If a type implements a Stringer or error interface with a pointer receiver
and the value being formatted is addressable, the interface should be
invoked even when the DisablePointerMethods option is set.
DisablePointerMethods is only intended to prevent the potentially unsafe
action of stepping around type-safety restriction to invoke a Stringer or
error interface with a pointer to an unaddressable value.
This commit implements feature request #3. In particular, it allows the
formatter to respond to %#v and %#+v. The # flag (%#v) adds type
information to the output and the combination of the # and + flags (%#+v)
adds both type information and pointer information. This allows the
consumer a choice between displaying types, pointer information, or both.
This paves the way to support individual configuration options through a
separate type while still providing the simple global config and package
level methods.
Dave Collins
Thomas NJ Shadwell