cmd/go: go mod tidy -v does not print information about modules removed from go.sum

[SunRunAway]

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

$ go version
go version go1.14 darwin/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

What did you do?

go help mod tidy

usage: go mod tidy [-v]

Tidy makes sure go.mod matches the source code in the module.
It adds any missing modules necessary to build the current module's
packages and dependencies, and it removes unused modules that
don't provide any relevant packages. It also adds any missing entries
to go.sum and removes any unnecessary ones.

The -v flag causes tidy to print information about removed modules
to standard error.

go mod tidy -v
echo $?

What did you expect to see?

Print information about removed modules as the documentation says

What did you see instead?

no information printed.

[bcmills]

Duplicate of #33284

[bcmills]

Actually, maybe not. What information did you expect it to print?

Ideally, please provide a code sample, such as a reference to a specific repository and commit, for which go mod tidy removes modules from the dependency graph (as reported by go mod graph) but does not print that those modules have been removed.

[SunRunAway]

Hi, @bcmills
Thanks for your reply. Sorry for the lack of information.
Normally when I use go mod tidy -v, it will print the unused package.

For example, this repository (https://github.com/SunRunAway/testgomod) works normally.

[sunrunaway:/tmp/testgomod]$ go mod tidy -v
unused go.uber.org/atomic

But in this repository (https://github.com/SunRunAway/tidb/tree/964f9baa063c5ce282dfeee60678762e0bdc4c46),

When I run go mod tidy -v, it prints nothing but actually removed two line in the go.sum file.

[sunrunaway:...src/github.com/pingcap/tidb]$ git checkout 964f9baa063c5ce282dfeee60678762e0bdc4c46                                                   (964f9baa0) 
HEAD is now at 964f9baa0 build: `make tidy` should reports error
[sunrunaway:...src/github.com/pingcap/tidb]$ git status -s                                                                                           (964f9baa0) 
[sunrunaway:...src/github.com/pingcap/tidb]$ go mod tidy -v                                                                                          (964f9baa0) 
[sunrunaway:...src/github.com/pingcap/tidb]$ git status -s                                                                                          (964f9baa0✱) 
 M go.sum

[bcmills]

go.sum entries are checksums, not dependencies. (Dependencies are listed in the go.mod file and in the go.mod files of the module versions listed therein.)

go mod tidy only prints information about dependencies removed from the go.mod graph, not the go.sum file.

[bcmills]

As far as I can tell this is working as documented, but please let us know if you have additional detail that may indicate a bug.

[SunRunAway]

Thank you for your patient explanation. Sorry for bothering you.
Have no other questions.