cmd/compile: internal compiler error "not lowered: ArrayMake0" for pointer-shaped struct with zero-sized array field

[Splizard]

Go 1.26.0 regression

package main

type T struct {
	_ [0]*int
	p *int
}

type W struct{ T }

//go:noinline
func f(n *int) W { return W{T{p: n}} }

//go:noinline
func g(w W) any { return w }

func main() {
	n := 1
	x := f(&n)
	switch g(x) {
	case x:
		println("x")
	}
}

https://go.dev/play/p/fsNLSEBlIpB

./prog.go:20:2: internal compiler error: 'main': not lowered: v7, ArrayMake0 ARRAY

Please file a bug report including a short program that triggers the error.
https://go.dev/issue/new

[Jorropo]

cc @randall77

[gabyhelp]

Related Issues

• cmd/compile: internal compiler error: zero for type [2]int not implemented #77868
• cmd/compile: internal compiler error: 'main.func1': not lowered: v15, Load STRUCT PTR SSA #77534 (closed)
• cmd/compile: internal compiler error: not lowered: v7, StructMake0 STRUCT #63433 (closed)
• cmd/compile: internal compiler error: cannot represent parameters of type struct ... #77635 (closed)
• cmd/compile: internal compiler error: not lowered: v46, Load ARRAY PTR64 SSA #26120 (closed)
• cmd/compile: ICE when StructMake not lowered #74908 (closed)
• cmd/compile: internal compiler error: not lowered: v22, StructMake0 STRUCT #48049 (closed)
• cmd/compile: internal compiler error when struct with greater than 14 fields is passed to generic function #77775 (closed)
• cmd/gc: internal compiler error in haspointers #14405 (closed)
• cmd/compile: internal compiler error: assigning to non-1-length array #19671 (closed)

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[thepudds]

Hi @Splizard, does this reproduce on tip for you?

There have been some fixes for how zero sized objects are treated.

Your example seems to pass for me on the playground using tip:

https://go.dev/play/p/fsNLSEBlIpB?v=gotip

[randall77]

This looks fixed with https://go-review.googlesource.com/c/go/+/747760 (issue 77534)

The fix should be in 1.26.1.