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x/tools/go/loader: panic loading cgo program #11627

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jeremyschlatter opened this issue Jul 8, 2015 · 9 comments
Closed

x/tools/go/loader: panic loading cgo program #11627

jeremyschlatter opened this issue Jul 8, 2015 · 9 comments
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FrozenDueToAge Tools This label describes issues relating to any tools in the x/tools repository.
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Unreleased

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@jeremyschlatter
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When trying to load a simple cgo program I get a panic: "internal error: unexpected import: C"

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

$ go version
go version go1.4.1 darwin/amd64

What operating system and processor architecture are you using?
OS X and amd64

$ uname -a
Darwin Jeremys-MacBook-Pro.local 14.3.0 Darwin Kernel Version 14.3.0: Mon Mar 23 11:59:05 PDT 2015; root:xnu-2782.20.48~5/RELEASE_X86_64 x86_64
$ go env GOOS
darwin
$ go env GOARCH
amd64

What did you do?

Ran this program:

package main

import "golang.org/x/tools/go/loader"

func main() {
    var conf loader.Config
    conf.CreateFromFilenames("main", "p.go")
    conf.Load()
}

Which loads this program:

package main

// typedef int (*intFunc) ();
//
// int
// bridge_int_func(intFunc f)
// {
//      return f();
// }
//
// int fortytwo()
// {
//      return 42;
// }
import "C"
import "fmt"

func main() {
    f := C.intFunc(C.fortytwo)
    fmt.Println(int(C.bridge_int_func(f)))
    // Output: 42
}

What did you expect to see?

The loading program run successfully.

What did you see instead?

$ go run load.go
panic: internal error: unexpected import: C [recovered]
    panic: internal error: unexpected import: C

goroutine 1 [running]:
golang.org/x/tools/go/types.(*Checker).handleBailout(0x208494000, 0x208439740)
    /Users/jeremy/src/golang.org/x/tools/go/types/check.go:219 +0xfc
golang.org/x/tools/go/loader.(*importer).doImport(0x2084554f0, 0x208480c80, 0x2084166f7, 0x1, 0x208438eb8, 0x0, 0x0)
    /Users/jeremy/src/golang.org/x/tools/go/loader/loader.go:716 +0x1d6
golang.org/x/tools/go/loader.func·007(0x208446e10, 0x2084166f7, 0x1, 0x1, 0x0, 0x0)
    /Users/jeremy/src/golang.org/x/tools/go/loader/loader.go:919 +0x5c
golang.org/x/tools/go/types.(*Checker).collectObjects(0x208494000)
    /Users/jeremy/src/golang.org/x/tools/go/types/resolver.go:189 +0x26fc
golang.org/x/tools/go/types.(*Checker).Files(0x208494000, 0x2084520a8, 0x1, 0x1, 0x0, 0x0)
    /Users/jeremy/src/golang.org/x/tools/go/types/check.go:229 +0xba
golang.org/x/tools/go/loader.(*importer).addFiles(0x2084554f0, 0x208480c80, 0x2084520a8, 0x1, 0x1, 0x0)
    /Users/jeremy/src/golang.org/x/tools/go/loader/loader.go:889 +0x25b
golang.org/x/tools/go/loader.func·003(0x281fc0, 0x4, 0x2084520a8, 0x1, 0x1, 0x208416660, 0x0, 0x1)
    /Users/jeremy/src/golang.org/x/tools/go/loader/loader.go:532 +0x151
golang.org/x/tools/go/loader.(*Config).Load(0x208480be0, 0x281fc0, 0x0, 0x0)
    /Users/jeremy/src/golang.org/x/tools/go/loader/loader.go:549 +0xcd9
main.main()
    /Users/jeremy/july7/load.go:8 +0xc1
exit status 2
@jeremyschlatter
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I reproduced the issue in a Linux VM:

$ go version
go version go1.3.1 linux/amd64

$ go run load.go
panic: internal error: unexpected import: C [recovered]
    panic: internal error: unexpected import: C

goroutine 16 [running]:
runtime.panic(0x5cb500, 0xc2080c7770)
    /usr/local/go/src/pkg/runtime/panic.c:279 +0xf5
golang.org/x/tools/go/types.(*Checker).handleBailout(0xc20806e000, 0x7f78af17a6f0)
    /home/vagrant/goworld/src/golang.org/x/tools/go/types/check.go:219 +0xcd
runtime.panic(0x5cb500, 0xc2080c7770)
    /usr/local/go/src/pkg/runtime/panic.c:248 +0x18d
golang.org/x/tools/go/loader.(*importer).doImport(0xc208019720, 0xc208042be0, 0xc208000527, 0x1, 0xc208000527, 0x0, 0x0)
    /home/vagrant/goworld/src/golang.org/x/tools/go/loader/loader.go:716 +0x1d9
golang.org/x/tools/go/loader.func·007(0xc208022d50, 0xc208000527, 0x1, 0x1, 0x0, 0x0)
    /home/vagrant/goworld/src/golang.org/x/tools/go/loader/loader.go:919 +0x5b
golang.org/x/tools/go/types.(*Checker).collectObjects(0xc20806e000)
    /home/vagrant/goworld/src/golang.org/x/tools/go/types/resolver.go:189 +0x237d
golang.org/x/tools/go/types.(*Checker).Files(0xc20806e000, 0xc208034078, 0x1, 0x1, 0x0, 0x0)
    /home/vagrant/goworld/src/golang.org/x/tools/go/types/check.go:229 +0xb7
golang.org/x/tools/go/loader.(*importer).addFiles(0xc208019720, 0xc208042be0, 0xc208034078, 0x1, 0x1, 0x0)
    /home/vagrant/goworld/src/golang.org/x/tools/go/loader/loader.go:889 +0x21c
golang.org/x/tools/go/loader.func·003(0x66de70, 0x4, 0xc208034078, 0x1, 0x1, 0xc208000440, 0x0, 0x1)
    /home/vagrant/goworld/src/golang.org/x/tools/go/loader/loader.go:532 +0x156
golang.org/x/tools/go/loader.(*Config).Load(0xc208042b40, 0x66de70, 0x0, 0x0)
    /home/vagrant/goworld/src/golang.org/x/tools/go/loader/loader.go:549 +0xac6
main.main()
    /home/vagrant/july7/load.go:8 +0xb9

goroutine 19 [finalizer wait]:
runtime.park(0x412ce0, 0x7b2e10, 0x7b1969)
    /usr/local/go/src/pkg/runtime/proc.c:1369 +0x89
runtime.parkunlock(0x7b2e10, 0x7b1969)
    /usr/local/go/src/pkg/runtime/proc.c:1385 +0x3b
runfinq()
    /usr/local/go/src/pkg/runtime/mgc0.c:2644 +0xcf
runtime.goexit()
    /usr/local/go/src/pkg/runtime/proc.c:1445
exit status 2

@josharian josharian added this to the Unreleased milestone Jul 8, 2015
@alandonovan
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Thanks for reporting this; I can reproduce it easily on Linux.

The problem is very simple but not simple to fix: go/loader only performs cgo preprocessing on imported packages, not ad hoc packages such as the one consisting of ["p.go"]. The workarounds is to move the cgo code into a separate package and import it. The fix is to rethink go/loader, which I will do after go1.5.

Notes to self: we need to copy and adapt the logic of goFilesPackage (from $GOROOT/src/cmd/go/build.go). Once this is done, all the loader.Config methods (Import and Create) will return the same kind of entity, essentially a build.Package. Perhaps we can even reuse this type directly.

Also: we should support swig.

alandonovan pushed a commit to golang/tools that referenced this issue Jul 14, 2015
@adonovan
go/loader: issue informative error (not panic) if cgo used in ad hoc …
c5ca59a 
…package

See golang/go#11627.

Change-Id: I458bc4ea54d0db34f3ba96060d284eda4bad7111
Reviewed-on: https://go-review.googlesource.com/12190
Reviewed-by: David Crawshaw <crawshaw@golang.org>
@alandonovan
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As a workaround I submitted this CL https://go-review.googlesource.com/#/c/12190/, which reports an internal error instead of panicking.

@sbinet sbinet mentioned this issue Aug 10, 2015
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@bradfitz
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bradfitz commented Dec 7, 2015

@alandonovan, is this the same bug as users being unable to use tools like gorename (which use x/tools/go/loader) with packages using cgo + pkg-config? @martine was asking me about this today and I had no clue.

@alandonovan
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No, this bug occurs only when files containing 'import "C"' appear on the command line, as opposed to being imported.

This is the first I've heard of the cgo + pkg-config problem, but now that you mention it, support for pkg--config is obviously missing. Feel free to file another issue for it.

@evmar
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evmar commented Dec 7, 2015

Filed #13526.

@pkorotkov
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Ping, any progress on this issue?

@alandonovan
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Sorry, no. (The required fix is invasive and entails an API change.)

@codeactual codeactual mentioned this issue May 31, 2017
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@gcmurphy gcmurphy mentioned this issue Jan 27, 2018
Closed
@gopherbot gopherbot added the Tools This label describes issues relating to any tools in the x/tools repository. label Sep 12, 2019
@stamblerre
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Since support golang.org/x/tools/go/loader is now deprecated, I'll go ahead and close this issue.

@golang golang locked and limited conversation to collaborators Apr 14, 2021
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