godoc/vfs/mapfs: panic on invalid New usage

mapfs.New documentation says:

> Map keys should be forward slash-separated pathnames
> and not contain a leading slash.

It is invalid input if a provided path contains a leading slash, and it
causes the returned filesystem to have undefined behavior. Package mapfs
is often used in tests, so this can lead to a serious problem elsewhere.

Help detect invalid API usage sooner by validating input, and panicking
when it contains leading slashes. Programs that use mapfs API correctly
will be unaffected, and it will be faster for incorrect programs—if any
exist today or will be created in the future—to detect and correct such
problems.

Fixes golang/go#34591.

Change-Id: I77e5f0f4628edf83480604135f58bfb62e521d80
Reviewed-on: https://go-review.googlesource.com/c/tools/+/197859
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>
1 file changed
tree: 24f301d8c042a2998950b8ea09b0fbcb026700e0
  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. txtar/
  15. .gitattributes
  16. .gitignore
  17. AUTHORS
  18. codereview.cfg
  19. CONTRIBUTING.md
  20. CONTRIBUTORS
  21. go.mod
  22. go.sum
  23. LICENSE
  24. PATENTS
  25. 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.

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