[core] always implement operator != in terms of == (#4188)

src/core/mac/channel_mask.hpp

@@ -234,7 +234,7 @@ public:
      * @returns TRUE if the two masks are different, FALSE otherwise.
      *
      */
-    bool operator!=(const ChannelMask &aAnother) const { return (mMask != aAnother.mMask); }
+    bool operator!=(const ChannelMask &aAnother) const { return !(*this == aAnother); }
 
     /**
      * This method converts the channel mask into a human-readable string.

src/core/mac/mac_frame.cpp

@@ -56,11 +56,6 @@ bool ExtAddress::operator==(const ExtAddress &aOther) const
     return memcmp(m8, aOther.m8, sizeof(ExtAddress)) == 0;
 }
 
-bool ExtAddress::operator!=(const ExtAddress &aOther) const
-{
-    return memcmp(m8, aOther.m8, sizeof(ExtAddress)) != 0;
-}
-
 ExtAddress::InfoString ExtAddress::ToString(void) const
 {
     return InfoString("%02x%02x%02x%02x%02x%02x%02x%02x", m8[0], m8[1], m8[2], m8[3], m8[4], m8[5], m8[6], m8[7]);
@@ -95,11 +90,6 @@ bool ExtendedPanId::operator==(const ExtendedPanId &aOther) const
     return memcmp(m8, aOther.m8, sizeof(ExtendedPanId)) == 0;
 }
 
-bool ExtendedPanId::operator!=(const ExtendedPanId &aOther) const
-{
-    return memcmp(m8, aOther.m8, sizeof(ExtendedPanId)) != 0;
-}
-
 ExtendedPanId::InfoString ExtendedPanId::ToString(void) const
 {
     return InfoString("%02x%02x%02x%02x%02x%02x%02x%02x", m8[0], m8[1], m8[2], m8[3], m8[4], m8[5], m8[6], m8[7]);

src/core/mac/mac_frame.hpp

@@ -223,7 +223,7 @@ public:
      * @retval FALSE  If the Extended Addresses match.
      *
      */
-    bool operator!=(const ExtAddress &aOther) const;
+    bool operator!=(const ExtAddress &aOther) const { return !(*this == aOther); }
 
     /**
      * This method converts an address to a string.
@@ -463,7 +463,7 @@ public:
      * @retval FALSE  If the Extended Addresses match.
      *
      */
-    bool operator!=(const ExtendedPanId &aOther) const;
+    bool operator!=(const ExtendedPanId &aOther) const { return !(*this == aOther); }
 
     /**
      * This method converts an address to a string.

src/core/net/ip6_address.cpp

@@ -252,11 +252,6 @@ bool Address::operator==(const Address &aOther) const
     return memcmp(mFields.m8, aOther.mFields.m8, sizeof(mFields.m8)) == 0;
 }
 
-bool Address::operator!=(const Address &aOther) const
-{
-    return memcmp(mFields.m8, aOther.mFields.m8, sizeof(mFields.m8)) != 0;
-}
-
 otError Address::FromString(const char *aBuf)
 {
     otError     error  = OT_ERROR_NONE;

src/core/net/ip6_address.hpp

@@ -365,7 +365,7 @@ public:
      * @retval FALSE  If the IPv6 addresses do not differ.
      *
      */
-    bool operator!=(const Address &aOther) const;
+    bool operator!=(const Address &aOther) const { return !(*this == aOther); }
 
     /**
      * This method converts an IPv6 address string to binary.

src/core/thread/device_mode.hpp

@@ -221,7 +221,7 @@ public:
      * @retval FALSE  If the device modes are equal.
      *
      */
-    bool operator!=(const DeviceMode &aOther) const { return (mMode != aOther.mMode); }
+    bool operator!=(const DeviceMode &aOther) const { return !(*this == aOther); }
 
     /**
      * This method converts the device mode into a human-readable string.

src/core/thread/key_manager.hpp

@@ -85,7 +85,7 @@ public:
      * @retval FALSE  If the Thread Master Keys match.
      *
      */
-    bool operator!=(const MasterKey &aOther) const { return memcmp(m8, aOther.m8, sizeof(MasterKey)) != 0; }
+    bool operator!=(const MasterKey &aOther) const { return !(*this == aOther); }
 
 } OT_TOOL_PACKED_END;