoEscape()) {
Ctx.Diags.diagnose(DRE->getLoc(), diag::bitcasting_away_noescape,
fromTy, toTy);
}
// Changing function representation (say, to try to force a
// @convention(c) function pointer to exist) is also unlikely to work.
if (fromFnTy->getRepresentation() != toFnTy->getRepresentation()) {
Ctx.Diags.diagnose(DRE->getLoc(),
diag::bitcasting_to_change_function_rep, fromTy,
toTy);
}
return;
}
}
// Unchecked casting to a subclass is better done by unsafeDowncast.
if (fromTy->isBindableToSuperclassOf(toTy)) {
Ctx.Diags.diagnose(DRE->getLoc(), diag::bitcasting_to_downcast,
fromTy, toTy)
.fixItReplace(DRE->getNameLoc().getBaseNameLoc(),
"unsafeDowncast");
return;
}
// Casting among pointer types should use the Unsafe*Pointer APIs for
// rebinding typed memory or accessing raw memory instead.
PointerTypeKind fromPTK, toPTK;
Type fromPointee = fromTy->getAnyPointerElementType(fromPTK);
Type toPointee = toTy->getAnyPointerElementType(toPTK);
if (fromPointee && toPointee) {
// Casting to a pointer to the same type or UnsafeRawPointer can use