Implement a rudimentary form of generic lambdas.
Specifically, the following features are not included in this commit:
- any sort of capturing within generic lambdas
- nested lambdas
- conversion operator for captureless lambdas
- ensuring all visitors are generic lambda aware
As an example of what compiles:
template <class F1, class F2>
struct overload : F1, F2 {
using F1::operator();
using F2::operator();
overload(F1 f1, F2 f2) : F1(f1), F2(f2) { }
};
auto Recursive = [](auto Self, auto h, auto ... rest) {
return 1 + Self(Self, rest...);
};
auto Base = [](auto Self, auto h) {
return 1;
};
overload<decltype(Base), decltype(Recursive)> O(Base, Recursive);
int num_params = O(O, 5, 3, "abc", 3.14, 'a');
Please see attached tests for more examples.
Some implementation notes:
- Add a new Declarator context => LambdaExprParameterContext to
clang::Declarator to allow the use of 'auto' in declaring generic
lambda parameters
- Augment AutoType's constructor (similar to how variadic
template-type-parameters ala TemplateTypeParmDecl are implemented) to
accept an IsParameterPack to encode a generic lambda parameter pack.
- Add various helpers to CXXRecordDecl to facilitate identifying
and querying a closure class
- LambdaScopeInfo (which maintains the current lambda's Sema state)
was augmented to house the current depth of the template being
parsed (id est the Parser calls Sema::RecordParsingTemplateParameterDepth)
so that Sema::ActOnLambdaAutoParameter may use it to create the
appropriate list of corresponding TemplateTypeParmDecl for each
auto parameter identified within the generic lambda (also stored
within the current LambdaScopeInfo). Additionally,
a TemplateParameterList data-member was added to hold the invented
TemplateParameterList AST node which will be much more useful
once we teach TreeTransform how to transform generic lambdas.
- SemaLambda.h was added to hold some common lambda utility
functions (this file is likely to grow ...)
- Teach Sema::ActOnStartOfFunctionDef to check whether it
is being called to instantiate a generic lambda's call
operator, and if so, push an appropriately prepared
LambdaScopeInfo object on the stack.
- Teach Sema::ActOnStartOfLambdaDefinition to set the
return type of a lambda without a trailing return type
to 'auto' in C++1y mode, and teach the return type
deduction machinery in SemaStmt.cpp to process either
C++11 and C++14 lambda's correctly depending on the flag.
- various tests were added - but much more will be needed.
A greatful thanks to all reviewers including Eli Friedman,
James Dennett and the ever illuminating Richard Smith. And
yet I am certain that I have allowed unidentified bugs to creep in;
bugs, that I will do my best to slay, once identified!
Thanks!
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@188977 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaLambda.cpp b/lib/Sema/SemaLambda.cpp
index ae3a938..bed71a6 100644
--- a/lib/Sema/SemaLambda.cpp
+++ b/lib/Sema/SemaLambda.cpp
@@ -14,6 +14,7 @@
#include "clang/AST/ExprCXX.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Sema/Initialization.h"
+#include "clang/Sema/SemaLambda.h"
#include "clang/Sema/Lookup.h"
#include "clang/Sema/Scope.h"
#include "clang/Sema/ScopeInfo.h"
@@ -120,11 +121,69 @@
llvm_unreachable("unexpected context");
}
+
+ParmVarDecl *Sema::ActOnLambdaAutoParameter(ParmVarDecl *PVD) {
+ LambdaScopeInfo *LSI = getCurLambda();
+ assert(LSI && "No LambdaScopeInfo on the stack!");
+ const unsigned TemplateParameterDepth = LSI->AutoTemplateParameterDepth;
+ const unsigned AutoParameterPosition = LSI->AutoTemplateParams.size();
+ // Invent a template type parameter corresponding to the auto
+ // containing parameter.
+ TemplateTypeParmDecl *TemplateParam =
+ TemplateTypeParmDecl::Create(Context,
+ // Temporarily add to the TranslationUnit DeclContext. When the
+ // associated TemplateParameterList is attached to a template
+ // declaration (such as FunctionTemplateDecl), the DeclContext
+ // for each template parameter gets updated appropriately via
+ // a call to AdoptTemplateParameterList.
+ Context.getTranslationUnitDecl(),
+ SourceLocation(),
+ PVD->getLocation(),
+ TemplateParameterDepth,
+ AutoParameterPosition, // our template param index
+ /* Identifier*/ 0, false, PVD->isParameterPack());
+ LSI->AutoTemplateParams.push_back(TemplateParam);
+ QualType AutoTy = PVD->getType();
+ // Now replace the 'auto' in the function parameter with this invented
+ // template type parameter.
+ QualType TemplParamType = QualType(TemplateParam->getTypeForDecl(), 0);
+
+ TypeSourceInfo *AutoTSI = PVD->getTypeSourceInfo();
+ TypeSourceInfo *NewTSI = SubstAutoTypeSourceInfo(AutoTSI, TemplParamType);
+ PVD->setType(NewTSI->getType());
+ PVD->setTypeSourceInfo(NewTSI);
+ return PVD;
+}
+
+
+static inline TemplateParameterList *
+ getGenericLambdaTemplateParameterList(LambdaScopeInfo *LSI,
+ Sema &SemaRef) {
+ if (LSI->GLTemplateParameterList)
+ return LSI->GLTemplateParameterList;
+ else if (LSI->AutoTemplateParams.size()) {
+ SourceRange IntroRange = LSI->IntroducerRange;
+ SourceLocation LAngleLoc = IntroRange.getBegin();
+ SourceLocation RAngleLoc = IntroRange.getEnd();
+ LSI->GLTemplateParameterList =
+ TemplateParameterList::Create(SemaRef.Context,
+ /* Template kw loc */ SourceLocation(),
+ LAngleLoc,
+ (NamedDecl**)LSI->AutoTemplateParams.data(),
+ LSI->AutoTemplateParams.size(), RAngleLoc);
+ }
+ return LSI->GLTemplateParameterList;
+}
+
+
+
CXXMethodDecl *Sema::startLambdaDefinition(CXXRecordDecl *Class,
SourceRange IntroducerRange,
TypeSourceInfo *MethodType,
SourceLocation EndLoc,
ArrayRef<ParmVarDecl *> Params) {
+ TemplateParameterList *TemplateParams =
+ getGenericLambdaTemplateParameterList(getCurLambda(), *this);
// C++11 [expr.prim.lambda]p5:
// The closure type for a lambda-expression has a public inline function
// call operator (13.5.4) whose parameters and return type are described by
@@ -152,6 +211,17 @@
// Temporarily set the lexical declaration context to the current
// context, so that the Scope stack matches the lexical nesting.
Method->setLexicalDeclContext(CurContext);
+ // Create a function template if we have a template parameter list
+ FunctionTemplateDecl *const TemplateMethod = TemplateParams ?
+ FunctionTemplateDecl::Create(Context, Class,
+ Method->getLocation(), MethodName,
+ TemplateParams,
+ Method) : 0;
+ if (TemplateMethod) {
+ TemplateMethod->setLexicalDeclContext(CurContext);
+ TemplateMethod->setAccess(AS_public);
+ Method->setDescribedFunctionTemplate(TemplateMethod);
+ }
// Add parameters.
if (!Params.empty()) {
@@ -177,15 +247,16 @@
return Method;
}
-LambdaScopeInfo *Sema::enterLambdaScope(CXXMethodDecl *CallOperator,
+void Sema::buildLambdaScope(LambdaScopeInfo *LSI,
+ CXXMethodDecl *CallOperator,
SourceRange IntroducerRange,
LambdaCaptureDefault CaptureDefault,
SourceLocation CaptureDefaultLoc,
bool ExplicitParams,
bool ExplicitResultType,
bool Mutable) {
- PushLambdaScope(CallOperator->getParent(), CallOperator);
- LambdaScopeInfo *LSI = getCurLambda();
+ LSI->CallOperator = CallOperator;
+ LSI->Lambda = CallOperator->getParent();
if (CaptureDefault == LCD_ByCopy)
LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByval;
else if (CaptureDefault == LCD_ByRef)
@@ -208,8 +279,6 @@
} else {
LSI->HasImplicitReturnType = true;
}
-
- return LSI;
}
void Sema::finishLambdaExplicitCaptures(LambdaScopeInfo *LSI) {
@@ -358,7 +427,7 @@
}
void Sema::deduceClosureReturnType(CapturingScopeInfo &CSI) {
- assert(CSI.HasImplicitReturnType);
+ assert(CSI.HasImplicitReturnType || CSI.ReturnType->isUndeducedType());
// C++ Core Issue #975, proposed resolution:
// If a lambda-expression does not include a trailing-return-type,
@@ -392,7 +461,7 @@
// Second case: at least one return statement has dependent type.
// Delay type checking until instantiation.
assert(!CSI.ReturnType.isNull() && "We should have a tentative return type.");
- if (CSI.ReturnType->isDependentType())
+ if (CSI.ReturnType->isDependentType() || CSI.ReturnType->isUndeducedType())
return;
// Try to apply the enum-fuzz rule.
@@ -519,15 +588,25 @@
}
void Sema::ActOnStartOfLambdaDefinition(LambdaIntroducer &Intro,
- Declarator &ParamInfo,
- Scope *CurScope) {
+ Declarator &ParamInfo, Scope *CurScope) {
// Determine if we're within a context where we know that the lambda will
// be dependent, because there are template parameters in scope.
bool KnownDependent = false;
- if (Scope *TmplScope = CurScope->getTemplateParamParent())
- if (!TmplScope->decl_empty())
+ LambdaScopeInfo *const LSI = getCurLambda();
+ assert(LSI && "LambdaScopeInfo should be on stack!");
+ TemplateParameterList *TemplateParams =
+ getGenericLambdaTemplateParameterList(LSI, *this);
+
+ if (Scope *TmplScope = CurScope->getTemplateParamParent()) {
+ // Since we have our own TemplateParams, so check if an outer scope
+ // has template params, only then are we in a dependent scope.
+ if (TemplateParams) {
+ TmplScope = TmplScope->getParent();
+ TmplScope = TmplScope ? TmplScope->getTemplateParamParent() : 0;
+ }
+ if (TmplScope && !TmplScope->decl_empty())
KnownDependent = true;
-
+ }
// Determine the signature of the call operator.
TypeSourceInfo *MethodTyInfo;
bool ExplicitParams = true;
@@ -542,7 +621,11 @@
FunctionProtoType::ExtProtoInfo EPI;
EPI.HasTrailingReturn = true;
EPI.TypeQuals |= DeclSpec::TQ_const;
- QualType MethodTy = Context.getFunctionType(Context.DependentTy, None,
+ // For C++1y, use the new return type deduction machinery, by imaginging
+ // 'auto' if no trailing return type.
+ QualType DefaultTypeForNoTrailingReturn = getLangOpts().CPlusPlus1y ?
+ Context.getAutoDeductType() : Context.DependentTy;
+ QualType MethodTy = Context.getFunctionType(DefaultTypeForNoTrailingReturn, None,
EPI);
MethodTyInfo = Context.getTrivialTypeSourceInfo(MethodTy);
ExplicitParams = false;
@@ -560,14 +643,15 @@
if (!FTI.hasMutableQualifier())
FTI.TypeQuals |= DeclSpec::TQ_const;
+ ExplicitResultType = FTI.hasTrailingReturnType();
+ // In C++11 if there is no explicit return type, the return type is
+ // artificially set to DependentTy, whereas in C++1y it is set to AutoTy
+ // (through ConvertDeclSpecToType) which allows us to support both
+ // C++11 and C++1y return type deduction semantics.
MethodTyInfo = GetTypeForDeclarator(ParamInfo, CurScope);
assert(MethodTyInfo && "no type from lambda-declarator");
EndLoc = ParamInfo.getSourceRange().getEnd();
- ExplicitResultType
- = MethodTyInfo->getType()->getAs<FunctionType>()->getResultType()
- != Context.DependentTy;
-
if (FTI.NumArgs == 1 && !FTI.isVariadic && FTI.ArgInfo[0].Ident == 0 &&
cast<ParmVarDecl>(FTI.ArgInfo[0].Param)->getType()->isVoidType()) {
// Empty arg list, don't push any params.
@@ -588,7 +672,6 @@
CXXMethodDecl *Method = startLambdaDefinition(Class, Intro.Range,
MethodTyInfo, EndLoc, Params);
-
if (ExplicitParams)
CheckCXXDefaultArguments(Method);
@@ -598,9 +681,8 @@
// Introduce the function call operator as the current declaration context.
PushDeclContext(CurScope, Method);
- // Introduce the lambda scope.
- LambdaScopeInfo *LSI
- = enterLambdaScope(Method,
+ // Build the lambda scope.
+ buildLambdaScope(LSI, Method,
Intro.Range,
Intro.Default, Intro.DefaultLoc,
ExplicitParams,
@@ -812,6 +894,8 @@
SourceRange IntroducerRange,
CXXRecordDecl *Class,
CXXMethodDecl *CallOperator) {
+ // FIXME: The conversion operator needs to be fixed for generic lambdas.
+ if (Class->isGenericLambda()) return;
// Add the conversion to function pointer.
const FunctionProtoType *Proto
= CallOperator->getType()->getAs<FunctionProtoType>();
@@ -849,10 +933,9 @@
Conversion->setAccess(AS_public);
Conversion->setImplicit(true);
Class->addDecl(Conversion);
-
- // Add a non-static member function "__invoke" that will be the result of
- // the conversion.
- Name = &S.Context.Idents.get("__invoke");
+ // Add a non-static member function that will be the result of
+ // the conversion with a certain unique ID.
+ Name = &S.Context.Idents.get(getLambdaStaticInvokerName());
CXXMethodDecl *Invoke
= CXXMethodDecl::Create(S.Context, Class, Loc,
DeclarationNameInfo(Name, Loc), FunctionTy,
@@ -1000,8 +1083,11 @@
// If a lambda-expression does not include a
// trailing-return-type, it is as if the trailing-return-type
// denotes the following type:
+ // Skip for C++1y return type deduction semantics which uses
+ // different machinery currently.
+ // FIXME: Refactor and Merge the return type deduction machinery.
// FIXME: Assumes current resolution to core issue 975.
- if (LSI->HasImplicitReturnType) {
+ if (LSI->HasImplicitReturnType && !getLangOpts().CPlusPlus1y) {
deduceClosureReturnType(*LSI);
// - if there are no return statements in the
@@ -1019,13 +1105,18 @@
LSI->ReturnType, Proto->getArgTypes(), Proto->getExtProtoInfo());
CallOperator->setType(FunctionTy);
}
-
// C++ [expr.prim.lambda]p7:
// The lambda-expression's compound-statement yields the
// function-body (8.4) of the function call operator [...].
ActOnFinishFunctionBody(CallOperator, Body, IsInstantiation);
CallOperator->setLexicalDeclContext(Class);
- Class->addDecl(CallOperator);
+ Decl *TemplateOrNonTemplateCallOperatorDecl =
+ !CallOperator->getDescribedFunctionTemplate() ? cast<Decl>(CallOperator)
+ : CallOperator->getDescribedFunctionTemplate();
+
+ TemplateOrNonTemplateCallOperatorDecl->setLexicalDeclContext(Class);
+ Class->addDecl(TemplateOrNonTemplateCallOperatorDecl);
+
PopExpressionEvaluationContext();
// C++11 [expr.prim.lambda]p6:
@@ -1065,7 +1156,7 @@
CaptureInits, ArrayIndexVars,
ArrayIndexStarts, Body->getLocEnd(),
ContainsUnexpandedParameterPack);
-
+ Class->setLambdaExpr(Lambda);
// C++11 [expr.prim.lambda]p2:
// A lambda-expression shall not appear in an unevaluated operand
// (Clause 5).
@@ -1085,7 +1176,15 @@
break;
}
}
-
+ // TODO: Implement capturing.
+ if (Lambda->isGenericLambda()) {
+ if (Lambda->getCaptureDefault() != LCD_None) {
+ Diag(Lambda->getIntroducerRange().getBegin(),
+ diag::err_glambda_not_fully_implemented)
+ << " capturing not implemented yet";
+ return ExprError();
+ }
+ }
return MaybeBindToTemporary(Lambda);
}