let constructor is legacy (do not use in tree!) since the tableGen
backend emits most of the glue logic to build a pass.
Note: The following constructor has been retired:
```cpp
std::unique_ptr<Pass> createExpandReallocPass(bool emitDeallocs = true);
```
To update your codebase, replace it with the new options-based API:
```cpp
memref::ExpandReallocPassOptions expandAllocPassOptions{
/*emitDeallocs=*/false};
pm.addPass(memref::createExpandReallocPass(expandAllocPassOptions));
```
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