From 1e6e551b738f61ac83883061fac00870eed13a28 Mon Sep 17 00:00:00 2001
From: Jeff Bezanson <jeff.bezanson@gmail.com>
Date: Thu, 18 Oct 2018 22:24:32 -0400
Subject: [PATCH] fix #29718, union field alignment

---
 src/cgutils.cpp |  8 ++++----
 test/core.jl    | 20 ++++++++++++++++++++
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/src/cgutils.cpp b/src/cgutils.cpp
index 248cbe4c902e2..61a8bbc586676 100644
--- a/src/cgutils.cpp
+++ b/src/cgutils.cpp
@@ -556,10 +556,10 @@ static bool julia_struct_has_layout(jl_datatype_t *dt, jl_unionall_t *ua)
 
 static unsigned jl_field_align(jl_datatype_t *dt, size_t i)
 {
-    unsigned al = jl_field_offset(dt, i);
-    al |= 16;
-    al &= -al;
-    return std::min(al, jl_datatype_align(dt));
+    jl_value_t *ty = jl_field_type(dt, i);
+    size_t fsz = 0, al = 1;
+    (void)jl_islayout_inline(ty, &fsz, &al);
+    return al;
 }
 
 static Type *julia_struct_to_llvm(jl_value_t *jt, jl_unionall_t *ua, bool *isboxed)
diff --git a/test/core.jl b/test/core.jl
index b7db56af115e0..17d2b0c6161ac 100644
--- a/test/core.jl
+++ b/test/core.jl
@@ -6324,6 +6324,26 @@ let A=[0, missing], B=[missing, 0], C=Vector{Union{Int, Missing}}(undef, 6)
     @test isequal(C, [0, missing, missing, missing, 0, missing])
 end
 
+# issue #29718
+function f29718()
+    nt = NamedTuple{(:a, :b, :c, :d, :e, :f,),
+                    Tuple{Union{Missing, Float64},
+                          Tuple{UInt8},
+                          Union{Missing, Int8},
+                          Int8,
+                          Tuple{UInt8,UInt8},
+                          Union{Missing, Int16}}
+                    }((missing,
+                       (1,),
+                       1,
+                       41,
+                       (1,2),
+                       1915,
+                       ))
+    return Ref{Any}(nt)[].f
+end
+@test f29718() == 1915
+
 end # module UnionOptimizations
 
 # issue #6614, argument destructuring