std.cfg: Added a overlappingWriteFunction-check to strncat

cfg/std.cfg

@@ -4916,6 +4916,7 @@ The obsolete function 'gets' is called. With 'gets' you'll get a buffer overrun
     <returnValue type="char *"/>
     <noreturn>false</noreturn>
     <leak-ignore/>
+    <not-overlapping-data ptr1-arg="1" ptr2-arg="2" size-arg="3"/>
     <arg nr="1" direction="inout">
       <not-null/>
       <not-uninit/>

test/cfg/std.cpp

@@ -93,6 +93,20 @@ char * overlappingWriteFunction_strcat(char *src, char *dest)
     return strcat(src, src);
 }
 
+char * overlappingWriteFunction_strncat(char *src, char *dest, const std::size_t count)
+{
+    // No warning shall be shown:
+    (void)strncat(dest, src, 42);
+    (void)strncat(dest, src, count);
+    // cppcheck-suppress overlappingWriteFunction
+    (void)strncat(dest, dest+1, 2);
+    char buffer[] = "strncat";
+    // cppcheck-suppress overlappingWriteFunction
+    (void)strncat(buffer, buffer + 1, 3);
+    // TODO-cppcheck-suppress overlappingWriteFunction
+    return strncat(src, src, count);
+}
+
 wchar_t * overlappingWriteFunction_wcscpy(wchar_t *src, wchar_t *dest)
 {
     // No warning shall be shown: