https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118667
Bug ID: 118667
Summary: lambda references to bit-fields via structure binding
is invalid
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Keywords: accepts-invalid, c++-lambda
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: pinskia at gcc dot gnu.org
Target Milestone: ---
Forwarded from https://github.com/llvm/llvm-project/issues/124444 since GCC
also accepts it.
Take:
```
void test1() {
struct S { int a : 4; };
const auto [x] = S{};
[&x] {}(); // #1
[&] { (void)x; }(); // #2
}
void test2() {
struct S { const int a : 4; };
auto [x] = S{};
[&x] {}(); // #3
[&] { (void)x; }(); // #4
}
```
All 4 lines marked with #1 should be rejected as invalid as you cannot do a
lambda reference to a bitfield.
According to [expr.prim.lambda.capture]/12, all of these 4 cases should be
ill-formed:
... A bit-field or a member of an anonymous union shall not be captured by
reference.
You can see examples in P1381R1 (https://wg21.link/P1381R1#what-can-we-do)
showing that capturing structured bindings refering bit-fields "means"
capturing the bit-fields.
