905481 - |mach build| should make error messages easier to spot

Status: RESOLVED WONTFIX

(Firefox Build System :: General, defect)

Description

[Nicholas Nethercote [inactive]]

Finding the errors among all the other spew in a browser build can be difficult.  I have a |mach build| wrapper that ends with this code:

    echo
    echo "======================================="
    echo "errors"
    echo "======================================="
    echo
    # Show up to five errors, with 10 lines of trailing context each.  But
    # first, truncate line length to 300 chars (because I sometimes get
    # extremely long lines describing the command line used, which are
    # annoying).
    perl -p -e 's/^(.{300}).*$/\1/' $objdir/log | \
        grep --max-count=5 --before-context=3 --after-context=10 "\<error:"

The idea is that it plucks out the first five compile errors, each with a bit of context.  It would be nice if |mach build| did this for me.

Comment 1

[Nicholas Nethercote [inactive]]

> It would be nice if |mach build| did this for me.

Make that "absolutely delightful", actually.

Comment 2

[Nicholas Nethercote [inactive]]

Something relevant:  glandium mentioned the mach statusbar today and I had absolutely no idea what he was talking about.  Turns out you don't see it if you redirect mach's output...

Comment 3

[Gregory Szorc [:gps]]

(In reply to Nicholas Nethercote [:njn] from comment #2)
> Something relevant:  glandium mentioned the mach statusbar today and I had
> absolutely no idea what he was talking about.  Turns out you don't see it if
> you redirect mach's output...

The status bar is only rendered if isatty(stdout) because it sends terminal escaping sequences that you probably don't want printed to a file/pipe. There is currently no way to override this, although we could probably offer one.

Comment 4

[Nicholas Nethercote [inactive]]

> The status bar is only rendered if isatty(stdout)

Which is perfectly reasonable.  My point, which I should have made clearer, is that if mach nicely pulled out the error messages, people might not have to redirect its output for their own ad hoc post-processing, and then they would see the status bar :)

(I would still redirect, though, because I need the output in a file to use vim's quickfix mode.  Hmm, if |mach build| could do the redirection itself, I could get the statusbar and the redirection I need...)

Comment 5

[Mike Hommey [:glandium]]

Also note this is going to be made increasingly important as we make the build system more parallel. Because it's harder to find error in parallel builds.