This has been broken out of D104170 since it should be merged whether or
not we go ahead with the module map changes.
Differential Revision: https://reviews.llvm.org/D104175
This started as an attempt to fix a GCC 11 warning of misplaced parentheses.
I then noticed that trying to fix the parentheses warning actually triggered
errors in the tests, showing that we were incorrectly assuming that the
implementation of ranges::advance was using operator+= or operator-=.
This commit fixes that issue and makes the tests easier to follow by
localizing the assertions it makes.
Differential Revision: https://reviews.llvm.org/D103272
Most of our private headers need to be treated as submodules so that
Clang modules can export things correctly. Previous commits that split
monolithic headers into smaller chunks were unaware of this requirement,
and so this is being addressed in one fell swoop. Moving forward, most
new headers will need to have their own submodule (anything that's
conditionally included is exempt from this rule, which means `__support`
headers aren't made into submodules).
This hasn't been marked NFC, since I'm not 100% sure that's the case.
Differential Revision: https://reviews.llvm.org/D103551