From aa3db7cc15520228c0b44328198c78a31e194209 Mon Sep 17 00:00:00 2001
From: mlugg <mlugg@mlugg.co.uk>
Date: Wed, 12 Mar 2025 03:00:45 +0000
Subject: Sema: correctly handle empty by-ref initializers

Resolves: #23210
---
 test/behavior/array.zig | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

(limited to 'test/behavior/array.zig')

diff --git a/test/behavior/array.zig b/test/behavior/array.zig
index 61225aa3e0..14b2a9694b 100644
--- a/test/behavior/array.zig
+++ b/test/behavior/array.zig
@@ -1094,3 +1094,44 @@ test "@splat zero-length array" {
     try S.doTheTest(?*anyopaque, null);
     try comptime S.doTheTest(?*anyopaque, null);
 }
+
+test "initialize slice with reference to empty array initializer" {
+    const a: []const u8 = &.{};
+    comptime assert(a.len == 0);
+}
+
+test "initialize many-pointer with reference to empty array initializer" {
+    const a: [*]const u8 = &.{};
+    _ = a; // nothing meaningful to test; points to zero bits
+}
+
+test "initialize sentinel-terminated slice with reference to empty array initializer" {
+    const a: [:0]const u8 = &.{};
+    comptime assert(a.len == 0);
+    comptime assert(a[0] == 0);
+}
+
+test "initialize sentinel-terminated many-pointer with reference to empty array initializer" {
+    const a: [*:0]const u8 = &.{};
+    comptime assert(a[0] == 0);
+}
+
+test "pass pointer to empty array initializer to anytype parameter" {
+    const S = struct {
+        fn TypeOf(x: anytype) type {
+            return @TypeOf(x);
+        }
+    };
+    comptime assert(S.TypeOf(&.{}) == @TypeOf(&.{}));
+}
+
+test "initialize pointer to anyopaque with reference to empty array initializer" {
+    const ptr: *const anyopaque = &.{};
+    // The above acts like an untyped initializer, since the `.{}` has no result type.
+    // So, `ptr` points in memory to an empty tuple (`@TypeOf(.{})`).
+    const casted: *const @TypeOf(.{}) = @alignCast(@ptrCast(ptr));
+    const loaded = casted.*;
+    // `val` should be a `@TypeOf(.{})`, as expected.
+    // We can't check the value, but it's zero-bit, so the type matching is good enough.
+    comptime assert(@TypeOf(loaded) == @TypeOf(.{}));
+}
-- 
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