From 30b1ec85dd5d11a7dd767275ae3e65f17035d2f3 Mon Sep 17 00:00:00 2001
From: Ryan Liptak <squeek502@hotmail.com>
Date: Tue, 20 Oct 2026 01:27:43 -0700
Subject: [PATCH] Sema: include sentinel in dest elems when coercing tuple to
 array

---
 src/Sema.zig            | 3 ++-
 test/behavior/array.zig | 3 +++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/Sema.zig b/src/Sema.zig
index 733703bffe2328f314bd176de8bcbec8ba3e38cf..a83f9ec67af8088d413abdce43e246b2ccb0deff 100644
--- a/src/Sema.zig
+++ b/src/Sema.zig
@@ -30670,6 +30670,7 @@ fn coerceTupleToArray(
     const inst_ty = sema.typeOf(inst);
     const inst_len = inst_ty.arrayLen(zcu);
     const dest_len = dest_ty.arrayLen(zcu);
+    const dest_len_including_sent = dest_ty.arrayLenIncludingSentinel(zcu);
 
     if (dest_len != inst_len) {
         const msg = msg: {
@@ -30682,7 +30683,7 @@ fn coerceTupleToArray(
         return sema.failWithOwnedErrorMsg(block, msg);
     }
 
-    const dest_elems = try sema.usizeCast(block, dest_ty_src, dest_len);
+    const dest_elems = try sema.usizeCast(block, dest_ty_src, dest_len_including_sent);
     const element_vals = try sema.arena.alloc(InternPool.Index, dest_elems);
     const element_refs = try sema.arena.alloc(Air.Inst.Ref, dest_elems);
     const dest_elem_ty = dest_ty.childType(zcu);
diff --git a/test/behavior/array.zig b/test/behavior/array.zig
index 10cbdd6f731658795f030c4167c6d204079767bc..574d0f2a007134d1bccc5bce2a300da0abd43fc7 100644
--- a/test/behavior/array.zig
+++ b/test/behavior/array.zig
@@ -591,6 +591,9 @@ test "tuple to array handles sentinel" {
         var b: [3:0]u8 = a;
     };
     try expect(S.b[0] == 1);
+    try expect(S.b[1] == 2);
+    try expect(S.b[2] == 3);
+    try expect(S.b[3] == 0);
 }
 
 test "array init of container level array variable" {
-- 
2.54.0