[llvm] [ADT] Require base equality in indexed_accessor_iterator::operator==() (PR #107856)

[Andrei Golubev via llvm-commits]

andrey-golubev wrote:

> Worth a go - you've run check-all with this & verified to a reasonable degree that there aren't existing violations of this invariant?

I did run `check-llvm` && `check-mlir` locally under debug (so with assertions). Haven't seen anything suspicious (fwiw, it seems like this iterator type is only used by MLIR). I do see some crash in check-llvm though:
```
# <path>/llvm-project/build/bin/llc -mtriple=x86_64-pc-linux-gnu -enable-new-pm -print-pipeline-passes -filetype=null <path>/llvm-project/llvm/test/tools/llc/new-pm/pipeline.ll

free(): invalid pointer
```

with stack trace pointing to:
```
#15 0x0000563920481835 llvm::MachineVerifierPass::~MachineVerifierPass() <path>/llvm-project/llvm/include/llvm/CodeGen/MachineVerifier.h:16:7
#16 0x000056392049510b llvm::detail::PassModel<llvm::MachineFunction, llvm::MachineVerifierPass, llvm::AnalysisManager<llvm::MachineFunction>>::~PassModel() <path>/llvm-project/llvm/include/llvm/IR/PassManagerInternal.h:71:8
```

but i don't think it's related?

also, could someone click merge for this one (I do not have merge writes)?

https://github.com/llvm/llvm-project/pull/107856