cmd/install: Failure to fetch from git repo using semver tag when module is in subdirectory

[wkaluza]

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

$ go version
go version go1.17.2 linux/amd64

Does this issue reproduce with the latest release?

Yes ( go1.17beta1-2430-g6c36c332fe )

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

go env Output

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/wkaluza/.cache/go-build"
GOENV="/home/wkaluza/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/wkaluza/go/pkg/mod"
GONOPROXY="github.com/wkaluza/*"
GONOSUMDB="github.com/wkaluza/*"
GOOS="linux"
GOPATH="/home/wkaluza/go"
GOPRIVATE="github.com/wkaluza/*"
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.17.2"
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-build1159245153=/tmp/go-build -gno-record-gcc-switches"
GOROOT/bin/go version: go version go1.17.2 linux/amd64
GOROOT/bin/go tool compile -V: compile version go1.17.2
uname -sr: Linux 5.11.0-40-generic
Distributor ID:	Ubuntu
Description:	Ubuntu 20.04.3 LTS
Release:	20.04
Codename:	focal
/lib/x86_64-linux-gnu/libc.so.6: GNU C Library (Ubuntu GLIBC 2.31-0ubuntu9.2) stable release version 2.31.
lldb --version: lldb version 10.0.0
gdb --version: GNU gdb (Ubuntu 9.2-0ubuntu1~20.04) 9.2

What did you do?

I attempted to run go install of a package whose module is located in a subdirectory of the git repo.

I created two specimen repositories to illustrate the problem:

• https://github.com/wkaluza/go_issue_root contains a simple app wise_app_root with the canonical cmd+pkg directory structure.
• https://github.com/wkaluza/go_issue_subdir contains an essentially identical app wise_app_subdir, but the directory tree (including go.mod and go.sum) has been placed in a subdirectory subdir.

Both repositories contain a default branch main and a semver tag v0.0.1.

The command go install github.com/wkaluza/go_issue_root/cmd/[email protected] works fine and places the executable wise_app_root in $GOPATH/bin. Attempting to run github.com/wkaluza/go_issue_subdir/subdir/cmd/[email protected] fails.

Curiously, installing a non-semver tag does not show this behaviour and works for both repos. Likewise, installations using "latest", a branch name or the commit digest (SHA-1) are not affected by the project structure. The following script can be used to replicate the failure:

#!/usr/bin/env bash

set -euo pipefail

function clean_test_env {
  rm -f $GOPATH/bin/wise_app_root
  rm -f $GOPATH/bin/wise_app_subdir

  go clean -cache -modcache -testcache
}

function run_tests {
  local revision1="$1"
  local revision2="${2:-$revision1}"

  local URL_ROOT="github.com/wkaluza/go_issue_root/cmd/wise_app_root"
  local URL_SUBDIR="github.com/wkaluza/go_issue_subdir/subdir/cmd/wise_app_subdir"

  echo ""
  echo "Install app from repo root directory (revision: $revision1)"
  echo "go install $URL_ROOT@$revision1"
  echo ""

  clean_test_env
  go install "$URL_ROOT@$revision1"
  $GOPATH/bin/wise_app_root

  echo ""
  echo "Install app from repo subdirectory (revision: $revision2)"
  echo "go install $URL_SUBDIR@$revision2"
  echo ""

  clean_test_env
  go install "$URL_SUBDIR@$revision2"
  $GOPATH/bin/wise_app_subdir
}

function main {

  ### All of these work fine:
  # run_tests latest
  # run_tests main
  # run_tests \
  #   3f2f5eb664072317111c17ec80aca61e04f2d943 \
  #   60038133a59943847cd9a830f218ca3491943c5b
  # run_tests branch_not_main
  # run_tests tag_not_semver

  ### A semver tag fails for the subdir case
  run_tests v0.0.1

  echo Success
}

# Entry point
main

What did you expect to see?

I expected go install to work with semver-tagged revisions irrespective of project structure and install the executable wise_app_subdir in $GOPATH/bin.

What did you see instead?

$ go install github.com/wkaluza/go_issue_subdir/subdir/cmd/[email protected]

go: downloading github.com/wkaluza/go_issue_subdir v0.0.1
go install: github.com/wkaluza/go_issue_subdir/subdir/cmd/[email protected]: module github.com/wkaluza/[email protected] found, but does not contain package github.com/wkaluza/go_issue_subdir/subdir/cmd/wise_app_subdir

[seankhliao]

This is working as intended, see https://golang.org/ref/mod#vcs-version

If a module is defined in a subdirectory within the repository, that is, the module subdirectory portion of the module path is not empty, then each tag name must be prefixed with the module subdirectory, followed by a slash.