Print the value's type help for undocumented bindings

exclude macros as this is just exposing their internals

closes #13002

base/docs/Docs.jl

@@ -97,7 +97,17 @@ end
 
 function doc(b::Binding)
     d = invoke(doc, Tuple{Any}, b)
-    d == nothing ? doc(getfield(b.mod, b.var)) : d
+    if d == nothing
+        v = getfield(b.mod,b.var)
+        d = doc(v)
+        if d == nothing
+            # check to see if the binding var is not a macro
+            if !startswith(string(b.var),'@')
+                d = typesummary(typeof(v))
+            end
+        end
+    end
+    return d
 end
 
 # Function / Method support

test/docs.jl

@@ -116,6 +116,13 @@ import .Inner.@m
 "Inner.@m"
 :@m
 
+type Foo
+    x
+end
+
+# value with no docs
+const val = Foo(1.0)
+
 end
 
 import Base.Docs: meta
@@ -209,6 +216,13 @@ let fields = meta(DocsTest)[DocsTest.FieldDocs].fields
     @test haskey(fields, :two) && fields[:two] == doc"two"
 end
 
+# test that when no docs exist, they fallback to
+# the docs for the typeof(value)
+let d1 = @doc(DocsTest.val)
+    d2 = @doc(DocsTest.Foo)
+    @test docstrings_equal(d1,d2)
+end
+
 # Issue #12700.
 @test @doc(DocsTest.@m) == doc"Inner.@m"