Merge pull request #5485 from pan-/non-copyable-warning

Platform: Allow copy of non copyable objects

Author: 0xc0170

platform/NonCopyable.h

@@ -16,153 +16,196 @@
 #ifndef MBED_NONCOPYABLE_H_
 #define MBED_NONCOPYABLE_H_
 
-namespace mbed { 
+#if (!defined(MBED_DEBUG) && (MBED_CONF_PLATFORM_FORCE_NON_COPYABLE_ERROR == 0))
+#include "mbed_toolchain.h"
+#include "mbed_debug.h"
+#endif
+
+namespace mbed {
 
 /**
- * Inheriting from this class autogeneration of copy construction and copy 
- * assignement operations. 
- * 
- * Classes which are not value type should inherit privately from this class 
+ * Inheriting from this class autogeneration of copy construction and copy
+ * assignement operations.
+ *
+ * Classes which are not value type should inherit privately from this class
  * to avoid generation of invalid copy constructor or copy assignement operator
- * which can lead to unoticeable programming errors. 
- * 
- * As an example consider the following signature: 
- * 
+ * which can lead to unoticeable programming errors.
+ *
+ * As an example consider the following signature:
+ *
  * @code
- * class Resource; 
+ * class Resource;
  *
- * class Foo { 
- * public:     
+ * class Foo {
+ * public:
  *   Foo() : _resource(new Resource()) { }
- *   ~Foo() { delete _resource; } 
+ *   ~Foo() { delete _resource; }
  * private:
  *   Resource* _resource;
  * }
- * 
+ *
  * Foo get_foo();
- * 
+ *
  * Foo foo = get_foo();
- * @endcode 
- * 
- * There is a bug in this function, it returns a temporary value which will be 
- * byte copied into foo then destroyed. Unfortunately, internaly the Foo class 
- * manage a pointer to a Resource object. This pointer will be released when the 
- * temporary is destroyed and foo will manage a pointer to an already released 
+ * @endcode
+ *
+ * There is a bug in this function, it returns a temporary value which will be
+ * byte copied into foo then destroyed. Unfortunately, internaly the Foo class
+ * manage a pointer to a Resource object. This pointer will be released when the
+ * temporary is destroyed and foo will manage a pointer to an already released
  * Resource.
- * 
- * Two issues has to be fixed in the example above: 
- *   - Function signature has to be changed to reflect the fact that Foo 
- *     instances cannot be copied. In that case accessor should return a 
- *     reference to give access to objects already existing and managed. 
+ *
+ * Two issues has to be fixed in the example above:
+ *   - Function signature has to be changed to reflect the fact that Foo
+ *     instances cannot be copied. In that case accessor should return a
+ *     reference to give access to objects already existing and managed.
  *     Generator on the other hand should return a pointer to the created object.
- * 
- * @code 
+ *
+ * @code
  * // return a reference to an already managed Foo instance
- * Foo& get_foo(); 
+ * Foo& get_foo();
  * Foo& foo = get_foo();
- * 
+ *
  * // create a new Foo instance
  * Foo* make_foo();
  * Foo* m = make_foo();
  * @endcode
- * 
- *   - Copy constructor and copy assignement operator has to be made private 
- *     in the Foo class. It prevents unwanted copy of Foo objects. This can be 
- *     done by declaring copy constructor and copy assignement in the private 
+ *
+ *   - Copy constructor and copy assignement operator has to be made private
+ *     in the Foo class. It prevents unwanted copy of Foo objects. This can be
+ *     done by declaring copy constructor and copy assignement in the private
  *     section of the Foo class.
- *     
- * @code 
- * class Foo { 
- * public:     
+ *
+ * @code
+ * class Foo {
+ * public:
  *   Foo() : _resource(new Resource()) { }
- *   ~Foo() { delete _resource; } 
+ *   ~Foo() { delete _resource; }
  * private:
- *   // disallow copy operations 
+ *   // disallow copy operations
  *   Foo(const Foo&);
  *   Foo& operator=(const Foo&);
- *   // data members 
+ *   // data members
  *   Resource* _resource;
  * }
  * @endcode
- * 
- * Another solution is to inherit privately from the NonCopyable class. 
- * It reduces the boiler plate needed to avoid copy operations but more 
+ *
+ * Another solution is to inherit privately from the NonCopyable class.
+ * It reduces the boiler plate needed to avoid copy operations but more
  * importantly it clarifies the programer intent and the object semantic.
  *
- * class Foo : private NonCopyable<Foo> { 
- * public:     
+ * class Foo : private NonCopyable<Foo> {
+ * public:
  *   Foo() : _resource(new Resource()) { }
- *   ~Foo() { delete _resource; } 
+ *   ~Foo() { delete _resource; }
  * private:
  *   Resource* _resource;
  * }
- * 
- * @tparam T The type that should be made non copyable. It prevent cases where 
- * the empty base optimization cannot be applied and therefore ensure that the 
- * cost of this semantic sugar is null. 
- * 
- * As an example, the empty base optimization is prohibited if one of the empty 
- * base class is also a base type of the first non static data member: 
- * 
- * @code 
+ *
+ * @tparam T The type that should be made non copyable. It prevent cases where
+ * the empty base optimization cannot be applied and therefore ensure that the
+ * cost of this semantic sugar is null.
+ *
+ * As an example, the empty base optimization is prohibited if one of the empty
+ * base class is also a base type of the first non static data member:
+ *
+ * @code
  * struct A { };
- * struct B : A { 
+ * struct B : A {
  *    int foo;
  * };
  * // thanks to empty base optimization, sizeof(B) == sizeof(int)
- * 
- * struct C : A { 
+ *
+ * struct C : A {
  *   B b;
  * };
- * 
+ *
  * // empty base optimization cannot be applied here because A from C and A from
- * // B shall have a different address. In that case, with the alignement 
+ * // B shall have a different address. In that case, with the alignement
  * // sizeof(C) == 2* sizeof(int)
  * @endcode
- * 
- * The solution to that problem is to templatize the empty class to makes it 
- * unique to the type it is applied to: 
- * 
- * @code 
+ *
+ * The solution to that problem is to templatize the empty class to makes it
+ * unique to the type it is applied to:
+ *
+ * @code
  * template<typename T>
  * struct A<T> { };
- * struct B : A<B> { 
+ * struct B : A<B> {
  *    int foo;
  * };
- * struct C : A<C> { 
+ * struct C : A<C> {
  *   B b;
  * };
- * 
- * // empty base optimization can be applied B and C does not refer to the same 
+ *
+ * // empty base optimization can be applied B and C does not refer to the same
  * // kind of A. sizeof(C) == sizeof(B) == sizeof(int).
  * @endcode
+ *
+ * @note Compile time errors are disabled if the develop or the release profile
+ * is used. To override this behavior and force compile time errors in all profile
+ * set the configuration parameter "platform.force-non-copyable-error" to true.
  */
 template<typename T>
-class NonCopyable { 
+class NonCopyable {
 protected:
-    /** 
+    /**
      * Disalow construction of NonCopyable objects from outside of its hierarchy.
      */
     NonCopyable() { }
-    /** 
+    /**
      * Disalow destruction of NonCopyable objects from outside of its hierarchy.
      */
     ~NonCopyable() { }
 
-private: 
+#if (!defined(MBED_DEBUG) && (MBED_CONF_PLATFORM_FORCE_NON_COPYABLE_ERROR == 0))
+    /**
+     * NonCopyable copy constructor.
+     *
+     * A compile time warning is issued when this function is used and a runtime
+     * warning is printed when the copy construction of the non copyable happens.
+     *
+     * If you see this warning, your code is probably doing something unspecified.
+     * Copy of non copyable resources can lead to resource leak and random error.
+     */
+    MBED_DEPRECATED("Invalid copy construction of a NonCopyable resource.")
+    NonCopyable(const NonCopyable&)
+    {
+        debug("Invalid copy construction of a NonCopyable resource: %s\r\n", MBED_PRETTY_FUNCTION);
+    }
+
+    /**
+     * NonCopyable copy assignment operator.
+     *
+     * A compile time warning is issued when this function is used and a runtime
+     * warning is printed when the copy construction of the non copyable happens.
+     *
+     * If you see this warning, your code is probably doing something unspecified.
+     * Copy of non copyable resources can lead to resource leak and random error.
+     */
+    MBED_DEPRECATED("Invalid copy assignment of a NonCopyable resource.")
+    NonCopyable& operator=(const NonCopyable&)
+    {
+        debug("Invalid copy assignment of a NonCopyable resource: %s\r\n", MBED_PRETTY_FUNCTION);
+        return *this;
+    }
+
+#else
+private:
     /**
-     * Declare copy constructor as private, any attempt to copy construct 
+     * Declare copy constructor as private, any attempt to copy construct
      * a NonCopyable will fail at compile time.
      */
     NonCopyable(const NonCopyable&);
 
     /**
-     * Declare copy assignement operator as private, any attempt to copy assign 
+     * Declare copy assignement operator as private, any attempt to copy assign
      * a NonCopyable will fail at compile time.
      */
     NonCopyable& operator=(const NonCopyable&);
+#endif
 };
 
-} // namespace mbed 
+} // namespace mbed
 
 #endif /* MBED_NONCOPYABLE_H_ */

platform/mbed_lib.json

@@ -19,6 +19,11 @@
         "default-serial-baud-rate": {
             "help": "Default baud rate for a Serial or RawSerial instance (if not specified in the constructor)",
             "value": 9600
+        },
+
+        "force-non-copyable-error": {
+            "help": "Force compile time error when a NonCopyable object is copied",
+            "value": false
         }
     },
     "target_overrides": {

platform/mbed_toolchain.h

@@ -5,7 +5,7 @@
  * \defgroup platform_toolchain Toolchain functions
  * @{
  */
- 
+
 /* mbed Microcontroller Library
  * Copyright (c) 2006-2013 ARM Limited
  *
@@ -63,7 +63,7 @@
  *
  *  @note
  *  IAR does not support alignment greater than word size on the stack
- *  
+ *
  *  @code
  *  #include "mbed_toolchain.h"
  *
@@ -125,16 +125,16 @@
  *  should contain a regular function declaration to insure the function is emitted.
  *  A function marked weak will not be emitted if an alternative non-weak
  *  implementation is defined.
- *  
+ *
  *  @note
  *  Weak functions are not friendly to making code re-usable, as they can only
  *  be overridden once (and if they are multiply overridden the linker will emit
  *  no warning). You should not normally use weak symbols as part of the API to
  *  re-usable modules.
- *  
+ *
  *  @code
  *  #include "mbed_toolchain.h"
- *  
+ *
  *  MBED_WEAK void foo() {
  *      // a weak implementation of foo that can be overriden by a definition
  *      // without  __weak
@@ -173,9 +173,9 @@
  *
  *  @code
  *  #include "mbed_toolchain.h"
- *  
+ *
  *  MBED_NOINLINE void foo() {
- *  
+ *
  *  }
  *  @endcode
  */
@@ -195,9 +195,9 @@
  *
  *  @code
  *  #include "mbed_toolchain.h"
- *  
+ *
  *  MBED_FORCEINLINE void foo() {
- *  
+ *
  *  }
  *  @endcode
  */
@@ -216,7 +216,7 @@
  *
  *  @code
  *  #include "mbed_toolchain.h"
- *  
+ *
  *  MBED_NORETURN void foo() {
  *      // must never return
  *      while (1) {}
@@ -266,7 +266,7 @@
  *
  *  @code
  *  #include "mbed_toolchain.h"
- *  
+ *
  *  MBED_DEPRECATED("don't foo any more, bar instead")
  *  void foo(int arg);
  *  @endcode
@@ -330,6 +330,20 @@
 #endif
 #endif
 
+/**
+ * Macro expanding to a string literal of the enclosing function name.
+ *
+ * The string returned takes into account language specificity and yield human
+ * readable content.
+ *
+ * As an example, if the macro is used within a C++ function then the string
+ * literal containing the function name will contain the complete signature of
+ * the function - including template parameters - and namespace qualifications.
+ */
+#ifndef MBED_PRETTY_FUNCTION
+#define MBED_PRETTY_FUNCTION __PRETTY_FUNCTION__
+#endif
+
 #ifndef MBED_PRINTF
 #if defined(__GNUC__) || defined(__CC_ARM)
 #define MBED_PRINTF(format_idx, first_param_idx) __attribute__ ((__format__(__printf__, format_idx, first_param_idx)))