builtin: llgo.advance

internal/runtime/z_string.go

@@ -56,14 +56,19 @@ func StringData(s String) unsafe.Pointer {
 }
 
 // StringCat concatenates strings.
-func StringCat(args ...String) String {
+func StringCat(args ...String) (ret String) {
 	n := 0
 	for _, v := range args {
 		n += v.len
 	}
-	ret := Alloc(uintptr(n))
-	_ = ret
-	panic("todo")
+	dest := Alloc(uintptr(n))
+	ret.data = dest
+	ret.len = n
+	for _, v := range args {
+		c.Memcpy(dest, v.data, uintptr(v.len))
+		dest = c.Advance(dest, v.len)
+	}
+	return
 }
 
 // -----------------------------------------------------------------------------