https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114170
--- Comment #1 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Nathaniel Shead <nsh...@gcc.gnu.org>: https://gcc.gnu.org/g:852b58552991099141f9df5782e1f28d8606af9d commit r14-9267-g852b58552991099141f9df5782e1f28d8606af9d Author: Nathaniel Shead <nathanielosh...@gmail.com> Date: Fri Mar 1 11:08:23 2024 +1100 c++: Stream definitions for implicit instantiations [PR114170] An implicit instantiation has an initializer depending on whether DECL_INITIALIZED_P is set (like normal VAR_DECLs) which needs to be written to ensure that consumers of header modules properly emit definitions for these instantiations. This patch ensures that we correctly fallback to checking this flag when DECL_INITIAL is not set for a template instantiation. For variables with non-trivial dynamic initialization, DECL_INITIAL can be empty after 'split_nonconstant_init' but DECL_INITIALIZED_P is still set; we need to check the latter to determine if we need to go looking for a definition to emit (often in 'static_aggregates' here). This is the case in the linked testcase. However, for template specialisations (not instantiations?) we primarily care about DECL_INITIAL; if the variable has initialization depending on a template parameter then we'll need to emit that definition even though it doesn't yet have DECL_INITIALIZED_P set; this is the case in e.g. template <int N> int value = N; As a drive-by fix, also ensures that the count of initializers matches the actual number of initializers written. This doesn't seem to be necessary for correctness in the current testsuite, but feels wrong and makes debugging harder when initializers aren't properly written for other reasons. PR c++/114170 gcc/cp/ChangeLog: * module.cc (has_definition): Fall back to DECL_INITIALIZED_P when DECL_INITIAL is not set on a template. (module_state::write_inits): Only increment count when initializers are actually written. gcc/testsuite/ChangeLog: * g++.dg/modules/var-tpl-2_a.H: New test. * g++.dg/modules/var-tpl-2_b.C: New test. Signed-off-by: Nathaniel Shead <nathanielosh...@gmail.com>
