cmd/go: 'go build -race' with a cross-compiled GOOS should not suggest setting CGO_ENABLED #37021

MasterDimmy · 2020-02-04T19:02:38Z

$ go version
go version go1.13.7 windows/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
set GO111MODULE=

set GOARCH=amd64

set GOBIN=

set GOCACHE=C:\Users\8\AppData\Local\go-build

set GOENV=C:\Users\8\AppData\Roaming\go\env

set GOEXE=.exe

set GOFLAGS=

set GOHOSTARCH=amd64

set GOHOSTOS=windows

set GONOPROXY=

set GONOSUMDB=

set GOOS=windows

set GOPATH=C:\gopath

set GOPRIVATE=

set GOPROXY=https://proxy.golang.org,direct

set GOROOT=C:\Go

set GOSUMDB=sum.golang.org

set GOTMPDIR=

set GOTOOLDIR=C:\Go\pkg\tool\windows_amd64

set GCCGO=gccgo

set AR=ar

set CC=gcc

set CXX=g++

set CGO_ENABLED=1

set GOMOD=C:\Go\src\go.mod

set CGO_CFLAGS=-g -O2

set CGO_CPPFLAGS=

set CGO_CXXFLAGS=-g -O2

set CGO_FFLAGS=-g -O2

set CGO_LDFLAGS=-g -O2

set PKG_CONFIG=pkg-config

set GOGCCFLAGS=-m64 -mthreads -fmessage-length=0 -fdebug-prefix-map=d:\TEMP\go-build345576314=/tmp/go-build -gno-record-gcc-switches

What did you do?

i compile this file for test:

package main

import (
"fmt"
)

func main() {
c := make(chan bool)
m := make(map[string]string)
go func() {
m["1"] = "a" // First conflicting access.
c <- true
}()
m["2"] = "b" // Second conflicting access.
<-c
for k, v := range m {
fmt.Println(k, v)
}
}

with

set CGO_ENABLED=1
set GOOS=linux
set GO_ARCH=amd64
go build -race

What did you expect to see?

success compile

What did you see instead?

# runtime/cgo
gcc_linux_amd64.c: In function '_cgo_sys_thread_start':
gcc_linux_amd64.c:66:2: error: implicit declaration of function 'sigfillset' [-Werror=implicit-function-declaration]
   66 |  sigfillset(&ign);
      |  ^~~~~~~~~~
cc1.exe: all warnings being treated as errors

Note, that

set CGO_ENABLED=1
set GOOS=linux
go build

is succecced, but i need to compile with "-race" detector. If CGO_ENABLED=0

set CGO_ENABLED=0
set GOOS=linux
go build -race

then i got

go build: -race requires cgo; enable cgo by setting CGO_ENABLED=1

The text was updated successfully, but these errors were encountered:

bcmills · 2020-02-04T19:51:08Z

Cross-compiling programs with C dependencies is generally not supported, and the runtime support for -race mode relies on C dependencies.

If you want to build a race-enabled binary, you need to either compile for GOOS=windows or build the binary on a Linux machine.

bcmills · 2020-02-04T19:51:53Z

Probably the best we can do here is emit a clearer diagnostic for cross-compiled -race builds. (We should not prompt the user to “enable cgo” if we don't have reason to believe that such a build would succeed.)

CC @jayconrod @matloob

MasterDimmy · 2020-02-04T19:53:06Z

just try to cross compile this:

package main

import (
"fmt"
)

func main() {
c := make(chan bool)
m := make(map[string]string)
go func() {
m["1"] = "a" // First conflicting access.
c <- true
}()
m["2"] = "b" // Second conflicting access.
<-c
for k, v := range m {
fmt.Println(k, v)
}
}

from windows\amd64 to linux\amd64 with gox

MasterDimmy · 2020-02-04T19:54:52Z

I think "'go build -race' with a cross-compiled GOOS should not suggest setting CGO_ENABLED" is not what this issue is for, that is another issue\suggestion.

Current issue is unavailability to crosscompile "-race" with gox.

bcmills · 2020-02-04T20:01:40Z

@MasterDimmy, the fact that go test -race has C dependencies is not something we can feasibly fix. (The race detector uses a fairly extensive C library, and the folks on the Go team are not in a position to rewrite it from scratch in pure Go.)

If you want to volunteer to rewrite the race-detector library in pure Go, you're welcome to do so, but as far as “things we can feasibly plan to fix” are concerned, a better error message for this case is about the limit.

keyan · 2020-04-26T05:14:16Z

@bcmills I took a stab at just modifying the error message in #38670. I'm just trying getting my feet wet and orient myself in the codebase.

gopherbot · 2020-04-26T05:15:42Z

Change https://golang.org/cl/230202 mentions this issue: work: add error for cross-compiled -race builds

ianlancetaylor · 2020-04-28T00:26:41Z

Wait, I'm not following the suggestion here. Cross-compiling cgo code works fine if you have a cross-compiler.

We may want a general fix to do better checking of whether you are using a cross-compiler when doing a cross-build that uses cgo. But that seems separate from the narrow issue of "go build -race", which should work if a cross-compiler is installed.

keyan · 2020-04-28T03:11:27Z

I misunderstood Bryan's comment:

Cross-compiling programs with C dependencies is generally not supported

If I understand correctly now, the short term move is just to not mention setting CGO_ENABLED because that isn't sufficient on its' own and it is too verbose to explain that you need to have a cross-compiler installed?

Race builds require C dependencies, but cross-compiled cgo builds are not always possible, so don't suggest enabling CGO in those cases. Fixes golang#37021 Change-Id: I1fd675efc9cef958a926bd63eac8e6858bc59d0a GitHub-Last-Rev: cbf43c1 GitHub-Pull-Request: golang#38670 Reviewed-on: https://go-review.googlesource.com/c/go/+/230202 Reviewed-by: Bryan C. Mills <bcmills@google.com>

MasterDimmy mentioned this issue Feb 4, 2020

build with "-race" option mitchellh/gox#141

Open

bcmills changed the title ~~cannot compile go build -race with GOOS=linux on windows~~ cmd/go: 'go build -race' with a cross-compiled GOOS should not suggest setting CGO_ENABLED Feb 4, 2020

bcmills added help wanted NeedsFix The path to resolution is known, but the work has not been done. labels Feb 4, 2020

bcmills added this to the Backlog milestone Feb 4, 2020

keyan mentioned this issue Apr 26, 2020

cmd/go: add error for cross-compiled -race builds #38670

Closed

gopherbot closed this as completed in e87b064 Apr 30, 2020

golang locked and limited conversation to collaborators Apr 30, 2021

gopherbot added the FrozenDueToAge label Apr 30, 2021

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cmd/go: 'go build -race' with a cross-compiled GOOS should not suggest setting CGO_ENABLED #37021

cmd/go: 'go build -race' with a cross-compiled GOOS should not suggest setting CGO_ENABLED #37021

MasterDimmy commented Feb 4, 2020 •

edited

bcmills commented Feb 4, 2020

bcmills commented Feb 4, 2020

MasterDimmy commented Feb 4, 2020

MasterDimmy commented Feb 4, 2020

bcmills commented Feb 4, 2020 •

edited

keyan commented Apr 26, 2020

gopherbot commented Apr 26, 2020

ianlancetaylor commented Apr 28, 2020

keyan commented Apr 28, 2020

cmd/go: 'go build -race' with a cross-compiled GOOS should not suggest setting CGO_ENABLED #37021

cmd/go: 'go build -race' with a cross-compiled GOOS should not suggest setting CGO_ENABLED #37021

Comments

MasterDimmy commented Feb 4, 2020 • edited

Does this issue reproduce with the latest release?

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

What did you do?

What did you expect to see?

What did you see instead?

bcmills commented Feb 4, 2020

bcmills commented Feb 4, 2020

MasterDimmy commented Feb 4, 2020

MasterDimmy commented Feb 4, 2020

bcmills commented Feb 4, 2020 • edited

keyan commented Apr 26, 2020

gopherbot commented Apr 26, 2020

ianlancetaylor commented Apr 28, 2020

keyan commented Apr 28, 2020

MasterDimmy commented Feb 4, 2020 •

edited

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

bcmills commented Feb 4, 2020 •

edited