cmd/compile: dev.typeparams commit 0a0e3a3 broke dev.boringcrypto; fixed again at a72a499

[mdempsky]

Merging 0a0e3a3 into dev.boringcrypto causes make.bash to fail due to:

Building Go toolchain2 using go_bootstrap and Go toolchain1.
# crypto/internal/boring
<autogenerated>:1: internal compiler error: offset for r1 at $WORK/b060/_cgo_gotypes.go:842:75 changed from 8 to 0

This build failure was fixed a few commits later at a72a499.

That later commit was just an optimization, so it shouldn't be essential to correctly handling compiling this code. It would be good to get a minimal, standalone reproducer for what failed and add it as a compiler regress test.

To reproduce the issue:

1. Checkout dev.boringcrypto.
2. Run git merge 0a0e3a3
3. Run ./make.bash in src.

/cc @cherrymui @cuonglm

[cuonglm]

I haven't looked deeper, but here's a simple reproducer:

package p

// static void f(int i) {}
import "C"

func f() {
	defer C.f(C.int(1))
}

Just checkout commit 0a0e3a3 on dev.typeparams.

[gopherbot]

Change https://golang.org/cl/334882 mentions this issue: [dev.typeparams] test: add regression test for go/defer wrapper

[gopherbot]

Change https://golang.org/cl/334883 mentions this issue: [dev.typeparams] cmd/compile: make ssagen analyze ABI correctly for static function value

[cuonglm]

@mdempsky @cherrymui So the problem is not related to 0a0e3a3 and a72a499. This failed to compile even with current dev.typeparams tip:

$ cat _cgo_gotypes.go
package p

//go:cgo_unsafe_args
func g(*int) (r1 struct{}) {
	return
}

func f() {
	x := g
	defer x(new(int))
}

The problem is that ssagen/ssa.go:state.call does't handle direct function value, so it use the wrong ABI to set the offset, which causes offset changed.

[gopherbot]

Change https://golang.org/cl/336629 mentions this issue: cmd/compile: do not change field offset in ABI analysis

[gopherbot]

Change https://golang.org/cl/336610 mentions this issue: [dev.typeparams] cmd/compile: remove outdate TODO in escape analysis