cmd/go: 'go build' encountered invalid C headers under MacOS

[hbprotoss]

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

$ go version
go version go1.11.5 darwin/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="/Users/hbprotoss/Library/Caches/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/hbprotoss/.go:/Users/hbprotoss/Documents/dev/Projects/go"
GOPROXY=""
GORACE=""
GOROOT="/usr/local/Cellar/go/1.11.5/libexec"
GOTMPDIR=""
GOTOOLDIR="/usr/local/Cellar/go/1.11.5/libexec/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
CXX="clang++"
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=/var/folders/s_/2knwlbxn7dvc7zqdkk8x850r0000gn/T/go-build921630012=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

Actually, I'm using Golang to debug go program, after I hit the debug button, it didn't compile.

The command used to compile is

go build -gcflags "all=-N -l" main.go

What did you expect to see?

No error

What did you see instead?

It reports

runtime/cgo

In file included from gcc_libinit.c:8:
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk/usr/include/pthread.h:232:66: error: unknown type name 'size_t'
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk/usr/include/pthread.h:249:43: error: unknown type name 'size_t'
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk/usr/include/pthread.h:256:66: error: unknown type name 'size_t'
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk/usr/include/pthread.h:524:1: error: unknown type name 'size_t'
gcc_libinit.c:97:18: error: variable has incomplete type 'struct timespec'
gcc_libinit.c:97:9: note: forward declaration of 'struct timespec'
gcc_libinit.c:105:14: error: use of undeclared identifier 'EAGAIN'
gcc_libinit.c:110:3: error: implicit declaration of function 'nanosleep' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
gcc_libinit.c:112:9: error: use of undeclared identifier 'EAGAIN'

[bcmills]

These sorts of symptoms on macOS often indicate a broken Xcode install or some other, incompatible gcc toolchain earlier in $PATH.

In this particular case, it appears that you have an invalid pthread.h: size_t is defined in stddef.h, which pthread.h should #include as needed. Similarly, struct timespec should be provided by time.h (#included here); the fact that it is missing suggests that something is very wrong in your C include path.

[bcmills]

Are you able to build C programs in the same environment?

You may be able to run which clang and/or find / -name time.h to locate the bad headers; as a last resort, you could try removing and reinstalling Xcode.

[gopherbot]

Timed out in state WaitingForInfo. Closing.

(I am just a bot, though. Please speak up if this is a mistake or you have the requested information.)

[drwasho]

FYI if anyone like me found themselves in this situation, check your /usr/local/include folder for header files *.h.

Delete these and you'll get unstuck. Don't ask me how I got myself into that situation, but I think it was screwing around with brew.

[zhulinwei]

Are you able to build C programs in the same environment?

You may be able to run which clang and/or find / -name time.h to locate the bad headers; as a last resort, you could try removing and reinstalling Xcode.

@bcmills Please help me, I meet this problem too.

I can build C programs in the project, but when I run go test . command, then terimnal will show the message of gcc_libinit.c: 105:14: error: use of undeclared identifier 'EAGAIN😭

[ianlancetaylor]

@zhulinwei This issue is closed, and at this point there is no reason to think that there is a problem with Go. You will most likely find a better answer on a forum. See https://golang.org/wiki/Questions.

[zhulinwei]

@ianlancetaylor thanks very much, I fix this problem by env CGO_ENABLED=0 go test, but I am not sure if it will cause other problems.

[gautamp8]

FYI if anyone like me found themselves in this situation, check your /usr/local/include folder for header files *.h.

Delete these and you'll get unstuck. Don't ask me how I got myself into that situation, but I think it was screwing around with brew.

Same. This worked for me. Was afraid of removing to bulk renamed them to .x from .h

[zhulinwei]

I solved this problem, and I hope my answer can help others.

If you don't need to work with c lang, you can export CGO_ENABLED=0,

else you can change your CC, replace clang with gcc, eg export CC=gcc