[llvm-dev] MemoryBuffer: Migrating to Expected/llvm::Error from ErrorOr/std::error_code

[Fāng-ruì Sòng via llvm-dev]

On Sun, Sep 19, 2021 at 2:44 PM David Blaikie via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
>
> Hey folks - I'm/we're considering a somewhat laborious/disruptive refactoring for MemoryBuffer's APIs to improve error handling safety. Details here:  https://reviews.llvm.org/D109345
>
> Duncan's pointed out that a reasonable migration strategy would be to:
>
> Add MemoryBufferErrorAPI (wrapping APIs with errorOrToExpected) and MemoryBufferErrorCodeAPI (alias for MemoryBuffer) in the same commit.
> Migrate in-tree callers to MemoryBufferErrorCodeAPI (via mass rename). (Could even move some to MemoryBufferErrorAPI?)
> Update MemoryBuffer to use Error/Expected APIs, change MemoryBufferErrorAPI to an alias of it, and leave behind MemoryBufferErrorCodeAPI (wrapping APIs with expectedToErrorOr).
> One or more commits:
>
> Migrate in-tree callers to MemoryBuffer.
> Delete MemoryBufferErrorAPI alias.
>
> Delete MemoryBufferErrorCodeAPI wrappers.
>
> (this isn't the only option (some variations discussed on the code review) - but something along these lines that separates the semantic changes from the renaming and makes it easier for folks with stable release branches to still cherry pick pieces of this without other pieces (eg: they can pick any amount of 1-4 without 5, specifically they could take 1-2, do a mass-rename on their branch of "MemoryBuffer:: -> MemoryBufferErrorCodeAPI::" and then be pretty stable/relatively easy to cherry pick things after that)
>
> What do folks think of this? Any major objections (including "the churn doesn't seem worth the benefit" - happy to discuss that further), nuanced situations/tweaks/particular scenarios that we should make an effort to account for?
>
> If there aren't huge objections - I'll probably start this in the next O(weeks).

Sounds good!