cmd/go: remove hint when no module is suggested

Fixes #46528

Change-Id: I2453d321ece878ea7823865758aa4a16b3ed7fe8
Reviewed-on: https://go-review.googlesource.com/c/go/+/325430
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Bryan C. Mills <bcmills@google.com>
Trust: Heschi Kreinick <heschi@google.com>
Trust: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>

diff --git a/src/cmd/go/internal/modload/import.go b/src/cmd/go/internal/modload/import.go
index f76befcfe3525920697738b9b8de3c671fe121cc..60bd26fb22f019ee21ae29c95f1cf9ea8d3a2e8b 100644 (file)
--- a/src/cmd/go/internal/modload/import.go
+++ b/src/cmd/go/internal/modload/import.go
@@ -178,11 +178,13 @@ func (e *ImportMissingSumError) Error() string {
                // Importing package is unknown, or the missing package was named on the
                // command line. Recommend 'go mod download' for the modules that could
                // provide the package, since that shouldn't change go.mod.
-               args := make([]string, len(e.mods))
-               for i, mod := range e.mods {
-                       args[i] = mod.Path
+               if len(e.mods) > 0 {
+                       args := make([]string, len(e.mods))
+                       for i, mod := range e.mods {
+                               args[i] = mod.Path
+                       }
+                       hint = fmt.Sprintf("; to add:\n\tgo mod download %s", strings.Join(args, " "))
                }
-               hint = fmt.Sprintf("; to add:\n\tgo mod download %s", strings.Join(args, " "))
        } else {
                // Importing package is known (common case). Recommend 'go get' on the
                // current version of the importing package.

diff --git a/src/cmd/go/testdata/script/mod_install_hint.txt b/src/cmd/go/testdata/script/mod_install_hint.txt
new file mode 100644 (file)
index 0000000..ab02840
--- /dev/null
+++ b/src/cmd/go/testdata/script/mod_install_hint.txt
@@ -0,0 +1,5 @@
+# Module is replaced but not required. No hint appears as no module is suggested.\r
+go mod init m\r
+go mod edit -replace=github.com/notrequired@v0.5.0=github.com/doesnotexist@v0.5.0\r
+! go install github.com/notrequired\r
+! stderr 'to add it:'
\ No newline at end of file