cmd/compile: full go file paths produced in .a and bin files even with -trimpath

[wak-google]

What version of Go are you using (go version)?

go1.9

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

linux/amd64

What did you do?

set GOPATH=/tmp/my-go-build/go
set CGO_CFLAGS="-fdebug-prefix-map=/tmp/my-go-build=/no-such-path"
go get -d leb.io/hashland
go build "-asmflags" "-trimpath=/tmp/my-go-build" "-gcflags" "-trimpath=/tmp/my-go-build" -v "leb.io/hashland/keccak"

What did you expect to see?

No references to my-go-build. This is the case on go1.8.3 and older

What did you see instead?

This produces a /tmp/my-go-build/go/pkg/linux_amd64/leb.io/hashland/keccak.a that contains a full path reference to /tmp/my-go-build even when the -trimpath flag was specified.

[FiloSottile]

@mholt was looking at the same thing.

[mdempsky]

I think using -trimpath in this manner is unsupported anyway. Currently, we only support setting -trimpath once, and cmd/go already sets it when invoking the compiler and assembler.

Moreover, I believe it's supported for the purpose of trimming temporary directories that are generated during the build, so that repeat builds that use different temporary directories will still produce the same output.

Your intended use case appears to be to hide your $GOPATH directory. I don't think that's a supported use case currently.

/cc @rsc for input on whether this is something we want to support.

[rsc]

Why did Go 1.8 vs Go 1.9 change? I agree that it's not something I intended to support but I'm curious why it stopped "working".

[mdempsky]

I see the same behavior with Go 1.8.3:

mdempsky@bento-glaptop3:/tmp/my-go-build$ echo $GOPATH
/tmp/my-go-build/go
mdempsky@bento-glaptop3:/tmp/my-go-build$ go version
go version go1.8.3 linux/amd64
mdempsky@bento-glaptop3:/tmp/my-go-build$ go build -a -o keccak.a "-asmflags" "-trimpath=/tmp/my-go-build" "-gcflags" "-trimpath=/tmp/my-go-build -v" leb.io/hashland/keccak
mdempsky@bento-glaptop3:/tmp/my-go-build$ strings keccak.a | grep /tmp/my-go-build
/tmp/my-go-build/go/src/leb.io/hashland/keccak
/tmp/my-go-build/go/src/leb.io/hashland/keccak
/tmp/my-go-build/go/src/leb.io/hashland/keccak
/tmp/my-go-build/go/src/leb.io/hashland/keccak
/tmp/my-go-build/go/src/leb.io/hashland/keccak
/tmp/my-go-build/go/src/leb.io/hashland/keccak
/tmp/my-go-build/go/src/leb.io/hashland/keccak/KeccakF-1600-opt64.c
/tmp/my-go-build/go/src/leb.io/hashland/keccak/KeccakNISTInterface.c
/tmp/my-go-build/go/src/leb.io/hashland/keccak/KeccakSponge.c

[mdempsky]

@wak-google I just tested with Go 1.6, Go 1.7, and Go 1.8.3, and they all appear to behave the same as Go 1.9 with regards to "/tmp/my-go-build" appearing in the compiled .a file. Do you mind double checking this?

[wak-google]

@mdempsky My understanding is that all of the strings in the go1.8 case are coming from the c compiler. I forgot to mention in the initial report that I have CGO_CFLAGS="-fdebug-prefix-map=/tmp/my-go-build=/no-such-path". If you set that environment variable or pass the CFLAGS in some other way all references to my-go-build go away in 1.8. In the 1.9 case you still get

my-go-build
gofile../tmp/my-go-build/go/src/leb.io/hashland/keccak/keccak.go

[mdempsky]

@wak-google Thanks, I can repro your issue now. I'll figure out what changed.

[gopherbot]

Change https://golang.org/cl/63693 mentions this issue: cmd/compile: replace GOROOT in //line directives

[Ei5enheim]

@mdempsky @rsc
I'm facing the same issue.

What version of Go are you using (go version)?
go version go1.8 linux/amd64

Does this issue reproduce with the latest release?
I don't know

What operating system and processor architecture are you using (go env)?
GOARCH="amd64"
GOBIN="/home/dev/Documents/iox/go/bin"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/dev/Documents/iox/proj/"
GORACE=""
GOROOT="/home/dev/Documents/iox/go"
GOTOOLDIR="/home/dev/Documents/iox/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build694052321=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="1"
PKG_CONFIG="pkg-config"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"

What did you do?
go build -x -v -gcflags "-trimpath=$GOPATH" -asmflags "-trimpath=$GOPATH"

What did you expect to see?
No $GOPATH in my stack trace, but I do see that.
panic: assignment to entry in nil map

goroutine 1 [running]:
main.main()
/home/dev/Documents/iox/proj/src/ioxclient/ioxclient.go:2193 +0x59

I also noticed that go is creating a temp directory for build process and the command used to compile the binary starts with

/home/dev/Documents/iox/go/pkg/tool/linux_amd64/compile -o $WORK/ioxclient.a -trimpath $WORK -trimpath=/home/dev/Documents/iox/proj/

Is it failing because trimpath can only be used once to remove $WORK?