[Bug libstdc++/71960] __glibcxx_assert and Debug Mode checks can't be used in constexpr functions
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71960 Jonathan Wakely changed: What|Removed |Added Status|ASSIGNED|RESOLVED Resolution|--- |FIXED --- Comment #9 from Jonathan Wakely --- I think these assertions should always have been OK in constexpr functions, but G++ was incorrectly evaluating the untaken branch. That has been fixed for some time, so the checks work. The commented out checks in string_view have been enabled on all branches, and on trunk the assertions are now unconditionally checked during constant evaluation, not only when _GLIBCXX_ASSERTIONS is defined.
[Bug libstdc++/71960] __glibcxx_assert and Debug Mode checks can't be used in constexpr functions
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71960 --- Comment #8 from CVS Commits --- The releases/gcc-8 branch has been updated by Jonathan Wakely : https://gcc.gnu.org/g:877cdcc714704e242f477580d81397cc1d0fc90e commit r8-10444-g877cdcc714704e242f477580d81397cc1d0fc90e Author: Jonathan Wakely Date: Thu Sep 10 15:49:26 2020 +0100 libstdc++: Enable assertions in constexpr string_view members [PR 71960] There is no longer any reason we can't just use __glibcxx_assert in constexpr functions. As long as the condition is true, there will be no call to std::__replacement_assert that would make the function ineligible for constant evaluation. PR libstdc++/71960 * include/experimental/string_view (basic_string_view): Enable debug assertions. * include/std/string_view (basic_string_view): Likewise.
[Bug libstdc++/71960] __glibcxx_assert and Debug Mode checks can't be used in constexpr functions
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71960
--- Comment #7 from CVS Commits ---
The master branch has been updated by Jonathan Wakely :
https://gcc.gnu.org/g:10f51543bb81cc953792270b40a9c812049e8b4c
commit r11-2971-g10f51543bb81cc953792270b40a9c812049e8b4c
Author: Jonathan Wakely
Date: Tue Sep 1 20:52:26 2020 +0100
libstdc++: Add compile-time checks to__glibcxx_assert [PR 71960]
This change evaluates __glibcxx_assert checks unconditionally when a
function is being constant evaluated (when std::is_constant_evaluated()
is true). If the check fails, compilation will fail with an error.
If the function isn't being constant evaluated, the normal runtime check
will be done if enabled by _GLIBCXX_ASSERTIONS or _GLIBCXX_DEBUG, the
same as before.
Tangentially, the __glibcxx_assert and _GLIBCXX_PARALLEL_ASSERT macros
are changed to expand to 'do { } while (false)' when assertions are
disabled, instead of expanding to nothing. This avoids -Wempty-body
warnings when a disabled assertion is used in an 'if' or 'else'
statement e.g.
if constexpr (/* precondition is testable */)
__glibcxx_assert(precondition);
a.C:9:27: warning: suggest braces around empty body in an âifâ
statement [-Wempty-body]
9 | __glibcxx_assert(precondition);
| ^
libstdc++-v3/ChangeLog:
PR libstdc++/71960
* include/bits/c++config (__glibcxx_assert_impl): Remove
do-while so that uses of the macro need to add it.
(__glibcxx_assert): Rename macro for runtime assertions
to __glibcxx_assert_2.
(__glibcxx_assert_1): Define macro for constexpr assertions.
(__glibcxx_assert): Define macro for constexpr and runtime
assertions.
* include/bits/range_access.h (ranges::advance): Remove
redundant precondition checks during constant evaluation.
* include/parallel/base.h (_GLIBCXX_PARALLEL_ASSERT): Always
use do-while in macro expansion.
* include/std/ranges (iota_view::iota_view(W, B)): Remove
redundant braces.
[Bug libstdc++/71960] __glibcxx_assert and Debug Mode checks can't be used in constexpr functions
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71960 --- Comment #6 from CVS Commits --- The releases/gcc-9 branch has been updated by Jonathan Wakely : https://gcc.gnu.org/g:42fb390082b59c0b5af6a9f1e5a2e608ccb8e193 commit r9-8833-g42fb390082b59c0b5af6a9f1e5a2e608ccb8e193 Author: Jonathan Wakely Date: Wed Aug 26 14:47:51 2020 +0100 libstdc++: Enable assertions in constexpr string_view members [PR 71960] Since GCC 6.1 there is no reason we can't just use __glibcxx_assert in constexpr functions in string_view. As long as the condition is true, there will be no call to std::__replacement_assert that would make the function ineligible for constant evaluation. PR libstdc++/71960 * include/experimental/string_view (basic_string_view): Enable debug assertions. * include/std/string_view (basic_string_view): Likewise. (cherry picked from commit 3eefb302d2bd8502cb3d8fe44e672b11092ccaf6)
[Bug libstdc++/71960] __glibcxx_assert and Debug Mode checks can't be used in constexpr functions
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71960 --- Comment #5 from CVS Commits --- The releases/gcc-10 branch has been updated by Jonathan Wakely : https://gcc.gnu.org/g:85847fd421d7760f45f0e69c7ae3607f2f898bb8 commit r10-8676-g85847fd421d7760f45f0e69c7ae3607f2f898bb8 Author: Jonathan Wakely Date: Wed Aug 26 14:47:51 2020 +0100 libstdc++: Enable assertions in constexpr string_view members [PR 71960] Since GCC 6.1 there is no reason we can't just use __glibcxx_assert in constexpr functions in string_view. As long as the condition is true, there will be no call to std::__replacement_assert that would make the function ineligible for constant evaluation. PR libstdc++/71960 * include/experimental/string_view (basic_string_view): Enable debug assertions. * include/std/string_view (basic_string_view): Likewise. (cherry picked from commit 3eefb302d2bd8502cb3d8fe44e672b11092ccaf6)
[Bug libstdc++/71960] __glibcxx_assert and Debug Mode checks can't be used in constexpr functions
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71960 --- Comment #4 from CVS Commits --- The master branch has been updated by Jonathan Wakely : https://gcc.gnu.org/g:3eefb302d2bd8502cb3d8fe44e672b11092ccaf6 commit r11-2881-g3eefb302d2bd8502cb3d8fe44e672b11092ccaf6 Author: Jonathan Wakely Date: Wed Aug 26 14:47:51 2020 +0100 libstdc++: Enable assertions in constexpr string_view members [PR 71960] Since GCC 6.1 there is no reason we can't just use __glibcxx_assert in constexpr functions in string_view. As long as the condition is true, there will be no call to std::__replacement_assert that would make the function ineligible for constant evaluation. PR libstdc++/71960 * include/experimental/string_view (basic_string_view): Enable debug assertions. * include/std/string_view (basic_string_view): Likewise.
[Bug libstdc++/71960] __glibcxx_assert and Debug Mode checks can't be used in constexpr functions
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71960 Jonathan Wakely changed: What|Removed |Added Target Milestone|--- |11.0 Assignee|unassigned at gcc dot gnu.org |redi at gcc dot gnu.org Status|NEW |ASSIGNED
[Bug libstdc++/71960] __glibcxx_assert and Debug Mode checks can't be used in constexpr functions
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71960 Jonathan Wakely changed: What|Removed |Added Status|UNCONFIRMED |NEW Last reconfirmed||2018-04-17 Ever confirmed|0 |1 --- Comment #3 from Jonathan Wakely --- See patch and discussion at https://gcc.gnu.org/ml/libstdc++/2018-03/msg00032.html and https://gcc.gnu.org/ml/libstdc++/2018-03/msg00033.html
[Bug libstdc++/71960] __glibcxx_assert and Debug Mode checks can't be used in constexpr functions
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71960 Jonathan Wakely changed: What|Removed |Added CC||lukibartl at gmail dot com --- Comment #2 from Jonathan Wakely --- *** Bug 77303 has been marked as a duplicate of this bug. ***
[Bug libstdc++/71960] __glibcxx_assert and Debug Mode checks can't be used in constexpr functions
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71960 --- Comment #1 from Jonathan Wakely --- Alternatively, compiler magic which allows the checks to be skipped when used in a constant expression would allow us to support all valid code, at the expense of not diagnosing misuses in constant expressions.
