| Ticket UUID: | c0bc269178df938974e19cbe60e69fc0e711da5 | |||
| Title: | switch -regexp -matchvar -indexvar broken when optional subexpression does not match | |||
| Type: | Bug | Version: | 8.6.13 | |
| Submitter: | apnadkarni | Created on: | 2022-09-20 18:40:42 | |
| Subsystem: | 18. Commands M-Z | Assigned To: | jan.nijtmans | |
| Priority: | 7 High | Severity: | Minor | |
| Status: | Closed | Last Modified: | 2022-09-21 13:15:16 | |
| Resolution: | Fixed | Closed By: | jan.nijtmans | |
| Closed on: | 2022-09-21 13:15:16 | |||
| Description: |
The third element of m below should be the empty string as the (b)? is not
matched.
```
% switch -regexp -matchvar m -indexvar i ac {
{(a)(b)?(c)} {puts m:$m; puts i:$i}
}
m:ac a ac c
i:{0 1} {0 0} {-1 -1} {1 1}
% info patch
8.7a6
```
core-8-6-branch also exhibits this bug.
**However, 8.6.12 shows correct behavior**
```
D:\src\ruff\doc\nroff>d:\tcl\magic\bin\tclsh.exe
% switch -regexp -matchvar m -indexvar i ac {
{(a)(b)?(c)} {puts m:$m; puts i:$i}
}
m:ac a {} c
i:{0 1} {0 0} {-1 -1} {1 1}
% info patch
8.6.12
```
So clearly something was broken post-8.6.12 release.
| |||
| User Comments: |
jan.nijtmans added on 2022-09-21 13:15:16:
Fix committed [92ab43ecd6cdd9a4|here] jan.nijtmans added on 2022-09-20 20:44:39: Proposed fix [ea165f0333f93885|here] Thanks for the report, and for the testcase! dgp added on 2022-09-20 19:06:49: How did Tcl behave in release 8.6.10 ? See TIP 623 for more background. apnadkarni added on 2022-09-20 18:50:44: The bug seems to have been introduced with [this](https://core.tcl-lang.org/tcl/info/26539e78a71993cc) checkin on this [line](https://core.tcl-lang.org/tcl/file?ci=94f71d598512687b&name=generic/tclStringObj.c&ln=823). However, it seems a deliberate change so not clear to me that just reverting is the correct fix. /Ashok | |||
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