Merge with override using bool values gives unexpected behavior.

[neppi]

type SomeBools struct {
	BoolA bool
	BoolB bool
	BoolC bool
	BoolD bool
}

func testBoolMerge() {
	A := SomeBools{
		BoolA: true,
		BoolB: true,
		BoolC: false,
		BoolD: false,
	}
	B := SomeBools{
		BoolA: true,
		BoolB: false,
		BoolC: true,
		BoolD: false,
	}

	log.Info("merging with Override option")
	log.Info(A)
	log.Info(B)
	mergo.Merge(&A, B, mergo.WithOverride)
	log.Info(A)
}

results in

  INFO ▶ testBoolMerge ▶  merging with Override option
  INFO ▶ testBoolMerge ▶  {true true false false}
  INFO ▶ testBoolMerge ▶  {true false true false}
  INFO ▶ testBoolMerge ▶  {true true true false}

BoolB is expected to be false too.

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[dgurns]

Having the same issue here. Merging will update false to true, but will not update true to false, since perhaps it sees the incoming false as a zero value. Seems like a pretty basic use case though. Am I missing something?

[dionysius]

Yes, this is definitely it what @dgurns wrote. false is the zero value for bool so it is IMO correct that mergo acts that way. You have the option WithOverwriteWithEmptyValue to include zero values also to ovewrite

[darccio]

@dgurns Please refer to the official documentation about zero values: https://golang.org/ref/spec#The_zero_value

As you already wrote, and @dionysius confirmed, false is the zero value for bool.