Attached is a patch that begins building an AST for lambda expressions.
It is still incomplete (notably no LambdaExpr yet), but I feel like I
reached a stopping point and would like a review before I get too deep.
There are quite a few FIXMEs sprinkled throughout. Not all of them
indicate problems; many just mark design/API/coding convention questions
for the reviewer. When it came to decisions, I just went with my gut
figuring I could always fix it later if I was wrong.
Thank you,
John
diff --git include/clang/AST/DeclBase.h include/clang/AST/DeclBase.h
index 8355e36..ed7ce88 100644
--- include/clang/AST/DeclBase.h
+++ include/clang/AST/DeclBase.h
@@ -39,6 +39,7 @@ class ObjCCategoryImplDecl;
class ObjCImplDecl;
class LinkageSpecDecl;
class BlockDecl;
+class LambdaDecl;
class DeclarationName;
class CompoundStmt;
class StoredDeclsMap;
diff --git include/clang/AST/DeclCXX.h include/clang/AST/DeclCXX.h
index 01ca2e3..5e68b96 100644
--- include/clang/AST/DeclCXX.h
+++ include/clang/AST/DeclCXX.h
@@ -16,6 +16,8 @@
#define LLVM_CLANG_AST_DECLCXX_H
#include "clang/AST/Expr.h"
+// FIXME: Including this only for CXXThisExpr. Is that bad?
+#include "clang/AST/ExprCXX.h"
#include "clang/AST/Decl.h"
#include "clang/AST/TypeLoc.h"
#include "clang/AST/UnresolvedSet.h"
@@ -2566,6 +2568,53 @@ public:
friend class ASTDeclReader;
};
+/// LambdaDecl - Represents a C++0x lambda expression.
+class LambdaDecl : public Decl, public DeclContext {
+public:
+ class Capture {
+ enum {
+ CaptureThis,
+ CaptureByRef,
+ CaptureByCopy
+ } Kind;
+
+ Expr* Init;
+
+ public:
+ Capture(CXXThisExpr *Init)
+ : Kind(CaptureThis), Init(Init) {}
+
+ Capture(DeclRefExpr *Init, bool ByRef)
+ : Kind(ByRef ? CaptureByRef : CaptureByCopy), Init(Init) {}
+
+ bool isThisCapture() const { return Kind == CaptureThis; }
+ bool isReferenceCapture() const { return Kind == CaptureByRef; }
+ bool isCopyCapture() const { return Kind == CaptureByCopy; }
+
+ /// The initializing Expr for the captured entity. Will be either
+ /// CXXThisExpr or DeclRefExpr.
+ Expr* getInit() const { return Init; }
+
+ };
+
+ Capture *Explicits;
+ unsigned NumExplicits;
+
+ /// Declaration for the function object class implementing the lambda
+ /// expression.
+ CXXRecordDecl *D;
+
+protected:
+ LambdaDecl(DeclContext *DC, SourceLocation L)
+ : Decl(Lambda, DC, L), DeclContext(Lambda) {}
+
+public:
+ static LambdaDecl *Create(ASTContext &C, DeclContext *DC, SourceLocation L) {
+ return new (C) LambdaDecl(DC, L);
+ }
+
+};
+
/// Insertion operator for diagnostics. This allows sending AccessSpecifier's
/// into a diagnostic with <<.
const DiagnosticBuilder &operator<<(const DiagnosticBuilder &DB,
diff --git include/clang/AST/RecursiveASTVisitor.h
include/clang/AST/RecursiveASTVisitor.h
index 85c5c08..ccdb202 100644
--- include/clang/AST/RecursiveASTVisitor.h
+++ include/clang/AST/RecursiveASTVisitor.h
@@ -1114,6 +1114,8 @@ DEF_TRAVERSE_DECL(FriendTemplateDecl, {
}
})
+DEF_TRAVERSE_DECL(LambdaDecl, { })
+
DEF_TRAVERSE_DECL(LinkageSpecDecl, { })
DEF_TRAVERSE_DECL(ObjCClassDecl, {
diff --git include/clang/Basic/DeclNodes.td include/clang/Basic/DeclNodes.td
index ddd0827..3c3f590 100644
--- include/clang/Basic/DeclNodes.td
+++ include/clang/Basic/DeclNodes.td
@@ -74,3 +74,4 @@ def Friend : Decl;
def FriendTemplate : Decl;
def StaticAssert : Decl;
def Block : Decl, DeclContext;
+def Lambda : Decl, DeclContext;
diff --git include/clang/Basic/DiagnosticSemaKinds.td
include/clang/Basic/DiagnosticSemaKinds.td
index 81fb8b6..a598f6b 100644
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -1151,6 +1151,19 @@ def err_for_range_begin_end_types_differ : Error<
def note_for_range_type : Note<"range has type %0">;
def note_for_range_begin_end : Note<
"selected '%select{begin|end}0' %select{function|template }1%2 with iterator
type %3">;
+
+// C++0x lambda expressions
+def err_capture_more_than_once : Error<
+ "%0 can appear only once in a capture list">;
+// FIXME: Is this note overkill? It will almost always appear on the same line
+// as the error.
+def note_previously_captured_here : Note<"previously captured here">;
+def err_reference_capture_with_reference_default : Error<
+ "'&' cannot precede a capture when the capture default is '&'">;
+def err_this_capture_with_copy_default : Error<
+ "'this' cannot appear in a capture list when the capture default is '='">;
+def err_copy_capture_with_copy_default : Error<
+ "'&' must precede a capture when the capture default is '='">;
// Objective-C++
def err_objc_decls_may_only_appear_in_global_scope : Error<
diff --git include/clang/Sema/Sema.h include/clang/Sema/Sema.h
index 1258d59..36c6b52 100644
--- include/clang/Sema/Sema.h
+++ include/clang/Sema/Sema.h
@@ -4940,6 +4940,18 @@ public:
DeclContext *FindInstantiatedContext(SourceLocation Loc, DeclContext *DC,
const MultiLevelTemplateArgumentList &TemplateArgs);
+
//===--------------------------------------------------------------------===//
+ // C++ Lambda Expressions (C++0x [expr.prim.lambda])
+
+ // FIXME: Change to DeclResult later? Is there a better way to pass the
Lambda
+ // through each action? The introducer does not begin a function scope,
+ // so cannot mimic blocks. Should we condense these into one action, or
should
+ // we try semantic checking as early as possible?
+ LambdaDecl *ActOnLambdaIntroducer(const LambdaIntroducer &Intro);
+ void ActOnLambdaDeclarator(const Declarator &D);
+ void ActOnLambdaBody(LambdaDecl *Lambda, Stmt *Body);
+
+
//===--------------------------------------------------------------------===//
// Objective-C declarations.
Decl *ActOnStartClassInterface(SourceLocation AtInterfaceLoc,
IdentifierInfo *ClassName,
diff --git lib/Parse/ParseExprCXX.cpp lib/Parse/ParseExprCXX.cpp
index 757d86e..20ee777 100644
--- lib/Parse/ParseExprCXX.cpp
+++ lib/Parse/ParseExprCXX.cpp
@@ -672,6 +672,10 @@ bool Parser::TryParseLambdaIntroducer(LambdaIntroducer
&Intro) {
/// expression.
ExprResult Parser::ParseLambdaExpressionAfterIntroducer(
LambdaIntroducer &Intro) {
+ LambdaDecl *Lambda = Actions.ActOnLambdaIntroducer(Intro);
+ if (!Lambda)
+ return ExprError();
+
// Parse lambda-declarator[opt].
DeclSpec DS(AttrFactory);
Declarator D(DS, Declarator::PrototypeContext);
@@ -747,6 +751,8 @@ ExprResult Parser::ParseLambdaExpressionAfterIntroducer(
Attr, DeclEndLoc);
}
+ Actions.ActOnLambdaDeclarator(D);
+
// Parse compound-statement.
if (Tok.is(tok::l_brace)) {
// FIXME: Rename BlockScope -> ClosureScope if we decide to continue using
@@ -758,6 +764,9 @@ ExprResult Parser::ParseLambdaExpressionAfterIntroducer(
StmtResult Stmt(ParseCompoundStatementBody());
BodyScope.Exit();
+
+ if (!Stmt.isInvalid())
+ Actions.ActOnLambdaBody(Lambda, Stmt.take());
} else {
Diag(Tok, diag::err_expected_lambda_body);
}
diff --git lib/Sema/SemaExprCXX.cpp lib/Sema/SemaExprCXX.cpp
index 4f49463..781d6fc 100644
--- lib/Sema/SemaExprCXX.cpp
+++ lib/Sema/SemaExprCXX.cpp
@@ -4655,3 +4655,264 @@ bool Sema::CheckMicrosoftIfExistsSymbol(CXXScopeSpec
&SS,
LookupParsedName(R, getCurScope(), &SS);
return !R.empty();
}
+
+// FIXME: Several areas in the below ActOnLambda* functions may benefit from
+// calling existing Sema functions, or from factoring out some essential bits
to
+// share. These are marked with FIXMEs that begin "Compare with ...".
+//
+// Additionally, there are a few checks sprinkled throughout these actions
+// merely to ensure their correct implementation. I did not think it worth
+// wrapping them in separate functions just so they can be asserted. They
should
+// be removed after code review for performance reasons. They are marked with
+// FIXMEs stating "Remove this check later.".
+LambdaDecl *Sema::ActOnLambdaIntroducer(const LambdaIntroducer &Intro) {
+ // Diagnose the explicit capture list.
+ SourceLocation CapturesThis;
+ // FIXME: Are typedefs encouraged? What is the naming convention?
+ llvm::DenseMap<const IdentifierInfo*, SourceLocation> CapturesSoFar;
+
+ // Check captures before we allocate a LambdaDecl.
+ // FIXME: If we hit an error, should we continue as if it didn't exist, or
+ // immediately return failure? For now, return failure.
+ for (llvm::SmallVector<LambdaCapture, 4>::const_iterator
+ C = Intro.Captures.begin(), E = Intro.Captures.end(); C != E; ++C) {
+ if (C->Kind == LCK_This) {
+ if (CapturesThis.isValid()) {
+ Diag(C->Loc, diag::err_capture_more_than_once) << "'this'";
+ Diag(CapturesThis, diag::note_previously_captured_here);
+ return NULL;
+ }
+
+ if (Intro.Default == LCD_ByCopy) {
+ Diag(C->Loc, diag::err_this_capture_with_copy_default);
+ return NULL;
+ }
+
+ CapturesThis = C->Loc;
+ continue;
+ }
+
+ assert(C->Id && "missing identifier for capture");
+
+ if (C->Kind == LCK_ByRef && Intro.Default == LCD_ByRef) {
+ Diag(C->Loc, diag::err_reference_capture_with_reference_default);
+ return NULL;
+ } else if (C->Kind == LCK_ByCopy && Intro.Default == LCD_ByCopy) {
+ Diag(C->Loc, diag::err_copy_capture_with_copy_default);
+ return NULL;
+ }
+
+ llvm::DenseMap<const IdentifierInfo*, SourceLocation>::iterator Appearance;
+ bool IsFirstAppearance;
+ llvm::tie(Appearance, IsFirstAppearance)
+ = CapturesSoFar.insert(std::make_pair(C->Id, C->Loc));
+
+ if (!IsFirstAppearance) {
+ Diag(C->Loc, diag::err_capture_more_than_once) << C->Id;
+ Diag(Appearance->second, diag::note_previously_captured_here);
+ return NULL;
+ }
+ }
+
+ // Avoid new Capture[] because we don't want to provide a default
constructor.
+ // FIXME: Do we need to align?
+ LambdaDecl::Capture *Explicits
+ = static_cast<LambdaDecl::Capture*>(
+ Context.Allocate(Intro.Captures.size() * sizeof(LambdaDecl::Capture)));
+
+ // FIXME: Try to merge with the above loop somehow?
+ LambdaDecl::Capture *Explicit = Explicits;
+ for (llvm::SmallVector<LambdaCapture, 4>::const_iterator
+ C = Intro.Captures.begin(), E = Intro.Captures.end(); C != E; ++C) {
+ if (C->Kind == LCK_This) {
+ CXXThisExpr *This =
static_cast<CXXThisExpr*>(ActOnCXXThis(C->Loc).take());
+ new (Explicit) LambdaDecl::Capture(This);
+ ++Explicit;
+ continue;
+ }
+
+ UnqualifiedId Name;
+ CXXScopeSpec ScopeSpec;
+ Name.setIdentifier(C->Id, C->Loc);
+ // FIXME: Can we do better than ActOnIdExpression?
+ DeclRefExpr *Var
+ = static_cast<DeclRefExpr*>(
+ ActOnIdExpression(getCurScope(),
+ ScopeSpec, Name,
+ /*HasTrailingLParen=*/false,
+ /*IsAddressOfOperand=*/false).take());
+
+ // FIXME: Check that we have a local variable with automatic storage
+ // duration.
+
+ new (Explicit) LambdaDecl::Capture(Var, C->Kind == LCK_ByRef);
+ ++Explicit;
+ }
+
+ // Find the nearest block, class, or namespace scope.
+ DeclContext *DC = CurContext;
+ while (!(DC->isFunctionOrMethod() || DC->isRecord() || DC->isNamespace()))
+ DC = DC->getParent();
+
+ LambdaDecl *Lambda = LambdaDecl::Create(Context, DC,
+ Intro.Range.getBegin());
+ Lambda->Explicits = Explicits;
+ Lambda->NumExplicits = Intro.Captures.size();
+
+ return Lambda;
+}
+
+void Sema::ActOnLambdaDeclarator(const Declarator &D) {}
+void Sema::ActOnLambdaBody(LambdaDecl *Lambda, Stmt *Body) {
+ SourceLocation ClassLoc;
+ CXXRecordDecl *Class = CXXRecordDecl::Create(Context,
+ TTK_Class,
+ Lambda->getDeclContext(),
+ /*StartLoc=*/ClassLoc,
+ /*IdLoc=*/SourceLocation(),
+ /*Id=*/0);
+ Class->startDefinition();
+
+ CanQualType ClassType
+ = Context.getCanonicalType(Context.getTypeDeclType(Class));
+ DeclarationName CtorName
+ = Context.DeclarationNames.getCXXConstructorName(ClassType);
+
+ CXXConstructorDecl *Ctor
+ = CXXConstructorDecl::Create(Context,
+ Class,
+ ClassLoc,
+ DeclarationNameInfo(CtorName, ClassLoc),
+ // Chicken and egg problem: we need the Ctor
to
+ // build the CtorParams and the CtorParams to
+ // build the Ctor. Favor one call on the Ctor
+ // to set its type instead of one call on each
+ // CtorParam to set their DeclContext.
+ QualType(),
+ /*TInfo=*/0,
+ /*isExplicit=*/true,
+ /*isInline=*/true,
+ /*isImplicitlyDeclared=*/true);
+
+ // FIXME: When we support implicit captures later, this number will need to
be
+ // updated.
+ unsigned NumCaptures = Lambda->NumExplicits;
+
+ llvm::SmallVector<QualType, 4> CtorParamTys;
+ CtorParamTys.reserve(NumCaptures);
+ llvm::SmallVector<ParmVarDecl*, 4> CtorParams;
+ CtorParams.reserve(NumCaptures);
+ CXXCtorInitializer **CtorInits
+ = new (Context) CXXCtorInitializer*[NumCaptures];
+
+ CXXCtorInitializer **CtorInit = CtorInits;
+ for (LambdaDecl::Capture *C = Lambda->Explicits,
+ *E = Lambda->Explicits + Lambda->NumExplicits; C != E; ++C) {
+
+ Expr *Init = C->getInit();
+
+ IdentifierInfo *Id;
+ if (C->isThisCapture()) {
+ Id = PP.getIdentifierInfo("__this");
+ } else {
+ Id = cast<DeclRefExpr>(Init)->getDecl()->getIdentifier();
+ }
+
+ DeclarationName CaptureName
+ = Context.DeclarationNames.getIdentifier(Id);
+
+ // FIXME: Find the correct type. There are capture type transformations
+ // remaining to be implemented. What is the difference between CanQualType
+ // and QualType? How is template instantiation handled? If some of these
+ // have dependent type, how is that treated?
+ QualType CaptureType = Init->getType();
+ if (C->isReferenceCapture()) {
+ // FIXME: Compare with Sema::BuildReferenceType.
+ CaptureType = Context.getLValueReferenceType(CaptureType,
+ /*SpelledAsLValue=*/true);
+ }
+
+ FieldDecl *Field = CheckFieldDecl(CaptureName,
+ CaptureType,
+ /*TInfo=*/0,
+ Class,
+ /*StartLoc=*/SourceLocation(),
+ /*Mutable=*/false,
+ /*BitWidth=*/0,
+ /*HasInit=*/false,
+ /*IdLoc=*/SourceLocation(),
+ AS_private,
+ /*PrevDecl=*/0);
+
+ Class->addDecl(Field);
+
+ CtorParamTys.push_back(CaptureType);
+
+ // FIXME: Compare with Sema::CheckParameter.
+ ParmVarDecl *CtorParam = ParmVarDecl::Create(Context,
+ Ctor,
+ /*StartLoc=*/SourceLocation(),
+ /*IdLoc=*/SourceLocation(),
+ Id,
+
Context.getAdjustedParameterType(CaptureType),
+ /*TInfo=*/0,
+ SC_None,
+ SC_None,
+ /*DefArg=*/0);
+ CtorParams.push_back(CtorParam);
+
+ DeclRefExpr *CtorInitArg
+ = DeclRefExpr::Create(Context,
+ /*QualifierLoc=*/NestedNameSpecifierLoc(),
+ CtorParam,
+ /*NameLoc=*/SourceLocation(),
+ CaptureType.getNonReferenceType(),
+ VK_LValue);
+ // FIXME: Compare with Sema::BuildMemberInitializer.
+ *CtorInit = new (Context) CXXCtorInitializer(Context,
+ Field,
+
/*MemberLoc=*/SourceLocation(),
+ /*L=*/SourceLocation(),
+ CtorInitArg,
+ /*R=*/SourceLocation());
+ ++CtorInit;
+
+ }
+
+ // FIXME: Compare with Sema::BuildFunctionType.
+ QualType CtorType = Context.getFunctionType(Context.VoidTy,
+ CtorParamTys.data(),
+ CtorParamTys.size(),
+
FunctionProtoType::ExtProtoInfo());
+
+ Ctor->setAccess(AS_public);
+ Ctor->setImplicit();
+ Ctor->setType(CtorType);
+ // FIXME: Compare with Sema::CheckParmsForFunctionDef.
+ Ctor->setParams(CtorParams.data(), CtorParams.size());
+ // FIXME: Compare with Sema::ActOnMemInitializers.
+ // FIXME: Compare with Sema::SetCtorInitializers.
+ Ctor->setNumCtorInitializers(NumCaptures);
+ Ctor->setCtorInitializers(CtorInits);
+
+ // FIXME: Remove this check later.
+ bool Redeclaration = false;
+ LookupResult Previous(*this,
+ CtorName,
+ SourceLocation(),
+ LookupOrdinaryName,
+ ForRedeclaration);
+ CheckFunctionDeclaration(getCurScope(),
+ Ctor,
+ Previous,
+ /*IsExplicitSpecialization=*/false,
+ Redeclaration);
+ assert(!Ctor->isInvalidDecl() && "bad lambda constructor");
+
+ Class->addDecl(Ctor);
+
+ Class->completeDefinition();
+ // FIXME: Remove this check later.
+ CheckCompletedCXXClass(Class);
+}
+
diff --git test/Parser/objcxx0x-lambda-expressions.mm
test/Parser/objcxx0x-lambda-expressions.mm
index d100e2e..8d2d9f6 100644
--- test/Parser/objcxx0x-lambda-expressions.mm
+++ test/Parser/objcxx0x-lambda-expressions.mm
@@ -9,7 +9,7 @@ class C {
[foo,+] {}; // expected-error {{expected expression}}
[]; // expected-error {{expected body of lambda expression}}
- [=,foo+] {}; // expected-error {{expected ',' or ']' in lambda capture
list}}
+ [=,&foo+] {}; // expected-error {{expected ',' or ']' in lambda capture
list}}
[&this] {}; // expected-error {{address expression must be an lvalue}}
[] {};
[=] (int i) {};
diff --git test/SemaCXX/lambda-expressions.cpp
test/SemaCXX/lambda-expressions.cpp
new file mode 100644
index 0000000..c9427aa
--- /dev/null
+++ test/SemaCXX/lambda-expressions.cpp
@@ -0,0 +1,17 @@
+// RUN: %clang_cc1 -std=c++0x -fsyntax-only -verify %s
+
+class C {
+ void f() {
+ int foo;
+
+ [foo, foo] () {}; // expected-error {{'foo' can appear only once}}
expected-note {{previously captured here}}
+ [this, this] () {}; // expected-error {{'this' can appear only once}}
expected-note {{previously captured here}}
+ [=, foo] () {}; // expected-error {{'&' must precede a capture when}}
+ [=, &foo] () {};
+ [=, this] () {} // expected-error {{'this' cannot appear}}
+ [&, foo] () {};
+ [&, &foo] () {}; // expected-error {{'&' cannot precede a capture when}}
+ [&, this] () {};
+ }
+};
+
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