vsapsai added a comment.
In D124287#3474369 <https://reviews.llvm.org/D124287#3474369>, @jansvoboda11
wrote:
> This sounds reasonable to me. What use-cases does `ASTStructuralEquivalence`
> fit better than ODR hashes?
I think the biggest advantage of `ASTStructuralEquivalence` is that it doesn't
affect memory consumption by Decls. But it makes repeated comparisons more
expensive.
Another `ASTStructuralEquivalence` advantage is that it's easier to add new
checks. For example, comparing ivars is pretty trivial with
`ASTStructuralEquivalence` but with ODR hash we need to handle that ivar types
can be structs/unions, including anonymous and nested structs.
Cannot say that for sure but I think `ASTStructuralEquivalence` is easier to
extend and to adopt for different purposes, while ODR hash seems to be more
invasive. But this argument is more hand-wavy.
Most likely `ASTStructuralEquivalence` has other positive qualities but that's
what I was able to come up off the top of my head. And you can see that in my
decision-making `ASTStructuralEquivalence` doesn't look like a compelling
option.
================
Comment at: clang/include/clang/Sema/Sema.h:3300
+ typename = std::enable_if_t<std::is_base_of<NamedDecl, T>::value>>
+ bool ActOnDuplicateDefinition(T *Duplicate, T *Previous) {
+ if (Duplicate->getODRHash() != Previous->getODRHash())
----------------
jansvoboda11 wrote:
> I'm not sure I'm a fan of using the exact same function name for checking ODR
> hashes and structural equivalence.
That's my failure of imagination, will come with something different. And after
you've pointed it out, I've realized it's not a good use of overloading too.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D124287/new/
https://reviews.llvm.org/D124287
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