nickdesaulniers added inline comments.
================
Comment at: clang/lib/AST/ExprConstant.cpp:11740
+ LVal.getLValueBase().dyn_cast<const ValueDecl *>());
+ Result += VD->getFlexibleArrayInitChars(Info.Ctx);
+ }
----------------
nickdesaulniers wrote:
> erichkeane wrote:
> > nickdesaulniers wrote:
> > > erichkeane wrote:
> > > > Isn't this a possible null-deref?
> > > I don't think so; in fact, I can use `cast` and `get` rather than
> > > `dyn_cast_or_null` and `dyn_cast` here.
> > >
> > > Just because we have a pointer doesn't mean it's possibly `nullptr`; I
> > > don't think we can reach this code patch for evaluating the
> > > `__builtin_object_size` of a struct with a flexible array member if the
> > > LValue doesn't have a corresponding VarDecl.
> > Of course that is a possibility. You shouldn't use dyn_cast right before a
> > dereference, this should definitely be using `cast`/`get`, since they
> > assert.
> >
> > What does the LValue have when the dynamic struct does not have an
> > initializer? Or just an empty one?
> s/code patch/code path/
> What does the LValue have when the dynamic struct does not have an
> initializer? Or just an empty one?
Tested:
```
struct foo {
int x;
int y[];
};
static struct foo instance = {
.x = 3,
// .y = { 5, 10, 15, },
};
unsigned long foo (void) {
return __builtin_object_size(&instance, 1);
}
```
With the following values for `.y` in `instance`:
1. `.y = { 5, 10, 15 }`: `foo` returns `16`.
2. `.y = {},`: `foo` returns `4`.
3. <`.y` is not specified or explicitly initialized>: `foo` returns `4`.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D150892/new/
https://reviews.llvm.org/D150892
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
