[Tcl-bugs] [ tcl-Bugs-2798939 ] Non-greedy quantifiers revert to greedy when branched

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Bugs item #2798939, was opened at 2009-05-30 22:15
Message generated for change (Tracker Item Submitted) made by bilgexa
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Category: 43. Regexp
Group: current: 8.5.7
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Bilge (bilgexa)
Assigned to: Pavel Goran (pvgoran)
Summary: Non-greedy quantifiers revert to greedy when branched

Initial Comment:
Non-greedy quantifiers revert to greedy when used in conjunction with branches (pipe character).

The following branch-free expression matches each letter in the test string and therefore correctly returns 14
regexp -all .+? {this is a test}

The following branched expression matches the entire string only once because the quantifier reverts to greedy and therefore incorrectly returns 1
regexp -all .+?|x {this is a test}

This breaks a lot of complex regular expressions that require non-greedy quantifiers and branches.

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You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=110894&aid=2798939&group_id=10894