// N4606 Committee Draft, Standard for Programming Language C++
// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/n4606.pdf 
#define msg "p97.cpp (37)5.1.5 Lambda expressions [expr.prim.lambda]"

#include <iostream>
#include <cassert>
#include <algorithm>
#include <cmath>
#include <utility> 
#include <type_traits>

void abssort(float* x, unsigned N) {
std::sort(x, x + N,
[](float a, float b) {
return std::abs(a) < std::abs(b);
});
}

auto monoid = [](auto v) { return [=] { return v; }; };
auto add = [](auto m1) constexpr {
auto ret = m1();
return [=](auto m2) mutable {
auto m1val = m1();
auto plus = [=](auto m2val) mutable constexpr
{ return m1val += m2val; };
ret = plus(m2());
return monoid(ret);
};
};
constexpr auto zero = monoid(0);
constexpr auto one = monoid(1);
static_assert(add(one)(zero)() == one()); // OK
// Since two below is not declared constexpr, an evaluation of its constexpr member function call operator
// cannot perform an lvalue-to-rvalue conversion on one of its subobjects (that represents its capture)
// in a constant expression.
auto two = monoid(2);
assert(two() == 2); // OK, not a constant expression.
static_assert(add(one)(one)() == two()); // ill-formed: two() is not a constant expression
static_assert(add(one)(one)() == monoid(2)()); // OK

auto x1 = [](int i){ return i; }; // OK: return type is int
auto x2 = []{ return { 1, 2 }; }; // error: deducing return type from braced-init-list
int j;
auto x3 = []()->auto&& { return j; }; // OK: return type is int&

auto glambda = [](auto a, auto&& b) { return a < b; };
bool b = glambda(3, 3.14); // OK
auto vglambda = [](auto printer) {
return [=](auto&& ... ts) { // OK: ts is a function parameter pack
printer(std::forward<decltype(ts)>(ts)...);
return [=]() {
printer(ts ...);
};
};
};
auto p = vglambda( [](auto v1, auto v2, auto v3)
{ std::cout << v1 << v2 << v3; } );
auto q = p(1, 'a', 3.14); // OK: outputs 1a3.14
q(); // OK: outputs 1a3.14

auto ID = [](auto a) { return a; };
static_assert(ID(3) == 3); // OK
struct NonLiteral {
NonLiteral(int n) : n(n) { }
int n;
};

static_assert(ID(NonLiteral{3}).n == 3); // function template. Consider the following:
auto glambda = [](auto a) { return a; };
int (*fp)(int) = glambda;

struct Closure {
template<class T> auto operator()(T t) const { ... }
template<class T> static auto lambda_call_operator_invoker(T a) {
// forwards execution to operator()(a) and therefore has
// the same return type deduced
...
}
template<class T> using fptr_t =
decltype(lambda_call_operator_invoker(declval<T>())) (*)(T);
template<class T> operator fptr_t<T>() const
{ return &lambda_call_operator_invoker; }
};

void f1(int (*)(int)) { }
void f2(char (*)(int)) { }
void g(int (*)(int)) { } // #1
void g(char (*)(char)) { } // #2
void h(int (*)(int)) { } // #3
void h(char (*)(int)) { } // #4
auto glambda = [](auto a) { return a; };
f1(glambda); // OK
f2(glambda); // error: ID is not convertible
g(glambda); // error: ambiguous
h(glambda); // OK: calls #3 since it is convertible from ID
int& (*fpi)(int*) = [](auto* a) -> auto& { return *a; }; // OK

auto GL = [](auto a) { std::cout << a; return a; };
int (*GL_int)(int) = GL; // OK: through conversion function template
GL_int(3); // OK: same as GL(3)

auto Fwd = [](int (*fp)(int), auto a) { return fp(a); };
auto C = [](auto a) { return a; };
static_assert(Fwd(C,3) == 3); // OK
// No specialization of the function call operator template can be constexpr (due to the local static).
auto NC = [](auto a) { static int s; return a; };
static_assert(Fwd(NC,3) == 3); // ill-formed

struct S1 {
int x, y;
int operator()(int);
void f() {
[=]()->int {
return operator()(this->x + y); // equivalent to S1::operator()(this->x + (*this).y)
// this has type S1*
};
}
};

struct S2 { void f(int i); };
void S2::f(int i) {
[&, i]{ }; // OK
[&, &i]{ }; // error: i preceded by & when & is the default
[=, *this]{ }; // OK
[=, this]{ }; // error: this when = is the default
[i, i]{ }; // error: i repeated
[this, *this]{ }; // error: this appears twice
}

void f(int, const int (&)[2] = {}) { } // #1
void f(const int&, const int (&)[1]) { } // #2
void test() {
const int x = 17;
auto g = [](auto a) {
f(x); // OK: calls #1, does not capture x
};
auto g2 = [=](auto a) {
int selector[sizeof(a) == 1 ? 1 : 2]{};
f(x, selector); // OK: is a dependent expression, so captures x
};
}

void f1(int i) {
int const N = 20;
auto m1 = [=]{
int const M = 30;
auto m2 = [i]{
int x[N][M]; // OK: N and M are not odr-used
x[0][0] = i; // OK: i is explicitly captured by m2
// and implicitly captured by m1
};
};
struct s1 {
int f;
void work(int n) {
int m = n*n;
int j = 40;
auto m3 = [this,m] {
auto m4 = [&,j] { // error: j not captured by m3
int x = n; // error: n implicitly captured by m4
// but not captured by m3
x += m; // OK: m implicitly captured by m4
// and explicitly captured by m3
x += i; // error: i is outside of the reaching scope
x += f; // OK: this captured implicitly by m4
// and explicitly by m3
};
};
}
};
}
struct


int main(int argc, char *argv[], char *envp[]){
　p p1=argv;
  int i=3;
  q q1 = &i;
  pi pi1 = &q1;
  pci pci1 = &pi1;
  std::cout << "p1="<<p1 <<" q1=" << q1 << " pi1="<<pi1<<" pci1="<<pci1<<std::endl;
  std::cout << msg << std::endl;
  return EXIT_SUCCESS;
}

struct s2 {
double ohseven = .007;
auto f() {
return [this] {
return [*this] {
return ohseven; // OK
}
}();
}
auto g() {
return [] {
return [*this] { }; // error: *this not captured by outer lambda-expression
}();
}
};


void f2() {
int i = 1;
void g1(int = ([i]{ return i; })()); // ill-formed
void g2(int = ([i]{ return 0; })()); // ill-formed
void g3(int = ([=]{ return i; })()); // ill-formed
void g4(int = ([=]{ return 0; })()); // OK
void g5(int = ([]{ return sizeof i; })()); // OK


void f(const int*);
void g() {
const int N = 10;
[=] {
int arr[N]; // OK: not an odr-use, refers to automatic variable
f(&N); // OK: causes N to be captured; &N points to the
// corresponding member of the closure type
};
}


// The inner closure type must be a literal type regardless of how reference captures are represented.
static_assert([](int n) { return [&n] { return ++n; }(); }(3) == 4);

Example: the nested lambda expressions and invocations below will output 123234.
int a = 1, b = 1, c = 1;
auto m1 = [a, &b, &c]() mutable {
auto m2 = [a, b, &c]() mutable {
std::cout << a << b << c;
a = 4; b = 4; c = 4;
};
a = 3; b = 3; c = 3;
m2();
};
a = 2; b = 2; c = 2;
m1();
std::cout << a << b << c;

void f3() {
float x, &r = x;
[=] { // x and r are not captured (appearance in a decltype operand is not an odr-use)
decltype(x) y1; // y1 has type float
decltype((x)) y2 = y1; // y2 has type float const& because this lambda
// is not mutable and x is an lvalue
decltype(r) r1 = y1; // r1 has type float& (transformation not considered)
decltype((r)) r2 = y2; // r2 has type float const&
};
}
template<class... Args>
void f(Args... args) {
auto lm = [&, args...] { return g(args...); };
lm();


}
int main(int argc, char *argv[], char *envp[]){


  std::cout << msg << std::endl;
  return EXIT_SUCCESS;
}

$ ./cppgl17.sh p97
$ clang++ p97.cpp
p97.cpp:37:1: error: expected parameter declarator
assert(two() == 2); // OK, not a constant expression.
^
/usr/include/assert.h:93:23: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                      ^
p97.cpp:37:1: error: expected ')'
/usr/include/assert.h:93:23: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                      ^
p97.cpp:37:1: note: to match this '('
/usr/include/assert.h:93:22: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                     ^
p97.cpp:37:1: error: expected ')'
assert(two() == 2); // OK, not a constant expression.
^
/usr/include/assert.h:93:32: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
                               ^
p97.cpp:37:1: note: to match this '('
/usr/include/assert.h:93:5: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
    ^
p97.cpp:37:1: error: C++ requires a type specifier for all declarations
assert(two() == 2); // OK, not a constant expression.
^
/usr/include/assert.h:93:6: note: expanded from macro 'assert'
    (__builtin_expect(!(e), 0) ? __assert_rtn(__func__, __FILE__, __LINE__, #e) : (void)0)
     ^
p97.cpp:38:15: error: static_assert expression is not an integral constant expression
static_assert(add(one)(one)() == two()); // ill-formed: two() is not a constant expression
              ^~~~~~~~~~~~~~~~~~~~~~~~
p97.cpp:19:48: note: read of non-constexpr variable 'two' is not allowed in a constant expression
auto monoid = [](auto v) { return [=] { return v; }; };
                                               ^
p97.cpp:38:34: note: in call to '&two->operator()()'
static_assert(add(one)(one)() == two()); // ill-formed: two() is not a constant expression
                                 ^
p97.cpp:36:6: note: declared here
auto two = monoid(2);
     ^
p97.cpp:42:22: error: cannot deduce lambda return type from initializer list
auto x2 = []{ return { 1, 2 }; }; // error: deducing return type from braced-init-list
                     ^~~~~~~~
p97.cpp:59:1: error: C++ requires a type specifier for all declarations
q(); // OK: outputs 1a3.14
^
p97.cpp:68:15: error: static_assert expression is not an integral constant expression
static_assert(ID(NonLiteral{3}).n == 3); // function template. Consider the following:
              ^~~~~~~~~~~~~~~~~~~~~~~~
p97.cpp:68:15: note: non-literal type 'NonLiteral' cannot be used in a constant expression
p97.cpp:69:6: error: redefinition of 'glambda'
auto glambda = [](auto a) { return a; };
     ^
p97.cpp:46:6: note: previous definition is here
auto glambda = [](auto a, auto&& b) { return a < b; };
     ^
p97.cpp:70:7: error: no viable conversion from '(lambda at p97.cpp:46:16)' to 'int (*)(int)'
int (*fp)(int) = glambda;
      ^          ~~~~~~~
p97.cpp:46:16: note: candidate template ignored: failed template argument deduction
auto glambda = [](auto a, auto&& b) { return a < b; };
               ^
p97.cpp:80:39: error: no template named 'declval'; did you mean 'std::declval'?
decltype(lambda_call_operator_invoker(declval<T>())) (*)(T);
                                      ^~~~~~~
                                      std::declval
/usr/local/Cellar/llvm/6.0.0/include/c++/v1/type_traits:1147:1: note: 'std::declval' declared here
declval() _NOEXCEPT;
^
p97.cpp:80:39: error: no template named 'declval'; did you mean 'std::declval'?
decltype(lambda_call_operator_invoker(declval<T>())) (*)(T);
                                      ^~~~~~~
                                      std::declval
/usr/local/Cellar/llvm/6.0.0/include/c++/v1/type_traits:1147:1: note: 'std::declval' declared here
declval() _NOEXCEPT;
^
p97.cpp:73:48: error: expected expression
template<class T> auto operator()(T t) const { ... }
                                               ^
p97.cpp:77:1: error: expected expression
...
^
p97.cpp:91:6: error: redefinition of 'glambda'
auto glambda = [](auto a) { return a; };
     ^
p97.cpp:46:6: note: previous definition is here
auto glambda = [](auto a, auto&& b) { return a < b; };
     ^
p97.cpp:92:1: error: unknown type name 'f1'
f1(glambda); // OK
^
p97.cpp:93:1: error: unknown type name 'f2'
f2(glambda); // error: ID is not convertible
^
p97.cpp:94:1: error: unknown type name 'g'
g(glambda); // error: ambiguous
^
p97.cpp:95:1: error: unknown type name 'h'
h(glambda); // OK: calls #3 since it is convertible from ID
^
fatal error: too many errors emitted, stopping now [-ferror-limit=]
20 errors generated.

$ g++-7 p97.cpp
p97.cpp:176:1: error: stray '\343' in program
 ???p p1=argv;
 ^
p97.cpp:176:2: error: stray '\200' in program
 ???p p1=argv;
  ^
p97.cpp:176:3: error: stray '\200' in program
 ??p p1=argv;
   ^
In file included from /usr/local/Cellar/gcc/7.3.0_1/include/c++/7.3.0/cassert:44:0,
                 from p97.cpp:6:
p97.cpp:37:1: error: expected ')' before '(' token
 assert(two() == 2); // OK, not a constant expression.
 ^
p97.cpp:38:1: error: non-constant condition for static assertion
 static_assert(add(one)(one)() == two()); // ill-formed: two() is not a constant expression
 ^~~~~~~~~~~~~
p97.cpp:38:37:   in constexpr expansion of 'two.<lambda(auto:1)> [with auto:1 = int]::<lambda()>()'
p97.cpp:38:1: error: the value of 'two' is not usable in a constant expression
p97.cpp:36:6: note: 'two' was not declared 'constexpr'
 auto two = monoid(2);
      ^~~
p97.cpp: In lambda function:
p97.cpp:42:29: error: returning initializer list
 auto x2 = []{ return { 1, 2 }; }; // error: deducing return type from braced-init-list
                             ^
p97.cpp: At global scope:
p97.cpp:59:4: error: expected constructor, destructor, or type conversion before ';' token
 q(); // OK: outputs 1a3.14
    ^
p97.cpp:68:1: error: non-constant condition for static assertion
 static_assert(ID(NonLiteral{3}).n == 3); // function template. Consider the following:
 ^~~~~~~~~~~~~
p97.cpp:68:17: error: temporary of non-literal type 'NonLiteral' in a constant expression
 static_assert(ID(NonLiteral{3}).n == 3); // function template. Consider the following:
               ~~^~~~~~~~~~~~~~~
p97.cpp:63:8: note: 'NonLiteral' is not literal because:
 struct NonLiteral {
        ^~~~~~~~~~
p97.cpp:63:8: note:   'NonLiteral' is not an aggregate, does not have a trivial default constructor, and has no constexpr constructor that is not a copy or move constructor
p97.cpp:69:6: error: conflicting declaration 'auto glambda'
 auto glambda = [](auto a) { return a; };
      ^~~~~~~
p97.cpp:46:6: note: previous declaration as '<lambda(auto:5, auto:6&&)> glambda'
 auto glambda = [](auto a, auto&& b) { return a < b; };
      ^~~~~~~
p97.cpp:70:18: error: cannot convert '<lambda(auto:5, auto:6&&)>' to 'int (*)(int)' in initialization
 int (*fp)(int) = glambda;
                  ^~~~~~~
p97.cpp:80:39: error: 'declval' was not declared in this scope
 decltype(lambda_call_operator_invoker(declval<T>())) (*)(T);
                                       ^~~~~~~
p97.cpp:80:39: note: suggested alternative:
In file included from /usr/local/Cellar/gcc/7.3.0_1/include/c++/7.3.0/bits/move.h:54:0,
                 from /usr/local/Cellar/gcc/7.3.0_1/include/c++/7.3.0/bits/nested_exception.h:40,
                 from /usr/local/Cellar/gcc/7.3.0_1/include/c++/7.3.0/exception:143,
                 from /usr/local/Cellar/gcc/7.3.0_1/include/c++/7.3.0/ios:39,
                 from /usr/local/Cellar/gcc/7.3.0_1/include/c++/7.3.0/ostream:38,
                 from /usr/local/Cellar/gcc/7.3.0_1/include/c++/7.3.0/iostream:39,
                 from p97.cpp:5:
/usr/local/Cellar/gcc/7.3.0_1/include/c++/7.3.0/type_traits:2254:5: note:   'std::declval'
     declval() noexcept
     ^~~~~~~
p97.cpp:80:39: error: 'declval' was not declared in this scope
 decltype(lambda_call_operator_invoker(declval<T>())) (*)(T);
                                       ^~~~~~~
p97.cpp:80:39: note: suggested alternative:
In file included from /usr/local/Cellar/gcc/7.3.0_1/include/c++/7.3.0/bits/move.h:54:0,
                 from /usr/local/Cellar/gcc/7.3.0_1/include/c++/7.3.0/bits/nested_exception.h:40,
                 from /usr/local/Cellar/gcc/7.3.0_1/include/c++/7.3.0/exception:143,
                 from /usr/local/Cellar/gcc/7.3.0_1/include/c++/7.3.0/ios:39,
                 from /usr/local/Cellar/gcc/7.3.0_1/include/c++/7.3.0/ostream:38,
                 from /usr/local/Cellar/gcc/7.3.0_1/include/c++/7.3.0/iostream:39,
                 from p97.cpp:5:
/usr/local/Cellar/gcc/7.3.0_1/include/c++/7.3.0/type_traits:2254:5: note:   'std::declval'
     declval() noexcept
     ^~~~~~~
p97.cpp:80:48: error: expected primary-expression before '>' token
 decltype(lambda_call_operator_invoker(declval<T>())) (*)(T);
                                                ^
p97.cpp:80:50: error: expected primary-expression before ')' token
 decltype(lambda_call_operator_invoker(declval<T>())) (*)(T);
                                                  ^
p97.cpp:81:28: error: 'fptr_t' does not name a type; did you mean 'fpos_t'?
 template<class T> operator fptr_t<T>() const
                            ^~~~~~
                            fpos_t
p97.cpp: In member function 'auto Closure::operator()(T) const':
p97.cpp:73:48: error: expected primary-expression before '...' token
 template<class T> auto operator()(T t) const { ... }
                                                ^~~
p97.cpp: In static member function 'static auto Closure::lambda_call_operator_invoker(T)':
p97.cpp:77:1: error: expected primary-expression before '...' token
 ...
 ^~~
p97.cpp: At global scope:
p97.cpp:91:6: error: conflicting declaration 'auto glambda'
 auto glambda = [](auto a) { return a; };
      ^~~~~~~
p97.cpp:46:6: note: previous declaration as '<lambda(auto:5, auto:6&&)> glambda'
 auto glambda = [](auto a, auto&& b) { return a < b; };
      ^~~~~~~
p97.cpp:92:3: error: expected constructor, destructor, or type conversion before '(' token
 f1(glambda); // OK
   ^
p97.cpp:93:3: error: expected constructor, destructor, or type conversion before '(' token
 f2(glambda); // error: ID is not convertible
   ^
p97.cpp:94:2: error: expected constructor, destructor, or type conversion before '(' token
 g(glambda); // error: ambiguous
  ^
p97.cpp:95:2: error: expected constructor, destructor, or type conversion before '(' token
 h(glambda); // OK: calls #3 since it is convertible from ID
  ^
p97.cpp:100:7: error: expected constructor, destructor, or type conversion before '(' token
 GL_int(3); // OK: same as GL(3)
       ^
p97.cpp:107:1: error: non-constant condition for static assertion
 static_assert(Fwd(NC,3) == 3); // ill-formed
 ^~~~~~~~~~~~~
p97.cpp:107:18:   in constexpr expansion of 'Fwd.<lambda(int (*)(int), auto:17)>(NC.<lambda(auto:19)>::operator int (*)(int)<int>(), 3)'
p97.cpp:107:1: error: call to non-constexpr function '<lambda(auto:19)> [with auto:19 = int]'
p97.cpp:106:20: note: '<lambda(auto:19)> [with auto:19 = int]' is not usable as a constexpr function because:
 auto NC = [](auto a) { static int s; return a; };
                    ^
p97.cpp:106:35: error: 's' declared 'static' in 'constexpr' function
 auto NC = [](auto a) { static int s; return a; };
                                   ^
p97.cpp: In member function 'void S2::f(int)':
p97.cpp:123:6: warning: explicit by-reference capture of 'i' redundant with by-reference capture default
 [&, &i]{ }; // error: i preceded by & when & is the default
      ^
p97.cpp:125:5: warning: explicit by-copy capture of 'this' redundant with by-copy capture default
 [=, this]{ }; // error: this when = is the default
     ^~~~
p97.cpp:126:5: warning: already captured 'i' in lambda expression
 [i, i]{ }; // error: i repeated
     ^
p97.cpp:127:9: warning: already captured 'this' in lambda expression
 [this, *this]{ }; // error: this appears twice
         ^~~~
p97.cpp: In lambda function:
p97.cpp:159:14: error: 'j' is not captured
 auto m4 = [&,j] { // error: j not captured by m3
              ^
p97.cpp:158:18: note: the lambda has no capture-default
 auto m3 = [this,m] {
                  ^
p97.cpp:157:5: note: 'int j' declared here
 int j = 40;
     ^
p97.cpp: In lambda function:
p97.cpp:160:9: error: 'n' is not captured
 int x = n; // error: n implicitly captured by m4
         ^
p97.cpp:158:18: note: the lambda has no capture-default
 auto m3 = [this,m] {
                  ^
p97.cpp:155:15: note: 'int n' declared here
 void work(int n) {
               ^
p97.cpp:164:6: error: 'i' is not captured
 x += i; // error: i is outside of the reaching scope
      ^
p97.cpp:158:18: note: the lambda has no capture-default
 auto m3 = [this,m] {
                  ^
p97.cpp:143:13: note: 'int i' declared here
 void f1(int i) {
             ^
p97.cpp: At global scope:
p97.cpp:175:1: error: expected identifier before 'int'
 int main(int argc, char *argv[], char *envp[]){
 ^~~
p97.cpp:175:46: error: two or more data types in declaration of 'main'
 int main(int argc, char *argv[], char *envp[]){
                                              ^
p97.cpp: In lambda function:
p97.cpp:193:1: error: expected ';' before '}' token
 }();
 ^
p97.cpp: In lambda function:
p97.cpp:197:10: error: 'this' was not captured for this lambda function
 return [*this] { }; // error: *this not captured by outer lambda-expression
          ^~~~
p97.cpp: In function 'void f2()':
p97.cpp:205:35: error: default argument '<lambda closure object>f2()::<lambda()>{i}.f2()::<lambda()>()' uses local variable 'i'
 void g1(int = ([i]{ return i; })()); // ill-formed
                                   ^
p97.cpp:206:35: error: default argument '<lambda closure object>f2()::<lambda()>{i}.f2()::<lambda()>()' uses local variable 'i'
 void g2(int = ([i]{ return 0; })()); // ill-formed
                                   ^
p97.cpp:207:35: error: default argument '<lambda closure object>f2()::<lambda()>{i}.f2()::<lambda()>()' uses local variable 'i'
 void g3(int = ([=]{ return i; })()); // ill-formed
                                   ^
p97.cpp:213:10: error: a function-definition is not allowed here before '{' token
 void g() {
          ^
p97.cpp:226:10: error: 'the' was not declared in this scope
 Example: the nested lambda expressions and invocations below will output 123234.
          ^~~
p97.cpp:228:12: error: 'a' was not declared in this scope
 auto m1 = [a, &b, &c]() mutable {
            ^
p97.cpp:228:16: warning: capture of variable 'b' with non-automatic storage duration
 auto m1 = [a, &b, &c]() mutable {
                ^
p97.cpp:47:6: note: 'bool b' declared here
 bool b = glambda(3, 3.14); // OK
      ^
p97.cpp:228:20: error: 'c' was not declared in this scope
 auto m1 = [a, &b, &c]() mutable {
                    ^
p97.cpp: In lambda function:
p97.cpp:229:12: error: 'a' is not captured
 auto m2 = [a, b, &c]() mutable {
            ^
p97.cpp:228:21: note: the lambda has no capture-default
 auto m1 = [a, &b, &c]() mutable {
                     ^
p97.cpp:228:12: note: '<typeprefixerror>a' declared here
 auto m1 = [a, &b, &c]() mutable {
            ^
p97.cpp:229:15: warning: capture of variable 'b' with non-automatic storage duration
 auto m2 = [a, b, &c]() mutable {
               ^
p97.cpp:47:6: note: 'bool b' declared here
 bool b = glambda(3, 3.14); // OK
      ^
p97.cpp:229:19: error: 'c' is not captured
 auto m2 = [a, b, &c]() mutable {
                   ^
p97.cpp:228:21: note: the lambda has no capture-default
 auto m1 = [a, &b, &c]() mutable {
                     ^
p97.cpp:228:20: note: '<typeprefixerror>c' declared here
 auto m1 = [a, &b, &c]() mutable {
                    ^
p97.cpp: In lambda function:
p97.cpp:230:14: error: 'a' is not captured
 std::cout << a << b << c;
              ^
p97.cpp:229:20: note: the lambda has no capture-default
 auto m2 = [a, b, &c]() mutable {
                    ^
p97.cpp:228:12: note: '<typeprefixerror>a' declared here
 auto m1 = [a, &b, &c]() mutable {
            ^
p97.cpp:230:24: error: 'c' is not captured
 std::cout << a << b << c;
                        ^
p97.cpp:229:20: note: the lambda has no capture-default
 auto m2 = [a, b, &c]() mutable {
                    ^
p97.cpp:228:20: note: '<typeprefixerror>c' declared here
 auto m1 = [a, &b, &c]() mutable {
                    ^
p97.cpp:231:1: error: 'a' is not captured
 a = 4; b = 4; c = 4;
 ^
p97.cpp:229:20: note: the lambda has no capture-default
 auto m2 = [a, b, &c]() mutable {
                    ^
p97.cpp:228:12: note: '<typeprefixerror>a' declared here
 auto m1 = [a, &b, &c]() mutable {
            ^
p97.cpp:231:15: error: 'c' is not captured
 a = 4; b = 4; c = 4;
               ^
p97.cpp:229:20: note: the lambda has no capture-default
 auto m2 = [a, b, &c]() mutable {
                    ^
p97.cpp:228:20: note: '<typeprefixerror>c' declared here
 auto m1 = [a, &b, &c]() mutable {
                    ^
p97.cpp: In lambda function:
p97.cpp:233:1: error: 'a' is not captured
 a = 3; b = 3; c = 3;
 ^
p97.cpp:228:21: note: the lambda has no capture-default
 auto m1 = [a, &b, &c]() mutable {
                     ^
p97.cpp:228:12: note: '<typeprefixerror>a' declared here
 auto m1 = [a, &b, &c]() mutable {
            ^
p97.cpp:233:15: error: 'c' is not captured
 a = 3; b = 3; c = 3;
               ^
p97.cpp:228:21: note: the lambda has no capture-default
 auto m1 = [a, &b, &c]() mutable {
                     ^
p97.cpp:228:20: note: '<typeprefixerror>c' declared here
 auto m1 = [a, &b, &c]() mutable {
                    ^
p97.cpp: In function 'void f2()':
p97.cpp:240:11: error: a function-definition is not allowed here before '{' token
 void f3() {
           ^
p97.cpp:250:1: error: a template declaration cannot appear at block scope
 template<class... Args>
 ^~~~~~~~
p97.cpp:262:1: error: expected '}' at end of input
 }
 ^