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/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
index 29ddb37..b1b52fb 100644
--- a/lib/AST/ASTContext.cpp
+++ b/lib/AST/ASTContext.cpp
@@ -3649,20 +3649,24 @@
/// deduced to the given type, or to the canonical undeduced 'auto' type, or the
/// canonical deduced-but-dependent 'auto' type.
QualType ASTContext::getAutoType(QualType DeducedType, bool IsDecltypeAuto,
- bool IsDependent) const {
- if (DeducedType.isNull() && !IsDecltypeAuto && !IsDependent)
+ bool IsDependent, bool IsParameterPack) const {
+ if (DeducedType.isNull() && !IsDecltypeAuto && !IsDependent &&
+ !IsParameterPack)
return getAutoDeductType();
-
+ assert(!IsParameterPack || DeducedType.isNull()
+ && "Auto parameter pack: auto ... a should always be undeduced!");
// Look in the folding set for an existing type.
void *InsertPos = 0;
llvm::FoldingSetNodeID ID;
- AutoType::Profile(ID, DeducedType, IsDecltypeAuto, IsDependent);
+ AutoType::Profile(ID, DeducedType, IsDecltypeAuto, IsDependent,
+ IsParameterPack);
if (AutoType *AT = AutoTypes.FindNodeOrInsertPos(ID, InsertPos))
return QualType(AT, 0);
AutoType *AT = new (*this, TypeAlignment) AutoType(DeducedType,
IsDecltypeAuto,
- IsDependent);
+ IsDependent,
+ IsParameterPack);
Types.push_back(AT);
if (InsertPos)
AutoTypes.InsertNode(AT, InsertPos);
@@ -3702,7 +3706,8 @@
if (AutoDeductTy.isNull())
AutoDeductTy = QualType(
new (*this, TypeAlignment) AutoType(QualType(), /*decltype(auto)*/false,
- /*dependent*/false),
+ /*dependent*/false,
+ /*IsParameterPack*/false),
0);
return AutoDeductTy;
}