For example:

==== Doxyfile ====
MULTILINE_CPP_IS_BRIEF = YES

==== test.h ====
/** @class foo test.h */
/// Foo
/// bar
/** baz */
class foo {
public:
    foo() { }
};

The expected brief description of class foo is "Foo bar" but instead it appears as "Foo /// bar".

This was introduced in svn change 730, when src/scanner.l's docBlock variable was changed from QCString to QGString.

The problem appears on line 5194 of src/scanner.l:

<DocLine>[^\n]*"\n"[ \t]*"//"[/!]       { // continuation of multiline C++-style comment
                                           docBlock+=yytext;
                                           docBlock.resize(docBlock.size() - 3);
                                           yyLineNr++;
                                        }

QGString::size() doesn't mean the same thing as QCString::size().  Using "docBlock.length() - 3" instead would work, or maybe changing the meaning of QGString::size() is better.

Also QGString::resize() removes one character too many.  Consider for example what qtools/qgstring.cpp's resize()'s "m_data[newlen-1]='\0';" does for docBlock.resize(1).