fixes #2963

compiler/ccgexprs.nim

@@ -347,8 +347,8 @@ proc genAssignment(p: BProc, dest, src: TLoc, flags: TAssignmentFlags) =
     else:
       useStringh(p.module)
       linefmt(p, cpsStmts,
-           "memcpy((void*)$1, (NIM_CONST void*)$2, sizeof($1));$n",
-           rdLoc(dest), rdLoc(src))
+           "memcpy((void*)$1, (NIM_CONST void*)$2, sizeof($3));$n",
+           rdLoc(dest), rdLoc(src), getTypeDesc(p.module, ty))
   of tyOpenArray, tyVarargs:
     # open arrays are always on the stack - really? What if a sequence is
     # passed to an open array?

compiler/ccgstmts.nim

@@ -1101,7 +1101,10 @@ proc genAsgn(p: BProc, e: PNode, fastAsgn: bool) =
     genGotoVar(p, e.sons[1])
   elif not fieldDiscriminantCheckNeeded(p, e):
     var a: TLoc
-    initLocExpr(p, e.sons[0], a)
+    if e[0].kind in {nkDerefExpr, nkHiddenDeref}:
+      genDeref(p, e[0], a, enforceDeref=true)
+    else:
+      initLocExpr(p, e.sons[0], a)
     if fastAsgn: incl(a.flags, lfNoDeepCopy)
     assert(a.t != nil)
     loadInto(p, e.sons[0], e.sons[1], a)

tests/ccgbugs/tmissingderef.nim

@@ -1,5 +1,7 @@
 discard """
-  output: '''255
+  output: '''[10, 0, 0, 0, 0, 0, 0, 0]
+
+255
 1 1
 0.5'''
 """
@@ -27,4 +29,13 @@ proc mainowar =
   var b = p[]
   echo b[0]
 
+
+# bug 2963
+var
+  a = [8, 7, 3, 10, 0, 0, 0, 1]
+  b = [10, 0, 0, 0, 0, 0, 0, 0]
+  ap = addr a
+ap[] = b
+echo repr(a)
+
 mainowar()