#3655 TclArraySet crash

[Don Porter]

% array set a {}
% set elements {1 2 3 4}
1 2 3 4
% trace add variable a write {string length $elements ;#}
% array set a $elements
Segmentation fault

Same crash also happens with the HEAD.

Problem is that TclArraySet
doesn't preserve the elemPtrs
it pulls from a ListObj, and
keeps trying to access it
after it's shimmered out of validity.

[Don Porter]

[Don Porter]

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Here's a patch to review.
File Added: 1669489.patch

[Don Porter]

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Patch committed to HEAD.
Backport still needs examination.

[Don Porter]

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Commit different fix
for 8.4.15.