cmd/go: GO111MODULE=on go build requires gcc

[nqv]

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

go version go1.11rc1 linux/amd64

Does this issue reproduce with the latest release?

Not sure

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

GOARCH="amd64"
GOBIN=""
GOCACHE="/home/nqv/.cache/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/nqv/go"
GOPROXY=""
GORACE=""
GOROOT="/home/nqv/Downloads/go"
GOTMPDIR=""
GOTOOLDIR="/home/nqv/Downloads/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD=""
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 -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build126805613=/tmp/go-build -gno-record-gcc-switches"

What did you do?

Build a minimal http server failed with GO111MODULE=on go build

$ cd ~/go/src/httpd
$ cat httpd.go
package main

import "net/http"

func main() {
	http.ListenAndServe(":8000", nil)
}
$ GO111MODULE=on go mod init
go: creating new go.mod: module httpd
$ GO111MODULE=on go build
# net
exec: "gcc": executable file not found in $PATH

What did you expect to see?

GO111MODULE=on go build produces binary.

What did you see instead?

Build failed due to missing gcc.
Either of these commands works fine though:

$ go build
$ GO111MODULE=on CGO_ENABLED=0 go build

[mvdan]

It's surprising that GO111MODULE=on go build is trying to build the net package, or any other part of the standard library. How did you install Go? Does go build std do nothing, like it should?

cc @myitcv

[myitcv]

Edit: fixed bad copy-paste.

Reproduced:

docker run --rm -i -t ubuntu:16.04 bash
apt-get -y update < /dev/null > /dev/null
apt-get -y install wget < /dev/null > /dev/null
cd /tmp
wget -q https://dl.google.com/go/go1.11rc1.linux-amd64.tar.gz
tar -zxf go1.11rc1.linux-amd64.tar.gz
export PATH=/tmp/go/bin:$PATH
cd
mkdir -p go/src/httpd
cd go/src/httpd
cat <<EOD > httpd.go
package main

import "net/http"

func main() {
http.ListenAndServe(":8000", nil)
}
EOD
GO111MODULE=on go mod init
GO111MODULE=on go build

exits non-zero with:

# net
exec: "gcc": executable file not found in $PATH

whereas:

go build

just works.

/cc @rsc @bcmills @ianlancetaylor

[nqv]

I installed go1.11 from archive

$ cd ~/Downloads
$ curl -L -O https://dl.google.com/go/go1.11rc1.linux-amd64.tar.gz
$ tar xf go1.11rc1.linux-amd64.tar.gz

FYI, go build -v outputs

$ go build -v
httpd

$ rm -r ~/.cache/go-build/
$ GO111MODULE=on go build -v
golang_org/x/crypto/cryptobyte/asn1
golang_org/x/net/dns/dnsmessage
golang_org/x/crypto/internal/chacha20
golang_org/x/crypto/poly1305
golang_org/x/crypto/cryptobyte
golang_org/x/crypto/curve25519
golang_org/x/crypto/chacha20poly1305
golang_org/x/text/transform
golang_org/x/text/unicode/bidi
golang_org/x/net/http2/hpack
net
# net
exec: "gcc": executable file not found in $PATH
golang_org/x/text/unicode/norm
golang_org/x/text/secure/bidirule
golang_org/x/net/idna

$ rm -r ~/.cache/go-build/
$ GO111MODULE=on CGO_ENABLED=0 go build -v
golang_org/x/crypto/cryptobyte/asn1
golang_org/x/net/dns/dnsmessage
golang_org/x/crypto/curve25519
golang_org/x/crypto/internal/chacha20
golang_org/x/crypto/cryptobyte
golang_org/x/crypto/poly1305
golang_org/x/text/transform
golang_org/x/crypto/chacha20poly1305
golang_org/x/text/unicode/bidi
golang_org/x/text/unicode/norm
net
golang_org/x/net/http2/hpack
golang_org/x/text/secure/bidirule
golang_org/x/net/idna
golang_org/x/net/http/httpproxy
net/textproto
crypto/x509
golang_org/x/net/http/httpguts
crypto/tls
net/http/httptrace
net/http
httpd

[rsc]

It's not that surprising, and it's fine for Go 1.11.

[pda]

I find it surprising. It's a pain when there's no gcc.
Here's a minimal reproduction:

$ docker run --rm -w /notgo golang:1.11-alpine sh -c 'go mod init x && go build std'
go: creating new go.mod: module x
# net
exec: "gcc": executable file not found in $PATH

It looks like setting CGO_ENABLED=0 avoids the error, but I'm not sure what the implications are…

$ docker run --rm -w /x golang:1.11-alpine sh -c 'go mod init x && CGO_ENABLED=0 go build std'
go: creating new go.mod: module x