Try to simplify the numba extension a little

[eric-wieser]

Rather than using contextlib.ExitStack to manage our state, this uses LLVM basic blocks instead.

cc @stuartarchibald

---

Unfortunately this didn't appear to improve compile-time performance.

[lgtm-com]

This pull request introduces 1 alert when merging fc55af8 into eb8d41e - view on LGTM.com

new alerts:

• 1 for Unused local variable

[hameerabbasi]

CI fails with: NameError: name 'lower_builtin' is not defined.

[lgtm-com]

This pull request introduces 1 alert when merging 53b0e2a into 8c1193c - view on LGTM.com

new alerts:

• 1 for Unused local variable

[hameerabbasi]

Is this ready for review?

[codecov]

Codecov Report

Merging #324 into master will increase coverage by 0.03%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #324      +/-   ##
==========================================
+ Coverage   93.98%   94.01%   +0.03%     
==========================================
  Files          19       19              
  Lines        2327     2340      +13     
==========================================
+ Hits         2187     2200      +13     
  Misses        140      140

[eric-wieser]

Is this ready for review?

Yeah, I think so. Hopefully CI passes now. There are some open questions about NativeValue.cleanup that I was hoping to resolve here, but I'm realizing that that opens a can of worms that numba needs to look at - so I'll leave that to a follow-up.

[hameerabbasi]

Pinging @stuartarchibald for a review.

[hameerabbasi]

I'll wait a day or two for review before merging.

[hameerabbasi]

Whoops, forgot about this one. Thanks, @eric-wieser!