From 1667e05f62c6b9dd581547a5ca7128963fe11899 Mon Sep 17 00:00:00 2001
From: Rene Donner <code@donner.at>
Date: Tue, 4 Aug 2015 17:41:54 +0200
Subject: [PATCH] fix #12451 by providing a better error message

---
 base/dict.jl | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/base/dict.jl b/base/dict.jl
index d19d9ed448a055..5dc216230ec6dd 100644
--- a/base/dict.jl
+++ b/base/dict.jl
@@ -432,7 +432,19 @@ Dict{K  }(ps::Pair{K}...,)             = Dict{K,Any}(ps)
 Dict{V  }(ps::Pair{TypeVar(:K),V}...,) = Dict{Any,V}(ps)
 Dict(     ps::Pair...)                 = Dict{Any,Any}(ps)
 
-Dict(kv) = dict_with_eltype(kv, eltype(kv))
+function Dict(kv)
+    try
+        Base.dict_with_eltype(kv, eltype(kv))
+    catch e
+        if any(x->isempty(methods(x, (typeof(kv),))), [start, next, done]) ||
+            !all(x->isa(x,Union{Tuple,Pair}),kv)
+            error("Dict(kv): kv needs to be an interator of tuples or pairs")
+        else
+            rethrow(e)
+        end
+    end
+end
+
 dict_with_eltype{K,V}(kv, ::Type{Tuple{K,V}}) = Dict{K,V}(kv)
 dict_with_eltype{K,V}(kv, ::Type{Pair{K,V}}) = Dict{K,V}(kv)
 dict_with_eltype(kv, t) = Dict{Any,Any}(kv)