pcre is used indirectly by glib-2.0 https://github.com/labapart/gattlib/blob/master/CrossCompilation.cmake#L73 and no functions from it are called from the code directly, in particular it is only explicitly linked in the example and test codes. Current versions of glib-2.0 use pcre2, so this should be used instead. If there are platforms where only pcre is available, an option should be added to link to that.