fd5277c063
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!
llvm-svn: 188977
56 lines
1.3 KiB
C++
56 lines
1.3 KiB
C++
// RUN: %clang_cc1 -fsyntax-only -std=c++11 %s -verify
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// RUN: %clang_cc1 -fsyntax-only -std=c++1y %s -verify -DCPP1Y
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void missing_lambda_declarator() {
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[](){}();
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}
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template<typename T> T get();
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void infer_void_return_type(int i) {
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if (i > 17)
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return []() { }();
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if (i > 11)
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return []() { return; }();
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return [](int x) {
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switch (x) {
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case 0: return get<void>();
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case 1: return;
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case 2: return { 1, 2.0 }; //expected-error{{cannot deduce}}
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}
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}(7);
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}
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struct X { };
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X infer_X_return_type(X x) {
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return [&x](int y) {
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if (y > 0)
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return X();
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else
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return x;
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}(5);
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}
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X infer_X_return_type_fail(X x) {
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return [x](int y) {
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if (y > 0)
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return X();
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else
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return x;
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#if __cplusplus <= 201103L
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// expected-error@-2 {{return type 'const X' must match previous return type 'X' when lambda expression has unspecified explicit return type}}
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#endif
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}(5);
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}
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struct Incomplete; // expected-note{{forward declaration of 'Incomplete'}}
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void test_result_type(int N) {
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auto l1 = [] () -> Incomplete { }; // expected-error{{incomplete result type 'Incomplete' in lambda expression}}
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typedef int vla[N];
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auto l2 = [] () -> vla { }; // expected-error{{function cannot return array type 'vla' (aka 'int [N]')}}
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}
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