From 1b19c28c79ac20c4b8880742172834f881b47dea Mon Sep 17 00:00:00 2001
From: Jonathan Marler <johnnymarler@gmail.com>
Date: Sat, 24 Aug 2019 01:54:44 -0600
Subject: [PATCH] Fix issue 3058: zig build segfault

---
 src/analyze.cpp                |  9 +++++++--
 test/stage1/behavior/union.zig | 10 ++++++++++
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/src/analyze.cpp b/src/analyze.cpp
index 35c598ab9..fa239808f 100644
--- a/src/analyze.cpp
+++ b/src/analyze.cpp
@@ -7198,8 +7198,13 @@ static void resolve_llvm_types_union(CodeGen *g, ZigType *union_type, ResolveSta
     ZigType *most_aligned_union_member = union_type->data.unionation.most_aligned_union_member;
     ZigType *tag_type = union_type->data.unionation.tag_type;
     if (most_aligned_union_member == nullptr) {
-        union_type->llvm_type = get_llvm_type(g, tag_type);
-        union_type->llvm_di_type = get_llvm_di_type(g, tag_type);
+        if (tag_type == nullptr) {
+            union_type->llvm_type = g->builtin_types.entry_void->llvm_type;
+            union_type->llvm_di_type = g->builtin_types.entry_void->llvm_di_type;
+        } else {
+            union_type->llvm_type = get_llvm_type(g, tag_type);
+            union_type->llvm_di_type = get_llvm_di_type(g, tag_type);
+        }
         union_type->data.unionation.resolve_status = ResolveStatusLLVMFull;
         return;
     }
diff --git a/test/stage1/behavior/union.zig b/test/stage1/behavior/union.zig
index 7d6a8154e..3df8aef3b 100644
--- a/test/stage1/behavior/union.zig
+++ b/test/stage1/behavior/union.zig
@@ -457,3 +457,13 @@ test "@unionInit can modify a pointer value" {
     value_ptr.* = @unionInit(UnionInitEnum, "Byte", 2);
     expect(value.Byte == 2);
 }
+
+test "union no tag with struct member" {
+    const Struct = struct { };
+    const Union = union {
+        s : Struct,
+        pub fn foo(self: *@This()) void { }
+    };
+    var u = Union { .s = Struct {} };
+    u.foo();
+}