steakhal added a comment.
I notices some inconsistency between this `-fstrict-flex-arrays=N` flag and
what the `RecordDecl::hasFlexibleArrayMember()` returns for an example like
this:
typedef unsigned long size_t;
void *malloc(size_t);
void free(void *);
void field(void) {
struct vec { size_t len; int data[0]; };
struct vec *a = (struct vec*) malloc(sizeof(struct vec) + 10*sizeof(int));
free(a);
}
In the example, I use don't specify the `-fstrict-flex-arrays` flag, thus it
should default to `0`, which means that any trailing arrays (let it be
incomplete or of any concrete size), to be considered as a
flexible-array-member.
In the AST, for the `RecordDecl`, I'd expect that the
`hasFlexibleArrayMember()` member function would reflect this, and return
`true`, however, it returns `false` instead.
It does so because in SemaDecl.cpp Sema::ActOnFields()
<https://github.com/llvm/llvm-project/blob/0ce056a814f8dbfd8d9b7720ce1df489c6ba5ddb/clang/lib/Sema/SemaDecl.cpp#L18884-L18893>
before doing some FAM-related checks and diagnostics it performs this check,
guarding that branch:
bool IsLastField = (i + 1 == Fields.end());
if (FDTy->isFunctionType()) {
// ...
} else if (FDTy->isIncompleteArrayType() &&
(Record || isa<ObjCContainerDecl>(EnclosingDecl))) {
//This is the FAM handling branch.
// ...
}
Consequently, Sema will only set the bit for `hasFlexibleArrayMember` if the
array is //incomplete//.
So my question is, if the `RecordDecl::hasFlexibleArrayMember()` should be
consistent with the `-fstrict-flex-arrays` flag, or not?
@serge-sans-paille @aaron.ballman
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D126864/new/
https://reviews.llvm.org/D126864
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