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Request-ify synthesis of the main function for the @main attribute #32767

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Merged
merged 5 commits into from
Jul 9, 2020
Merged

Request-ify synthesis of the main function for the @main attribute #32767

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1ac9acb
Sema: We don't have to explicitly set the type of the main function
slavapestov Jul 8, 2020
56a0b82
Sema: Lazily synthesize body of main function
slavapestov Jul 8, 2020
50632d2
Sema: Add a request to synthesize the main function
slavapestov Jul 8, 2020
f858309
Sema: EmittedMembersRequest forces SynthesizeMainFunctionRequest
slavapestov Jul 8, 2020
7bc5088
Sema: Check declaration attributes before checking members
slavapestov Jul 8, 2020
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1 change: 1 addition & 0 deletions include/swift/AST/ASTTypeIDZone.def
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Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,7 @@ SWIFT_TYPEID_NAMED(ConstructorDecl *, ConstructorDecl)
SWIFT_TYPEID_NAMED(CustomAttr *, CustomAttr)
SWIFT_TYPEID_NAMED(Decl *, Decl)
SWIFT_TYPEID_NAMED(EnumDecl *, EnumDecl)
SWIFT_TYPEID_NAMED(FuncDecl *, FuncDecl)
SWIFT_TYPEID_NAMED(GenericParamList *, GenericParamList)
SWIFT_TYPEID_NAMED(GenericTypeParamType *, GenericTypeParamType)
SWIFT_TYPEID_NAMED(InfixOperatorDecl *, InfixOperatorDecl)
Expand Down
1 change: 1 addition & 0 deletions include/swift/AST/ASTTypeIDs.h
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Expand Up @@ -30,6 +30,7 @@ class ConstructorDecl;
class CustomAttr;
class Decl;
class EnumDecl;
class FuncDecl;
enum class FunctionBuilderBodyPreCheck : uint8_t;
class GenericParamList;
class GenericSignature;
Expand Down
17 changes: 17 additions & 0 deletions include/swift/AST/TypeCheckRequests.h
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Expand Up @@ -2564,6 +2564,23 @@ class CustomAttrTypeRequest
void cacheResult(Type value) const;
};

class SynthesizeMainFunctionRequest
: public SimpleRequest<SynthesizeMainFunctionRequest,
FuncDecl *(Decl *),
RequestFlags::Cached> {
public:
using SimpleRequest::SimpleRequest;

private:
friend SimpleRequest;

// Evaluation.
FuncDecl *evaluate(Evaluator &evaluator, Decl *) const;

public:
bool isCached() const { return true; }
};

// Allow AnyValue to compare two Type values, even though Type doesn't
// support ==.
template<>
Expand Down
2 changes: 2 additions & 0 deletions include/swift/AST/TypeCheckerTypeIDZone.def
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Expand Up @@ -274,3 +274,5 @@ SWIFT_REQUEST(TypeChecker, LookupAllConformancesInContextRequest,
Uncached, NoLocationInfo)
SWIFT_REQUEST(TypeChecker, SimpleDidSetRequest,
bool(AccessorDecl *), Cached, NoLocationInfo)
SWIFT_REQUEST(TypeChecker, SynthesizeMainFunctionRequest,
FuncDecl *(Decl *), Cached, NoLocationInfo)
182 changes: 94 additions & 88 deletions lib/Sema/TypeCheckAttr.cpp
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Expand Up @@ -1782,7 +1782,76 @@ void AttributeChecker::visitUIApplicationMainAttr(UIApplicationMainAttr *attr) {
C.getIdentifier("UIApplicationMain"));
}

void AttributeChecker::visitMainTypeAttr(MainTypeAttr *attr) {
namespace {
struct MainTypeAttrParams {
FuncDecl *mainFunction;
MainTypeAttr *attr;
};

}
static std::pair<BraceStmt *, bool>
synthesizeMainBody(AbstractFunctionDecl *fn, void *arg) {
ASTContext &context = fn->getASTContext();
MainTypeAttrParams *params = (MainTypeAttrParams *) arg;

FuncDecl *mainFunction = params->mainFunction;
auto location = params->attr->getLocation();
NominalTypeDecl *nominal = fn->getDeclContext()->getSelfNominalTypeDecl();

auto *typeExpr = TypeExpr::createImplicit(nominal->getDeclaredType(), context);

SubstitutionMap substitutionMap;
if (auto *environment = mainFunction->getGenericEnvironment()) {
substitutionMap = SubstitutionMap::get(
environment->getGenericSignature(),
[&](SubstitutableType *type) { return nominal->getDeclaredType(); },
LookUpConformanceInModule(nominal->getModuleContext()));
} else {
substitutionMap = SubstitutionMap();
}

auto funcDeclRef = ConcreteDeclRef(mainFunction, substitutionMap);

auto *memberRefExpr = new (context) MemberRefExpr(
typeExpr, SourceLoc(), funcDeclRef, DeclNameLoc(location),
/*Implicit*/ true);
memberRefExpr->setImplicit(true);

auto *callExpr = CallExpr::createImplicit(context, memberRefExpr, {}, {});
callExpr->setImplicit(true);
callExpr->setThrows(mainFunction->hasThrows());
callExpr->setType(context.TheEmptyTupleType);

Expr *returnedExpr;

if (mainFunction->hasThrows()) {
auto *tryExpr = new (context) TryExpr(
SourceLoc(), callExpr, context.TheEmptyTupleType, /*implicit=*/true);
returnedExpr = tryExpr;
} else {
returnedExpr = callExpr;
}

auto *returnStmt =
new (context) ReturnStmt(SourceLoc(), callExpr, /*Implicit=*/true);

SmallVector<ASTNode, 1> stmts;
stmts.push_back(returnStmt);
auto *body = BraceStmt::create(context, SourceLoc(), stmts,
SourceLoc(), /*Implicit*/true);

return std::make_pair(body, /*typechecked=*/false);
}

FuncDecl *
SynthesizeMainFunctionRequest::evaluate(Evaluator &evaluator,
Decl *D) const {
auto &context = D->getASTContext();

MainTypeAttr *attr = D->getAttrs().getAttribute<MainTypeAttr>();
if (attr == nullptr)
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Should this be an assert instead?

return nullptr;

auto *extension = dyn_cast<ExtensionDecl>(D);

IterableDeclContext *iterableDeclContext;
Expand All @@ -1802,25 +1871,19 @@ void AttributeChecker::visitMainTypeAttr(MainTypeAttr *attr) {
braces = nominal->getBraces();
}

if (!nominal) {
assert(false && "Should have already recognized that the MainType decl "
assert(nominal && "Should have already recognized that the MainType decl "
"isn't applicable to decls other than NominalTypeDecls");
return;
}
assert(iterableDeclContext);
assert(declContext);

// The type cannot be generic.
if (nominal->isGenericContext()) {
diagnose(attr->getLocation(),
diag::attr_generic_ApplicationMain_not_supported, 2);
context.Diags.diagnose(attr->getLocation(),
diag::attr_generic_ApplicationMain_not_supported, 2);
attr->setInvalid();
return;
return nullptr;
}

SourceFile *file = cast<SourceFile>(declContext->getModuleScopeContext());
assert(file);

// Create a function
//
// func $main() {
Expand All @@ -1832,8 +1895,6 @@ void AttributeChecker::visitMainTypeAttr(MainTypeAttr *attr) {
// usual type-checking. The alternative would be to directly call
// mainType.main() from the entry point, and that would require fully
// type-checking the call to mainType.main().
auto &context = D->getASTContext();
auto location = attr->getLocation();

auto resolution = resolveValueMember(
*declContext, nominal->getInterfaceType(), context.Id_main);
Expand Down Expand Up @@ -1861,107 +1922,52 @@ void AttributeChecker::visitMainTypeAttr(MainTypeAttr *attr) {
}

if (viableCandidates.size() != 1) {
diagnose(attr->getLocation(), diag::attr_MainType_without_main,
nominal->getBaseName());
context.Diags.diagnose(attr->getLocation(),
diag::attr_MainType_without_main,
nominal->getBaseName());
attr->setInvalid();
return;
return nullptr;
}
mainFunction = viableCandidates[0];
}

bool mainFunctionThrows = mainFunction->hasThrows();

auto voidToVoidFunctionType =
FunctionType::get({}, context.TheEmptyTupleType,
FunctionType::ExtInfo().withThrows(mainFunctionThrows));
auto nominalToVoidToVoidFunctionType = FunctionType::get({AnyFunctionType::Param(nominal->getInterfaceType())}, voidToVoidFunctionType);
auto *func = FuncDecl::create(
context, /*StaticLoc*/ SourceLoc(), StaticSpellingKind::KeywordStatic,
/*FuncLoc*/ SourceLoc(),
DeclName(context, DeclBaseName(context.Id_MainEntryPoint),
ParameterList::createEmpty(context)),
/*NameLoc*/ SourceLoc(), /*Throws=*/mainFunctionThrows,
/*NameLoc*/ SourceLoc(), /*Throws=*/mainFunction->hasThrows(),
/*ThrowsLoc=*/SourceLoc(),
/*GenericParams=*/nullptr, ParameterList::createEmpty(context),
/*FnRetType=*/TypeLoc::withoutLoc(TupleType::getEmpty(context)),
declContext);
func->setImplicit(true);
func->setSynthesized(true);

auto *typeExpr = TypeExpr::createImplicit(nominal->getDeclaredType(), context);

SubstitutionMap substitutionMap;
if (auto *environment = mainFunction->getGenericEnvironment()) {
substitutionMap = SubstitutionMap::get(
environment->getGenericSignature(),
[&](SubstitutableType *type) { return nominal->getDeclaredType(); },
LookUpConformanceInModule(nominal->getModuleContext()));
} else {
substitutionMap = SubstitutionMap();
}

auto funcDeclRef = ConcreteDeclRef(mainFunction, substitutionMap);

auto *memberRefExpr = new (context) MemberRefExpr(
typeExpr, SourceLoc(), funcDeclRef, DeclNameLoc(location),
/*Implicit*/ true);
memberRefExpr->setImplicit(true);

auto *callExpr = CallExpr::createImplicit(context, memberRefExpr, {}, {});
callExpr->setImplicit(true);
callExpr->setThrows(mainFunctionThrows);
callExpr->setType(context.TheEmptyTupleType);

Expr *returnedExpr;
auto *params = context.Allocate<MainTypeAttrParams>();
params->mainFunction = mainFunction;
params->attr = attr;
func->setBodySynthesizer(synthesizeMainBody, params);

if (mainFunctionThrows) {
auto *tryExpr = new (context) TryExpr(
SourceLoc(), callExpr, context.TheEmptyTupleType, /*implicit=*/true);
returnedExpr = tryExpr;
} else {
returnedExpr = callExpr;
}
iterableDeclContext->addMember(func);

auto *returnStmt =
new (context) ReturnStmt(SourceLoc(), callExpr, /*Implicit=*/true);
return func;
}

SmallVector<ASTNode, 1> stmts;
stmts.push_back(returnStmt);
auto *body = BraceStmt::create(context, SourceLoc(), stmts,
SourceLoc(), /*Implicit*/true);
func->setBodyParsed(body);
func->setInterfaceType(nominalToVoidToVoidFunctionType);
void AttributeChecker::visitMainTypeAttr(MainTypeAttr *attr) {
auto &context = D->getASTContext();

iterableDeclContext->addMember(func);
SourceFile *file = D->getDeclContext()->getParentSourceFile();
assert(file);

// This function must be type-checked. Why? Consider the following scenario:
//
// protocol AlmostMainable {}
// protocol ReallyMainable {}
// extension AlmostMainable where Self : ReallyMainable {
// static func main() {}
// }
// @main struct Main : AlmostMainable {}
//
// Note in particular that Main does not conform to ReallyMainable.
//
// In this case, resolveValueMember will find the function main in the
// extension, and so, since there is one candidate, the function $main will
// accordingly be formed as usual:
//
// func $main() {
// return Main.main()
// }
//
// Of course, this function's body does not type-check.
file->DelayedFunctions.push_back(func);
auto *func = evaluateOrDefault(context.evaluator,
SynthesizeMainFunctionRequest{D},
nullptr);

// Register the func as the main decl in the module. If there are multiples
// they will be diagnosed.
if (file->registerMainDecl(func, attr->getLocation())) {
if (file->registerMainDecl(func, attr->getLocation()))
attr->setInvalid();
return;
}
}

/// Determine whether the given context is an extension to an Objective-C class
Expand Down
6 changes: 6 additions & 0 deletions lib/Sema/TypeCheckDecl.cpp
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Expand Up @@ -2523,6 +2523,12 @@ EmittedMembersRequest::evaluate(Evaluator &evaluator,
forceConformance(Context.getProtocol(KnownProtocolKind::Hashable));
forceConformance(Context.getProtocol(KnownProtocolKind::Differentiable));

// If the class has a @main attribute, we need to force synthesis of the
// $main function.
(void) evaluateOrDefault(Context.evaluator,
SynthesizeMainFunctionRequest{CD},
nullptr);

for (auto *member : CD->getMembers()) {
if (auto *var = dyn_cast<VarDecl>(member)) {
// The projected storage wrapper ($foo) might have dynamically-dispatched
Expand Down
21 changes: 11 additions & 10 deletions lib/Sema/TypeCheckDeclPrimary.cpp
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Expand Up @@ -1797,13 +1797,13 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
checkGenericParams(ED);

// Check for circular inheritance of the raw type.
(void)ED->hasCircularRawValue();
(void) ED->hasCircularRawValue();

TypeChecker::checkDeclAttributes(ED);

for (Decl *member : ED->getMembers())
visit(member);

TypeChecker::checkDeclAttributes(ED);

checkInheritanceClause(ED);

checkAccessControl(ED);
Expand Down Expand Up @@ -1845,13 +1845,13 @@ class DeclChecker : public DeclVisitor<DeclChecker> {

installCodingKeysIfNecessary(SD);

TypeChecker::checkDeclAttributes(SD);

for (Decl *Member : SD->getMembers())
visit(Member);

TypeChecker::checkPatternBindingCaptures(SD);

TypeChecker::checkDeclAttributes(SD);

checkInheritanceClause(SD);

checkAccessControl(SD);
Expand Down Expand Up @@ -1974,6 +1974,8 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
// Force creation of an implicit destructor, if any.
(void) CD->getDestructor();

TypeChecker::checkDeclAttributes(CD);

for (Decl *Member : CD->getEmittedMembers())
visit(Member);

Expand Down Expand Up @@ -2084,8 +2086,6 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
}
}

TypeChecker::checkDeclAttributes(CD);

checkInheritanceClause(CD);

checkAccessControl(CD);
Expand All @@ -2105,12 +2105,12 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
// Check for circular inheritance within the protocol.
(void)PD->hasCircularInheritedProtocols();

TypeChecker::checkDeclAttributes(PD);

// Check the members.
for (auto Member : PD->getMembers())
visit(Member);

TypeChecker::checkDeclAttributes(PD);

checkAccessControl(PD);

checkInheritanceClause(PD);
Expand Down Expand Up @@ -2428,14 +2428,15 @@ class DeclChecker : public DeclVisitor<DeclChecker> {

checkGenericParams(ED);

TypeChecker::checkDeclAttributes(ED);

for (Decl *Member : ED->getMembers())
visit(Member);

TypeChecker::checkPatternBindingCaptures(ED);

TypeChecker::checkConformancesInContext(ED);

TypeChecker::checkDeclAttributes(ED);
checkAccessControl(ED);

checkExplicitAvailability(ED);
Expand Down
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