cmd/compile: ssa panics on a continue in a switch without a loop #19934
Description
What version of Go are you using (go version)?
go version devel +69261ecad6 Tue Apr 11 12:25:55 2017 +0000 linux/amd64
What operating system and processor architecture are you using (go env)?
not relevant
What did you do?
Build f.go (reduced manually):
package foo
func Foo(a string) {
switch a {
case "b":
continue
}
}
What did you expect to see?
What Go 1.8.1 gives:
./f.go:6: continue is not in a loop
What did you see instead?
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x30 pc=0xa248e4]
goroutine 1 [running]:
cmd/compile/internal/ssa.(*Block).AddEdgeTo(...)
/home/mvdan/tip/src/cmd/compile/internal/ssa/block.go:150
cmd/compile/internal/gc.(*state).stmt(0xc4202a60e0, 0xc4202f21b0)
/home/mvdan/tip/src/cmd/compile/internal/gc/ssa.go:783 +0x11e4
cmd/compile/internal/gc.(*state).stmtList(0xc4202a60e0, 0xc42034a040)
/home/mvdan/tip/src/cmd/compile/internal/gc/ssa.go:503 +0x5a
cmd/compile/internal/gc.(*state).stmt(0xc4202a60e0, 0xc4202f2090)
/home/mvdan/tip/src/cmd/compile/internal/gc/ssa.go:878 +0x48f4
cmd/compile/internal/gc.(*state).stmtList(0xc4202a60e0, 0xc4202c1fe0)
/home/mvdan/tip/src/cmd/compile/internal/gc/ssa.go:503 +0x5a
cmd/compile/internal/gc.buildssa(0xc42009e280, 0x0)
/home/mvdan/tip/src/cmd/compile/internal/gc/ssa.go:189 +0x84b
cmd/compile/internal/gc.compile(0xc42009e280)
/home/mvdan/tip/src/cmd/compile/internal/gc/pgen.go:301 +0x112
cmd/compile/internal/gc.funccompile(0xc42009e280)
/home/mvdan/tip/src/cmd/compile/internal/gc/dcl.go:1054 +0xb7
cmd/compile/internal/gc.Main(0xb9d528)
/home/mvdan/tip/src/cmd/compile/internal/gc/main.go:545 +0x25e5
main.main()
/home/mvdan/tip/src/cmd/compile/main.go:49 +0x95
Placing my bets on c03e75e by @josharian, will try that version its parent and report back.