[release-branch.go1.15] cmd/go: relax version's error on unexpected flags
In https://golang.org/cl/221397 we made commands like "go version -v"
error, since both of the command's flags only make sense when arguments
follow them. Without arguments, the command only reports Go's own
version, and the flags are most likely a mistake.
However, the script below is entirely reasonable:
export GOFLAGS=-v # make all Go commands verbose
go version
go build
After the previous CL, "go version" would error. Instead, only error if
the flag was passed explicitly, and not via GOFLAGS.
The patch does mean that we won't error on "GOFLAGS=-v go version -v",
but that very unlikely false negative is okay. The error is only meant
to help the user not misuse the flags, anyway - it's not a critical
error of any sort.
To reuse inGOFLAGS, we move it to the base package and export it there,
since it's where the rest of the GOFLAGS funcs are.
Fixes #41464.
Change-Id: I74003dd25d94bacf9ac507b5cad778fd65233321
Reviewed-on: https://go-review.googlesource.com/c/go/+/254157
Trust: Daniel Martí <mvdan@mvdan.cc>
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
(cherry picked from commit
de0957dc081e1ec49c99a0f37403ceadbaaedf85)
Reviewed-on: https://go-review.googlesource.com/c/go/+/255498
Trust: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Bryan C. Mills <bcmills@google.com>