ahatanak marked an inline comment as done.
ahatanak added inline comments.
================
Comment at: lib/CodeGen/CGExpr.cpp:4100
+ if (E->getType().isDestructedType() == QualType::DK_nontrivial_c_struct)
+ pushDestroy(QualType::DK_nontrivial_c_struct, DeclPtr, E->getType());
+
----------------
rjmccall wrote:
> ahatanak wrote:
> > rjmccall wrote:
> > > rjmccall wrote:
> > > > Unfortunately, the lifetime of compound literals in C is not this
> > > > simple; they're like blocks in that they're destroyed at the end of the
> > > > enclosing scope rather than at the end of the current statement. (The
> > > > cleanup here will be popped at the end of the full-expression if we've
> > > > entered an `ExprWithCleanups`.) And the l-value case is exactly the
> > > > case where this matters.
> > > >
> > > > I think you need to do something like what we do with blocks, where we
> > > > record all the blocks in the full-expression on the `ExprWithCleanups`
> > > > so that we can push an inactive cleanup for them and then activate it
> > > > when we emit the block.
> > > Can we make the check here something like (1) this is a block-scope
> > > compound literal and (2) it has a non-trivially-destructed type (of any
> > > kind)? That way we're not conflating two potentially unrelated elements,
> > > the lifetime of the object and the kinds of types that can be constructed
> > > by the literal.
> > >
> > > Oh, actually, there's a concrete reason to do this: C99 compound literals
> > > are not required to have struct type; they can have any object type,
> > > including arrays but also scalars. So we could, even without non-trivial
> > > C structs, have a block-scope compound of type `__strong id[]`; I guess
> > > we've always just gotten this wrong. Please add tests for this case. :)
> > There is a check `E->isFileScope()` above this. Is that sufficient to check
> > for block-scoped compound literals?
> That plus the C/C++ difference; compound literals in C++ are just temporaries.
I haven't been able to come up with a piece of C++ code that executes
`EmitCompoundLiteralLValue`. The following code gets rejected because you can't
take the address of a temporary object in C++:
```
StrongSmall *p = &(StrongSmall){ 1, 0 };
```
If a bind a reference to it, `AggExprEmitter::VisitCompoundLiteralExpr` is
called.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D64464/new/
https://reviews.llvm.org/D64464
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