https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124785
--- Comment #5 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-15 branch has been updated by Nathaniel Shead <[email protected]>: https://gcc.gnu.org/g:aed9f193aae331f2d473f714665ab0fc4bfe8a35 commit r15-11047-gaed9f193aae331f2d473f714665ab0fc4bfe8a35 Author: Nathaniel Shead <[email protected]> Date: Mon Apr 6 00:34:33 2026 +1000 c++/modules: Fix propagating noexcept for templates [PR124785] We triggered a checking assertion because when propagating deduced noexcept, we were updating the type of the existing TEMPLATE_DECL but not the type of its DECL_TEMPLATE_RESULT, violating assumptions made later on during modules streaming. But actually there was nothing to propagate here anyway, these declarations are identical, so this patch also fixes the condition for checking whether we need to propagate anything. And so now I don't think there is ever a case we should have a noexcept-spec to propagate for a TEMPLATE_DECL, so add an assertion to validate this. PR c++/124785 gcc/cp/ChangeLog: * module.cc (trees_in::is_matching_decl): Narrow condition for when noexcept propagation occurs; assert that we don't propagate noexcept-specs for TEMPLATE_DECLs. gcc/testsuite/ChangeLog: * g++.dg/modules/noexcept-5.h: New test. * g++.dg/modules/noexcept-5_a.C: New test. * g++.dg/modules/noexcept-5_b.C: New test. * g++.dg/modules/noexcept-5_c.C: New test. Signed-off-by: Nathaniel Shead <[email protected]> Reviewed-by: Jason Merrill <[email protected]> (cherry picked from commit ca20148d0b784ce52f83a33fc3abb2693a0d6a41)
