rsmith added inline comments.
================
Comment at: clang/lib/Sema/SemaInit.cpp:6198-6199
+
dyn_cast<CXXRecordDecl>(DestType->getAs<RecordType>()->getDecl());
+ S.getLangOpts().CPlusPlus20 && RD && RD->isAggregate() && Failed() &&
+ getFailureKind() == FK_ConstructorOverloadFailed &&
+ onlyHasDefaultedCtors(getFailedCandidateSet())) {
----------------
For when you look at re-landing this, we encountered a regression for this case:
```
struct A {};
struct B : A { Noncopyable nc; };
```
Here, given `B b`, a `B(b)` direct-initialization should be rejected because it
selects a deleted copy constructor of `B`, but it looks like Clang instead
performed aggregate initialization, as if by `B{(const A&)b, {}}`. This is
pretty bad -- copies that should be disallowed end up working but not actually
copying any members of the derived class!
The general problem is that Clang's overload resolution incorrectly handles
deleted functions, treating them as an overload resolution failure rather than
a success. In this particular case, what happens is constructor overload
resolution produces `OR_Deleted`, which gets mapped into
`FK_ConstructorOverloadFailed` despite the fact that overload resolution
succeeded and picked a viable function.
I guess we can split `FK_*OverloadFailed` into separate "failed" and "succeeded
but found a deleted function" cases?
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D129531/new/
https://reviews.llvm.org/D129531
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