go/doc/next/3-tools.md

## Tools {#tools}

### Go command {#go-command}

The `go build` and `go install` commands now accept a `-json` flag that reports
build output and failures as structured JSON output on standard output.
For details of the reporting format, see `go help buildjson`.

Furthermore, `go test -json` now reports build output and failures in JSON,
interleaved with test result JSON.
These are distinguished by new `Action` types, but if they cause problems in
a test integration system, you can revert to the text build output by setting
`GODEBUG=gotestjsonbuildtext=1`.

### Cgo {#cgo}

Cgo currently refuses to compile calls to a C function which has multiple
incompatible declarations. For instance, if `f` is declared as both `void f(int)`
and `void f(double)`, cgo will report an error instead of possibly generating an
incorrect call sequence for `f(0)`. New in this release is a better detector for
this error condition when the incompatible declarations appear in different
files. See [#67699](/issue/67699).

### Vet

The new `tests` analyzer reports common mistakes in declarations of
tests, fuzzers, benchmarks, and examples in test packages, such as
malformed names, incorrect signatures, or examples that document
non-existent identifiers. Some of these mistakes may cause tests not
to run.

This analyzer is among the subset of analyzers that are run by `go test`.

### GOCACHEPROG

The `cmd/go` internal binary and test caching mechanism can now be implemented
by child processes implementing a JSON protocol between the `cmd/go` tool
and the child process named by the `GOCACHEPROG` environment variable.
This was previously behind a GOEXPERIMENT.
For protocol details, see [#59719](/issue/59719).