Enable documenting C++20 'requires' clauses in doxygen.

diff --git a/doc/doxygen/options.dox.in b/doc/doxygen/options.dox.in
index b465370b59b1987eb85f5ffbb397cf08154775b2..9af33e651098797fa093c0ec8d4bc3b5d1c8d4c8 100644 (file)
--- a/doc/doxygen/options.dox.in
+++ b/doc/doxygen/options.dox.in
@@ -93,6 +93,8 @@ ALIASES += dealiiWriggersA{2}="@note For a discussion of the background of this
 
 ALIASES += dealiiHolzapfelA{2}="@note For a discussion of the background of this function, see G. A. Holzapfel: \"Nonlinear solid mechanics. A Continuum Approach for Engineering\" (2007), and in particular formula (\2) on p. \1 (or thereabouts). "
 
+ALIASES += dealiiConceptRequires{1}="@note This class, function, or variable is a template, and it can only be instantiated if the following condition is true: @code \1 @endcode If your compiler supports the C++20 standard, then this constraint will be enforced by a [C++20 requires clause](https://en.cppreference.com/w/cpp/language/constraints)."
+
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