ir: Various fixes for comptime ptr handling

* Correctly fold ptrToInt on optional types
* Generate null as ConstPtrSpecialNull in intToPtr
* Correctly stop ptrToInt on ?*T where T is zero-sized

Closes #4535

1 files changed, 12 insertions, 0 deletions

diff --git a/test/stage1/behavior/pointers.zig b/test/stage1/behavior/pointers.zig
index fdaa5867d7..bcc1d62df3 100644
--- a/test/stage1/behavior/pointers.zig
+++ b/test/stage1/behavior/pointers.zig
@@ -318,3 +318,15 @@ test "pointer arithmetic affects the alignment" {
         expect(@typeInfo(@TypeOf(ptr4)).Pointer.alignment == 4);
     }
 }
+
+test "@ptrToInt on null optional at comptime" {
+    {
+        const pointer = @intToPtr(?*u8, 0x000);
+        const x = @ptrToInt(pointer);
+        comptime expect(0 == @ptrToInt(pointer));
+    }
+    {
+        const pointer = @intToPtr(?*u8, 0xf00);
+        comptime expect(0xf00 == @ptrToInt(pointer));
+    }
+}