From 294f51814f491ae4a09348d9e7221ae3e550c16f Mon Sep 17 00:00:00 2001
From: Anton Lilja <12533691+antlilja@users.noreply.github.com>
Date: Sun, 17 Mar 2024 12:25:09 +0100
Subject: [PATCH] LLVM lowerDebugType: Lower union types without a layout into
 an empty namespace

---
 src/codegen/llvm.zig                   |  5 ++++-
 test/cases/union_unresolved_layout.zig | 15 +++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)
 create mode 100644 test/cases/union_unresolved_layout.zig

diff --git a/src/codegen/llvm.zig b/src/codegen/llvm.zig
index 2a5a187e0d..6273ce0942 100644
--- a/src/codegen/llvm.zig
+++ b/src/codegen/llvm.zig
@@ -2598,7 +2598,10 @@ pub const Object = struct {
                 defer gpa.free(name);
 
                 const union_type = ip.loadUnionType(ty.toIntern());
-                if (!union_type.haveFieldTypes(ip) or !ty.hasRuntimeBitsIgnoreComptime(mod)) {
+                if (!union_type.haveFieldTypes(ip) or
+                    !ty.hasRuntimeBitsIgnoreComptime(mod) or
+                    !union_type.haveLayout(ip))
+                {
                     const debug_union_type = try o.makeEmptyNamespaceDebugType(owner_decl_index);
                     try o.debug_type_map.put(gpa, ty, debug_union_type);
                     return debug_union_type;
diff --git a/test/cases/union_unresolved_layout.zig b/test/cases/union_unresolved_layout.zig
new file mode 100644
index 0000000000..f76c929e8a
--- /dev/null
+++ b/test/cases/union_unresolved_layout.zig
@@ -0,0 +1,15 @@
+const std = @import("std");
+
+const U = union(enum) {
+    foo: u8,
+    bar: f64,
+};
+
+pub fn main() !void {
+    const t = U.foo;
+    _ = t;
+}
+
+// run
+// backend=llvm
+//