Fznamznon added inline comments.
================
Comment at: clang/lib/Sema/SemaInit.cpp:808
unsigned NumElems = numStructUnionElements(ILE->getType());
- if (RDecl->hasFlexibleArrayMember())
+ if (!RDecl->isUnion() && RDecl->hasFlexibleArrayMember())
++NumElems;
----------------
shafik wrote:
> Fznamznon wrote:
> > Just for some context, numStructUnionElements checks that there is a
> > flexible array member and returns number_of_initializable_fields-1 for
> > structs. For unions it just returns 1 or 0, so flexible array member caused
> > adding one more element to initlistexpr that was never properly handled.
> >
> > Instead of doing this change, we could probably never enter initialization
> > since the record (union) declaration is not valid, but that is not the case
> > even for other types of errors in code, for example, I've tried declaring
> > field of struct with a typo:
> >
> > ```
> > struct { cha x[]; } r = {1};
> > ```
> > Initialization is still performed by clang.
> > Also, it seems MSVC considers flexible array member inside union as valid,
> > so the test code is probably not always invalid.
> I am not sure what to think here, looking at gcc documentation for this
> extension: https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
>
> and using the following code:
>
> ```
> struct f1 {
> int x; int y[];
> } f1 = { 1, { 2, 3, 4 } }; // #1
>
> struct f2 {
> struct f1 f1; int data[3];
> } f2 = { { 1 }, { 2, 3, 4 } }; // #2
>
> struct { char x[]; } r = {1}; // #3
> ```
>
> gcc rejects 2 and 3 even though 2 comes from their documentation. Clang warns
> on 2 and MSVC rejects 2
>
> CC @aaron.ballman @rsmith
Yes, I also had a feeling that we probably need to refine how these extensions
are supported by clang, that is probably a bit out of scope of the fix though.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D147626/new/
https://reviews.llvm.org/D147626
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