From 6f115a8eeea41d383dfb1bbb1af6ac9a97aee180 Mon Sep 17 00:00:00 2001 From: Nathaniel Shead Date: Sun, 18 Aug 2024 11:36:40 +1000 Subject: [PATCH] c++/modules: Handle transitive reachability for deduction guides [PR116403] Currently we implement [temp.deduct.guide] p1 by forcing all deduction guides to be considered as exported. However this is not sufficient: for transitive non-exported imports we will still hide the deduction guide from name lookup, causing errors. This patch instead adjusts name lookup to have a new ANY_REACHABLE flag to allow for this case. Currently this is only used by deduction guides but there are some other circumstances where this may be useful in the future (e.g. finding existing temploid friends). PR c++/116403 gcc/cp/ChangeLog: * pt.cc (deduction_guides_for): Use ANY_REACHABLE for lookup of deduction guides. * module.cc (depset::hash::add_deduction_guides): Likewise. (module_state::write_cluster): No longer override deduction guides as exported. * name-lookup.cc (name_lookup::search_namespace_only): Ignore visibility when LOOK_want::ANY_REACHABLE is specified. (check_module_override): Ignore visibility when checking for ambiguating deduction guides. * name-lookup.h (LOOK_want): New flag 'ANY_REACHABLE'. gcc/testsuite/ChangeLog: * g++.dg/modules/dguide-4_a.C: New test. * g++.dg/modules/dguide-4_b.C: New test. * g++.dg/modules/dguide-4_c.C: New test. Signed-off-by: Nathaniel Shead Reviewed-by: Jason Merrill --- gcc/cp/module.cc | 7 +---- gcc/cp/name-lookup.cc | 38 ++++++++++++++++++----- gcc/cp/name-lookup.h | 5 ++- gcc/cp/pt.cc | 3 +- gcc/testsuite/g++.dg/modules/dguide-4_a.C | 18 +++++++++++ gcc/testsuite/g++.dg/modules/dguide-4_b.C | 9 ++++++ gcc/testsuite/g++.dg/modules/dguide-4_c.C | 15 +++++++++ 7 files changed, 79 insertions(+), 16 deletions(-) create mode 100644 gcc/testsuite/g++.dg/modules/dguide-4_a.C create mode 100644 gcc/testsuite/g++.dg/modules/dguide-4_b.C create mode 100644 gcc/testsuite/g++.dg/modules/dguide-4_c.C diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc index 0a4ceffa3d63..ce0ba69641b2 100644 --- a/gcc/cp/module.cc +++ b/gcc/cp/module.cc @@ -13645,7 +13645,7 @@ depset::hash::add_deduction_guides (tree decl) if (find_binding (ns, name)) return; - tree guides = lookup_qualified_name (ns, name, LOOK_want::NORMAL, + tree guides = lookup_qualified_name (ns, name, LOOK_want::ANY_REACHABLE, /*complain=*/false); if (guides == error_mark_node) return; @@ -15228,11 +15228,6 @@ module_state::write_cluster (elf_out *to, depset *scc[], unsigned size, flags |= cbf_hidden; else if (DECL_MODULE_EXPORT_P (STRIP_TEMPLATE (bound))) flags |= cbf_export; - else if (deduction_guide_p (bound)) - /* Deduction guides are always exported so that they are - visible to name lookup whenever their class template - is reachable. */ - flags |= cbf_export; } gcc_checking_assert (DECL_P (bound)); diff --git a/gcc/cp/name-lookup.cc b/gcc/cp/name-lookup.cc index 872f1af0b2e3..70ad4cbf3b50 100644 --- a/gcc/cp/name-lookup.cc +++ b/gcc/cp/name-lookup.cc @@ -916,7 +916,8 @@ name_lookup::search_namespace_only (tree scope) if (unsigned base = cluster->indices[jx].base) if (unsigned span = cluster->indices[jx].span) do - if (bitmap_bit_p (imports, base)) + if (bool (want & LOOK_want::ANY_REACHABLE) + || bitmap_bit_p (imports, base)) goto found; while (++base, --span); continue; @@ -960,9 +961,17 @@ name_lookup::search_namespace_only (tree scope) dup_detect |= dup; } - if (STAT_TYPE_VISIBLE_P (bind)) - type = STAT_TYPE (bind); - bind = STAT_VISIBLE (bind); + if (bool (want & LOOK_want::ANY_REACHABLE)) + { + type = STAT_TYPE (bind); + bind = STAT_DECL (bind); + } + else + { + if (STAT_TYPE_VISIBLE_P (bind)) + type = STAT_TYPE (bind); + bind = STAT_VISIBLE (bind); + } } /* And process it. */ @@ -3761,6 +3770,10 @@ check_module_override (tree decl, tree mvec, bool hiding, tree nontmpl = STRIP_TEMPLATE (decl); bool attached = DECL_LANG_SPECIFIC (nontmpl) && DECL_MODULE_ATTACH_P (nontmpl); + /* For deduction guides we don't do normal name lookup, but rather consider + any reachable declaration, so we should check for overriding here too. */ + bool any_reachable = deduction_guide_p (decl); + if (BINDING_VECTOR_SLOTS_PER_CLUSTER == BINDING_SLOTS_FIXED) { cluster++; @@ -3775,7 +3788,8 @@ check_module_override (tree decl, tree mvec, bool hiding, continue; if (!cluster->indices[jx].base) continue; - if (!bitmap_bit_p (imports, cluster->indices[jx].base)) + if (!any_reachable + && !bitmap_bit_p (imports, cluster->indices[jx].base)) continue; /* Is it loaded? */ if (cluster->slots[jx].is_lazy ()) @@ -3795,9 +3809,17 @@ check_module_override (tree decl, tree mvec, bool hiding, /* If there was a matching STAT_TYPE here then xref_tag should have found it, but we need to check anyway because a conflicting using-declaration may exist. */ - if (STAT_TYPE_VISIBLE_P (bind)) - type = STAT_TYPE (bind); - bind = STAT_VISIBLE (bind); + if (any_reachable) + { + type = STAT_TYPE (bind); + bind = STAT_DECL (bind); + } + else + { + if (STAT_TYPE_VISIBLE_P (bind)) + type = STAT_TYPE (bind); + bind = STAT_VISIBLE (bind); + } } if (type) diff --git a/gcc/cp/name-lookup.h b/gcc/cp/name-lookup.h index 7c4193444dd8..f39f53091501 100644 --- a/gcc/cp/name-lookup.h +++ b/gcc/cp/name-lookup.h @@ -385,9 +385,12 @@ enum class LOOK_want TYPE = 1 << 1, /* We only want TYPE_DECLS. */ NAMESPACE = 1 << 2, /* We only want NAMESPACE_DECLS. */ - HIDDEN_FRIEND = 1 << 3, /* See hidden friends. */ + HIDDEN_FRIEND = 1 << 3, /* See hidden friends. */ HIDDEN_LAMBDA = 1 << 4, /* See lambda-ignored entities. */ + ANY_REACHABLE = 1 << 5, /* Include reachable module declarations not + normally visible to name lookup. */ + TYPE_NAMESPACE = TYPE | NAMESPACE, /* Either NAMESPACE or TYPE. */ }; constexpr LOOK_want operator| (LOOK_want a, LOOK_want b) diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc index 76edc7aad50c..ea660a5a5c6a 100644 --- a/gcc/cp/pt.cc +++ b/gcc/cp/pt.cc @@ -30743,7 +30743,8 @@ deduction_guides_for (tree tmpl, bool &any_dguides_p, tsubst_flags_t complain) { guides = lookup_qualified_name (CP_DECL_CONTEXT (tmpl), dguide_name (tmpl), - LOOK_want::NORMAL, /*complain*/false); + LOOK_want::ANY_REACHABLE, + /*complain=*/false); if (guides == error_mark_node) guides = NULL_TREE; else diff --git a/gcc/testsuite/g++.dg/modules/dguide-4_a.C b/gcc/testsuite/g++.dg/modules/dguide-4_a.C new file mode 100644 index 000000000000..5a9da44cdd62 --- /dev/null +++ b/gcc/testsuite/g++.dg/modules/dguide-4_a.C @@ -0,0 +1,18 @@ +// PR c++/116403 +// { dg-additional-options "-fmodules-ts -Wno-global-module" } +// { dg-module-cmi A } + +module; + +template struct GMF { + GMF(int); +}; +GMF(int) -> GMF; + +export module A; +export using ::GMF; + +export template struct Attached { + Attached(int); +}; +Attached(int) -> Attached; diff --git a/gcc/testsuite/g++.dg/modules/dguide-4_b.C b/gcc/testsuite/g++.dg/modules/dguide-4_b.C new file mode 100644 index 000000000000..9276ffbb3c82 --- /dev/null +++ b/gcc/testsuite/g++.dg/modules/dguide-4_b.C @@ -0,0 +1,9 @@ +// PR c++/116403 +// { dg-additional-options "-fmodules-ts" } +// { dg-module-cmi B } + +export module B; +import A; // not exported + +export using ::GMF; +export using ::Attached; diff --git a/gcc/testsuite/g++.dg/modules/dguide-4_c.C b/gcc/testsuite/g++.dg/modules/dguide-4_c.C new file mode 100644 index 000000000000..898ffa6ac815 --- /dev/null +++ b/gcc/testsuite/g++.dg/modules/dguide-4_c.C @@ -0,0 +1,15 @@ +// PR c++/116403 +// { dg-additional-options "-fmodules-ts" } + +import B; + +int main() { + GMF gmf(123); + GMF test_gmf = gmf; + + Attached attached(456); + Attached test_attached = attached; +} + +GMF(int) -> GMF; // { dg-error "ambiguating" } +Attached(int) -> Attached; // { dg-error "ambiguating" } -- 2.47.2