implement naked returns

[sbinet]

Fixes #188.

[codecov-io]

Codecov Report

Merging #189 into master will decrease coverage by 0.01%.
The diff coverage is 28.57%.

@@            Coverage Diff             @@
##           master     #189      +/-   ##
==========================================
- Coverage   50.54%   50.53%   -0.02%     
==========================================
  Files          22       22              
  Lines       10016    10025       +9     
==========================================
+ Hits         5063     5066       +3     
- Misses       4452     4458       +6     
  Partials      501      501

Impacted Files	Coverage Δ
typecheck/typecheck.go	22.4% <28.57%> (+0.03%)	⬆️

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[crawshaw]

It looks like you're building and passing the retNames slice and then only using the fact that it's non-zero in length. Do you have a use for the names later?

If not, it may be worth simplifying the object. Maybe:

type returnType struct {
retType *tipe.Tuple
isNamed bool
}

[sbinet]

I started with only passing the len of the slice, but for detecting when there is shadowing, I'll probably need to get the names of the variable too.

[crawshaw]

OK, sounds good.