deprecated reflect mode has been replaced with package mode

[tulzke]

re-open of: #198

resolves #175
resolves #197
resolves #128

It is impossible to create an mock for a generic interface via reflect mode, because it is impossible to compile a generic type without instantiation.
This PR replaces the reflect mod for parsing using go/types.

All exists mocks have been regenerated and the tests have been passed. But since this radically changes the behavior of reflect mode, I would be grateful if there are those who want to add additional test cases that I did not provide.

We can also come up with another name instead of import mode.

benefits:
generation mocks for generic interfaces
generation mocks for aliases to interfaces
correct names for method arguments

[tulzke]

@JacobOaks
What do you think about this problem?
#198 (comment)

[JacobOaks]

@tulzke - thanks for re-opening this and apologies again for the git mistakes on the other PR.

I think for now it makes sense to just use the unaliased names until we're able to update go.mod to 1.23. From the perspective of type-checking, types and their aliases are interchangeable so there shouldn't be any missing functionality/bugs introduced by just uniformly using the unaliased names for now. This also keeps the generated code consistent between the two versions. Once 1.24 is out and we can upgrade go.mod to 1.23, we can definitely then switch over to using the alias names.

I think the changes to do this aren't too bad, we would just have a separate case in parseType like so:

case *types.Alias:
    return p.parseType(types.Unalias(t))

What are your thoughts?

[tulzke]

we would just have a separate case

I think, that alias for us is the same thing as a *types.Named. We need only his name and package.

types.Unalias(t) returns original type, so in mocks we will see original types. It is not completely correct behavior.

[tulzke]

So, if we have agreed on the functionality, can we think about the names? What is the name of the new mode to replace reflect?
Maybe Package mode? Source mode and Package mode. That sounds good.

[JacobOaks]

I don't have a strong opinion on a name. "package mode" or "types mode" is fine.

[tulzke]

I don't have a strong opinion on a name. "package mode" or "types mode" is fine.

I choose package mode. Check last commit changes please: 69210e9

If everything is OK, i'm waiting for a merge 🙂

[tulzke]

I realized that I had made a mistake.
I deleted 3 unused flags, and this may break the existing generation methods. Since now these flags have no effect, I think they can be removed from the readme and help, and when using write a WARNING message to the console.

@JacobOaks What do you think about this?

//UPD: flags cannot be removed from help, so i added "DEPRECATED" to them usages