[macOS] Revert Changes in file error after update to 2.51.0

[stepushchik]

Git GUI -> Commit -> Revert Changes
Both for "Revert Changes" and "Do Nothing" buttons

macOS Sequoia 15.6.1

can't read "err": no such variable
can't read "err": no such variable
    while executing
"string trim $err"
    (in namespace eval "::SimpleChord::__o1::eval" script line 2)
    invoked from within
"namespace eval [set ${__this}::eval_ns] [set ${__this}::body]"
    (procedure "::SimpleChord::notify_note_activation" line 9)
    invoked from within
"::SimpleChord::notify_note_activation ::SimpleChord::__o1::__d"
    ("eval" body line 1)
    invoked from within
"eval [list ::SimpleChord::$name ::SimpleChord::__o1::__d] $args"
    (procedure "::SimpleChord::__o1::__d" line 1)
    invoked from within
"[set ${__this}::chord] notify_note_activation"
    (procedure "::ChordNote::activate" line 4)
    invoked from within
"::ChordNote::activate ::ChordNote::__o2::__d"
    ("eval" body line 1)
    invoked from within
"eval [list ::ChordNote::$name ::ChordNote::__o2::__d] $args"
    (procedure "::ChordNote::__o2::__d" line 1)
    invoked from within
"::ChordNote::__o2::__d activate"
    ("uplevel" body line 1)
    invoked from within
"uplevel #0 $after"
    (procedure "write_checkout_index" line 21)
    invoked from within
"write_checkout_index file6 lib/presentation/screens/splash/splash_screen.dart 1 1 ::status_bar_operation::__o1::__d {::ChordNote::__o2::__d activate} ..."

[j6t]

I don't have macOS here, and the problem does not happen for me on Linux. That said, you haven't specified exactly what you did, so I may be testing differently.

Can you bisect the commit that caused the regression?

[stepushchik]

@j6t unfortunately, I can't open git-gui from the old commits:

/opt/homebrew/opt/git/libexec/git-core/git-gui: line 16: /opt/homebrew/opt/git/share/git-gui/lib/Git Gui.app/Contents/MacOS/Wish: No such file or directory
/opt/homebrew/opt/git/libexec/git-core/git-gui: line 16: exec: /opt/homebrew/opt/git/share/git-gui/lib/Git Gui.app/Contents/MacOS/Wish: cannot execute: No such file or directory

Steps to reproduce the issue on macOS:

• make minor changes to a project (tried different projects). For example, add a new line to the file.
• open git gui via Terminal
• select the file in Unstaged Changes
• go to panel Commit -> Revert Changes

• Tap Do Nothing or Revert Changes
• Error appears

[stepushchik]

@j6t the same error on old macOS Monterey 12.7.6 after updating to git 2.51.0 and git-gui 2.51.0_1.

[j6t]

I know a bit more now, but I have not the slightest idea what a correct fix is. I can only a work-around.

If I read the code correctly, the string trim $err in this section of the code is evaluated in the global context.

I can reproduce the error if I insert

unset err

as last line in git-gui.sh. This means, that for some reason my platform leaves a variable err behind in the global namespace, but it is not present on your platform. If I remove the variable in this way, I see the same error. The work-around is now to insert

set err ""

as the last thing in git-gui.sh, so that the variable is always present. Of course, this cures just the symptom. Which variable err the code intends to use and how it is supposed to set, I am totally clueless.

Can you try the work-around?

[stepushchik]

set err "" in git-gui.sh doesn't work,

but there is no more error with

if {[info exists err] && [string trim $err] != ""} {
...
} 

Maybe the error is caused by updating to Tcl 9.0 (tcl-tk on my side is 9.0.2)?

[stepushchik]

https://www.tcl-lang.org/software/tcltk/9.0.html

Important Incompatibilities in Tcl 9.0

• Namespace varname resolution: Current namespace, not global.

[j6t]

Thank you, this looks like the correct solution.

In my old Tk8.6, $err is looked up in the global namespace. When I provoke a situation that "Revert Changes" fails, the error is reported correctly. When I now repeat the action, but select "Do Nothing", I still get the same error. The reason is that the old error message was not cleared and still lingers in the global namespace.

My question is now, when $err is looked up in the correct namespace with Tk9, does that namespace and err survive the action, or is it erased and with it the variable. Can you please test this case after having applied the fix as above?

To provoke an error, make a change to a file, then make its directory read-only. Then when you select "Revert Changes", an error must appear. When you repeat, but choose "Do Nothing", does an error appear or not?

[stepushchik]

@j6t with fix:
Revert Changes:

then Do Nothing: there is no error.

[stepushchik]

@j6t without fix:
Revert Changes: Index Error (as above)
then Do Nothing: Application Error: can't read "err": no such variable

[j6t]

Thank you very much, this was very helpful.

I have a fix in c461528. It is your suggested change plus a work-around for Tcl 8.6.