Added support for cv-qualifiers in Callback class

Additionally, the following changes were don to avoid combinatorial
explosion in function overloads as a result of adding cv-qualifiers:
- Added convenience function for inferred type
- Deprecated callback overloads qhere cv-qualifiers are not scalable

Supported overloads:
callback(void (*f)(A...));
callback(const Callback<R(A...)> &);
callback(T *t,                void (*f)(T*, A...));
callback(const T *t,          void (*f)(const T*, A...));
callback(volatile T *t,       void (*f)(volatile T*, A...));
callback(const volatile T *t, void (*f)(const volatile T*, A...));
callback(T *t,                void (T::*f)(A...));
callback(const T *t,          void (T::*f)(A...) const);
callback(volatile T *t,       void (T::*f)(A...) volatile);
callback(const volatile T *t, void (T::*f)(A...) const volatile);

Author: geky

TESTS/mbed_drivers/callback/main.cpp

@@ -21,6 +21,7 @@
 #include "network-socket/NetworkStack.h"
 #include "rtos/Mutex.h"
 #include "Callback.h"
+#include "toolchain.h"
 
 
 /** Abstract socket class
@@ -168,10 +169,17 @@ class Socket {
      *
      *  @param obj      Pointer to object to call method on
      *  @param method   Method to call on state change
+     *
+     *  @deprecated
+     *      The attach function does not support cv-qualifiers. Replaced by
+     *      attach(callback(obj, method)).
      */
     template <typename T, typename M>
+    MBED_DEPRECATED_SINCE("mbed-os-5.1",
+        "The attach function does not support cv-qualifiers. Replaced by "
+        "attach(callback(obj, method)).")
     void attach(T *obj, M method) {
-        attach(mbed::Callback<void()>(obj, method));
+        attach(mbed::callback(obj, method));
     }
 
 protected:

features/net/network-socket/Socket.h

@@ -17,6 +17,7 @@
 #define MBED_CALLCHAIN_H
 
 #include "Callback.h"
+#include "toolchain.h"
 #include <string.h>
 
 namespace mbed {
@@ -87,10 +88,17 @@ class CallChain {
      *
      *  @returns
      *  The function object created for 'obj' and 'method'
+     *
+     *  @deprecated
+     *  The add function does not support cv-qualifiers. Replaced by
+     *  add(callback(obj, method)).
      */
     template<typename T, typename M>
+    MBED_DEPRECATED_SINCE("mbed-os-5.1",
+        "The add function does not support cv-qualifiers. Replaced by "
+        "add(callback(obj, method)).")
     pFunctionPointer_t add(T *obj, M method) {
-        return add(Callback<void()>(obj, method));
+        return add(callback(obj, method));
     }
 
     /** Add a function at the beginning of the chain
@@ -109,10 +117,17 @@ class CallChain {
      *
      *  @returns
      *  The function object created for 'tptr' and 'mptr'
+     *
+     *  @deprecated
+     *  The add_front function does not support cv-qualifiers. Replaced by
+     *  add_front(callback(obj, method)).
      */
     template<typename T, typename M>
+    MBED_DEPRECATED_SINCE("mbed-os-5.1",
+        "The add_front function does not support cv-qualifiers. Replaced by "
+        "add_front(callback(obj, method)).")
     pFunctionPointer_t add_front(T *obj, M method) {
-        return add_front(Callback<void()>(obj, method));
+        return add_front(callback(obj, method));
     }
 
     /** Get the number of functions in the chain