From 20d0ef8afbd4b7b74c24f069841cce52cd5beaff Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Arne=20D=C3=B6ring?= <arne.doering@gmx.net>
Date: Wed, 3 Jul 2019 08:00:40 +0200
Subject: [PATCH] [backport] fix #11320 (#11538)

* [backport] fix #11320
* fix test for 32 bit test
---
 compiler/sizealignoffsetimpl.nim     |  2 +-
 lib/system.nim                       |  4 ++--
 tests/errmsgs/tuncheckedarrayvar.nim |  4 +---
 tests/misc/tsizeof.nim               | 13 +++++++++++++
 4 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/compiler/sizealignoffsetimpl.nim b/compiler/sizealignoffsetimpl.nim
index 66fb3dc5b1..cf8f296b40 100644
--- a/compiler/sizealignoffsetimpl.nim
+++ b/compiler/sizealignoffsetimpl.nim
@@ -291,7 +291,7 @@ proc computeSizeAlign(conf: ConfigRef; typ: PType) =
   of tyUncheckedArray:
     let base = typ.lastSon
     computeSizeAlign(conf, base)
-    typ.size = szUnknownSize
+    typ.size = 0
     typ.align = base.align
   of tyEnum:
     if firstOrd(conf, typ) < 0:
diff --git a/lib/system.nim b/lib/system.nim
index 256410522f..d0149a1184 100644
--- a/lib/system.nim
+++ b/lib/system.nim
@@ -877,8 +877,8 @@ when defined(nimHasalignOf):
   proc offsetOfDotExpr(typeAccess: typed): int {.magic: "OffsetOf", noSideEffect, compileTime.}
 
   template offsetOf*[T](t: typedesc[T]; member: untyped): int =
-    var tmp: T
-    offsetOfDotExpr(tmp.member)
+    var tmp {.noinit.}: ptr T
+    offsetOfDotExpr(tmp[].member)
 
   template offsetOf*[T](value: T; member: untyped): int =
     offsetOfDotExpr(value.member)
diff --git a/tests/errmsgs/tuncheckedarrayvar.nim b/tests/errmsgs/tuncheckedarrayvar.nim
index 17965914a9..9376a01505 100644
--- a/tests/errmsgs/tuncheckedarrayvar.nim
+++ b/tests/errmsgs/tuncheckedarrayvar.nim
@@ -4,6 +4,4 @@ invalid type: 'UncheckedArray[uint8]' for var
 '''
 """
 
-var
-  rawMem = alloc0(20)
-  byteUA = cast[UncheckedArray[uint8]](rawMem)
+var byteUA: UncheckedArray[uint8]
diff --git a/tests/misc/tsizeof.nim b/tests/misc/tsizeof.nim
index 50d1c645a1..f3d946a564 100644
--- a/tests/misc/tsizeof.nim
+++ b/tests/misc/tsizeof.nim
@@ -536,3 +536,16 @@ proc main() =
   typeProcessing(mylocal)
 
 main()
+
+# issue #11320 use UncheckedArray
+
+type
+  Payload = object
+    something: int8
+    vals: UncheckedArray[int32]
+
+proc payloadCheck() =
+  doAssert offsetOf(Payload, vals) == 4
+  doAssert sizeOf(Payload) == 4
+
+payloadCheck()