example.cpp fails to compile - GCC v.10.3.0

[zingchen]

The example.cpp fails to compile.

Here is my compiler's info.

    $ gcc --version
    gcc.exe (Rev5, Built by MSYS2 project) 10.3.0
    Copyright (C) 2020 Free Software Foundation, Inc.
    This is free software; see the source for copying conditions.  There is NO
    warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Below is the command line and output.

$ g++ -std=c++2a -pedantic -Wall -Wextra -Werror -O3 -Isingle-header/ -o example example.cpp && ./example
In file included from example.cpp:4:
single-header/sql.hpp: In static member function 'static constexpr auto sql::query<Str, Schemas>::parse_negation()':
single-header/sql.hpp:1514:51: error: 'cexpr::string<char, 4>' is not a valid type for a template non-type parameter because it is not structural
 1514 |     using node = sql::operation<"NOT", Row, ranode>;
      |                                                   ^
single-header/sql.hpp:149:15: note: 'cexpr::string<char, 4>::size_' is not public
  149 |   std::size_t size_;
      |               ^~~~~
single-header/sql.hpp:1514:23: error: '<expression error>' in namespace 'sql' does not name a type
 1514 |     using node = sql::operation<"NOT", Row, ranode>;
      |                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
single-header/sql.hpp:1516:30: error: 'node' was not declared in this scope; did you mean 'ranode'?
 1516 |     return context<next.pos, node>{};
      |                              ^~~~
      |                              ranode
single-header/sql.hpp:1516:34: error: template argument 2 is invalid
 1516 |     return context<next.pos, node>{};
      |                                  ^
single-header/sql.hpp: In static member function 'static constexpr auto sql::query<Str, Schemas>::recurse_and()':
single-header/sql.hpp:1537:72: error: 'cexpr::string<char, 4>' is not a valid type for a template non-type parameter because it is not structural
 1537 |     using node = sql::operation<"AND", Row, typename Left::node, ranode>;
      |                                                                        ^
single-header/sql.hpp:149:15: note: 'cexpr::string<char, 4>::size_' is not public
  149 |   std::size_t size_;
      |               ^~~~~
single-header/sql.hpp:1537:23: error: '<expression error>' in namespace 'sql' does not name a type
 1537 |     using node = sql::operation<"AND", Row, typename Left::node, ranode>;
      |                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
single-header/sql.hpp:1539:42: error: 'node' was not declared in this scope; did you mean 'ranode'?
 1539 |     return recurse_and<context<next.pos, node>, Row>();
      |                                          ^~~~
      |                                          ranode
single-header/sql.hpp:1539:46: error: template argument 2 is invalid
 1539 |     return recurse_and<context<next.pos, node>, Row>();
      |                                              ^
single-header/sql.hpp: In static member function 'static constexpr auto sql::query<Str, Schemas>::recurse_or()':
single-header/sql.hpp:1565:71: error: 'cexpr::string<char, 3>' is not a valid type for a template non-type parameter because it is not structural
 1565 |     using node = sql::operation<"OR", Row, typename Left::node, ranode>;
      |                                                                       ^
single-header/sql.hpp:149:15: note: 'cexpr::string<char, 3>::size_' is not public
  149 |   std::size_t size_;
      |               ^~~~~
single-header/sql.hpp:1565:23: error: '<expression error>' in namespace 'sql' does not name a type
 1565 |     using node = sql::operation<"OR", Row, typename Left::node, ranode>;
      |                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
single-header/sql.hpp:1567:41: error: 'node' was not declared in this scope; did you mean 'ranode'?
 1567 |     return recurse_or<context<next.pos, node>, Row>();
      |                                         ^~~~
      |                                         ranode
single-header/sql.hpp:1567:45: error: template argument 2 is invalid
 1567 |     return recurse_or<context<next.pos, node>, Row>();
      |                                             ^
example.cpp: At global scope:
example.cpp:8:30: error: 'cexpr::string<char, 6>' is not a valid type for a template non-type parameter because it is not structural
    8 |   "books", sql::index<"title">,
      |                              ^
In file included from example.cpp:4:
single-header/sql.hpp:149:15: note: 'cexpr::string<char, 6>::size_' is not public
  149 |   std::size_t size_;
      |               ^~~~~
example.cpp:9:35: error: 'cexpr::string<char, 6>' is not a valid type for a template non-type parameter because it is not structural
    9 |   sql::column<"title", std::string>,
      |                                   ^
In file included from example.cpp:4:
single-header/sql.hpp:149:15: note: 'cexpr::string<char, 6>::size_' is not public
  149 |   std::size_t size_;
      |               ^~~~~
example.cpp:10:35: error: 'cexpr::string<char, 6>' is not a valid type for a template non-type parameter because it is not structural
   10 |   sql::column<"genre", std::string>,
      |                                   ^
In file included from example.cpp:4:
single-header/sql.hpp:149:15: note: 'cexpr::string<char, 6>::size_' is not public
  149 |   std::size_t size_;
      |               ^~~~~
example.cpp:11:31: error: 'cexpr::string<char, 5>' is not a valid type for a template non-type parameter because it is not structural
   11 |   sql::column<"year", unsigned>,
      |                               ^
In file included from example.cpp:4:
single-header/sql.hpp:149:15: note: 'cexpr::string<char, 5>::size_' is not public
  149 |   std::size_t size_;
      |               ^~~~~
example.cpp:12:32: error: 'cexpr::string<char, 6>' is not a valid type for a template non-type parameter because it is not structural
   12 |   sql::column<"pages", unsigned>
      |                                ^
In file included from example.cpp:4:
single-header/sql.hpp:149:15: note: 'cexpr::string<char, 6>::size_' is not public
  149 |   std::size_t size_;
      |               ^~~~~
example.cpp:13:2: error: 'cexpr::string<char, 6>' is not a valid type for a template non-type parameter because it is not structural
   13 |  >;
      |  ^
In file included from example.cpp:4:
single-header/sql.hpp:149:15: note: 'cexpr::string<char, 6>::size_' is not public
  149 |   std::size_t size_;
      |               ^~~~~
example.cpp:13:2: error: template argument 2 is invalid
   13 |  >;
      |  ^
example.cpp:13:2: error: template argument 3 is invalid
example.cpp:13:2: error: template argument 4 is invalid
example.cpp:13:2: error: template argument 5 is invalid
example.cpp:13:2: error: template argument 6 is invalid
example.cpp:7:7: error: '<expression error>' in namespace 'sql' does not name a type
    7 |  sql::schema<
      |       ^~~~~~~
    8 |   "books", sql::index<"title">,
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    9 |   sql::column<"title", std::string>,
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   10 |   sql::column<"genre", std::string>,
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   11 |   sql::column<"year", unsigned>,
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   12 |   sql::column<"pages", unsigned>
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   13 |  >;
      |  ~
example.cpp:18:35: error: 'cexpr::string<char, 6>' is not a valid type for a template non-type parameter because it is not structural
   18 |   sql::column<"title", std::string>,
      |                                   ^
In file included from example.cpp:4:
single-header/sql.hpp:149:15: note: 'cexpr::string<char, 6>::size_' is not public
  149 |   std::size_t size_;
      |               ^~~~~
example.cpp:19:34: error: 'cexpr::string<char, 5>' is not a valid type for a template non-type parameter because it is not structural
   19 |   sql::column<"name", std::string>
      |                                  ^
In file included from example.cpp:4:
single-header/sql.hpp:149:15: note: 'cexpr::string<char, 5>::size_' is not public
  149 |   std::size_t size_;
      |               ^~~~~
example.cpp:20:2: error: 'cexpr::string<char, 9>' is not a valid type for a template non-type parameter because it is not structural
   20 |  >;
      |  ^
In file included from example.cpp:4:
single-header/sql.hpp:149:15: note: 'cexpr::string<char, 9>::size_' is not public
  149 |   std::size_t size_;
      |               ^~~~~
example.cpp:20:2: error: template argument 3 is invalid
   20 |  >;
      |  ^
example.cpp:20:2: error: template argument 4 is invalid
example.cpp:16:7: error: '<expression error>' in namespace 'sql' does not name a type
   16 |  sql::schema<
      |       ^~~~~~~
   17 |   "authored", sql::index<>,
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~
   18 |   sql::column<"title", std::string>,
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   19 |   sql::column<"name", std::string>
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   20 |  >;
      |  ~
example.cpp:27:3: error: 'books' was not declared in this scope
   27 |   books, authored
      |   ^~~~~
example.cpp:27:10: error: 'authored' was not declared in this scope
   27 |   books, authored
      |          ^~~~~~~~
example.cpp:28:2: error: 'cexpr::string<char, 193>' is not a valid type for a template non-type parameter because it is not structural
   28 |  >;
      |  ^
In file included from example.cpp:4:
single-header/sql.hpp:149:15: note: 'cexpr::string<char, 193>::size_' is not public
  149 |   std::size_t size_;
      |               ^~~~~
example.cpp:28:2: error: template argument 2 is invalid
   28 |  >;
      |  ^
example.cpp:28:2: error: template argument 3 is invalid
example.cpp:23:7: error: '<expression error>' in namespace 'sql' does not name a type
   23 |  sql::query<
      |       ^~~~~~
   24 |   "SELECT title AS book, name AS author, year, pages "
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   25 |   "FROM books NATURAL JOIN (SELECT * FROM authored WHERE name = \"Harlan Ellison\") "
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   26 |   "WHERE year = 1967 OR year >= 1972 AND genre = \"science fiction\"",
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   27 |   books, authored
      |   ~~~~~~~~~~~~~~~
   28 |  >;
      |  ~
example.cpp: In function 'int main()':
example.cpp:32:2: error: 'authored' was not declared in this scope
   32 |  authored a{ sql::load<authored>("tests/data/authored.tsv", '\t') };
      |  ^~~~~~~~
example.cpp:33:2: error: 'books' was not declared in this scope
   33 |  books b{ sql::load<books>("tests/data/books.tsv", '\t') };
      |  ^~~~~
example.cpp:35:7: error: 'query' was not declared in this scope; did you mean 'sql::query'?
   35 |  for (query q{ b, a }; auto const& [book, author, year, pages] : q)
      |       ^~~~~
      |       sql::query
In file included from example.cpp:4:
single-header/sql.hpp:1429:8: note: 'sql::query' declared here
 1429 |  class query
      |        ^~~~~
example.cpp:35:36: error: expected unqualified-id before '[' token
   35 |  for (query q{ b, a }; auto const& [book, author, year, pages] : q)
      |                                    ^
example.cpp:35:67: error: expected ';' before ')' token
   35 |  for (query q{ b, a }; auto const& [book, author, year, pages] : q)
      |                                                                   ^
      |                                                                   ;
example.cpp:37:16: error: 'book' was not declared in this scope; did you mean 'bool'?
   37 |   std::cout << book << '\t' << author << '\t' << year << '\t' << pages << '\n';
      |                ^~~~
      |                bool
example.cpp:37:32: error: 'author' was not declared in this scope; did you mean 'auto'?
   37 |   std::cout << book << '\t' << author << '\t' << year << '\t' << pages << '\n';
      |                                ^~~~~~
      |                                auto
example.cpp:37:50: error: 'year' was not declared in this scope
   37 |   std::cout << book << '\t' << author << '\t' << year << '\t' << pages << '\n';
      |                                                  ^~~~
example.cpp:37:66: error: 'pages' was not declared in this scope
   37 |   std::cout << book << '\t' << author << '\t' << year << '\t' << pages << '\n';
      |                                                                  ^~~~~

[zingchen]

It seems that the most serious problem is

error: 'sql::{anonymous}::value<double>' is not a valid type for a template non-type parameter because it is not structural
        using node = sql::constant<sql::convert<val>(name), Row>
              ^
              note: 'sql::{anonymous}::value<double>::val' has a non-structural type

[zingchen]

This is a workaround patch, just to make it compile. It's not about to solve the problem, which may be compiler bug.
workaround_patch.txt