https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99377
--- Comment #17 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:77c0b5b23f91404004a9bf710981f6d615b63f57 commit r14-9881-g77c0b5b23f91404004a9bf710981f6d615b63f57 Author: Nathaniel Shead <nathanielosh...@gmail.com> Date: Thu Apr 4 23:16:08 2024 +1100 c++: Track declarations imported from partitions [PR99377] The testcase in comment 15 of the linked PR is caused because the following assumption in depset::hash::make_dependency doesn't hold: if (DECL_LANG_SPECIFIC (not_tmpl) && DECL_MODULE_IMPORT_P (not_tmpl)) { /* Store the module number and index in cluster/section, so we don't have to look them up again. */ unsigned index = import_entity_index (decl); module_state *from = import_entity_module (index); /* Remap will be zero for imports from partitions, which we want to treat as-if declared in this TU. */ if (from->remap) { dep->cluster = index - from->entity_lwm; dep->section = from->remap; dep->set_flag_bit<DB_IMPORTED_BIT> (); } } This is because at least for template specialisations, we first see the declaration in the header unit imported from the partition, and then the instantiation provided by the partition itself. This means that the 'import_entity_index' lookup doesn't report that the specialisation was declared in the partition and thus should be considered as-if it was part of the TU, and get emitted into the CMI. We always need to emit definitions from module partitions into the primary module interface's CMI, as unlike with other kinds of transitive imports the built CMIs for module partitions are not visible to importers. To fix this, this patch allows, as a special case for installing an entity from a partition, to overwrite the entity_map entry with the (later) index into the partition so that this assumption holds again. We only do this for the first time we override with a partition, so that entities are at least still reported as originating from the first imported partition that declares them (rather than the last); existing tests check for this and this seems to be a friendlier approach to go for, albeit slightly more expensive. PR c++/99377 gcc/cp/ChangeLog: * module.cc (trees_in::install_entity): Overwrite entity map index if installing from a partition. gcc/testsuite/ChangeLog: * g++.dg/modules/pr99377-3_a.H: New test. * g++.dg/modules/pr99377-3_b.C: New test. * g++.dg/modules/pr99377-3_c.C: New test. * g++.dg/modules/pr99377-3_d.C: New test. Signed-off-by: Nathaniel Shead <nathanielosh...@gmail.com>
