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/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 80863e3..d5d8904 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -35,6 +35,7 @@
#include "clang/Sema/DeclSpec.h"
#include "clang/Sema/DelayedDiagnostic.h"
#include "clang/Sema/Initialization.h"
+#include "clang/Sema/SemaLambda.h"
#include "clang/Sema/Lookup.h"
#include "clang/Sema/ParsedTemplate.h"
#include "clang/Sema/Scope.h"
@@ -8909,6 +8910,7 @@
const DeclSpec &DS = D.getDeclSpec();
// Verify C99 6.7.5.3p2: The only SCS allowed is 'register'.
+
// C++03 [dcl.stc]p2 also permits 'auto'.
VarDecl::StorageClass StorageClass = SC_None;
if (DS.getStorageClassSpec() == DeclSpec::SCS_register) {
@@ -9015,6 +9017,14 @@
if (New->hasAttr<BlocksAttr>()) {
Diag(New->getLocation(), diag::err_block_on_nonlocal);
}
+
+ // Handle 'auto' within a generic lambda.
+ QualType ParamType = New->getType();
+ if (getLangOpts().CPlusPlus1y && ParamType->getContainedAutoType()) {
+ assert(getCurLambda() &&
+ "'auto' in parameter type only allowed in lambdas!");
+ New = ActOnLambdaAutoParameter(New);
+ }
return New;
}
@@ -9268,9 +9278,38 @@
FD = FunTmpl->getTemplatedDecl();
else
FD = cast<FunctionDecl>(D);
+ // If we are instantiating a generic lambda call operator, push
+ // a LambdaScopeInfo onto the function stack. But use the information
+ // that's already been calculated (ActOnLambdaExpr) when analyzing the
+ // template version, to prime the current LambdaScopeInfo.
+ if (getLangOpts().CPlusPlus1y
+ && isGenericLambdaCallOperatorSpecialization(D)) {
+ CXXMethodDecl *CallOperator = cast<CXXMethodDecl>(D);
+ CXXRecordDecl *LambdaClass = CallOperator->getParent();
+ LambdaExpr *LE = LambdaClass->getLambdaExpr();
+ assert(LE &&
+ "No LambdaExpr of closure class when instantiating a generic lambda!");
+ assert(ActiveTemplateInstantiations.size() &&
+ "There should be an active template instantiation on the stack "
+ "when instantiating a generic lambda!");
+ PushLambdaScope();
+ LambdaScopeInfo *LSI = getCurLambda();
+ LSI->CallOperator = CallOperator;
+ LSI->Lambda = LambdaClass;
+ LSI->ReturnType = CallOperator->getResultType();
- // Enter a new function scope
- PushFunctionScope();
+ if (LE->getCaptureDefault() == LCD_None)
+ LSI->ImpCaptureStyle = CapturingScopeInfo::ImpCap_None;
+ else if (LE->getCaptureDefault() == LCD_ByCopy)
+ LSI->ImpCaptureStyle = CapturingScopeInfo::ImpCap_LambdaByval;
+ else if (LE->getCaptureDefault() == LCD_ByRef)
+ LSI->ImpCaptureStyle = CapturingScopeInfo::ImpCap_LambdaByref;
+
+ LSI->IntroducerRange = LE->getIntroducerRange();
+ }
+ else
+ // Enter a new function scope
+ PushFunctionScope();
// See if this is a redefinition.
if (!FD->isLateTemplateParsed())