1 files changed, 13 insertions, 6 deletions
diff --git a/std/builtin.zig b/std/builtin.zig
index 76978a34b4..5371c2c99e 100644
--- a/std/builtin.zig
+++ b/std/builtin.zig
@@ -1,24 +1,31 @@
 // These functions are provided when not linking against libc because LLVM
 // sometimes generates code that calls them.
 
-// TODO dest should be nullable and return value should be nullable
-export fn memset(dest: &u8, c: u8, n: usize) -> &u8 {
+export fn memset(dest: ?&u8, c: u8, n: usize) -> ?&u8 {
     @setDebugSafety(this, false);
 
+    if (n == 0)
+        return dest;
+
+    const d = ??dest;
     var index: usize = 0;
     while (index != n; index += 1)
-        dest[index] = c;
+        d[index] = c;
 
     return dest;
 }
 
-// TODO dest, source, and return value should be nullable
-export fn memcpy(noalias dest: &u8, noalias src: &const u8, n: usize) -> &u8 {
+export fn memcpy(noalias dest: ?&u8, noalias src: ?&const u8, n: usize) -> ?&u8 {
     @setDebugSafety(this, false);
 
+    if (n == 0)
+        return dest;
+
+    const d = ??dest;
+    const s = ??src;
     var index: usize = 0;
     while (index != n; index += 1)
-        dest[index] = src[index];
+        d[index] = s[index];
 
     return dest;
 }