================
@@ -1094,6 +1094,24 @@ static bool pathOnlyHandlesGslPointer(IndirectLocalPath
&Path) {
return false;
}
+static bool
+isLifetimeboundInterleaveInGSL(llvm::ArrayRef<IndirectLocalPathEntry> PathRef)
{
----------------
hokein wrote:
> I am just wondering if this is the right approach to filter this problem out.
>
> I think in the problematic code example `[[clang::lifetimebound]]` describes
> the lifetime of the returned reference, not the lifetime of the
> `gsl::pointer` annotated type. So, I think the mismatch is trying to apply
> the lifetimebound logic to the `gsl::pointer` in this particular example.
>From an implementation perspective, we use the `lifetimebound` attribute to
>decide whether to continue traversing inner AST nodes (the return type doesn’t
>matter; it only affects the emitted diagnostic message). This process of each
>step is stateless -- it does not account for whether the existing path has
>been initialized for GSL.
Back to the problematic case,
```
class [[gsl::Pointer]] FooPointer {};
template<typename T>
class [[gsl::Owner]] Container {
public:
const T& get() const [[clang::lifetimebound]];
};
FooPointer abc2() {
Container<FooPointer> foo;
return foo.get(); // Clang emits a return-stack-address warning on `foo`.
}
```
When we report the local `foo` entity in the TemporaryVisitor callback:
- The Path is [GslPointerInit, Lifetimebound]
- foo is of type `Container<FooPointer>`
The code incorrectly interprets that the `FooPointer` is constructed from
`foo`, which is causing the issue here. I think it is essentially a bug in the
code that analyzes the gsl::pointer from gsl::owner construction case
(addressing this in the existing gsl::pointer filtering logic seems like a
natural approach, though it introduces new false negatives).
> I think my point is, probably not all interleavings are bad, but here the
> `gsl::pointer` and the `lifetimebound` apply to different levels of
> indirection and I am wondering it that needs to be part of our filtering.
I completely agree that not all interleavings are bad, and there are some
useful examples of where they work well. Better ideas are welcome.
https://github.com/llvm/llvm-project/pull/114044
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