Commit a8ec306b49

@@ -35010,6 +35010,7 @@ fn resolvePeerTypesInner(
             // if there were no actual slices. Else, we want the slice index to report a conflict.
             var opt_slice_idx: ?usize = null;
 
+            var any_abi_aligned = false;
             var opt_ptr_info: ?InternPool.Key.PtrType = null;
             var first_idx: usize = undefined;
             var other_idx: usize = undefined; // We sometimes need a second peer index to report a generic error
@@ -35054,17 +35055,14 @@ fn resolvePeerTypesInner(
                 } };
 
                 // Note that the align can be always non-zero; Type.ptr will canonicalize it
-                ptr_info.flags.alignment = Alignment.min(
-                    if (ptr_info.flags.alignment != .none)
-                        ptr_info.flags.alignment
-                    else
-                        try Type.fromInterned(ptr_info.child).abiAlignmentSema(pt),
-
-                    if (peer_info.flags.alignment != .none)
-                        peer_info.flags.alignment
-                    else
-                        try Type.fromInterned(peer_info.child).abiAlignmentSema(pt),
-                );
+                if (peer_info.flags.alignment == .none) {
+                    any_abi_aligned = true;
+                } else if (ptr_info.flags.alignment == .none) {
+                    any_abi_aligned = true;
+                    ptr_info.flags.alignment = peer_info.flags.alignment;
+                } else {
+                    ptr_info.flags.alignment = ptr_info.flags.alignment.minStrict(peer_info.flags.alignment);
+                }
 
                 if (ptr_info.flags.address_space != peer_info.flags.address_space) {
                     return generic_err;
@@ -35312,6 +35310,12 @@ fn resolvePeerTypesInner(
                 },
             }
 
+            if (any_abi_aligned and opt_ptr_info.?.flags.alignment != .none) {
+                opt_ptr_info.?.flags.alignment = opt_ptr_info.?.flags.alignment.minStrict(
+                    try Type.fromInterned(pointee).abiAlignmentSema(pt),
+                );
+            }
+
             return .{ .success = try pt.ptrTypeSema(opt_ptr_info.?) };
         },
 

@@ -995,3 +995,11 @@ test "sentinel-terminated 0-length slices" {
     try expect(comptime_known_array_value[0] == 2);
     try expect(runtime_array_value[0] == 2);
 }
+
+test "peer slices keep abi alignment with empty struct" {
+    var cond: bool = undefined;
+    cond = false;
+    const slice = if (cond) &[1]u32{42} else &.{};
+    comptime assert(@TypeOf(slice) == []const u32);
+    try expect(slice.len == 0);
+}