builtin: add charptr.vstring() and charptr.vstring_with_len() (#6830)

vlib/builtin/string.v

@@ -138,6 +138,24 @@ pub fn (bp byteptr) vstring_with_len(len int) string {
 	}
 }
 
+// charptr.vstring() - converts C char* to V string. NB: the string data is reused, NOT copied.
+[unsafe]
+pub fn (cp charptr) vstring() string {
+	return string{
+		str: byteptr(cp)
+		len: unsafe {C.strlen(cp)}
+	}
+}
+
+// charptr.vstring_with_len() - converts C char* to V string. NB: the string data is reused, NOT copied.
+[unsafe]
+pub fn (cp charptr) vstring_with_len(len int) string {
+	return string{
+		str: byteptr(cp)
+		len: len
+	}
+}
+
 // string.clone_static returns an independent copy of a given array
 // It should be used only in -autofree generated code.
 fn (a string) clone_static() string {

vlib/builtin/string_test.v

@@ -528,6 +528,14 @@ fn test_bytes_to_string() {
 	assert bytes.bytestr() == 'hello'
 }
 
+fn test_charptr() {
+	foo := charptr('VLANG'.str)
+	println(typeof(foo))
+	assert typeof(foo) == 'charptr'
+	assert unsafe { foo.vstring() } == 'VLANG'
+	assert unsafe { foo.vstring_with_len(3) } == 'VLA'
+}
+
 fn test_count() {
 	assert ''.count('') == 0
 	assert ''.count('a') == 0