go build -x runtime/cgo
[!short] stderr '[/\\]cgo'$GOEXE'["]? .* -importpath runtime/cgo'

# https://go.dev/issue/47215: a missing $(go env CC) caused the precompiled net
# to be stale. But as of https://go.dev/cl/452457 the precompiled libraries are
# no longer installed anyway! Since we're requiring a C compiler in order to
# build and use cgo libraries in the standard library, we should make sure it

[!GOOS:darwin] skip
[!cgo] skip

! go build
stderr 'invalid flag in #cgo LDFLAGS: -lto_library'

-- go.mod --
module ldflag

-- main.go --
package main

// #cgo CFLAGS: -flto
// #cgo LDFLAGS: -lto_library bad.dylib
import "C"

	XOR	R0, R0 // Note, newer kernels may not always set R0 to 0.
	MOVD	$runtime·rt0_go(SB), R12
	MOVD	R12, CTR
	MOVBZ	runtime·iscgo(SB), R5
	CMP	R5, $0
	BEQ	nocgo
	BR	(CTR)
nocgo:
	MOVD	0(R1), R3 // argc
	ADD	$8, R1, R4 // argv

# This test requires external linking. Assume that if cgo is supported
# then external linking works.
[!cgo] skip 'requires a C linker'

# Only run on Unix systems.
[GOOS:windows] skip
[GOOS:plan9] skip

# Ordinary build should work.
go build
exec ./hello
stdout Hello

# Building with -linkmode=external should not say anything about
# runtime/cgo (issue #31544).
go build -ldflags=-linkmode=external

	mksyscall="./mksyscall_libc.pl -aix"
	mktypes="GOARCH=$GOARCH go tool cgo -godefs"
	;;
darwin_amd64)
	mkerrors="$mkerrors -m64"
	mksyscall="./mksyscall.pl -darwin"
	mktypes="GOARCH=$GOARCH go tool cgo -godefs"
	mkasm="go run mkasm.go"
	;;
darwin_arm64)
	mkerrors="$mkerrors -m64"
	mksyscall="./mksyscall.pl -darwin"
	mktypes="GOARCH=$GOARCH go tool cgo -godefs"
	mkasm="go run mkasm.go"
	;;
dragonfly_amd64)

[!cgo] skip 'test verifies cgo pkg-config errors'
[!exec:pkg-config] skip 'test requires pkg-config tool'

! go list -export .
stderr '^# example\n# \[pkg-config .*\]\n(.*\n)*Package .* not found'

-- go.mod --
module example
go 1.20
-- example.go --
package example

// #cgo pkg-config: libnot-a-valid-cgo-library
import "C"

// Support for memory sanitizer. See runtime/cgo/mmap.go.

//go:build (linux && (amd64 || arm64 || loong64)) || (freebsd && amd64)

package runtime

import "unsafe"

// _cgo_mmap is filled in by runtime/cgo when it is linked into the
// program, so it is only non-nil when using cgo.
//
//go:linkname _cgo_mmap _cgo_mmap
var _cgo_mmap unsafe.Pointer

// _cgo_munmap is filled in by runtime/cgo when it is linked into the

	MOVD	$runtime·libpreinit(SB), R1
	BL	R1

	// Create a new thread to finish Go runtime initialization.
	MOVD	_cgo_sys_thread_create(SB), R1
	CMP	R1, $0
	BEQ	nocgo
	MOVD	$_rt0_s390x_lib_go(SB), R2
	MOVD	$0, R3
	BL	R1
	BR	restore

nocgo:
	MOVD	$0x800000, R1              // stacksize
	MOVD	R1, 0(R15)
	MOVD	$_rt0_s390x_lib_go(SB), R1
	MOVD	R1, 8(R15)                 // fn
	MOVD	$runtime·newosproc(SB), R1

environment variable when running the go tool: set it to 1 to enable
the use of cgo, and to 0 to disable it. The go tool will set the
build constraint "cgo" if cgo is enabled. The special import "C"
implies the "cgo" build constraint, as though the file also said
"//go:build cgo".  Therefore, if cgo is disabled, files that import
"C" will not be built by the go tool. (For more about build constraints

	"golang.org/x/tools/go/ast/astutil"
)

const debug = false

const Doc = `detect some violations of the cgo pointer passing rules

Check for invalid cgo pointer passing.
This looks for code that uses cgo to call C code passing values
whose types are almost always invalid according to the cgo pointer
sharing rules.
Specifically, it warns about attempts to pass a Go chan, map, func,