From b75ad05267bad6f10e1939354eac14ac821fb8c6 Mon Sep 17 00:00:00 2001
From: Araq <rumpf_a@web.de>
Date: Fri, 24 May 2019 00:12:36 +0200
Subject: [PATCH] fixes move analyser; refs #11257

---
 compiler/injectdestructors.nim      | 10 +++++-----
 tests/destructor/tconsume_twice.nim | 12 ++++++++++++
 2 files changed, 17 insertions(+), 5 deletions(-)
 create mode 100644 tests/destructor/tconsume_twice.nim

diff --git a/compiler/injectdestructors.nim b/compiler/injectdestructors.nim
index a02621aa3..b1a5e63c0 100644
--- a/compiler/injectdestructors.nim
+++ b/compiler/injectdestructors.nim
@@ -178,13 +178,13 @@ proc isLastRead(location: PNode; c: var Con; pc, comesFrom: int): int =
       pc = pc + c.g[pc].dest
     of fork:
       # every branch must lead to the last read of the location:
-      var variantA = isLastRead(location, c, pc+1, pc)
+      let variantA = isLastRead(location, c, pc+1, pc)
       if variantA < 0: return -1
-      let variantB = isLastRead(location, c, pc + c.g[pc].dest, pc)
+      var variantB = isLastRead(location, c, pc + c.g[pc].dest, pc)
       if variantB < 0: return -1
-      elif variantA == high(int):
-        variantA = variantB
-      pc = variantA
+      elif variantB == high(int):
+        variantB = variantA
+      pc = variantB
     of InstrKind.join:
       let dest = pc + c.g[pc].dest
       if dest == comesFrom: return pc + 1
diff --git a/tests/destructor/tconsume_twice.nim b/tests/destructor/tconsume_twice.nim
new file mode 100644
index 000000000..a06ea4efd
--- /dev/null
+++ b/tests/destructor/tconsume_twice.nim
@@ -0,0 +1,12 @@
+discard """
+  cmd: "nim c --newruntime $file"
+  errormsg: "sink parameter `a` is already consumed at tconsume_twice.nim(8, 6)"
+  line: 10
+"""
+
+proc consumeTwice(a: owned proc()): owned proc() =
+  if a == nil:
+    return
+  return a
+
+assert consumeTwice(proc() = discard) != nil