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fix(UB): the editing of elements in the set is breaking the comparator invariant and cause the crash with libc++ #3696

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mariadb-LeonidFedorov wants to merge 2 commits into from
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fix(UB): the editing of elements in the set is breaking the comparator invariant and cause the crash with libc++ #3696

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fix(UB): the editing of elements in the set is breaking the comparato…
mariadb-LeonidFedorov Aug 6, 2025
731152f
fix?
mariadb-LeonidFedorov Aug 26, 2025
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22 changes: 20 additions & 2 deletions dbcon/execplan/rewrites.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -217,8 +217,18 @@ execplan::ParseTree* newAndNode()
return new execplan::ParseTree(op);
}

template <typename T>
struct is_set : std::false_type
{
};

template <typename T, typename Compare, typename Alloc>
struct is_set<std::set<T, Compare, Alloc>> : std::true_type
{
};

template <typename Common>
execplan::ParseTree* appendToRoot(execplan::ParseTree* tree, const Common& common)
execplan::ParseTree* appendToRoot(execplan::ParseTree* tree, Common& common)
{
if (common.empty())
return tree;
Expand All @@ -230,7 +240,15 @@ execplan::ParseTree* appendToRoot(execplan::ParseTree* tree, const Common& commo
{
execplan::ParseTree* andCondition = *treenode;

++treenode;
// Increment or erase based on container type to avoid UB
if constexpr (is_set<Common>::value)
{
treenode = common.erase(treenode);
}
else
{
++treenode;
}
current->right(andCondition);

if ((treenode != common.end() && std::next(treenode) != common.end()) ||
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