Simple go program from the upstream repository fails to compile

[javgh]

Issue description

A year ago an issue was filed for the Go compiler ( golang/go#14669 ) that showed that passing optimization flags to cgo would break it. This bug was fixed upstream and a test case has been added.

That same testcase does not seem to compile under NixOS however. I'm new to both NixOS and go, so I'm not quite sure what's going on.

Steps to reproduce

Test case from upstream:

wget https://raw.githubusercontent.com/golang/go/master/misc/cgo/errors/issue14669.go
cat issue14669.go

// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Issue 14669: test that fails when build with CGO_CFLAGS selecting
// optimization.

package p

/*
const int E = 1;

typedef struct s {
	int       c;
} s;
*/
import "C"

func F() {
	_ = C.s{
		c: C.E,
	}
}

Attempt to build it:

nix-shell -p go gcc
go build -x issue14669.go 

warning: GOPATH set to GOROOT (/nix/store/k114bnw0gzag4b07492dgxi2gs858xrl-go-1.8/share/go) has no effect
WORK=/run/user/1000/go-build864270593
mkdir -p $WORK/command-line-arguments/_obj/
mkdir -p $WORK/
cd /tmp/g
CGO_LDFLAGS="-g" "-O2" /nix/store/k114bnw0gzag4b07492dgxi2gs858xrl-go-1.8/share/go/pkg/tool/linux_amd64/cgo -objdir $WORK/command-line-arguments/_obj/ -importpath command-line-arguments -- -I $WORK/command-line-arguments/_obj/ -g -O2 issue14669.go
# command-line-arguments
cgo-dwarf-inference:2:8: error: enumerator value for '__cgo_enum__0' is not an integer constant
cgo-dwarf-inference:5:8: error: enumerator value for '__cgo_enum__2' is not an integer constant
cgo-dwarf-inference:8:2: error: initializer element is not constant
cgo-dwarf-inference:8:2: note: (near initialization for '__cgodebug_data[0]')
cgo-dwarf-inference:10:2: error: initializer element is not constant
cgo-dwarf-inference:10:2: note: (near initialization for '__cgodebug_data[2]')

Technical details

• System: 17.09pre106916.c5badb123a (Hummingbird)
• Nix version: nix-env (Nix) 1.11.9
• Nixpkgs version: 17.09pre106916.c5badb123a
• Sandboxing enabled: false

[javgh]

Sorry, the referenced issue ( golang/go#14669 ) is a red herring. I now realized that it's not related at all.

The real problem is a mismatch between C compilers. The NixOS go package is built using clang, but I tried to use gcc while attempting to compile the small Go program. The problem goes away if I instead use clang.

It seems that the helper buildGoPackage also uses gcc by default, which then runs into the same problem for certain Go programs. I'll look into that some more and might then open a separate issue for it.

[sergei-mironov]

Wow, thank you! With this knowledge I was able to build the newest go-etherium using older expression. I didn't run any tests yet, but still its a ./result :) Below is the full 1.6.1 expression, for reference:

{ stdenv, fetchFromGitHub, go, gmp, leveldb, clang }:

stdenv.mkDerivation rec {
name = "geth-${version}";
version = "1.6.1";
buildInputs = [go gmp clang];

src = fetchFromGitHub {
owner = "ethereum";
repo = "go-ethereum";
rev = "021c3c281629baf2eae967dc2f0a7532ddfdc1fb";
sha256 = "02w5zjs40iznnph6c0kp34c84nrx3dkdarcpdyawkjpwjvxkw05g";
};

preBuild=''
export CC=clang
'';

installPhase = ''
mkdir -p "$out"
cp -r build/bin "$out/bin"
'';

meta = with stdenv.lib; {
description = "Ethereum blockchain client";
homepage = "https://ethereum.org/";
maintainers = with maintainers; [ dvc ];
license = licenses.gpl3;
};
}

[javgh]

Follow up issue regarding buildGoPackage: #25626