Re: [PATCH] doc: Add table of MI versions

[Simon Marchi <simon.marchi@polymtl.ca>]

On 2019-01-16 12:03, Eli Zaretskii wrote:
>> I don't think we require front ends to use the lowest common
>> denominator.  Instead, it should request
>> max(version_known_by_the_front_end, version_known_by_gdb).
> 
> And I think version_known_by_gdb needs this command, doesn't it?

There are multiple strategies to find this information, this could be 
one.  A front end could start GDB with "-i=mi" and issue -mi-version to 
get it.  It can then determine whether that version is satisfactory or 
if it should restart GDB with an earlier version of MI.

Another strategy, for a frontend that knows mi1, mi2 and mi3, could be 
to try to start GDB with "-i=mi3" first.  If GDB exits immediately with 
"Interpreter `mi3' unrecognized", try with mi2, and so forth.

The frontends I have worked with parse the output of "gdb --version" to 
find the GDB version, so they could deduce which MI version to use based 
on that.  It's not pretty, since different builds of GDB can have 
different looking version strings but it works well enough.  Knowing the 
GDB version is usually needed anyway, because they need to work around a 
variety of bugs, not necessarily related to MI.

Simon