TEXT ·x(SB),0,$0
        CALL foo(SB)
        RET
`)
	write("x.c", `
void undefined();

void foo() {
        undefined();
}
`)

	cc := strings.TrimSpace(runGo("env", "CC"))
	cflags := strings.Fields(runGo("env", "GOGCCFLAGS"))

	importcfgfile := filepath.Join(tmpdir, "importcfg")
	testenv.WriteImportcfg(t, importcfgfile, nil, "runtime")

	// Compile, assemble and pack the Go and C code.

	// quotes, which the normal freedesktop.org pkg-config does
	// support. See https://man.openbsd.org/pkg-config.1
	tg.tempFile("foo.pc", `
Name: foo
Description: The foo library
Version: 1.0.0
Cflags: -Dhello=10 -Dworld=+32 -DDEFINED_FROM_PKG_CONFIG=hello\ world
`)
	tg.tempFile("foo.go", `package main

/*
#cgo pkg-config: foo
int value() {
	return DEFINED_FROM_PKG_CONFIG;
}
*/

	}
	if strings.HasPrefix(s, "sizeof_") {
		return "sizeof(" + cname(s[len("sizeof_"):]) + ")"
	}
	return s
}

// ProcessCgoDirectives processes the import C preamble:
//  1. discards all #cgo CFLAGS, LDFLAGS, nocallback and noescape directives,
//     so they don't make their way into _cgo_export.h.
//  2. parse the nocallback and noescape directives.
func (f *File) ProcessCgoDirectives() {

			// Generate a PIC stub. This is ugly as the stub must determine its location using
			// POWER8 or older instruction. These stubs are likely the combination of using
			// GOPPC64 < 8 and linking external objects built with CFLAGS="... -mcpu=power10 ..."
			stub.AddUint32(ctxt.Arch, OP_MFLR_R0)  // mflr r0
			stub.AddUint32(ctxt.Arch, OP_BCL_NIA)  // bcl 20,31,1f

//		C code.
//	CGO_CFLAGS_ALLOW
//		A regular expression specifying additional flags to allow
//		to appear in #cgo CFLAGS source code directives.
//		Does not apply to the CGO_CFLAGS environment variable.
//	CGO_CFLAGS_DISALLOW
//		A regular expression specifying flags that must be disallowed
//		from appearing in #cgo CFLAGS source code directives.
//		Does not apply to the CGO_CFLAGS environment variable.