17ef5cad94
In this testcase, we pass the checks for mismatched new/delete because the pointer is deleted before it is returned. And then a subsequent evaluation uses the cached value, but the deleted heap var isn't in ctx->global->heap_vars anymore, so cxx_eval_outermost_constant_expr doesn't run find_heap_var_refs, and ends up with garbage. Fixed by not caching a reference to deleted. I considered rejecting such a reference immediately as non-constant, but I don't think that's valid; an invalid pointer value isn't UB until we try to do something with it or it winds up in the final result of constant evaluation. I also considered not caching other heap references (i.e. using find_heap_var_refs instead of adding find_deleted_heap_var), which would include heap pointers passed in from the caller, but those don't have the same heap_vars problem. We might want cxx_eval_outermost_constant_expr to prune constexpr_call entries that refer to objects created during the evaluation, but that applies to local variables and temporaries just as much as heap "variables". PR c++/119162 gcc/cp/ChangeLog: * constexpr.cc (find_deleted_heap_var): New. (cxx_eval_call_expression): Don't cache a reference to heap_deleted. gcc/testsuite/ChangeLog: * g++.dg/cpp2a/constexpr-new26.C: New test. |
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