cmd/go: go build -a rebuilds standard library on linux

[leemcloughlin]

Just trying out the newly released go 1.5 on Linux (Ubuntu 14.04) and found that:

go build -v -a

reports rebuilding everything including every standard library file I use. Pre-1.5 the standard library wasn't mentioned. Note that when I ran the above "go build..." I did not have permission to write to /usr/local/go/

go build -v -a -x

shows standard library being rebuilt:

$ go build -v -a -x
WORK=/tmp/go-build359871788
runtime
mkdir -p $WORK/runtime/_obj/
mkdir -p $WORK/
cd /usr/local/go/src/runtime
/usr/local/go/pkg/tool/linux_amd64/compile -o $WORK/runtime.a -trimpath $WORK -p runtime -+ -buildid 6d5354bd14cc24df376bca66e501e715c0c9847b -D _/usr/local/go/src/runtime -I $WORK -pack -asmhdr $WORK/runtime/_obj/go_asm.h ./alg.go ./arch1_amd64.go ./arch_amd64.go ./atomic_amd64x.go ./atomic_pointer.go ./cgo.go ./cgocall.go ./cgocallback.go ./chan.go ./compiler.go ./complex.go ./cpuprof.go ./cputicks.go ./debug.go ./defs_linux_amd64.go ./env_posix.go ./error.go ./extern.go ./hash64.go ./hashmap.go ./hashmap_fast.go ./heapdump.go ./iface.go ./lfstack.go ./lfstack_amd64.go ./lock_futex.go ./malloc.go ./mbarrier.go ./mbitmap.go ./mcache.go ./mcentral.go ./mem_linux.go ./mfinal.go ./mfixalloc.go ./mgc.go ./mgcmark.go ./mgcsweep.go ./mgcwork.go ./mheap.go ./mprof.go ./msize.go ./mstats.go ./netpoll.go ./netpoll_epoll.go ./os1_linux.go ./os2_linux.go ./os_linux.go ./panic.go ./panic1.go ./parfor.go ./print1.go ./print1_write.go ./proc.go ./proc1.go ./race0.go ./rdebug.go ./rune.go ./runtime.go ./runtime1.go ./runtime2.go ./select.go ./sema.go ./signal1_unix.go ./signal_amd64x.go ./signal_linux.go ./signal_linux_amd64.go ./signal_unix.go ./sigpanic_unix.go ./sigqueue.go ./slice.go ./softfloat64.go ./sqrt.go ./stack1.go ./stack2.go ./string.go ./string1.go ./stubs.go ./stubs2.go ./symtab.go ./sys_x86.go ./time.go ./trace.go ./traceback.go ./type.go ./typekind.go ./typekind1.go ./unaligned1.go ./vdso_linux_amd64.go ./wbfat.go ./zgoarch_amd64.go ./zgoos_linux.go ./zversion.go
/usr/local/go/pkg/tool/linux_amd64/asm -o $WORK/runtime/_obj/asm.o -trimpath $WORK -I $WORK/runtime/_obj/ -I /usr/local/go/pkg/include -D GOOS_linux -D GOARCH_amd64 ./asm.s
/usr/local/go/pkg/tool/linux_amd64/asm -o $WORK/runtime/_obj/asm_amd64.o -trimpath $WORK -I $WORK/runtime/_obj/ -I /usr/local/go/pkg/include -D GOOS_linux -D GOARCH_amd64 ./asm_amd64.s
/usr/local/go/pkg/tool/linux_amd64/asm -o $WORK/runtime/_obj/duff_amd64.o -trimpath $WORK -I $WORK/runtime/_obj/ -I /usr/local/go/pkg/include -D GOOS_linux -D GOARCH_amd64 ./duff_amd64.s
/usr/local/go/pkg/tool/linux_amd64/asm -o $WORK/runtime/_obj/memclr_amd64.o -trimpath $WORK -I $WORK/runtime/_obj/ -I /usr/local/go/pkg/include -D GOOS_linux -D GOARCH_amd64 ./memclr_amd64.s
/usr/local/go/pkg/tool/linux_amd64/asm -o $WORK/runtime/_obj/memmove_amd64.o -trimpath $WORK -I $WORK/runtime/_obj/ -I /usr/local/go/pkg/include -D GOOS_linux -D GOARCH_amd64 ./memmove_amd64.s
/usr/local/go/pkg/tool/linux_amd64/asm -o $WORK/runtime/_obj/rt0_linux_amd64.o -trimpath $WORK -I $WORK/runtime/_obj/ -I /usr/local/go/pkg/include -D GOOS_linux -D GOARCH_amd64 ./rt0_linux_amd64.s
/usr/local/go/pkg/tool/linux_amd64/asm -o $WORK/runtime/_obj/sys_linux_amd64.o -trimpath $WORK -I $WORK/runtime/_obj/ -I /usr/local/go/pkg/include -D GOOS_linux -D GOARCH_amd64 ./sys_linux_amd64.s
pack r $WORK/runtime.a $WORK/runtime/_obj/asm.o $WORK/runtime/_obj/asm_amd64.o $WORK/runtime/_obj/duff_amd64.o $WORK/runtime/_obj/memclr_amd64.o $WORK/runtime/_obj/memmove_amd64.o $WORK/runtime/_obj/rt0_linux_amd64.o $WORK/runtime/_obj/sys_linux_amd64.o # internal
...

$ go version
go version go1.5 linux/amd64

[ianlancetaylor]

In Go 1.5 "go build -a" will rebuild the standard library if the set of source files have changed. It should not rebuild if the time is out of date but the source files have not changed. How did you install the release?

CC @rsc

[leemcloughlin]

Hi

I'm working in a VMWare Fusion guest running Ubuntu 14.04. The under Ubuntu seems OK but I ran ntpdate manually to be sure but it didn't help.

I extracted the download under a sudo shell in /usr/local with:

tar xvf ~/Downloads/go1.5.linux-amd64.tar.gz

I just tried against but this time with:

tar xpvf ~/Downloads/go1.5.linux-amd64.tar.gz

but the issue remains.

When I rebuild my gofarmhash package it tries to rebuild runtime. The files in pkg/linux_amd64/runtime are all newer than the files in src/runtime:

pkg/linux_amd64/runtime:
total 664
-rw-r--r-- 1 root root 48284 Aug 19 07:16 cgo.a
-rw-r--r-- 1 root root 58378 Aug 19 07:16 debug.a
-rw-r--r-- 1 root root 229382 Aug 19 07:16 pprof.a
-rw-r--r-- 1 root root 330828 Aug 19 07:16 race.a
-rw-r--r-- 1 root root 3802 Aug 19 07:16 trace.a

src/runtime/:
total 3168
-rw-r--r-- 1 root root 8567 Aug 19 07:05 alg.go
-rw-r--r-- 1 root root 4461 Aug 19 07:05 append_test.go
-rw-r--r-- 1 root root 399 Aug 19 07:05 arch1_386.go
-rw-r--r-- 1 root root 339 Aug 19 07:05 arch1_amd64.go
-rw-r--r-- 1 root root 371 Aug 19 07:05 arch1_amd64p32.go
-rw-r--r-- 1 root root 334 Aug 19 07:05 arch1_arm64.go
... (all the files here have the same timestamp)

but still they are rebuilt.

[ianlancetaylor]

Do you have GOROOT set in the environment?

If not, what do you see in the directory printed by "go env GOROOT"?

[leemcloughlin]

Hi

I dont have GOROOT set in my environment

$ go env GOROOT
/usr/local/go
$ ls -l $(go env GOROOT)
total 128
drwxr-xr-x 2 root root 4096 Aug 19 07:05 api
-rw-r--r-- 1 root root 21139 Aug 19 07:05 AUTHORS
drwxr-xr-x 2 root root 4096 Aug 19 07:16 bin
drwxr-xr-x 4 root root 4096 Aug 19 07:16 blog
-rw-r--r-- 1 root root 1107 Aug 19 07:05 CONTRIBUTING.md
-rw-r--r-- 1 root root 28953 Aug 19 07:05 CONTRIBUTORS
drwxr-xr-x 8 root root 4096 Aug 19 07:05 doc
-rw-r--r-- 1 root root 1150 Aug 19 07:05 favicon.ico
drwxr-xr-x 3 root root 4096 Aug 19 07:05 lib
-rw-r--r-- 1 root root 1479 Aug 19 07:05 LICENSE
drwxr-xr-x 13 root root 4096 Aug 19 07:16 misc
-rw-r--r-- 1 root root 1303 Aug 19 07:05 PATENTS
drwxr-xr-x 7 root root 4096 Aug 19 07:16 pkg
-rw-r--r-- 1 root root 1519 Aug 19 07:05 README.md
-rw-r--r-- 1 root root 26 Aug 19 07:05 robots.txt
drwxr-xr-x 43 root root 4096 Aug 19 07:05 src
drwxr-xr-x 16 root root 12288 Aug 19 07:15 test

[leemcloughlin]

I just deleted /usr/local/go, reinstalled go 1.4.2 and "go build -v -a" does not build the system libraries. So it is unlikely to be an issue with my system causing the problem with go 1.5

[leemcloughlin]

I believe its actually now the expected behaviour after reading:

https://go-review.googlesource.com/#/c/10761/ cmd/go: make -a apply to the standard library, like in Go 1.3

So consider this issue closed

[gopherbot]

CL https://golang.org/cl/13799 mentions this issue.