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### 4. `basic_string` `size_type` and `difference_type` should be implementation defined

Section: 21.3.3 [basic.string] Status: NAD Submitter: Beman Dawes Opened: 1997-11-16 Last modified: 2016-08-09

Priority: Not Prioritized

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Discussion:

In Morristown we changed the `size_type` and `difference_type` typedefs for all the other containers to implementation defined with a reference to 22.2 [container.requirements]. This should probably also have been done for strings.

Rationale:

Not a defect. [Originally classified as a defect, later reclassified.] `basic_string`, unlike the other standard library template containers, is severely constrained by its use of `char_traits`. Those types are dictated by the traits class, and are far from implementation defined.