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/Parse/ParseExprCXX.cpp b/lib/Parse/ParseExprCXX.cpp
index 9ac6d43..1ab7047 100644
--- a/lib/Parse/ParseExprCXX.cpp
+++ b/lib/Parse/ParseExprCXX.cpp
@@ -20,6 +20,7 @@
#include "clang/Sema/ParsedTemplate.h"
#include "clang/Sema/Scope.h"
#include "llvm/Support/ErrorHandling.h"
+#include "clang/AST/DeclTemplate.h"
using namespace clang;
@@ -908,12 +909,16 @@
PrettyStackTraceLoc CrashInfo(PP.getSourceManager(), LambdaBeginLoc,
"lambda expression parsing");
+
+
// FIXME: Call into Actions to add any init-capture declarations to the
// scope while parsing the lambda-declarator and compound-statement.
// Parse lambda-declarator[opt].
DeclSpec DS(AttrFactory);
Declarator D(DS, Declarator::LambdaExprContext);
+ TemplateParameterDepthRAII CurTemplateDepthTracker(TemplateParameterDepth);
+ Actions.PushLambdaScope();
if (Tok.is(tok::l_paren)) {
ParseScope PrototypeScope(this,
@@ -931,9 +936,17 @@
SmallVector<DeclaratorChunk::ParamInfo, 16> ParamInfo;
SourceLocation EllipsisLoc;
- if (Tok.isNot(tok::r_paren))
+
+ if (Tok.isNot(tok::r_paren)) {
+ sema::LambdaScopeInfo *LSI = Actions.getCurLambda();
+ if (getLangOpts().CPlusPlus1y)
+ Actions.RecordParsingTemplateParameterDepth(TemplateParameterDepth);
ParseParameterDeclarationClause(D, Attr, ParamInfo, EllipsisLoc);
-
+ // For a generic lambda, each 'auto' within the parameter declaration
+ // clause creates a template type parameter, so increment the depth.
+ if (getLangOpts().CPlusPlus1y && Actions.getCurGenericLambda())
+ ++CurTemplateDepthTracker;
+ }
T.consumeClose();
SourceLocation RParenLoc = T.getCloseLocation();
DeclEndLoc = RParenLoc;