runtime: eliminate scase.kind field

Currently, we include a "kind" field on scase to distinguish the three
kinds of cases in a select statement: sends, receives, and defaults.

This commit removes by kind field by instead arranging for the
compiler to always place sends before receives, and to provide their
counts separately. It also passes an explicit "block bool" parameter
to avoid needing to include a default case in the array.

It's safe to shuffle cases like this because the runtime will
randomize the order they're polled in anyway.

Fixes #40410.

Change-Id: Iaeaed4cf7bddd576d78f2c863bd91a03a5c82df2
Reviewed-by: Keith Randall <>
5 files changed
tree: a50c3c2cf3d82df52dfb6ed20245584c991d77a2
  1. .gitattributes
  2. .github/
  3. .gitignore
  11. api/
  12. doc/
  13. favicon.ico
  14. lib/
  15. misc/
  16. robots.txt
  17. src/
  18. test/

The Go Programming Language

Go is an open source programming language that makes it easy to build simple, reliable, and efficient software.

Gopher image Gopher image by Renee French, licensed under Creative Commons 3.0 Attributions license.

Our canonical Git repository is located at There is a mirror of the repository at

Unless otherwise noted, the Go source files are distributed under the BSD-style license found in the LICENSE file.

Download and Install

Binary Distributions

Official binary distributions are available at

After downloading a binary release, visit or load doc/install.html in your web browser for installation instructions.

Install From Source

If a binary distribution is not available for your combination of operating system and architecture, visit or load doc/install-source.html in your web browser for source installation instructions.


Go is the work of thousands of contributors. We appreciate your help!

To contribute, please read the contribution guidelines:

Note that the Go project uses the issue tracker for bug reports and proposals only. See for a list of places to ask questions about the Go language.