Add option for MatchName or similar for decodeMapFromStruct

[thespags]

Hi, is there a way for MapStructure to automatically convert camelCase identifiers to lower_underscore names without having to specify it for each MapStructure? Or is that information lost at runtime by Golang to do accurately?

type Settings struct {
FooBar string mapstructure:"foo_bar"
OneTwo string mapstructure:"one_two"
User string
}

[thespags]

Found MatchName.

[thespags]

Did some more digging. Viper asks for decodeMapFromStruct, not decodeStructFromMap, when looking for keys, so I can't use MatchName.
Specifically, I'm trying to have viper map something like FooBar to be loaded from an environmental variable FOO_BAR without having to create mapstructure for each key.
I can't use SetEnvKeyReplacer because by that time the casing has been lost, so I would get FOOBAR.