s/complications/compilations/ On Sat, Oct 18, 2014 at 7:46 PM, Egmont Koblinger <egm...@gmail.com> wrote:
> On Sat, Oct 18, 2014 at 7:23 PM, Paul Smith <p...@mad-scientist.net> > wrote: > >> >> Can someone describe the ccache support for this? I wonder how it might >> (or might not) interact with GNU make's method of determining whether >> there's a controlling TTY, in cases where make's output synchronization >> is enabled. >> >> > I'm really not the right guy to answer this, but here's what I believe > happens (after playing a bit with ccache+colors and taking a glimpse at the > patch that introduced this feature, and also quickly checking make's > --output-sync now). > > The most important thing is that ccache should always remain totally > transparent, and this is guaranteed with coloring too. ccache figures out > what kind of coloring gcc would use if it was called directly (rather than > via ccache), depending on whether the stdout/err is a tty, on > -f(no-)diagnostics-color=xx and $GCC_COLORS. It includes all these values > in the hash(*) and forces gcc to use color if necessary (because the actual > gcc's output is not a tty). > > (*) This means that if you perform the same complications with tty output > (colors enabled) and with redirected output (no colors), it won't share the > cache. This causes some performance regression in case you first do a > colored "gcc" to your tty, but upon seeing tons of errors you decide to run > "gcc | less" to examine them. Also if you alter GCC_COLORS you won't get > any cache hits. > > (Theoretically, ccache could instead always invoke gcc by forcing one > particular color set where every kind of message has a different color, and > then do a search-replace to the actual runtime colors or no colors; then it > could share cache results. That would be the more conventional and better > stacking order: caching below, coloring above. I understand it's harder to > implement/maintain and the benefits would be quite low compared to the > current solution.) > > make's --output-sync causes gcc (without ccache) not to use any coloring > by default (since gcc's output is not a tty but a pipe or tmpfile to make), > and having ccache in front of gcc doesn't change this. You might specify > -fdiagnostics-color=always in your Makefile, again, I believe the presence > of ccache should be transparent and you'd get colors. > > Don't trust me blindly, I might be wrong in anything I said above :) > > > egmont > _______________________________________________ ccache mailing list ccache@lists.samba.org https://lists.samba.org/mailman/listinfo/ccache
