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

$ go version
go version go1.13 windows/amd64

Does this issue reproduce with the latest release?

Yes

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

$ go env
set GO111MODULE=
set GOARCH=amd64
set GOBIN=
set GOCACHE=REDACTED
set GOENV=REDACTED
set GOEXE=.exe
set GOFLAGS=
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GONOPROXY=
set GONOSUMDB=
set GOOS=windows
set GOPATH=REDACTED
set GOPRIVATE=
set GOPROXY=https://proxy.golang.org,direct
set GOROOT=c:\go
set GOSUMDB=sum.golang.org
set GOTMPDIR=
set GOTOOLDIR=c:\go\pkg\tool\windows_amd64
set GCCGO=gccgo
set AR=ar
set CC=gcc
set CXX=g++
set CGO_ENABLED=1
set GOMOD=
set CGO_CFLAGS=-g -O2
set CGO_CPPFLAGS=
set CGO_CXXFLAGS=-g -O2
set CGO_FFLAGS=-g -O2
set CGO_LDFLAGS=-g -O2
set PKG_CONFIG=pkg-config
set GOGCCFLAGS=-m64 -mthreads -fmessage-length=0 -fdebug-prefix-map=C:\Tools\Cygwin\tmp\go-build079254262=/tmp/go-build -gno-record-gcc-switches

What did you do?

• gitlab.com/firelizzard/golang-issue-34300
  • a
    • go.mod
    • b
      • main.go - just println("hello world")
  • c
    • go.mod
    • d
      • main.go - println("hello world") and a package import

• Issues with -trimpath

  1. Build from the parent directory - builds
     • go build -trimpath -o a.exe ./a/b
  2. Build from the module directory - builds
     • cd ./a && go build -trimpath -o ../b.exe ./b
  3. Build from the parent directory, forcing modules - fails with "cannot find main module"
     • GO111MODULE=on go build -trimpath -o am.exe ./a/b

• Issues with imports

  1. Build from the parent directory - fails with "cannot find package"
     • go build ./c/d
  2. Build from the module directory - builds
     • cd ./c && go build ./d
  3. Build from the parent directory, forcing modules - fails with "cannot find main module"
     • GO111MODULE=on go build ./c/d

I used this script, sym.go to dump the paths stored in the executables.

What did you expect to see?

I expected builds to work from both directories, and I expected -trimpath to... trim paths.

What did you see instead?

Weird paths for the main package (results for b.exe are what I expected for both):

% go run $GOROOT/src/cmd/objtest/sym.go a.exe
main.main => _/C_/Source/test/a/b/main.go:3

% go run $GOROOT/src/cmd/objtest/sym.go b.exe
main.main => test@/b/main.go:3

Errors when building:

c\d\main.go:3:8: cannot find package "github.com/etcd-io/bbolt" in any of:
        GOROOT\src\github.com\etcd-io\bbolt (from $GOROOT)
        GOPATH\src\github.com\etcd-io\bbolt (from $GOPATH)

go: cannot find main module, but found .git/config in C:\Source\test
        to create a module there, run:
        go mod init