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### 1453. Default constructed `match_results` behavior for certain operations

Section: 30.9.5 [re.results.acc] Status: Resolved Submitter: BSI Opened: 2010-08-25 Last modified: 2016-01-28

Priority: Not Prioritized

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Discussion:

Addresses GB-126

It's unclear how match_results should behave if it has been default-constructed. The sub_match objects returned by operator[], prefix and suffix cannot point to the end of the sequence that was searched if no search was done. The iterators held by unmatched sub_match objects might be singular.

[ Resolution proposed by ballot comment: ]

> Add to match_results::operator[], match_results::prefix and match_results::suffix:
> Requires: !empty()

[ 2010-10-24 Daniel adds: ]

> Accepting n3158 would solve this issue.

Proposed resolution:

Addressed by paper n3158.