Keyword-like forms of logical operators are not supported in C++ requires clause

[MiroPalmu]

Describe the bug
Keyword-like forms of logical operators and, or and not are not supported in required clause.

For example for following class:

template<typename T>
    requires std::is_enum_v<T> and std::unsigned_integral<std::underlying_type_t<T>>
class flags_t {...};

"Detailed Description" in html documentation would contain:

template<typename T>
requires std::is_enum_v<T>
class idg::sstd::flags::flags_t< T >

If one would change and -> && missing std::unsigned_integral<std::underlying_type_t<T>> would appear in the documentation.

Expected behavior
Support for keyword-like forms of logical opeators.

Screenshots

To Reproduce
doxygen_bug.tar.gz

Version
Doxygen 1.9.6 on Arch Linux

Additional context
I don't understand the implementation enough to say for sure but it seems that the bug lies in doxygen/src/scanner.I:2343:

<RequiresClause>"||"|"&&"               { // "requires A || B" or "requires A && B"
                                          yyextra->current->req+=yytext;
                                        }

[albert-github]

What kind of file is your Doxyfile in the doxygen_bug.tar.gz?

[albert-github]

In your code you have

requires std::is_enum_v<T> and std::unsigned_integral<std::underlying_type_t<T>>

• from where do you get that the word and is supported?
• does did this compile?

As part of the draft C++ 2023 standard I see:

requires-clause:
  requires constraint-logical-or-expression

constraint-logical-or-expression:
  constraint-logical-and-expression
  constraint-logical-or-expression || constraint-logical-and-expression

constraint-logical-and-expression:
  primary-expression
  constraint-logical-and-expression && primary-expression

so, I think, for or you have to use ||, for and use && and for not use !.

[doxygen]

@albert-github These are so called "alternative operators", see https://en.cppreference.com/w/cpp/language/operator_alternative

[albert-github]

@doxygen I see (found them also in the standard as paragraph "5.5 Alternative tokens", some horrible sequences like <% and <: I see there. Maybe we should support the and, or, not as well where now the &&, || and ! are supported (in scanner.l and code.l). Probably some others as well.

[MiroPalmu]

What kind of file is your Doxyfile in the doxygen_bug.tar.gz?

It is just the default generated one. There is also main.cpp which contains test cases for each and, or and not.

[doxygen]

@doxygen I see (found them also in the standard as paragraph "5.5 Alternative tokens", some horrible sequences like <% and <: I see there. Maybe we should support the and, or, not as well where now the &&, || and ! are supported (in scanner.l and code.l). Probably some others as well.

I think we should definitely not support the weird <% and <: sequences, I've never seen them used, so let's only do the && and || and ! and only at places where they make sense. Note that && is also used for forwarding/move references (see https://stackoverflow.com/a/71285923/784672 for some horrible abuse).

[doxygen]

@MiroPalmu Please verify if the referenced commit fixes the problem for you. Do not close the issue, this will be done automatically when the next official release becomes available.

[MiroPalmu]

@doxygen Yes, it worked! Thanks for the quick fix :)

[doxygen]

This issue was previously marked 'fixed but not released',
which means it should be fixed in doxygen version 1.10.0.
Please verify if this is indeed the case. Reopen the
issue if you think it is not fixed and please include any additional information
that you think can be relevant (preferably in the form of a self-contained example).