// N4606 Committee Draft, Standard for Programming Language C++
// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/n4606.pdf
#define msg "(203)14.8.2.1 Deducing template arguments from a function call [temp.deduct.call]p412.cpp"
// Edited by Dr. Ogawa Kiyoshi. Compile procedure and results record.

#include <iostream>

template<class T> void f(std::initializer_list<T>);
f({1,2,3}); // T deduced to int
f({1,"asdf"}); // error: T deduced to both int and const char*
template<class T> void g(T);
g({1,2,3}); // error: no argument deduced for T
template<class T, int N> void h(T const(&)[N]);
h({1,2,3}); // T deduced to int, N deduced to 3
template<class T> void j(T const(&)[3]);
j({42}); // T deduced to int, array bound not considered
struct Aggr {
  int i;
  int j;
};
template<int N> void k(Aggr const(&)[N]);
k({1,2,3}); // error: deduction fails, no conversion from int to Aggr
k({{1},{2},{3}}); // OK, N deduced to 3
template<int M, int N> void m(int const(&)[M][N]);
m({{1,2},{3,4}}); // M and N both deduced to 2
template<class T, int N> void n(T const(&)[N], T);
n({{1},{2},{3}},Aggr()); // OK, T is Aggr, N is 3

template<class ... Types> void f2(Types& ...);
template<class T1, class ... Types> void g2(T1, Types ...);
template<class T1, class ... Types> void g1(Types ..., T1);
void h2(int x, float& y) {
  const int z = x;
  f2(x, y, z); // Types is deduced to int, float, const int
  g2(x, y, z); // T1 is deduced to int; Types is deduced to float, int
  g1(x, y, z); // error: Types is not deduced
  g1<int, int, int>(x, y, z); // OK, no deduction occurs
}

template <class T> int f3(T&& heisenreference);
template <class T> int g3(const T&&);
int i;
int n1 = f3(i); // calls f<int&>(int&)
int n2 = f3(0); // calls f<int>(int&&)
int n3 = g3(i); // error: would call g<int>(const int&&), which
// would bind an rvalue reference to an lvalue

// Only one function of an overload set matches the call so the function
// parameter is a deduced context.
template <class T> int f4(T (*p)(T));
int g4(int);
int g4(char);
int i4 = f4(g4); // calls f4(int (*)(int))

// Ambiguous deduction causes the second function parameter to be a
// non-deduced context.
template <class T> int f5(T, T (*p)(T));
int g5(int);
char g5(char);
int i5 = f5(1, g5); // calls f5(int, int (*)(int))

// The overload set contains a template, causing the second function
// parameter to be a non-deduced context.
template <class T> int f6(T, T (*p)(T));
char g6(char);
template <class T> T g6(T);
int i6 = f6(1, g6); // calls f6(int, int (*)(int))

template <class T> struct Z7 {
  typedef typename T::x xx;
};
template <class T> typename Z7<T>::xx f7(void *, T); // #1
template <class T> void f7(int, T); // #2
struct A7 {} a;
int main() {
  f7(1, a); // OK, deduction fails for #1 because there is no conversion from int to void*
  std::cout<< msg << std::endl;
  return EXIT_SUCCESS;
}

$ ./cppgl17.sh p412
$ clang++ p412.cpp -std=c++17 
p412.cpp:9:1: error: C++ requires a type specifier for all declarations
f({1,2,3}); // T deduced to int
^
p412.cpp:10:1: error: C++ requires a type specifier for all declarations
f({1,"asdf"}); // error: T deduced to both int and const char*
^
p412.cpp:12:1: error: C++ requires a type specifier for all declarations
g({1,2,3}); // error: no argument deduced for T
^
p412.cpp:14:1: error: C++ requires a type specifier for all declarations
h({1,2,3}); // T deduced to int, N deduced to 3
^
p412.cpp:16:1: error: C++ requires a type specifier for all declarations
j({42}); // T deduced to int, array bound not considered
^
p412.cpp:19:1: error: C++ requires a type specifier for all declarations
k({1,2,3}); // error: deduction fails, no conversion from int to Aggr
^
p412.cpp:20:1: error: C++ requires a type specifier for all declarations
k({{1},{2},{3}}); // OK, N deduced to 3
^
p412.cpp:22:1: error: C++ requires a type specifier for all declarations
m({{1,2},{3,4}}); // M and N both deduced to 2
^
p412.cpp:24:1: error: C++ requires a type specifier for all declarations
n({{1},{2},{3}},Aggr()); // OK, T is Aggr, N is 3
^
p412.cpp:33:1: error: no matching function for call to 'g1'
g1(x, y, z); // error: Types is not deduced
^~
p412.cpp:28:42: note: candidate function not viable: requires 1 argument, but 3 were provided
template<class T1, class ... Types> void g1(Types ..., T1);
                                         ^
p412.cpp:42:10: error: no matching function for call to 'g3'
int n3 = g3(i); // error: would call g<int>(const int&&), which
         ^~
p412.cpp:38:24: note: candidate function [with T = int] not viable: no known conversion from 'int' to 'const int &&' for 1st argument
template <class T> int g3(const T&&);
                       ^
11 errors generated.

$ g++-7 p412.cpp -std=c++17 
p412.cpp:9:2: error: expected constructor, destructor, or type conversion before '(' token
 f({1,2,3}); // T deduced to int
  ^
p412.cpp:9:10: error: expected unqualified-id before ')' token
 f({1,2,3}); // T deduced to int
          ^
p412.cpp:10:2: error: expected constructor, destructor, or type conversion before '(' token
 f({1,"asdf"}); // error: T deduced to both int and const char*
  ^
p412.cpp:10:13: error: expected unqualified-id before ')' token
 f({1,"asdf"}); // error: T deduced to both int and const char*
             ^
p412.cpp:12:2: error: expected constructor, destructor, or type conversion before '(' token
 g({1,2,3}); // error: no argument deduced for T
  ^
p412.cpp:12:10: error: expected unqualified-id before ')' token
 g({1,2,3}); // error: no argument deduced for T
          ^
p412.cpp:14:2: error: expected constructor, destructor, or type conversion before '(' token
 h({1,2,3}); // T deduced to int, N deduced to 3
  ^
p412.cpp:14:10: error: expected unqualified-id before ')' token
 h({1,2,3}); // T deduced to int, N deduced to 3
          ^
p412.cpp:16:2: error: expected constructor, destructor, or type conversion before '(' token
 j({42}); // T deduced to int, array bound not considered
  ^
p412.cpp:16:7: error: expected unqualified-id before ')' token
 j({42}); // T deduced to int, array bound not considered
       ^
p412.cpp:19:2: error: expected constructor, destructor, or type conversion before '(' token
 k({1,2,3}); // error: deduction fails, no conversion from int to Aggr
  ^
p412.cpp:19:10: error: expected unqualified-id before ')' token
 k({1,2,3}); // error: deduction fails, no conversion from int to Aggr
          ^
p412.cpp:20:2: error: expected constructor, destructor, or type conversion before '(' token
 k({{1},{2},{3}}); // OK, N deduced to 3
  ^
p412.cpp:20:16: error: expected unqualified-id before ')' token
 k({{1},{2},{3}}); // OK, N deduced to 3
                ^
p412.cpp:22:2: error: expected constructor, destructor, or type conversion before '(' token
 m({{1,2},{3,4}}); // M and N both deduced to 2
  ^
p412.cpp:22:16: error: expected unqualified-id before ')' token
 m({{1,2},{3,4}}); // M and N both deduced to 2
                ^
p412.cpp:24:2: error: expected constructor, destructor, or type conversion before '(' token
 n({{1},{2},{3}},Aggr()); // OK, T is Aggr, N is 3
  ^
p412.cpp:24:16: error: expected unqualified-id before ',' token
 n({{1},{2},{3}},Aggr()); // OK, T is Aggr, N is 3
                ^
p412.cpp:24:23: error: expected constructor, destructor, or type conversion before ')' token
 n({{1},{2},{3}},Aggr()); // OK, T is Aggr, N is 3
                       ^
p412.cpp: In function 'void h2(int, float&)':
p412.cpp:33:11: error: no matching function for call to 'g1(int&, float&, const int&)'
 g1(x, y, z); // error: Types is not deduced
           ^
p412.cpp:28:42: note: candidate: template<class T1, class ... Types> void g1(Types ..., T1)
 template<class T1, class ... Types> void g1(Types ..., T1);
                                          ^~
p412.cpp:28:42: note:   template argument deduction/substitution failed:
p412.cpp:33:11: note:   candidate expects 1 argument, 3 provided
 g1(x, y, z); // error: Types is not deduced
           ^
p412.cpp: At global scope:
p412.cpp:42:14: error: cannot bind rvalue reference of type 'const int&&' to lvalue of type 'int'
 int n3 = g3(i); // error: would call g<int>(const int&&), which
              ^
p412.cpp:38:24: note:   initializing argument 1 of 'int g3(const T&&) [with T = int]'
 template <class T> int g3(const T&&);
                        ^~

#!/bin/bash
astyle -s2 -c < $1.cpp > $1s2.cpp
cat $1s2.cpp