cmd/compile: internal compiler error: found illegal assignment go.shape.int_0 -> main.F.T

[ALTree]

$ gotip version
go version devel go1.19-527ace0ffa Sat Jun 18 00:48:50 2022 +0000 linux/amd64

package main

import "unsafe"

func F[T int](v T) uintptr {
	return unsafe.Offsetof(struct{ f T }{
		func(T) T { return v }(v),
	}.f)
}

func main() {
	println(F(1))
}

$ gotip build crash.go
# command-line-arguments
./crash.go:7:25: internal compiler error: found illegal assignment go.shape.int_0 -> main.F.T; 

goroutine 1 [running]:
runtime/debug.Stack()
	./gotip/src/runtime/debug/stack.go:24 +0x65
cmd/compile/internal/base.FatalfAt({0x0?, 0x0?}, {0xd560d3, 0x27}, {0xc000412468, 0x3, 0x3})
	./gotip/src/cmd/compile/internal/base/print.go:227 +0x1d7
cmd/compile/internal/base.Fatalf(...)
	./gotip/src/cmd/compile/internal/base/print.go:196
cmd/compile/internal/noder.assignconvfn({0xeadd88, 0xc0003fdb80}, 0xc0003e12d0)
	./gotip/src/cmd/compile/internal/noder/transform.go:482 +0x1b2
cmd/compile/internal/noder.typecheckaste(0xc0?, {0xc0001726c0?, 0xeacb90?}, 0x0, 0x0?, {0xc00005ef80, 0x1, 0xc00005ef80?})
	./gotip/src/cmd/compile/internal/noder/transform.go:558 +0x16b
cmd/compile/internal/noder.transformCall(0xc0001726c0)
	./gotip/src/cmd/compile/internal/noder/transform.go:188 +0x1b6
cmd/compile/internal/noder.(*subster).node.func1({0xeacb90, 0xc000172240})
	./gotip/src/cmd/compile/internal/noder/stencil.go:1135 +0xe13
cmd/compile/internal/ir.editNodes(...)
	./gotip/src/cmd/compile/internal/ir/node_gen.go:1388
cmd/compile/internal/ir.(*CompLitExpr).editChildren(0xc000418380, 0xc000011db8)
	./gotip/src/cmd/compile/internal/ir/node_gen.go:359 +0xf5
cmd/compile/internal/ir.EditChildren(...)
	./gotip/src/cmd/compile/internal/ir/visit.go:185
cmd/compile/internal/noder.(*subster).node.func1({0xeace70, 0xc0003e1b90})
	./gotip/src/cmd/compile/internal/noder/stencil.go:994 +0x5b6
cmd/compile/internal/ir.(*SelectorExpr).editChildren(0xc000069d40, 0xc000011db8)
	./gotip/src/cmd/compile/internal/ir/node_gen.go:1012 +0x62
cmd/compile/internal/ir.EditChildren(...)
	./gotip/src/cmd/compile/internal/ir/visit.go:185
cmd/compile/internal/noder.(*subster).node.func1({0xeae348, 0xc000069bc0})
	./gotip/src/cmd/compile/internal/noder/stencil.go:994 +0x5b6
cmd/compile/internal/ir.editNodes(...)
	./gotip/src/cmd/compile/internal/ir/node_gen.go:1388

...

Likely related to #53390, either uncovered or caused by its fix.

[ALTree]

(does not crash on UNIFIED)

[gopherbot]

Change https://go.dev/cl/413114 mentions this issue: cmd/compile: only skip visit closures in generic function call

[mdempsky]

@ALTree This is a synthetic test case, like constructed by a fuzzer, right?

I think we can punt on this for 1.19. It's unfortunate that the non-unified frontend has such trouble with unsafe.{Align,Offset,Size}of and function literals, but I don't think it's worth investing any further engineering resources into fixing at this time.

I expect 1.20 will fix this by switching to Unified IR.

[ALTree]

It's a side effect of the fix for #53390 which itself is from a fuzzer so nothing urgent here.

[gopherbot]

Change https://go.dev/cl/449756 mentions this issue: test: add regression test for issue 53439