Maps with time.Time keys

[pjebs]

If I have a map with a time.Time type as a key, or alternatively a struct with a time.Time type as a field, with the struct used as a key, it appears as if the key comparisons use == instead of the Equal method as recommended by: https://golang.org/pkg/time/#Time.Equal

Equal reports whether t and u represent the same time instant. Two times can be equal even if they are in different locations. For example, 6:00 +0200 CEST and 4:00 UTC are Equal. See the documentation on the Time type for the pitfalls of using == with Time values; most code should use Equal instead.

[pjebs]

eg.

map[time.Time]int

OR 

type A struct {
t time.Time
}

map[A]int

[mvdan]

Maps don't call any functions or methods, they use equality as defined in the spec. What is your point here?

[pjebs]

#21829

[zigo101]

@pjebs
You should use time.Duration as the struct field type, and use aTime.Sub(time.Time{}) as the struct field values to make the struct values capable to act as map keys.

[zigo101]

filed a related issue: #22978

[richardartoul]

@pjebs I have a linter for this issue if you're interested: https://github.com/m3db/build-tools/blob/master/linters/badtime/README.md