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cmd/cgo: inconsistent definitions for C.uint #26743

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navytux opened this issue Aug 1, 2018 · 12 comments
Closed

cmd/cgo: inconsistent definitions for C.uint #26743

navytux opened this issue Aug 1, 2018 · 12 comments
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FrozenDueToAge NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. release-blocker
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Go1.11

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@navytux
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navytux commented Aug 1, 2018 •
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Please answer these questions before submitting your issue. Thanks!

What did you do?

I was trying to rebuild my software with gotip and got the following error:

# github.com/DataDog/czlib
cgo: inconsistent definitions for C.uint
FAIL    lab.nexedi.com/kirr/neo/go/zodb/btree [build failed]

The build is working with Go1.10 and earlier releases.

What did you expect to see?

Builds ok.

What did you see instead?

The build for github.com/DataDog/czlib fails with cgo: inconsistent definitions for C.uint error. I've extracted the minimal reproducer:

fastzlib.h:

#ifndef _A_XXX_H
#define _A_XXX_H

typedef unsigned int uint;
void c_compress2(char *input, uint length);

#endif

fastzlib.c:

#include "fastzlib.h"

void c_compress2(char *input, uint length) {
        return;
}

fastzlib.go:

package czlib

/*
#include "fastzlib.h"
*/
import "C"

func Compress(input []byte) {
        C.c_compress2(nil, C.uint(len(input)))
}

zstream.go (EDIT: originally posted fastzlib.go content here by mistake):

package czlib
  
/*
void zstream_set_in_buf(char *strm, void *buf, unsigned int len) {
        return;
}
*/
import "C"

func setInBuf(buf []byte, size int) {
        C.zstream_set_in_buf(nil, nil, C.uint(size))
}

Does this issue reproduce with the latest release (go1.10.3)?

No, it is a regression:

kirr@deco:~/src/neo/src/github.com/DataDog/czlib/a$ gotip build
# github.com/DataDog/czlib/a
cgo: inconsistent definitions for C.uint
kirr@deco:~/src/neo/src/github.com/DataDog/czlib/a$ go build
kirr@deco:~/src/neo/src/github.com/DataDog/czlib/a$ echo $?
0

kirr@deco:~/src/neo/src/github.com/DataDog/czlib/a$ gotip version
go version devel +6b9c782f9f Wed Aug 1 00:57:00 2018 +0000 linux/amd64
kirr@deco:~/src/neo/src/github.com/DataDog/czlib/a$ go version
go version go1.10.3 linux/amd64

System details

go version devel +6b9c782f9f Wed Aug 1 00:57:00 2018 +0000 linux/amd64
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/kirr/.cache/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/kirr/go"
GOPROXY=""
GORACE=""
GOROOT="/home/kirr/src/tools/go/gotip"
GOTMPDIR=""
GOTOOLDIR="/home/kirr/src/tools/go/gotip/pkg/tool/linux_amd64"
GCCGO="/usr/bin/gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD=""
GOROOT/bin/go version: go version devel +6b9c782f9f Wed Aug 1 00:57:00 2018 +0000 linux/amd64
GOROOT/bin/go tool compile -V: compile version devel +6b9c782f9f Wed Aug 1 00:57:00 2018 +0000
uname -sr: Linux 4.17.0-1-amd64
Distributor ID:	Debian
Description:	Debian GNU/Linux testing (buster)
Release:	testing
Codename:	buster
/lib/x86_64-linux-gnu/libc.so.6: GNU C Library (Debian GLIBC 2.27-5) stable release version 2.27.
gdb --version: GNU gdb (Debian 8.1-4) 8.1
@ianlancetaylor ianlancetaylor added NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. release-blocker labels Aug 1, 2018
@ianlancetaylor ianlancetaylor added this to the Go1.11 milestone Aug 1, 2018
@ianlancetaylor
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CC @randall77

@ianlancetaylor
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What does gcc --version print?

@ianlancetaylor
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Thanks for the reproduction case. Unfortunately it doesn't build:

> go build
# _/tmp/x/src/a
./zstream.go:8:6: Compress redeclared in this block
	previous declaration at ./fastzlib.go:8:23

When I change the name of Compress in one of the files it builds without error using GCC 7.3.0.

@ianlancetaylor
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Can you see if your issue is fixed on tip now that CL 127156 is committed?

@navytux
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navytux commented Aug 1, 2018

Thanks for feedback. My gcc is:

kirr@deco:~$ gcc --version
gcc (Debian 8.2.0-1) 8.2.0
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

The sample indeed does not build, after I tried downloading it afresh from here in another directory. I turned out I've made a copy-paste error. Here is correct zstream.go which should have been pasted in the first place:

zstream.go:

package czlib
  
/*
void zstream_set_in_buf(char *strm, void *buf, unsigned int len) {
        return;
}
*/
import "C"

func setInBuf(buf []byte, size int) {
        C.zstream_set_in_buf(nil, nil, C.uint(size))
}

(appologize for the pasting mistake on my side).

The problem persists with CL 127156 applied:

kirr@deco:~/tmp/trashme/bug$ gotip version
go version devel +b8669ef1ce Wed Aug 1 14:29:58 2018 +0000 linux/amd64

kirr@deco:~/tmp/trashme/bug$ gotip build
# _/home/kirr/tmp/trashme/bug
cgo: inconsistent definitions for C.uint

@navytux
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navytux commented Aug 1, 2018

I've edited original issue description and put zstream.go content into there.

@ianlancetaylor
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Thanks, I can recreate the problem now.

@navytux
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navytux commented Aug 1, 2018

Thanks, good.

@ianlancetaylor
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I think it's because cgo has its own definition of uint in nameToC, and the header file has typedef unsigned int uint;.

Shorter repro:

a.go:

package a

// typedef unsigned int uint;
// int C1(uint x) { return x; }
import "C"

var V1 = C.C1(0)

b.go:

package a

import "C"

var V2 C.uint

@gopherbot
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Change https://golang.org/cl/127356 mentions this issue: cmd/cgo: don't give inconsistent typedef error for cgo-defined types

@navytux
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navytux commented Aug 2, 2018

Thanks for the fix.

@gopherbot
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Change https://golang.org/cl/128396 mentions this issue: [release-branch.go1.10] cmd/cgo: don't give inconsistent typedef error for cgo-defined types

gopherbot pushed a commit that referenced this issue Aug 8, 2018
@ianlancetaylor
[release-branch.go1.10] cmd/cgo: don't give inconsistent typedef erro…
b8ae356 
…r for cgo-defined types

The cgo tool predefines some C types such as C.uint. Don't give an
error if the type that cgo defines does not match the type in a header file.

Fixes #26743

Change-Id: I9ed3b4c482b558d8ffa8bf61eb3209415b7a9e3c
Reviewed-on: https://go-review.googlesource.com/127356
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
(cherry picked from commit c29370c)
Reviewed-on: https://go-review.googlesource.com/128396
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
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