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[C++ PATCH] P0428R2 - familiar template syntax for generic lambdas
- From: Jakub Jelinek <jakub at redhat dot com>
- To: Jason Merrill <jason at redhat dot com>, Nathan Sidwell <nathan at acm dot org>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Fri, 10 Nov 2017 15:33:49 +0100
- Subject: [C++ PATCH] P0428R2 - familiar template syntax for generic lambdas
- Authentication-results: sourceware.org; auth=none
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
Hi!
This feature seems to be fully implemented from what I can see, except that we
pedwarn on it, which we shouldn't do for -std=c++2a or -std=gnu++2a when it is
standard.
I'm not really sure about the pedwarn wording(s), the reality is that
it is supported for C++14 and later as an extension and for C++2A and later
as standard feature.
Regtested on x86_64-linux with check-c++-all.
2017-11-10 Jakub Jelinek <jakub@redhat.com>
P0428R2 - familiar template syntax for generic lambdas
* parser.c (cp_parser_lambda_declarator_opt): Don't pedwarn
for cxx2a and above, reword pedwarn for C++14/C++17.
* g++.dg/cpp1y/lambda-generic-x.C: Adjust warnings and limit
to c++17_down target.
* g++.dg/cpp1y/lambda-generic-dep.C: Likewise.
* g++.dg/cpp1y/lambda-generic-77914.C: Adjust error and limit
to c++17_down target.
* g++.dg/cpp2a/lambda-generic1.C: New test.
--- gcc/cp/parser.c.jj 2017-11-01 22:49:15.000000000 +0100
+++ gcc/cp/parser.c 2017-11-10 13:21:16.475915963 +0100
@@ -10510,9 +10510,10 @@ cp_parser_lambda_declarator_opt (cp_pars
pedwarn (parser->lexer->next_token->location, 0,
"lambda templates are only available with "
"-std=c++14 or -std=gnu++14");
- else
+ else if (cxx_dialect < cxx2a)
pedwarn (parser->lexer->next_token->location, OPT_Wpedantic,
- "ISO C++ does not support lambda templates");
+ "lambda templates are only available with "
+ "-std=c++2a or -std=gnu++2a");
cp_lexer_consume_token (parser->lexer);
--- gcc/testsuite/g++.dg/cpp1y/lambda-generic-x.C.jj 2017-01-25 21:50:13.000000000 +0100
+++ gcc/testsuite/g++.dg/cpp1y/lambda-generic-x.C 2017-11-10 13:25:29.113922954 +0100
@@ -6,17 +6,17 @@
int main()
{
- auto glambda = [] <typename A, typename B> (A a, B&& b) { return a < b; }; // { dg-warning "does not support lambda templates" }
+ auto glambda = [] <typename A, typename B> (A a, B&& b) { return a < b; }; // { dg-warning "lambda templates are only available with" "" { target c++17_down } }
bool b = glambda(3, 3.14); // OK
- auto vglambda = [] <typename P> (P printer) { // { dg-warning "does not support lambda templates" }
+ auto vglambda = [] <typename P> (P printer) { // { dg-warning "lambda templates are only available with" "" { target c++17_down } }
return [=] <typename... T> (T&& ... ts) { // OK: ts is a function parameter pack
- printer(std::forward<decltype(ts)>(ts)...); // { dg-warning "does not support lambda templates" "" { target *-*-* } .-1 }
+ printer(std::forward<decltype(ts)>(ts)...); // { dg-warning "lambda templates are only available with" "" { target c++17_down } .-1 }
return [=]() {
printer(ts ...);
};
};
};
- auto p = vglambda( [] <typename A, // { dg-warning "does not support lambda templates" }
+ auto p = vglambda( [] <typename A, // { dg-warning "lambda templates are only available with" "" { target c++17_down } }
typename B,
typename C> (A v1, B v2, C v3)
{ std::cout << v1 << v2 << v3; } );
--- gcc/testsuite/g++.dg/cpp1y/lambda-generic-dep.C.jj 2017-01-25 21:50:13.000000000 +0100
+++ gcc/testsuite/g++.dg/cpp1y/lambda-generic-dep.C 2017-11-10 13:23:47.218130116 +0100
@@ -27,7 +27,7 @@ struct S {
int main()
{
- auto f = [] <typename T> (T const& s) mutable { // { dg-warning "does not support lambda templates" }
+ auto f = [] <typename T> (T const& s) mutable { // { dg-warning "lambda templates are only available with" "" { target c++17_down } }
typename T::N x;
return x.test ();
};
--- gcc/testsuite/g++.dg/cpp1y/lambda-generic-77914.C.jj 2017-01-25 21:50:13.000000000 +0100
+++ gcc/testsuite/g++.dg/cpp1y/lambda-generic-77914.C 2017-11-10 13:23:32.644302773 +0100
@@ -4,6 +4,6 @@
int
main ()
{
- auto l = [] <typename T> () {}; // { dg-error "does not support lambda templates" }
+ auto l = [] <typename T> () {}; // { dg-error "lambda templates are only available with" "" { target c++17_down } }
l.operator () <void> ();
}
--- gcc/testsuite/g++.dg/cpp2a/lambda-generic1.C.jj 2017-11-10 13:26:08.666448084 +0100
+++ gcc/testsuite/g++.dg/cpp2a/lambda-generic1.C 2017-11-10 13:29:03.518348714 +0100
@@ -0,0 +1,9 @@
+// P0428R2
+// { dg-do compile { target c++14 } }
+
+int i = [](int i, auto a) { return i; }(3, 4);
+int j = []<class T>(T t, int i) { return i; }(3, 4); // { dg-error "lambda templates are only available with" "" { target c++17_down } }
+int k[2] = { 5, 6 };
+int l = []<typename T>(T *p) { return *p; }(k); // { dg-error "lambda templates are only available with" "" { target c++17_down } }
+int m = []<typename T, int N>(T (&a)[N]) { return a[N - 1]; }(k); // { dg-error "lambda templates are only available with" "" { target c++17_down } }
+int n = []<typename T>(T a, auto b) { return a + b; }(7, 8); // { dg-error "lambda templates are only available with" "" { target c++17_down } }
Jakub