[PATCH] D90719: [DebugInfo] Modify ctor homing as workaround for unconstructed libcxx types

[David Blaikie via Phabricator via cfe-commits]

dblaikie added a comment.

In D90719#2377883 <https://reviews.llvm.org/D90719#2377883>, @rsmith wrote:

> Perhaps we could address both the UB and the debug info homing issue by adding a new attribute on the libc++ types that says it's valid to create an instance of the type without calling a constructor? (If we want to support old libc++ with trunk clang, we could detect those types and automatically synthesize the attribute, but libc++ is moving towards being version-locked to clang anyway, so I don't think we need to worry about that too much.)

My guess would be that this doesn't come up often enough to merit an attribute, etc, and that libc++ is fixable. (if the code really wants to do no work when constructing, changing the type to have a trivial ctor and the places that want non-trivial construction can initialize the members as needed seems like it'd be viable)

But it does present significant challenges/hamstring code optimization opportunities, sure, an attribute could be handy/a way forward.


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https://reviews.llvm.org/D90719