add setting to allow main.log truncation

[RJVB (René Bertin)]

Hi,

Looking at the changes in master/head I noticed commit 0be55cb9 from March 16th 2016 which changed logfile truncation to appending.

I can imagine how this would be of interest for some forms of port maintenance, but I see 2 main reasons why the previous truncation approach was better:

• hunting down build errors from a trac report is usually easier if one can request the reporter to do a 2nd port build or port destroot run and upload the shorter logfile too. This is all the more true when the log is made on a recent Mac that has 8 cores or even more.

• logfiles can grow significantly if one does incremental builds during (-devel) port development without frequent port cleans.

Ideally truncation/append would be controlled by a setting in macports.conf that determines the default, with a possibility to override that default on the commandline.

[ryandesign (Ryan Carsten Schmidt)]

Replying to RJVB:

• hunting down build errors from a trac report is usually easier if one can request the reporter to do a 2nd port build or port destroot run and upload the shorter logfile too.

We do the opposite: If a user has submitted a bug report with a truncated log, we ask them to redo the build from scratch and attach the full log. It's the first thing mentioned in the ​bug reporting instructions.

[RJVB (René Bertin)]

Please note that I mentioned the short log as a 2nd attachment.

[larryv (Lawrence Velázquez)]

There is no reason to ask for a second attachment that by definition contains less information than the first one.

[kurthindenburg (Kurt Hindenburg)]

I find this change to be annoying as well - it just causes you to have to remember to do a 'port clean' to avoid previous errors in the log