Affected subclauses: [forwardlist] and
[list]
Change: Return types of
remove,
remove_if, and
unique
changed from
void to
container::size_type. Rationale: Improve efficiency and convenience of finding number of removed elements
. Effect on original feature: Code that depends on the return types might have different semantics in this International Standard
. Translation units compiled against this version of C++ may be incompatible with
translation units compiled against C++ 2017, either failing to link or having undefined behavior
.