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|
package irutil
import (
"go/types"
"honnef.co/go/tools/go/ir"
)
// Terminates reports whether fn is supposed to return, that is if it
// has at least one theoretic path that returns from the function.
// Explicit panics do not count as terminating.
func Terminates(fn *ir.Function) bool {
if fn.Blocks == nil {
// assuming that a function terminates is the conservative
// choice
return true
}
for _, block := range fn.Blocks {
if _, ok := block.Control().(*ir.Return); ok {
if len(block.Preds) == 0 {
return true
}
for _, pred := range block.Preds {
switch ctrl := pred.Control().(type) {
case *ir.Panic:
// explicit panics do not count as terminating
case *ir.If:
// Check if we got here by receiving from a closed
// time.Tick channel – this cannot happen at
// runtime and thus doesn't constitute termination
iff := ctrl
if !ok {
return true
}
ex, ok := iff.Cond.(*ir.Extract)
if !ok {
return true
}
if ex.Index != 1 {
return true
}
recv, ok := ex.Tuple.(*ir.Recv)
if !ok {
return true
}
call, ok := recv.Chan.(*ir.Call)
if !ok {
return true
}
fn, ok := call.Common().Value.(*ir.Function)
if !ok {
return true
}
fn2, ok := fn.Object().(*types.Func)
if !ok {
return true
}
if fn2.FullName() != "time.Tick" {
return true
}
default:
// we've reached the exit block
return true
}
}
}
}
return false
}
|
