make internal calls to require use a fixed world

[JeffBezanson]

This avoids recompiling it, which speeds up package precompilation and loading. We already do this for the type inference code.

With this, the time to precompile CSV the first time goes from 240 sec to 90 sec for me.

[tknopp]

It would be interesting if these optimizations are things that regressed from 0.5 -> 0.6 -> 0.7 or if that cannot be really compared since the compiler has evolved (e.g. due to the new type system).

For reference: Julia 0.6.3 (on a macbook) requires 33 seconds to precompile CSV here.

[JeffBezanson]

This has to do with the code invalidation mechanism added to fix #265, so it wouldn't apply to 0.5.

[StefanKarpinski]

Does this essentially make require itself an exception to the 265 fix?

[JeffBezanson]

No; the fix still applies, but by preventing require from seeing new methods, rather than by recompiling it for those new methods.