std.cfg: Improved configuration of 'strncpy', which is vulnerable for overlapping write issues.

cfg/std.cfg

@@ -4853,6 +4853,7 @@ 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="out">
       <not-null/>
       <minsize type="argvalue" arg="3"/>

test/cfg/std.cpp

@@ -30,6 +30,12 @@
 #include <functional>
 #include <bitset>
 
+char * overlappingWriteFunction_strncpy(char *buf)
+{
+    // cppcheck-suppress overlappingWriteFunction
+    return strncpy(&buf[0], &buf[3], 2U);
+}
+
 std::bitset<10> std_bitset_test_ignoredReturnValue()
 {
     std::bitset<10> b1("1111010000");