I end up using "go list" to list dependencies, and rely on the makefile to cache builds, for the binary runs in docker and the host machine is a Mac, and cross compiling with race detector enable doesn't seem to easy in this case. Previously I had to give race detector up to use go build directly.
move-if-change sounds like a good approach, will come in handy when there is no need to cross compile, thanks for the tip. On Thursday, April 16, 2020 at 4:09:27 AM UTC+8, Ian Lance Taylor wrote: > > On Wed, Apr 15, 2020 at 4:55 AM Glen Huang <hey...@gmail.com <javascript:>> > wrote: > > > > I have a makefile where upon a new go binary being built, it builds some > other stuff that is not go related. > > > > The go binary is unconditionally built with a FORCE prerequisite, so the > go build command always runs, but that command always updates the output > binary, which leads to downstream being unnecessarily built. > > > > Is there a way to tell go not to touch the output file if it builds > purely from the cache? > > > > Currently it prevents me from using a makefile, and I don't really feel > like sidestepping go's cache system by manually listing all go files and > have the makefile functions as a cache, besides, it's really difficult to > correctly list dependencies if the module is big and the binary being built > only depends on a subset. > > Updating the binary is intentional, so that `go build` has consistent > behavior. > > The way to handle this in a Makefile is to use the move-if-change > dance, which looks more or less like > > real-target: stamp-target; @true > stamp-target: ... > go build -o temporary-target ... > if cmp temporary-target real-target; then \ > rm temporary-target; \ > else \ > mv temporary-target real-target > fi > touch stamp-target > > With this technique stamp-target will be rebuilt if any of its > dependencies change, and real-target will be rebuilt only if the build > generated a file that was different in some way. > > Ian > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/31a4ac61-69d7-4891-8b54-67fb22e082ce%40googlegroups.com.
