On Wed, 2 Nov 2022 at 13:42, Patrick Palka via Libstdc++
<libstd...@gcc.gnu.org> wrote:
>
> IIUC such variables should be declared inline to avoid potential ODR
> violations since they're otherwise considered to be distinct (internal
> linkage) entities across TUs.
>
> The changes inside the regex_constants and execution namespace seem to
> be unimplemented parts of P0607R0; the rest of the changes touch only
> implementation details.
>
> Tested on x86_64-pc-linux-gnu, does this look OK for trunk?
OK, thanks.
My understanding was that [basic.def.odr] p14.5 means we don't get ODR
violations, but I think that only works for sensible uses of the
variables. Any inline function that takes the address of (or binds a
reference to) one of these variables will get an ODR violation. So the
patch is an improvement.
>
> libstdc++-v3/ChangeLog:
>
> * include/bits/atomic_wait.h (_detail::__platform_wait_alignment):
> Declare inline. Remove redundant static specifier.
> (__detail::__atomic_spin_count_relax): Declare inline.
> (__detail::__atomic_spin_count): Likewise.
> * include/bits/regex_automaton.h (__detail::_S_invalid_state_id):
> Conditionally declare inline. Declare constexpr. Remove
> redundant const and static specifiers.
> * include/bits/regex_error.h (regex_constants::error_collate):
> Conditionally
> declare inline.
> (regex_constants::error_ctype): Likewise.
> (regex_constants::error_escape): Likewise.
> (regex_constants::error_backref): Likewise.
> (regex_constants::error_brack): Likewise.
> (regex_constants::error_paren): Likewise.
> (regex_constants::error_brace): Likewise.
> (regex_constants::error_badbrace): Likewise.
> (regex_constants::error_range): Likewise.
> (regex_constants::error_space): Likewise.
> (regex_constants::error_badrepeat): Likewise.
> (regex_constants::error_complexity): Likewise.
> (regex_constants::error_stack): Likewise.
> * include/ext/concurrence.h (__gnu_cxx::__default_lock_policy):
> Likewise. Remove redundant static specifier.
> * include/pstl/execution_defs.h (execution::seq): Conditionally
> declare
> inline.
> (execution::par): Likewise.
> (execution::par_unseq): Likewise.
> (execution::unseq): Likewise.
> ---
> libstdc++-v3/include/bits/atomic_wait.h | 8 +++----
> libstdc++-v3/include/bits/regex_automaton.h | 2 +-
> libstdc++-v3/include/bits/regex_error.h | 26 ++++++++++-----------
> libstdc++-v3/include/ext/concurrence.h | 2 +-
> libstdc++-v3/include/pstl/execution_defs.h | 8 +++----
> 5 files changed, 23 insertions(+), 23 deletions(-)
>
> diff --git a/libstdc++-v3/include/bits/atomic_wait.h
> b/libstdc++-v3/include/bits/atomic_wait.h
> index 76ed7409937..bd1ed56d157 100644
> --- a/libstdc++-v3/include/bits/atomic_wait.h
> +++ b/libstdc++-v3/include/bits/atomic_wait.h
> @@ -58,14 +58,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> #ifdef _GLIBCXX_HAVE_LINUX_FUTEX
> #define _GLIBCXX_HAVE_PLATFORM_WAIT 1
> using __platform_wait_t = int;
> - static constexpr size_t __platform_wait_alignment = 4;
> + inline constexpr size_t __platform_wait_alignment = 4;
> #else
> // define _GLIBCX_HAVE_PLATFORM_WAIT and implement __platform_wait()
> // and __platform_notify() if there is a more efficient primitive supported
> // by the platform (e.g. __ulock_wait()/__ulock_wake()) which is better than
> // a mutex/condvar based wait.
> using __platform_wait_t = uint64_t;
> - static constexpr size_t __platform_wait_alignment
> + inline constexpr size_t __platform_wait_alignment
> = __alignof__(__platform_wait_t);
> #endif
> } // namespace __detail
> @@ -142,8 +142,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> #endif
> }
>
> - constexpr auto __atomic_spin_count_relax = 12;
> - constexpr auto __atomic_spin_count = 16;
> + inline constexpr auto __atomic_spin_count_relax = 12;
> + inline constexpr auto __atomic_spin_count = 16;
>
> struct __default_spin_policy
> {
> diff --git a/libstdc++-v3/include/bits/regex_automaton.h
> b/libstdc++-v3/include/bits/regex_automaton.h
> index f95eb7dad6d..44bde42e212 100644
> --- a/libstdc++-v3/include/bits/regex_automaton.h
> +++ b/libstdc++-v3/include/bits/regex_automaton.h
> @@ -46,7 +46,7 @@ namespace __detail
> */
>
> typedef long _StateIdT;
> - static const _StateIdT _S_invalid_state_id = -1;
> + _GLIBCXX17_INLINE constexpr _StateIdT _S_invalid_state_id = -1;
>
> template<typename _CharT>
> using _Matcher = std::function<bool (_CharT)>;
> diff --git a/libstdc++-v3/include/bits/regex_error.h
> b/libstdc++-v3/include/bits/regex_error.h
> index 74a1428c2c7..ab207650d44 100644
> --- a/libstdc++-v3/include/bits/regex_error.h
> +++ b/libstdc++-v3/include/bits/regex_error.h
> @@ -66,60 +66,60 @@ namespace regex_constants
> };
>
> /** The expression contained an invalid collating element name. */
> - constexpr error_type error_collate(_S_error_collate);
> + _GLIBCXX17_INLINE constexpr error_type error_collate(_S_error_collate);
>
> /** The expression contained an invalid character class name. */
> - constexpr error_type error_ctype(_S_error_ctype);
> + _GLIBCXX17_INLINE constexpr error_type error_ctype(_S_error_ctype);
>
> /**
> * The expression contained an invalid escaped character, or a trailing
> * escape.
> */
> - constexpr error_type error_escape(_S_error_escape);
> + _GLIBCXX17_INLINE constexpr error_type error_escape(_S_error_escape);
>
> /** The expression contained an invalid back reference. */
> - constexpr error_type error_backref(_S_error_backref);
> + _GLIBCXX17_INLINE constexpr error_type error_backref(_S_error_backref);
>
> /** The expression contained mismatched [ and ]. */
> - constexpr error_type error_brack(_S_error_brack);
> + _GLIBCXX17_INLINE constexpr error_type error_brack(_S_error_brack);
>
> /** The expression contained mismatched ( and ). */
> - constexpr error_type error_paren(_S_error_paren);
> + _GLIBCXX17_INLINE constexpr error_type error_paren(_S_error_paren);
>
> /** The expression contained mismatched { and } */
> - constexpr error_type error_brace(_S_error_brace);
> + _GLIBCXX17_INLINE constexpr error_type error_brace(_S_error_brace);
>
> /** The expression contained an invalid range in a {} expression. */
> - constexpr error_type error_badbrace(_S_error_badbrace);
> + _GLIBCXX17_INLINE constexpr error_type error_badbrace(_S_error_badbrace);
>
> /**
> * The expression contained an invalid character range,
> * such as [b-a] in most encodings.
> */
> - constexpr error_type error_range(_S_error_range);
> + _GLIBCXX17_INLINE constexpr error_type error_range(_S_error_range);
>
> /**
> * There was insufficient memory to convert the expression into a
> * finite state machine.
> */
> - constexpr error_type error_space(_S_error_space);
> + _GLIBCXX17_INLINE constexpr error_type error_space(_S_error_space);
>
> /**
> * One of <em>*?+{</em> was not preceded by a valid regular expression.
> */
> - constexpr error_type error_badrepeat(_S_error_badrepeat);
> + _GLIBCXX17_INLINE constexpr error_type error_badrepeat(_S_error_badrepeat);
>
> /**
> * The complexity of an attempted match against a regular expression
> * exceeded a pre-set level.
> */
> - constexpr error_type error_complexity(_S_error_complexity);
> + _GLIBCXX17_INLINE constexpr error_type
> error_complexity(_S_error_complexity);
>
> /**
> * There was insufficient memory to determine whether the
> * regular expression could match the specified character sequence.
> */
> - constexpr error_type error_stack(_S_error_stack);
> + _GLIBCXX17_INLINE constexpr error_type error_stack(_S_error_stack);
>
> ///@}
> } // namespace regex_constants
> diff --git a/libstdc++-v3/include/ext/concurrence.h
> b/libstdc++-v3/include/ext/concurrence.h
> index aea861b534f..7fd81490eff 100644
> --- a/libstdc++-v3/include/ext/concurrence.h
> +++ b/libstdc++-v3/include/ext/concurrence.h
> @@ -50,7 +50,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>
> // Compile time constant that indicates prefered locking policy in
> // the current configuration.
> - static const _Lock_policy __default_lock_policy =
> + _GLIBCXX17_INLINE const _Lock_policy __default_lock_policy =
> #ifndef __GTHREADS
> _S_single;
> #elif defined _GLIBCXX_HAVE_ATOMIC_LOCK_POLICY
> diff --git a/libstdc++-v3/include/pstl/execution_defs.h
> b/libstdc++-v3/include/pstl/execution_defs.h
> index 13b002931e8..3eca558dac2 100644
> --- a/libstdc++-v3/include/pstl/execution_defs.h
> +++ b/libstdc++-v3/include/pstl/execution_defs.h
> @@ -107,10 +107,10 @@ class unsequenced_policy
> };
>
> // 2.8, Execution policy objects
> -constexpr sequenced_policy seq{};
> -constexpr parallel_policy par{};
> -constexpr parallel_unsequenced_policy par_unseq{};
> -constexpr unsequenced_policy unseq{};
> +_GLIBCXX17_INLINE constexpr sequenced_policy seq{};
> +_GLIBCXX17_INLINE constexpr parallel_policy par{};
> +_GLIBCXX17_INLINE constexpr parallel_unsequenced_policy par_unseq{};
> +_GLIBCXX17_INLINE constexpr unsequenced_policy unseq{};
>
> // 2.3, Execution policy type trait
> template <class _Tp>
> --
> 2.38.1.381.gc03801e19c
>
