https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94132
Bug ID: 94132
Summary: Valid usage of flexible array member failing to
compile
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: amir.ahmed.ansari at outlook dot com
Target Milestone: ---
Until gcc 9.2.0, the following usage was correct:
struct S {
int size;
int data[];
};
struct {
S s;
int data[16];
} var;
>From 9.2.1 onwards, this no longer compiles because the checking has gotten
stricter:
<source>:3:9: error: flexible array member 'S::data' not at end of
'struct<unnamed>'
3 | int data[];
| ^~~~
<source>:8:9: note: next member 'int <unnamed struct>::data [16]' declared here
8 | int data[16];
Funnily, the following workaround circumvents the check:
struct {
union {
struct {
S s;
int data[16];
};
};
} var;
Can we make this check more robust so valid usage isn't rejected? I will leave
it up to the experts to find the solution, but it would be easy for me to use
an attribute such as [[space_follows]] to tell the compiler that valid space
follows this member.
