jyknight wrote:
I note that this commit (probably unintentionally) fixed an issue with the
`-Wnonnull` warning for return values in Objective-C++ code.
Previously, `id _Nonnull foo() { return nullptr; }` does not warn under `clang
-fobjc-arc -target x86_64-apple-macos11 -x objective-c++ -fsyntax-only`. It did
warn with `-fno-objc-arc`, however. Now, it does warn in both cases. This seems
like an improvement -- but the state of things is still pretty weird.
But, that only started working with `return nullptr`, not with `return 0`,
though I'd expect those to be treated the same way. It also didn't start
working for `-x objective-c` mode with a `return (void*)0;`.
(https://godbolt.org/z/1voxqhKbE)
I'd also have expected that this change in behavior would have required test
changes to the objc nullability tests, but it didn't, because mostly tests
don't enable `-fobjc-arc`. The test case `returnsNilObjCInstanceDirectly` in
`clang/test/Analysis/nullability_nullonly.mm` does seem like it'd notice the
change in behavior, but it has defined `nil` as `0`, not `nullptr`. (Also,
that's primarily a test for Clang Static Analyzer's nullability checker, not
Sema's nullability warning. The same function in
`clang/test/Analysis/nullability-no-arc.mm` does see the Sema -Wnonnull warning
too, however.)
Anyways, I don't think it's _bad_ that this commit has had this particular
effect, but it's weird, and I wonder if this weirdness might affect other
situations than ObjC ARC types, too.
https://github.com/llvm/llvm-project/pull/82705
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