On Fri, 6 Mar 2026 at 11:42, Nathan Myers <[email protected]> wrote:
>
> Changes in v2:
> - Tested.
> - Also patch up UNRESOLVED complaint about subscript_const_neg.cc.
>
> C++11 forbids a compound statement, as seen in the definition
> of __glibcxx_assert(), in a constexpr function. This patch
> open-codes the assertion in `bitset<>::operator[] const` for
> C++11 to fix a failure in `g++.old-deja/g++.martin/bitset1.C`.
>
> Also, it adds `{ dg-do compile }` in another test to suppress
> a spurious UNRESOLVED complaint.
>
> libstdc++-v3/ChangeLog:
> * include/std/bitset (operator[]() const): Customize bounds
> check for C++11 case.
> * testsuite/20_util/bitset/access/subscript_const_neg.cc:
> Suppress UNRESOLVED complaint.
> ---
> libstdc++-v3/include/std/bitset | 8 ++++++++
> .../20_util/bitset/access/subscript_const_neg.cc | 1 +
> 2 files changed, 9 insertions(+)
>
> diff --git a/libstdc++-v3/include/std/bitset b/libstdc++-v3/include/std/bitset
> index eb200ab9246..a23545320ee 100644
> --- a/libstdc++-v3/include/std/bitset
> +++ b/libstdc++-v3/include/std/bitset
> @@ -1298,8 +1298,16 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
> _GLIBCXX_CONSTEXPR bool
> operator[](size_t __position) const
> {
> +#if __cplusplus != 201103L
> __glibcxx_assert(__position < _Nb);
> return _Unchecked_test(__position);
> +#elif defined(_GLIBCXX_ASSERTIONS)
> + // C++11 forbids a compound stmt in a constexpr function.
> + return __position < _Nb ? _Unchecked_test(__position)
> + : (__builtin_trap(), bool());
Please use 'false' here instead of 'bool()'
OK with that change, thanks.
> +#else
> + return _Unchecked_test(__position);
> +#endif
> }
> ///@}
>
> diff --git
> a/libstdc++-v3/testsuite/20_util/bitset/access/subscript_const_neg.cc
> b/libstdc++-v3/testsuite/20_util/bitset/access/subscript_const_neg.cc
> index 12d4f1eaf30..a5676d54a5e 100644
> --- a/libstdc++-v3/testsuite/20_util/bitset/access/subscript_const_neg.cc
> +++ b/libstdc++-v3/testsuite/20_util/bitset/access/subscript_const_neg.cc
> @@ -1,3 +1,4 @@
> +// { dg-do compile }
> #include <bitset>
>
> void test_const_subscript_assignment()
> --
> 2.52.0
>
