test/runner.sh failed to compile

[PragmaTwice]

‘cexpr::string<char, 4>’ is not a valid type for a template non-type parameter because it is not structural was reported by GCC 10, which is probably caused by missing of operator<=> for cexpr::string.
By the way, I am very curious how you can bypass the bug 96331 in GCC, which is a serious one about CTAD and NTTP.

Enverienment:

gcc 10.2.0
linux 5.8.6-1-MANJARO

There is no error while GCC 9 is used.

Log:

constexpr-sql/tests $ ./runner.sh
Test Generator
        Generating queries for "books" schema
        Generating queries for "stories" schema
        Generating queries for "authored" schema
        Generating queries for "collected" schema
Test Generator
        Generating queries for "books" schema
        Generating queries for "stories" schema
        Generating queries for "authored" schema
        Generating queries for "collected" schema
Test Runner
        Test queries selected
In file included from data.hpp:6,
                 from test.cpp:3:
../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>();
      |                                             ^
In file included from test.cpp:3:
data.hpp: At global scope:
data.hpp:14:35: error: ‘cexpr::string<char, 6>’ is not a valid type for a template non-type parameter because it is not structural
   14 |   sql::column<"title", std::string>,
      |                                   ^
In file included from data.hpp:6,
                 from test.cpp:3:
../single-header/sql.hpp:149:15: note: ‘cexpr::string<char, 6>::size_’ is not public
  149 |   std::size_t size_;
      |               ^~~~~
In file included from test.cpp:3:
data.hpp:16:35: error: ‘cexpr::string<char, 6>’ is not a valid type for a template non-type parameter because it is not structural
   16 |   sql::column<"genre", std::string>,
      |                                   ^
In file included from data.hpp:6,
                 from test.cpp:3:
../single-header/sql.hpp:149:15: note: ‘cexpr::string<char, 6>::size_’ is not public
  149 |   std::size_t size_;
      |               ^~~~~
In file included from test.cpp:3:
data.hpp:17:31: error: ‘cexpr::string<char, 5>’ is not a valid type for a template non-type parameter because it is not structural
   17 |   sql::column<"year", unsigned>,
      |                               ^
In file included from data.hpp:6,
                 from test.cpp:3:
../single-header/sql.hpp:149:15: note: ‘cexpr::string<char, 5>::size_’ is not public
  149 |   std::size_t size_;
      |               ^~~~~
In file included from test.cpp:3:
data.hpp:18:32: error: ‘cexpr::string<char, 6>’ is not a valid type for a template non-type parameter because it is not structural
   18 |   sql::column<"pages", unsigned>
      |                                ^
In file included from data.hpp:6,
                 from test.cpp:3:
../single-header/sql.hpp:149:15: note: ‘cexpr::string<char, 6>::size_’ is not public
  149 |   std::size_t size_;
      |               ^~~~~
In file included from test.cpp:3:
data.hpp:19:2: error: ‘cexpr::string<char, 6>’ is not a valid type for a template non-type parameter because it is not structural
   19 |  >;
      |  ^
In file included from data.hpp:6,
                 from test.cpp:3:
../single-header/sql.hpp:149:15: note: ‘cexpr::string<char, 6>::size_’ is not public
  149 |   std::size_t size_;
      |               ^~~~~
In file included from test.cpp:3:
data.hpp:19:2: error: template argument 3 is invalid
   19 |  >;
      |  ^
data.hpp:19:2: error: template argument 4 is invalid
data.hpp:19:2: error: template argument 5 is invalid
data.hpp:19:2: error: template argument 6 is invalid
data.hpp:9:7: error: ‘<expression error>’ in namespace ‘sql’ does not name a type
    9 |  sql::schema<
      |       ^~~~~~~
   10 |   "books", sql::index<>,
      |   ~~~~~~~~~~~~~~~~~~~~~~
   11 | #ifdef CROSS
      | ~~~~~~~~~~~~
   12 |   sql::column<"book", std::string>,
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   13 | #else
      | ~~~~~
   14 |   sql::column<"title", std::string>,
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   15 | #endif
      | ~~~~~~
   16 |   sql::column<"genre", std::string>,
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   17 |   sql::column<"year", unsigned>,
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   18 |   sql::column<"pages", unsigned>
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   19 |  >;
      |  ~
data.hpp:27:35: error: ‘cexpr::string<char, 6>’ is not a valid type for a template non-type parameter because it is not structural
   27 |   sql::column<"title", std::string>,
      |                                   ^
In file included from data.hpp:6,
                 from test.cpp:3:
../single-header/sql.hpp:149:15: note: ‘cexpr::string<char, 6>::size_’ is not public
  149 |   std::size_t size_;
      |               ^~~~~
In file included from test.cpp:3:
data.hpp:29:35: error: ‘cexpr::string<char, 6>’ is not a valid type for a template non-type parameter because it is not structural
   29 |   sql::column<"genre", std::string>,
      |                                   ^
In file included from data.hpp:6,
                 from test.cpp:3:
../single-header/sql.hpp:149:15: note: ‘cexpr::string<char, 6>::size_’ is not public
  149 |   std::size_t size_;
      |               ^~~~~
In file included from test.cpp:3:
data.hpp:30:31: error: ‘cexpr::string<char, 5>’ is not a valid type for a template non-type parameter because it is not structural
   30 |   sql::column<"year", unsigned>
      |                               ^
In file included from data.hpp:6,
                 from test.cpp:3:
../single-header/sql.hpp:149:15: note: ‘cexpr::string<char, 5>::size_’ is not public
  149 |   std::size_t size_;
      |               ^~~~~
In file included from test.cpp:3:
data.hpp:31:2: error: ‘cexpr::string<char, 8>’ is not a valid type for a template non-type parameter because it is not structural
   31 |  >;
      |  ^
In file included from data.hpp:6,
                 from test.cpp:3:
../single-header/sql.hpp:149:15: note: ‘cexpr::string<char, 8>::size_’ is not public
  149 |   std::size_t size_;
      |               ^~~~~
In file included from test.cpp:3:
data.hpp:31:2: error: template argument 3 is invalid
   31 |  >;
      |  ^
data.hpp:31:2: error: template argument 4 is invalid
data.hpp:31:2: error: template argument 5 is invalid
data.hpp:22:7: error: ‘<expression error>’ in namespace ‘sql’ does not name a type
   22 |  sql::schema<
      |       ^~~~~~~
   23 |   "stories", sql::index<>,
      |   ~~~~~~~~~~~~~~~~~~~~~~~~
   24 | #ifdef CROSS
      | ~~~~~~~~~~~~
   25 |   sql::column<"story", std::string>,
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   26 | #else
      | ~~~~~
   27 |   sql::column<"title", std::string>,
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   28 | #endif
      | ~~~~~~
   29 |   sql::column<"genre", std::string>,
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   30 |   sql::column<"year", unsigned>
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   31 |  >;
      |  ~
data.hpp:36:35: error: ‘cexpr::string<char, 6>’ is not a valid type for a template non-type parameter because it is not structural
   36 |   sql::column<"title", std::string>,
      |                                   ^
In file included from data.hpp:6,
                 from test.cpp:3:
../single-header/sql.hpp:149:15: note: ‘cexpr::string<char, 6>::size_’ is not public
  149 |   std::size_t size_;
      |               ^~~~~
In file included from test.cpp:3:
data.hpp:37:34: error: ‘cexpr::string<char, 5>’ is not a valid type for a template non-type parameter because it is not structural
   37 |   sql::column<"name", std::string>
      |                                  ^
In file included from data.hpp:6,
                 from test.cpp:3:
../single-header/sql.hpp:149:15: note: ‘cexpr::string<char, 5>::size_’ is not public
  149 |   std::size_t size_;
      |               ^~~~~
In file included from test.cpp:3:
data.hpp:38:2: error: ‘cexpr::string<char, 9>’ is not a valid type for a template non-type parameter because it is not structural
   38 |  >;
      |  ^
In file included from data.hpp:6,
                 from test.cpp:3:
../single-header/sql.hpp:149:15: note: ‘cexpr::string<char, 9>::size_’ is not public
  149 |   std::size_t size_;
      |               ^~~~~
In file included from test.cpp:3:
data.hpp:38:2: error: template argument 3 is invalid
   38 |  >;
      |  ^
data.hpp:38:2: error: template argument 4 is invalid
data.hpp:34:7: error: ‘<expression error>’ in namespace ‘sql’ does not name a type
   34 |  sql::schema<
      |       ^~~~~~~
   35 |   "authored", sql::index<>,
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~
   36 |   sql::column<"title", std::string>,
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   37 |   sql::column<"name", std::string>
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   38 |  >;
      |  ~
data.hpp:43:35: error: ‘cexpr::string<char, 6>’ is not a valid type for a template non-type parameter because it is not structural
   43 |   sql::column<"title", std::string>,
      |                                   ^
In file included from data.hpp:6,
                 from test.cpp:3:
../single-header/sql.hpp:149:15: note: ‘cexpr::string<char, 6>::size_’ is not public
  149 |   std::size_t size_;
      |               ^~~~~
In file included from test.cpp:3:
data.hpp:44:40: error: ‘cexpr::string<char, 11>’ is not a valid type for a template non-type parameter because it is not structural
   44 |   sql::column<"collection", std::string>,
      |                                        ^
In file included from data.hpp:6,
                 from test.cpp:3:
../single-header/sql.hpp:149:15: note: ‘cexpr::string<char, 11>::size_’ is not public
  149 |   std::size_t size_;
      |               ^~~~~
In file included from test.cpp:3:
data.hpp:45:32: error: ‘cexpr::string<char, 6>’ is not a valid type for a template non-type parameter because it is not structural
   45 |   sql::column<"pages", unsigned>
      |                                ^
In file included from data.hpp:6,
                 from test.cpp:3:
../single-header/sql.hpp:149:15: note: ‘cexpr::string<char, 6>::size_’ is not public
  149 |   std::size_t size_;
      |               ^~~~~
In file included from test.cpp:3:
data.hpp:46:2: error: ‘cexpr::string<char, 10>’ is not a valid type for a template non-type parameter because it is not structural
   46 |  >;
      |  ^
In file included from data.hpp:6,
                 from test.cpp:3:
../single-header/sql.hpp:149:15: note: ‘cexpr::string<char, 10>::size_’ is not public
  149 |   std::size_t size_;
      |               ^~~~~
In file included from test.cpp:3:
data.hpp:46:2: error: template argument 3 is invalid
   46 |  >;
      |  ^
data.hpp:46:2: error: template argument 4 is invalid
data.hpp:46:2: error: template argument 5 is invalid
data.hpp:41:7: error: ‘<expression error>’ in namespace ‘sql’ does not name a type
   41 |  sql::schema<
      |       ^~~~~~~
   42 |   "collected", sql::index<>,
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~
   43 |   sql::column<"title", std::string>,
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   44 |   sql::column<"collection", std::string>,
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   45 |   sql::column<"pages", unsigned>
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   46 |  >;
      |  ~
test.cpp:8:3: error: ‘books’ was not declared in this scope
    8 |   books
      |   ^~~~~
test.cpp:9:2: error: ‘cexpr::string<char, 24>’ is not a valid type for a template non-type parameter because it is not structural
    9 |  >;
      |  ^
In file included from data.hpp:6,
                 from test.cpp:3:
../single-header/sql.hpp:149:15: note: ‘cexpr::string<char, 24>::size_’ is not public
  149 |   std::size_t size_;
      |               ^~~~~
test.cpp:9:2: error: template argument 2 is invalid
    9 |  >;
      |  ^
test.cpp:6:7: error: ‘<expression error>’ in namespace ‘sql’ does not name a type
    6 |  sql::query<
      |       ^~~~~~
    7 |   "select title from books",
      |   ~~~~~~~~~~~~~~~~~~~~~~~~~~
    8 |   books
      |   ~~~~~
    9 |  >;
      |  ~
test.cpp: In function ‘int main()’:
test.cpp:13:2: error: ‘books’ was not declared in this scope
   13 |  books t0{ sql::load<books>(data_folder + books_data, '\t') };
      |  ^~~~~
test.cpp:15:7: error: ‘query’ was not declared in this scope; did you mean ‘sql::query’?
   15 |  for (query q{ t0 }; auto const& [c0] : q)
      |       ^~~~~
      |       sql::query
In file included from data.hpp:6,
                 from test.cpp:3:
../single-header/sql.hpp:1429:8: note: ‘sql::query’ declared here
 1429 |  class query
      |        ^~~~~
test.cpp:15:34: error: expected unqualified-id before ‘[’ token
   15 |  for (query q{ t0 }; auto const& [c0] : q)
      |                                  ^
test.cpp:15:42: error: expected ‘;’ before ‘)’ token
   15 |  for (query q{ t0 }; auto const& [c0] : q)
      |                                          ^
      |                                          ;
test.cpp:17:16: error: ‘c0’ was not declared in this scope
   17 |   std::cout << c0 << '\n';
      |                ^~
sh: ./test: No such file or directory
Traceback (most recent call last):
  File "/usr/lib/python3.8/subprocess.py", line 64, in <module>
    import msvcrt
ModuleNotFoundError: No module named 'msvcrt'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "scripts/runner.py", line 40, in <module>
    main()
  File "scripts/runner.py", line 25, in main
    stream = os.popen("diff cpp-results.txt sql-results.txt")
  File "/usr/lib/python3.8/os.py", line 981, in popen
    import subprocess, io
  File "/usr/lib/python3.8/subprocess.py", line 71, in <module>
    import selectors
  File "/usr/lib/python3.8/selectors.py", line 290, in <module>
    class SelectSelector(_BaseSelectorImpl):
  File "/usr/lib/python3.8/selectors.py", line 317, in SelectSelector
    _select = select.select
AttributeError: module 'select' has no attribute 'select'

[mkitzan]

Haven't been able to maintain this due to work. You're probably right about the operator<=> causing issues. I probably can still approve PRs, hard to say. If you have a fix, I might be able to merge it.

Might look into a solution this weekend.

[PragmaTwice]

I am willing to PR when I have time.
Missing of operator<=> can be confirmed via a GCC testcase, and all private data members may need to be public.