Conditional check with AND and OR is failing - if-statement

Question

I am trying to combine few conditional check
package main
import (
"fmt"
"reflect"
)
type ActionType string
const (
VNFHealthCheck ActionType = "vnf-health-check"
CollectAlaramAddToReport ActionType = "write-initial-report"
CollectResourcesAddCounters ActionType = "abc"
)
func main() {
var action, operationType interface{}
action = nil
operationType = "vnf-health-check"
if operationType == string(VNFHealthCheck) && action != nil && action.(ActionType) == CollectAlaramAddToReport {
fmt.Println("Type is ", reflect.TypeOf(action))
}
}
The above code does not print anything as action != nil check fails.
But when if condition changes to
if operationType == string(VNFHealthCheck) && action != nil && action.(ActionType) == CollectAlaramAddToReport || action.(ActionType) == CollectResourcesAddCounters {
fmt.Println("Hello, playground", reflect.TypeOf(action))
}
Panic is seen with message
panic: interface conversion: interface {} is nil, not main.ActionType
If condition check works fine after adding () around OR condition
if operationType == string(VNFHealthCheck) && action != nil && (action.(ActionType) == CollectAlaramAddToReport || action.(ActionType) == CollectResourcesAddCounters) {
fmt.Println("Hello, playground", reflect.TypeOf(action))
}
What could be cause of the behavior.? I couldn't find any explanation.

Answer 1

the && has higher precedence than ||
in the first condition,
operationType == string(VNFHealthCheck) && action != nil && action.(ActionType) == CollectAlaramAddToReport || action.(ActionType) == CollectResourcesAddCounters
cause action is nil, the condition becomes false || action.(ActionType) == CollectResourcesAddCounters. the nil cast trigger the panic
the second condition becomes false && (action.(ActionType) == CollectAlaramAddToReport || action.(ActionType) == CollectResourcesAddCounters). cause the false short circuit the expression, the cast won't be executed.

Answer 2

See the operator precedence section of the specification. The && operator has higher precedence than ||. The parentheses are required to get the grouping you intended.
A type assertion is not needed when comparing a value to an interface{}. If action is one of the specified values, then it follows that action != nil. Using these observations, simplify the code to:
if operationType == string(VNFHealthCheck) && (action == CollectAlaramAddToReport || action == CollectResourcesAddCounters) {
fmt.Printf("Hello, playground %T\n", action)
}