cmd/go: escape quoted strings in GOFLAGS

[bcmills]

In https://golang.org/cl/126656, @rsc added the GOFLAGS environment variable.

The variable is space-separated, but it is sometimes useful to include spaces within flags passed to the go command (for example, as the final argument to list -f). It would be nice to recognize at least a subset of the usual quoting conventions when parsing GOFLAGS.

~/go/src/cmd/go$ go list -e -deps -f="{{if .Error}}{{.Error}}{{end}}"

~/go/src/cmd/go$ export GOFLAGS='-e -deps -f="{{if .Error}}{{.Error}}{{end}}"'

~/go/src/cmd/go$ go list
go: parsing $GOFLAGS: non-flag ".Error}}{{.Error}}{{end}}\""

[alexbrainman]

@bcmills if you want to support cmd.exe users on Windows, you should consider how quoting works in cmd.exe. For example, this http://daviddeley.com/autohotkey/parameters/parameters.htm#WINCMDRULES shows cmd.exe rules.

Alex

[rsc]

Sorry, but no. I looked at this when I added GOFLAGS, and we don't do any special quoting for the other environment variables (go help environment | grep FLAGS)

This means you cant use GOFLAGS for your example.
That's OK, GOFLAGS is for things like -ldflags=-w.

[tianon]

That's OK, GOFLAGS is for things like -ldflags=-w.

My usage of -ldflags almost always also includes spaces -- I frequently use -d -s -w in order to get smaller static binaries (where size is the primary concern); combined with -tags netgo and CGO_ENABLED=0, this works pretty well.

I think -tags is another great problematic example -- multiple instances of -tags replace each other, and the argument to -tags is space separated, so -tags can't easily be used via GOFLAGS today except for the absolute simplest cases.

Respectfully, I would request that this be reopened and reconsidered, especially since the primary use case where this feature got me excited (building the same binary for a load of different architectures in a row) aren't actually helped by this feature today. ❤️ 😅

(I commented on the CL and was redirected here. ❤️)

[ianlancetaylor]

@rsc I'm not sure I understand the argument for not permitting quoting in the environment variable given the special support we have for quoting in -gcflags and friends. It seems to me that there are clear uses for passing multiple options to all builds, such as the -l -N that delve uses.

[andybons]

Ping @rsc @bcmills.