[glibmm/glibmm-2-66] Declare some copy constructors =default

[Kjell Ahlstedt <kjellahl src gnome org>]

commit 94ab1e5359f3bd9eb8204aadea88e08f52a291d8
Author: Kjell Ahlstedt <kjellahlstedt gmail com>
Date:   Tue Feb 15 12:59:22 2022 +0100

    Declare some copy constructors =default
    
    Avoid warnings from the clang++ compiler.
    
    It's deprecated to implicitly declare a copy constructor, if there
    is a user-defined or user-deleted (=delete) copy assignment operator.

 gio/giomm/socketsource.h  |  1 +
 glib/glibmm/main.h        |  4 ++++
 glib/glibmm/signalproxy.h |  1 +
 glib/glibmm/ustring.h     | 16 +++++++++-------
 4 files changed, 15 insertions(+), 7 deletions(-)
---
diff --git a/gio/giomm/socketsource.h b/gio/giomm/socketsource.h
index 0c507a56..a9046df5 100644
--- a/gio/giomm/socketsource.h
+++ b/gio/giomm/socketsource.h
@@ -35,6 +35,7 @@ class GIOMM_API SignalSocket
 public:
 #ifndef DOXYGEN_SHOULD_SKIP_THIS
   explicit inline SignalSocket(GMainContext* context);
+  SignalSocket(const SignalSocket& other) = default;
 #endif
 
   /** Connects an I/O handler that watches a socket.
diff --git a/glib/glibmm/main.h b/glib/glibmm/main.h
index c3bd7829..ca40dc37 100644
--- a/glib/glibmm/main.h
+++ b/glib/glibmm/main.h
@@ -84,6 +84,7 @@ class GLIBMM_API SignalTimeout
 public:
 #ifndef DOXYGEN_SHOULD_SKIP_THIS
   explicit inline SignalTimeout(GMainContext* context);
+  SignalTimeout(const SignalTimeout& other) = default;
 #endif
 
   /** Connects a timeout handler.
@@ -220,6 +221,7 @@ class GLIBMM_API SignalIdle
 public:
 #ifndef DOXYGEN_SHOULD_SKIP_THIS
   explicit inline SignalIdle(GMainContext* context);
+  SignalIdle(const SignalIdle& other) = default;
 #endif
 
   /** Connects an idle handler.
@@ -278,6 +280,7 @@ class GLIBMM_API SignalIO
 public:
 #ifndef DOXYGEN_SHOULD_SKIP_THIS
   explicit inline SignalIO(GMainContext* context);
+  SignalIO(const SignalIO& other) = default;
 #endif
 
   /** Connects an I/O handler that watches a file descriptor.
@@ -349,6 +352,7 @@ class GLIBMM_API SignalChildWatch
 public:
 #ifndef DOXYGEN_SHOULD_SKIP_THIS
   explicit inline SignalChildWatch(GMainContext* context);
+  SignalChildWatch(const SignalChildWatch& other) = default;
 #endif
   /** Connects a child watch handler.
    * @code
diff --git a/glib/glibmm/signalproxy.h b/glib/glibmm/signalproxy.h
index 0a94e849..82387b5b 100644
--- a/glib/glibmm/signalproxy.h
+++ b/glib/glibmm/signalproxy.h
@@ -51,6 +51,7 @@ class GLIBMM_API SignalProxyBase
 {
 public:
   SignalProxyBase(Glib::ObjectBase* obj);
+  SignalProxyBase(const SignalProxyBase& other) = default;
 
 #ifndef DOXYGEN_SHOULD_SKIP_THIS
   static inline sigc::slot_base* data_to_slot(void* data)
diff --git a/glib/glibmm/ustring.h b/glib/glibmm/ustring.h
index 949789be..8746ca6e 100644
--- a/glib/glibmm/ustring.h
+++ b/glib/glibmm/ustring.h
@@ -25,6 +25,7 @@
 #include <iterator>
 #include <sstream>
 #include <string>
+#include <type_traits> // std::enable_if, std::is_same
 #ifndef GLIBMM_HAVE_STD_ITERATOR_TRAITS
 #include <cstddef> /* for std::ptrdiff_t */
 #endif
@@ -198,7 +199,14 @@ public:
   using pointer = void;
 
   inline ustring_Iterator();
-  inline ustring_Iterator(const ustring_Iterator<std::string::iterator>& other);
+  // A std::string::iterator can be copied to a std::string::const_iterator.
+  template <typename T2, typename = typename std::enable_if<
+    std::is_same<std::string::const_iterator, T>::value &&
+    std::is_same<std::string::iterator, T2>::value, T2>::type>
+  inline ustring_Iterator(const ustring_Iterator<T2>& other)
+  : pos_(other.base())
+  { }
+  ustring_Iterator(const ustring_Iterator& other) = default;
   ustring_Iterator& operator=(const ustring_Iterator& other) = default;
 
   inline value_type operator*() const;
@@ -1161,12 +1169,6 @@ inline ustring_Iterator<T>::ustring_Iterator() : pos_()
 {
 }
 
-template <class T>
-inline ustring_Iterator<T>::ustring_Iterator(const ustring_Iterator<std::string::iterator>& other)
-: pos_(other.base())
-{
-}
-
 template <class T>
 inline typename ustring_Iterator<T>::value_type ustring_Iterator<T>::operator*() const
 {