[gcc r12-2344] libstdc++: Adjust doxygen markup for variable templates group [PR101307]

[Jonathan Wakely <redi@gcc.gnu.org>]

https://gcc.gnu.org/g:da89dfc2a0cb29d3d8a4f2394eee90d150cf6185

commit r12-2344-gda89dfc2a0cb29d3d8a4f2394eee90d150cf6185
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Jul 15 21:13:34 2021 +0100

    libstdc++: Adjust doxygen markup for variable templates group [PR101307]
    
    libstdc++-v3/ChangeLog:
    
            PR libstdc++/101307
            * include/std/type_traits: Adjust doxygen markup.

Diff:
---
 libstdc++-v3/include/std/type_traits | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
index 91d65234f23..8d9c6394cd8 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -3096,17 +3096,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 #if __cplusplus >= 201703L
 # define __cpp_lib_type_trait_variable_templates 201510L
   /**
-   * @defgroup variable_templates Variable templates for type traits.
+   * @defgroup variable_templates Variable templates for type traits
    * @ingroup metaprogramming
    *
-   * The variable `is_foo_v<T>` is a boolean constant with the same value
-   * as the type trait `is_foo<T>::value`.
+   * Each variable `is_xxx_v<T>` is a boolean constant with the same value
+   * as the `value` member of the corresponding type trait `is_xxx<T>`.
    *
    * @since C++17
    */
 
-  /** @ingroup variable_templates
+  /**
    * @{
+   * @ingroup variable_templates
    */
 template <typename _Tp>
   inline constexpr bool is_void_v = is_void<_Tp>::value;