Finish P0811R3 midpoint and lerp#1048

Merged

CaseyCarter merged 12 commits intomicrosoft:masterfrom

statementreply:lerp

Jul 30, 2020

Commits on Jul 16, 2020

Commits on Jul 22, 2020

Commits on Jul 29, 2020

Address review comments
statementreply
committed

Commits on Jul 30, 2020

Fix a subtle conformance issue.
StephanTLavavej
committed