cmd/vet: fix a bad case of shadow check about redeclaration

`go tools vet -shadow` ignored the case like this form
```golang
func shadowBlock() {
    var a int
    {
        var a = 3
        _ = a
    }
    _ = a
}
```
This commit fix it on "idiomaticRedecl" func, and add the code above in testcase.

Change-Id: I007f8287766f59cd7ded86072ba6bf6743c392be
GitHub-Last-Rev: b8b302b2048d709a39fb17496ba80917f9f4c889
GitHub-Pull-Request: golang/tools#143
Reviewed-on: https://go-review.googlesource.com/c/tools/+/189158
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
2 files changed
tree: 5fdd029ac21d85a45a55e20d97f706b68a15ad68
  1. benchmark/
  2. blog/
  3. cmd/
  4. container/
  5. cover/
  6. go/
  7. godoc/
  8. gopls/
  9. imports/
  10. internal/
  11. playground/
  12. present/
  13. refactor/
  14. .gitattributes
  15. .gitignore
  16. AUTHORS
  17. codereview.cfg
  18. CONTRIBUTING.md
  19. CONTRIBUTORS
  20. go.mod
  21. go.sum
  22. LICENSE
  23. PATENTS
  24. README.md
README.md

Go Tools

This subrepository holds the source for various packages and tools that support the Go programming language.

Some of the tools, godoc and vet for example, are included in binary Go distributions.

Others, including the Go guru and the test coverage tool, can be fetched with go get.

Packages include a type-checker for Go and an implementation of the Static Single Assignment form (SSA) representation for Go programs.

Download/Install

The easiest way to install is to run go get -u golang.org/x/tools/.... You can also manually git clone the repository to $GOPATH/src/golang.org/x/tools.

Report Issues / Send Patches

This repository uses Gerrit for code changes. To learn how to submit changes to this repository, see https://golang.org/doc/contribute.html.

The main issue tracker for the tools repository is located at https://github.com/golang/go/issues. Prefix your issue with “x/tools/(your subdir):” in the subject line, so it is easy to find.