cmd/dist: accept imports with leading space

[XiaodongLoong]

$ ./make.bash 
Building Go cmd/dist using /usr/lib/go-1.11. (go1.11.6 linux/amd64)
Building Go toolchain1 using /usr/lib/go-1.11.
../../../../src/cmd/compile/internal/mips64/ggen.go:9: cannot find package "cmd/compile/internal/objw" in any of:
	/usr/lib/go-1.11/src/cmd/compile/internal/objw (from $GOROOT)
	/home/liuxiaodong/go-orig/pkg/bootstrap/src/cmd/compile/internal/objw (from $GOPATH)
go tool dist: FAILED: /usr/lib/go-1.11/bin/go install -gcflags=-l -tags=math_big_pure_go compiler_bootstrap bootstrap/cmd/...: exit status 1

What version of Go are you using (go version)?

$ go version
go version go1.11.6 linux/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/liuxiaodong/.cache/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/liuxiaodong/go"
GOPROXY=""
GORACE=""
GOROOT="/usr/lib/go-1.11"
GOTMPDIR=""
GOTOOLDIR="/usr/lib/go-1.11/pkg/tool/linux_amd64"
GCCGO="/usr/bin/gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/home/liuxiaodong/go-orig/src/go.mod"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build598535792=/tmp/go-build -gno-record-gcc-switches"

What did you do?

I import packages and indent with spaces, just like this:

diff --git a/src/cmd/compile/internal/mips64/ggen.go b/src/cmd/compile/internal/mips64/ggen.go
index 37bb871958..881fe8776d 100644
--- a/src/cmd/compile/internal/mips64/ggen.go
+++ b/src/cmd/compile/internal/mips64/ggen.go
@@ -6,7 +6,7 @@ package mips64
 
 import (
        "cmd/compile/internal/ir"
-       "cmd/compile/internal/objw"    // indent with tab
+        "cmd/compile/internal/objw"   // indent with spaces
        "cmd/compile/internal/types"
        "cmd/internal/obj"
        "cmd/internal/obj/mips"

What did you expect to see?

When I import packages and indent with spaces, I can execute make.bash successfully.
Just keep consistent with the behavior of the go compiler.
Thanks!

What did you see instead?

[gopherbot]

Change https://golang.org/cl/340030 mentions this issue: cmd/dist: make.bash failed when import package and indent with spaces

[seankhliao]

Go 1.11 is not a supported version, does this reproduce on the latest release?

[XiaodongLoong]

Yes, the code that have bug is following:

go/src/cmd/dist/buildtool.go

Line 291 in 6e73886

inBlock && (strings.HasPrefix(line, "\t\"") || strings.HasPrefix(line, "\t. \"") || strings.HasPrefix(line, "\texec \"")) {

[seankhliao]

The go code should be formatted with gofmt which will rewrite it to use tabs though

[ianlancetaylor]

cmd/dist is only used to build the Go standard library and tools. It's OK for cmd/dist to assume that all the input files have gone through gofmt. In fact, it's a good thing if cmd/dist fails if the files have not gone through gofmt. So I don't think we should change this.

[XiaodongLoong]

IMO, code style and correct code might be different things. I usually develop Go code firstly and then modify the format with gofmt. Code development may occur in the process of debugging without a good editor. This issue was also found during debugging.
Thanks!

[erifan]

IMO, code style and correct code might be different things.

You can think of this as a coding style error in Go. Just like

if a > 0 {
...
}

can't be

if a > 0
{
...
}

This issue was also found during debugging.

This just shows that this check works.

[ianlancetaylor]

code style and correct code might be different things.

Sure. But our rule for the standard library and tools is simple: all files must be formatted using gofmt. No exceptions.

I usually develop Go code firstly and then modify the format with gofmt. Code development may occur in the process of debugging without a good editor. This issue was also found during debugging.

Thanks, but I don't find any of these arguments to be convincing. If cmd/dist supports files that are not formatted with gofmt, then it will be easier to accidentally submit such files to the repo. We don't want that to happen, so let's not change cmd/dist. Yes, this may requires using go fmt and it may occasionally lead to debugging, but it's still the right thing to do.

[XiaodongLoong]

@ianlancetaylor I got it. Thank you for answering my questions patiently. I will abandon the CL.

[ianlancetaylor]

Thanks.