Show closest candidates. Fixes JuliaLang#7686

base/replutil.jl

@@ -107,6 +107,9 @@ showerror(io::IO, e::ErrorException) = print(io, e.msg)
 showerror(io::IO, e::KeyError) = (print(io, "key not found: "); show(io, e.key))
 showerror(io::IO, e::InterruptException) = print(io, "interrupt")
 
+RED = "\e[31m"
+WHITE = "\e[37m"
+
 function showerror(io::IO, e::MethodError)
     name = isgeneric(e.f) ? e.f.env.name : :anonymous
     if isa(e.f, DataType)
@@ -130,6 +133,39 @@ function showerror(io::IO, e::MethodError)
             print(io, "you may have intended to import Base.$(name)")
         end
     end
+
+    lines = Array(String, 0)
+    for method in methods(e.f)
+        n = length(e.args)
+        if n != length(method.sig)
+            continue
+        end
+        line = "    $(e.f.env.name)("
+        first = true
+        all_wrong = true
+        for i in zip(e.args, method.sig)
+            if first
+                first = false
+            else
+                line = "$line, "
+            end
+            if typeof(i[1]) <: i[2]
+                all_wrong = false
+            else
+                line = "$line$RED"
+            end
+            line = "$line::$(i[2])$WHITE"
+        end
+        if !all_wrong
+            push!(lines, "$line)")
+        end
+    end
+    if length(lines) != 0
+        println(io, "\nClosest candidates are:$WHITE")
+        for line in lines
+            println(io, line)
+        end
+    end
 end
 
 function show_trace_entry(io, fname, file, line, n)