Parseable output generation from gcc.

[Eric Weiss <eweiss at apple dot com>]

I have been looking into providing a means of getting gcc to report 
error messages and warnings in a parseable format which is not front end 
dependent.

The general goal is to provide a format for expressing messages that can 
be read by an IDE quickly and accurately, where relevant data can be 
extracted.

A number of methods have been discussed and I would like to get feedback 
on a few of the ideas.  I will explain my current approach (and then 
duck;) :

A command line option would be added (-fparseable-log) to turn on 
parseable formatting.

At this point output is formatted as a delimited string which contains 
fields for:  file name, line begin, line end, column begin, column end, 
message type, message.  Any field for which the front end does not 
supply diagnostic context information is left empty.

We need to choose an appropriate delimiting character/sequence.  To this 
point, I have been using a pipe to delimit fields.  I am not sure what 
ramifications this may have or what option could be more appropriate....

Also, each output message should probably include a unique identifier, 
indicating which invocation of the compiler is currently issuing a 
complaint.  There are a couple ways we have looked at doing this.... one 
would be to internally generate a unique key, declare it at generation 
time, and place the key in its own field of every diagnostic message.  
Another would be to add another command line option which would allow an 
IDE itself to pass an identifier to be associated with an invocation.  I 
am unclear which of these approaches (or another) would be best.

For instance, I could invoke gcc -fparseable-log -inum 2112     : or 
something similar.  This number would be stored, and warning/error 
messages from this process would look like this:
|2112|foo.c|...|...|...|...|warn|warning message here

Otherwise, the compiler would generate this identifier itself, so you 
could say
gcc -fparseable-log foo.c bar.c

and get :
foo.c
id: 2112

bar.c
id: 1001
.......
|1001|bar.c|...|...|...|...|error|blah blah blah error
|2112|foo.c|...|...|...|...|warn|blah blah blah warning

Look forward to hearing suggestions,

Thanks,
Eric Weiss