| commit | 5113f5776620dfd0221bb876b9889c73d585371c | [log] [tgz] |
|---|---|---|
| author | Dan Scales <danscales@google.com> | Wed Mar 11 12:08:03 2020 -0700 |
| committer | Dan Scales <danscales@google.com> | Mon Mar 23 19:24:26 2020 +0000 |
| tree | 05d51bce9ea4d6ef4b8848228eec58a0d4650c9e | |
| parent | 6aded2524cb77eeab907e64512c5f7c54b530756 [diff] |
cmd/go: define a build tag for any GOEXPERIMENT which is enabled. For each experiment that has been enabled in the toolchain, define a build tag with the same name (but prefixed by "goexperiment.") which can be used for compiling alternative files for the experiment. This allows changes for the experiment, like extra struct fields in the runtime, without affecting the base non-experiment code at all. I use this capability in my CL for static lock ranking (https://go-review.googlesource.com/c/go/+/207619), so that static lock ranking can be fully enabled as a GOEXPERIMENT, but there is no overhead in the runtime when the experiment is not enabled. I added a test in cmd/go/testdata/scripts to make sure the build tags are being defined properly. In order to implement the test, I needed to provide environment variable GOEXPSTRING to the test scripts (with its value set from objabi.Expstring(), so that it can determine the experiments baked into the toolchain. I filed https://github.com/golang/go/issues/37937 to make a builder with GOEXPERIMENT set to 'staticlockranking'. This builder will ensure another variant of GOEXPERIMENT is being tested regularly for this change, as well as checking static lock ranking in the runtime. Change-Id: Ieb4b86107238febd105558c1e639d30cfe57ab5c Reviewed-on: https://go-review.googlesource.com/c/go/+/222925 Run-TryBot: Dan Scales <danscales@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Jay Conrod <jayconrod@google.com> Reviewed-by: Bryan C. Mills <bcmills@google.com>
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