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
136 lines
3.3 KiB
C++
136 lines
3.3 KiB
C++
// RUN: %clang_cc1 -fsyntax-only -verify %s -std=c++1y -DCXX1Y -emit-llvm
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namespace test_factorial {
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auto Fact = [](auto Self, unsigned n) -> unsigned {
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return !n ? 1 : Self(Self, n - 1) * n;
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};
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auto six = Fact(Fact, 3);
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}
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namespace overload_generic_lambda {
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template <class F1, class F2> struct overload : F1, F2 {
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using F1::operator();
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using F2::operator();
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overload(F1 f1, F2 f2) : F1(f1), F2(f2) { }
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};
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auto NumParams = [](auto Self, auto h, auto ... rest) -> unsigned {
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return 1 + Self(Self, rest...);
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};
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auto Base = [](auto Self, auto h) -> unsigned {
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return 1;
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};
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overload<decltype(Base), decltype(NumParams)> O(Base, NumParams);
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int num_params = O(O, 5, 3, "abc", 3.14, 'a');
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}
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namespace overload_generic_lambda_return_type_deduction {
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template <class F1, class F2> struct overload : F1, F2 {
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using F1::operator();
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using F2::operator();
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overload(F1 f1, F2 f2) : F1(f1), F2(f2) { }
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};
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auto NumParams = [](auto Self, auto h, auto ... rest) {
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return 1 + Self(Self, rest...);
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};
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auto Base = [](auto Self, auto h) {
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return 1;
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};
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overload<decltype(Base), decltype(NumParams)> O(Base, NumParams);
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int num_params = O(O, 5, 3, "abc", 3.14, 'a');
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}
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namespace test_standard_p5 {
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// FIXME: This test should eventually compile without an explicit trailing return type
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auto glambda = [](auto a, auto&& b) ->bool { return a < b; };
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bool b = glambda(3, 3.14); // OK
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}
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namespace test_deduction_failure {
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int test() {
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auto g = [](auto *a) { //expected-note{{candidate template ignored}}
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return a;
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};
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struct X { };
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X *x;
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g(x);
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g(3); //expected-error{{no matching function}}
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return 0;
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}
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}
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namespace test_instantiation_or_sfinae_failure {
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int test2() {
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{
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auto L = [](auto *a) {
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return (*a)(a); }; //expected-error{{called object type 'double' is not a function}}
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//l(&l);
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double d;
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L(&d); //expected-note{{in instantiation of}}
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auto M = [](auto b) { return b; };
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L(&M); // ok
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}
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{
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auto L = [](auto *a) ->decltype (a->foo()) { //expected-note2{{candidate template ignored:}}
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return (*a)(a); };
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//l(&l);
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double d;
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L(&d); //expected-error{{no matching function for call}}
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auto M = [](auto b) { return b; };
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L(&M); //expected-error{{no matching function for call}}
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}
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return 0;
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}
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}
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namespace test_misc {
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auto GL = [](auto a, decltype(a) b) //expected-note{{candidate function}}
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-> int { return a + b; };
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void test() {
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struct X { };
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GL(3, X{}); //expected-error{{no matching function}}
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}
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void test2() {
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auto l = [](auto *a) -> int {
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(*a)(a); return 0; }; //expected-error{{called object type 'double' is not a function}}
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l(&l);
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double d;
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l(&d); //expected-note{{in instantiation of}}
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}
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}
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namespace nested_lambdas {
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int test() {
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auto L = [](auto a) {
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return [=](auto b) { //expected-error{{unimplemented}}
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return a + b;
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};
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};
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// auto M = L(3.14);
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// return M('4');
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}
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auto get_lambda() {
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return [](auto a) {
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return a;
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};
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};
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int test2() {
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auto L = get_lambda();
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L(3);
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}
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}
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