If you writes comments including \cond and \endcond tags in the following style, doxygen will generate a warning: "Found \endcond command without matching \cond"

/// \cond CONDITION
/// \brief Brief description
///
/// \param p Parameter
void function(p);
/// \endcond

Workarounds to solve this problem can be:

1. Mixing documentation style like,

/** \cond CONDITION */
/// \brief Brief description
///
/// \param p Parameter
void function(p);
/** \endcond */

2. or adding extra lines of /// like,

///
/// \cond CONDITION
/// \brief Brief description
///
/// \param p Parameter
void function(p);
/// \endcond
///