cmd/go: inconsistency when go build -o is a file or directory

[perillo]

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

$ go version
go version go1.14rc1 linux/amd64

Does this issue reproduce with the latest release?

Yes.

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

go env Output

$ go env
GO111MODULE="on"
GOARCH="amd64"
GOBIN="/home/manlio/.local/bin"
GOCACHE="/home/manlio/.cache/go-build"
GOENV="/home/manlio/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/manlio/.local/lib/go:/home/manlio/src/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/home/manlio/sdk/go1.14rc1"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/home/manlio/sdk/go1.14rc1/pkg/tool/linux_amd64"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/dev/null"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build934357574=/tmp/go-build -gno-record-gcc-switches"
GOROOT/bin/go version: go version go1.14rc1 linux/amd64
GOROOT/bin/go tool compile -V: compile version go1.14rc1
uname -sr: Linux 5.5.4-arch1-1
/usr/lib/libc.so.6: GNU C Library (GNU libc) stable release version 2.31.
gdb --version: GNU gdb (GDB) 9.1

What did you do?

go build -o path behave differently when path is a file or directory.

As an example, go build -o file ./pkg, will build an executable if pkg is a main package or an archive otherwise.

On the other hand, go build -o dir ./..., will build all the main packages, saving the files in the build directory, using the last segment of the importpath as the name. This is done even if two executable happen to have the same name, without any notice.

For consistency, go build -o dir ./... should save the archive files in the build directory, when processing non main packages, using the same algorithm used for main packages.

I suspect that building an archive file is here only for compatibility reason.

[bcmills]

CC @jayconrod @matloob

[bcmills]

This is done even if two executable happen to have the same name, without any notice.

That seems like an independent bug. File it as a separate issue?

[bcmills]

For consistency, go build -o dir ./... should save the archive files in the build directory, when processing non main packages, using the same algorithm used for main packages.

I don't think I understand what you mean. Do you expect go build to write archive files into dir, or to build the archive files but not copy them in?

More generally (and following #36784 (comment)): what is the concrete problem that you're trying to address where the current behavior of the -o flag is causing trouble?

[gopherbot]

Timed out in state WaitingForInfo. Closing.

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