@types/reactstrap@8.0.0 runs out of memory on TS 3.4

[sandersn]

1. clone DefinitelyTyped
2. cd types/lodash, types/reactstrap, types/reactstrap/v7
3. tsc

For tsc 3.4.3 and above (and probably all 3.4.x)

Expected behavior:
No unexpected errors.

Actual behavior:
node runs out of memory.

This might be an unavoidable effect of the additional work that we do in 3.4 and above, but in that case, those three packages (at least) need to be rewritten to be more efficient.

[sandersn]

After cleaning node_modules on DefinitelyTyped, lodash passes.
On windows, reactstrap also doesn't repro -- it uses over 1500 MB of memory before succeeding though.

[sandersn]

reactstrap is now much smaller after some changes I made. For this bug, use 8.0.0, not 8.0.1 (or higher).

[sandersn]

Here's the performance of lodash over the 3.4 release, as measured by type count. The explosion was on 02/27, with only minor differences before and after. I'll bisect to find the exact commit.

[sandersn]

#29981 is the culprit here.
Edit: After talking to @weswigham the problem is probably that variance probing no longer applies to lodash as a whole and we end up doing a structural check now.

[weswigham]

@sandersn does #30416 fix that OOM? (I triggered a package build on it after making some small adjustments so it can be tested against)

[sandersn]

Fixes lodash -- 485k → 85k types. (vs 83k on 3.3)
Fixes reactstrap 8.0.0, basically -- 1538k → 591k types (vs 493k on 3.3)