cmd/go: error if -modfile used with 'go install pkg@version'

'go install pkg@version' runs without a main module or a module root directory. The -modfile flag cannot be used to set the module root directory or to substitute a different go.mod file. This error won't be reported if -modfile is set in GOFLAGS. Unsupported flags there are generally ignored. For #40276 Change-Id: I0b39b1fa9184c15c6e863b647d43c328710920f4 Reviewed-on: https://go-review.googlesource.com/c/go/+/258297 Trust: Jay Conrod <[email protected]> Run-TryBot: Jay Conrod <[email protected]> Reviewed-by: Bryan C. Mills <[email protected]> TryBot-Result: Go Bot <[email protected]>
cloudflare · Sep 30, 2020 · 8b0d00b · 8b0d00b
1 parent 3caaadd
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diff --git a/src/cmd/go/internal/modload/init.go b/src/cmd/go/internal/modload/init.go
@@ -163,8 +163,9 @@ func Init() {
  // Running 'go mod init': go.mod will be created in current directory.
  modRoot = base.Cwd
  } else if RootMode == NoRoot {
- // TODO(jayconrod): report an error if -mod -modfile is explicitly set on
- // the command line. Ignore those flags if they come from GOFLAGS.
+ if cfg.ModFile != "" && !base.InGOFLAGS("-modfile") {
+ base.Fatalf("go: -modfile cannot be used with commands that ignore the current module")
+ }
  modRoot = ""
  } else {
  modRoot = findModuleRoot(base.Cwd)

diff --git a/src/cmd/go/testdata/script/mod_install_pkg_version.txt b/src/cmd/go/testdata/script/mod_install_pkg_version.txt
@@ -26,6 +26,17 @@ rm $GOPATH/bin/a
 cd ..
 
 
+# 'go install -modfile=x.mod pkg@version' reports an error, but only if
+# -modfile is specified explicitly on the command line.
+cd m
+env GOFLAGS=-modfile=go.mod
+go install example.com/cmd/a@latest # same as above
+env GOFLAGS=
+! go install -modfile=go.mod example.com/cmd/a@latest
+stderr '^go: -modfile cannot be used with commands that ignore the current module$'
+cd ..
+
+
 # Every test case requires linking, so we only cover the most important cases
 # when -short is set.
 [short] stop