Fix #935: avoid the need to deallocate an object #937
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The problem that lead to the compiler warnings is that `discarded_results` in `ApplyFusedGate` is passed by value to the inner `ApplyFusedGate`. When `std::move(measure_result)` happens inside, it's moving from a stack object into a vector that is also on the stack (because it's a parameter passed by value). Then when the inner `ApplyFusedGate` returns, its copy of `mresults` is destroyed, triggering the warning. The solution used here is to refactor the logic into a separate implementation function that accepts a pointer to the results vector. This pointer can be `nullptr` to explicitly signal that measurement results should be discarded. This change eliminates the temporary `discarded_results` vector. Since the vector is never created, its destructor is never called, and the compiler warning vanishes. This is also faster, as you save the cost of constructing and destructing that temporary vector.
Sergei provided a better solution; it involves some mild refactoring. Also, he pointed out that there is a second very similar function in the file that should be changed in the same way.
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Nov 4, 2025
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The compiler is generating false positives. The solution (which is actually the work of @sergeisakov, via offline communications) involves slightly refactoring the code in a way that avoids creating a temporary vector.