ARM enum sizes diagnostic

[Mark Shinwell]

Nick Clifton wrote:
> Hi Mark,
> 
>> The diagnostic seen below should be marked as a warning rather
>> than an error; it is possible for the diagnostic to arise when compiling
>> with GCC and -fshort-enums in a situation where the values of such
>> short enumerations cannot escape the compilation unit.  It is in
>> fact already treated as a warning rather than an error as seen below.
> 
> This is OK, but if you are going to fix this message then you might as 
> well go the whole hog.  Specifically:
> 
>   * Report the two enum sizes.
>   * Explain to the user why this might not be a problem.
> 
> So maybe something like this:
> 
>   warning: <foo.o> places 'enum' values into <N> bytes whereas
>    <bar.o> places them into <M> bytes.  This will cause problems
>    if the two files attempt to share enum values.
> 
> You may also want to think about having a way of disabling this warning 
> message for users that do not want it.

Agreed on both counts; I'll work on that.

Mark