Styjun

Why should universal income be universal?

Why did the EU agree to delay the Brexit deadline?

Why is it that I can sometimes guess the next note?

Create all possible words using a set or letters

What is this called? Old film camera viewer?

Where does the bonus feat in the cleric starting package come from?

Is it safe to use olive oil to clean the ear wax?

Creepy dinosaur pc game identification

Pre-mixing cryogenic fuels and using only one fuel tank

How do you make your own symbol when Detexify fails?

What should you do when eye contact makes your subordinate uncomfortable?

Closed-form expression for certain product

I am looking for the correct translation of love for the phrase "in this sign love"

Fear of getting stuck on one programming language / technology that is not used in my country

Argument list too long when zipping large list of certain files in a folder

What does chmod -u do?

Offered money to buy a house, seller is asking for more to cover gap between their listing and mortgage owed

Why Shazam when there is already Superman?

Not using 's' for he/she/it

Multiplicative persistence

A social experiment. What is the worst that can happen?

Did arcade monitors have same pixel aspect ratio as TV sets?

Longest common substring in linear time

It grows, but water kills it

How do character array work as as template argument?

Why can templates only be implemented in the header file?Where and why do I have to put the “template” and “typename” keywords?C++11 introduced a standardized memory model. What does it mean? And how is it going to affect C++ programming?why does the array decay to a pointer in a template functionSpecializing template member function to handle both std::string and char[] argumentsC++11 make_pair with specified template parameters doesn't compileHow to fill const std::array<size_t, N> with values based on functionList of values (of any types) as a template argumentImplementing is_constexpr_copiablec++ template instantiation works with int, long, etc. but not float, double, etc

0

I have a bit of code that uses references to constexpr char arrays as template arguments. It turns out that new versions of MSVC fails to compile.

But it has no problems if I change the code to passing the array by value, which looks like this:

#include <cstddef>
#include <type_traits>
#include <utility>

template <char... Cs>
struct char_sequence ;

template <std::size_t N, const char (s)[N], typename T>
struct make_char_sequence_impl;

template <std::size_t N, const char (s)[N], std::size_t... i>
struct make_char_sequence_impl<N, s, std::index_sequence<i...>> 
 using type = char_sequence<s[i]...>;
;

template <std::size_t N, const char (Input)[N]>
using make_char_sequence =
 typename make_char_sequence_impl<N, Input,
 std::make_index_sequence<N - 1>>::type;

struct Delta 
 struct _alias_t 
 static constexpr const char _literal[] = "delta";
 using _name_t = make_char_sequence<sizeof(_literal), _literal>;
 ;
;

According the cppreference:

Array and function types may be written in a template declaration, but they are automatically replaced by pointer to object and pointer to function as appropriate.

But if the parameter Input is a pointer in make_char_sequence, then how can it be passed to make_char_sequence_impl, which is expecting an array of specific size? Is that legal C++?

templates c++14 language-lawyer

share|improve this question

asked 2 days ago

RumburakRumburak

1,855921

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Nothing expects an array of a specific size, since as you quoted every array parameter is implicitly replaced by a pointer parameter (which has no size information). Now if you were to have only make_char_sequence_impl take a const char (&)[N], you'd see the error you expect with e.g. Clang.
  
  – Quentin
  2 days ago
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @Quentin Oh dammit, struck by punctuation blindness again... Thanks for the explanation! So I can replace all the array stuff with pointers, which is much more readable anyway. Thanks again!
  
  – Rumburak
  2 days ago
  

  
  
  
  

add a comment | 

0

I have a bit of code that uses references to constexpr char arrays as template arguments. It turns out that new versions of MSVC fails to compile.

But it has no problems if I change the code to passing the array by value, which looks like this:

#include <cstddef>
#include <type_traits>
#include <utility>

template <char... Cs>
struct char_sequence ;

template <std::size_t N, const char (s)[N], typename T>
struct make_char_sequence_impl;

template <std::size_t N, const char (s)[N], std::size_t... i>
struct make_char_sequence_impl<N, s, std::index_sequence<i...>> 
 using type = char_sequence<s[i]...>;
;

template <std::size_t N, const char (Input)[N]>
using make_char_sequence =
 typename make_char_sequence_impl<N, Input,
 std::make_index_sequence<N - 1>>::type;

struct Delta 
 struct _alias_t 
 static constexpr const char _literal[] = "delta";
 using _name_t = make_char_sequence<sizeof(_literal), _literal>;
 ;
;

According the cppreference:

Array and function types may be written in a template declaration, but they are automatically replaced by pointer to object and pointer to function as appropriate.

But if the parameter Input is a pointer in make_char_sequence, then how can it be passed to make_char_sequence_impl, which is expecting an array of specific size? Is that legal C++?

templates c++14 language-lawyer

share|improve this question

asked 2 days ago

RumburakRumburak

1,855921

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Nothing expects an array of a specific size, since as you quoted every array parameter is implicitly replaced by a pointer parameter (which has no size information). Now if you were to have only make_char_sequence_impl take a const char (&)[N], you'd see the error you expect with e.g. Clang.
  
  – Quentin
  2 days ago
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  @Quentin Oh dammit, struck by punctuation blindness again... Thanks for the explanation! So I can replace all the array stuff with pointers, which is much more readable anyway. Thanks again!
  
  – Rumburak
  2 days ago
  

  
  
  
  

add a comment | 

I have a bit of code that uses references to constexpr char arrays as template arguments. It turns out that new versions of MSVC fails to compile.

But it has no problems if I change the code to passing the array by value, which looks like this:

#include <cstddef>
#include <type_traits>
#include <utility>

template <char... Cs>
struct char_sequence ;

template <std::size_t N, const char (s)[N], typename T>
struct make_char_sequence_impl;

template <std::size_t N, const char (s)[N], std::size_t... i>
struct make_char_sequence_impl<N, s, std::index_sequence<i...>> 
 using type = char_sequence<s[i]...>;
;

template <std::size_t N, const char (Input)[N]>
using make_char_sequence =
 typename make_char_sequence_impl<N, Input,
 std::make_index_sequence<N - 1>>::type;

struct Delta 
 struct _alias_t 
 static constexpr const char _literal[] = "delta";
 using _name_t = make_char_sequence<sizeof(_literal), _literal>;
 ;
;

According the cppreference:

Array and function types may be written in a template declaration, but they are automatically replaced by pointer to object and pointer to function as appropriate.

But if the parameter Input is a pointer in make_char_sequence, then how can it be passed to make_char_sequence_impl, which is expecting an array of specific size? Is that legal C++?

templates c++14 language-lawyer

share|improve this question

asked 2 days ago

RumburakRumburak

1,855921

#include <cstddef>
#include <type_traits>
#include <utility>

template <char... Cs>
struct char_sequence ;

template <std::size_t N, const char (s)[N], typename T>
struct make_char_sequence_impl;

template <std::size_t N, const char (s)[N], std::size_t... i>
struct make_char_sequence_impl<N, s, std::index_sequence<i...>> 
 using type = char_sequence<s[i]...>;
;

template <std::size_t N, const char (Input)[N]>
using make_char_sequence =
 typename make_char_sequence_impl<N, Input,
 std::make_index_sequence<N - 1>>::type;

struct Delta 
 struct _alias_t 
 static constexpr const char _literal[] = "delta";
 using _name_t = make_char_sequence<sizeof(_literal), _literal>;
 ;
;

share|improve this question

asked 2 days ago

RumburakRumburak

1,855921

share|improve this question

asked 2 days ago

RumburakRumburak

1,855921

asked 2 days ago

RumburakRumburak

1,855921

asked 2 days ago

RumburakRumburak

1,855921