| Message ID | 666e4e07.170a0220.f594a.008f@mx.google.com |
|---|---|
| State | New |
| Headers | show |
| Series | c++/modules: Ensure deduction guides are always reachable [PR115231] | expand |
On Sun, Jun 16, 2024 at 12:29:23PM +1000, Nathaniel Shead wrote: > Bootstrapped and regtested on x86_64-pc-linux-gnu, OK for trunk? > > This probably isn't the most efficient approach, since we need to do > name lookup to find deduction guides for a type which will also > potentially do a bunch of pointless lazy loading from imported modules, > but I wasn't able to work out a better approach without completely > reworking how deduction guides are stored and represented. This way at > least is correct (I believe), and we can maybe revisit this in the > future. > > -- >8 -- > > Deduction guides are represented as 'normal' functions currently, and > have no special handling in modules. However, this causes some issues; > by [temp.deduct.guide] a deduction guide is not found by normal name > lookup and instead all reachable deduction guides for a class template > should be considered, but this does not happen currently. > > To solve this, this patch ensures that all deduction guides are > considered exported to ensure that they are always visible to importers > if they are reachable. Another alternative here would be to add a new > kind of "all reachable" flag to name lookup, but that is complicated by > some difficulties in handling GM entities; this may be a better way to > go if more kinds of entities end up needing this handling, however. > > Another issue here is that because deduction guides are "unrelated" > functions, they will usually get discarded from the GMF, so this patch > ensures that when finding dependencies, GMF deduction guides will also > have bindings created. We do this in find_dependencies so that we don't > unnecessarily create bindings for GMF deduction guides that are never > reached; for consistency we do this for *all* deduction guides, not just > GM ones. > > Finally, when merging deduction guides from multiple modules, the name > lookup code may now return two-dimensional overload sets, so update > callers to match. > > As a small drive-by improvement this patch also updates the error pretty > printing code to add a space before the '->' when printing a deduction > guide, so we get 'S(int) -> S<int>' instead of 'S(int)-> S<int>'. > > PR c++/115231 > > gcc/cp/ChangeLog: > > * error.cc (dump_function_decl): Add a space before '->' when > printing deduction guides. > * module.cc (depset::hash::add_binding_entity): Skip deduction > guides here. > (depset::hash::add_deduction_guides): New. > (depset::hash::find_dependencies): Add deduction guide > dependencies for a class template. > (module_state::write_cluster): Always consider deduction guides > as exported. > * pt.cc (deduction_guides_for): Use 'lkp_iterator' instead of > 'ovl_iterator'. > > gcc/testsuite/ChangeLog: > > * g++.dg/modules/dguide-1_a.C: New test. > * g++.dg/modules/dguide-1_b.C: New test. > * g++.dg/modules/dguide-2_a.C: New test. > * g++.dg/modules/dguide-2_b.C: New test. > * g++.dg/modules/dguide-3_a.C: New test. > * g++.dg/modules/dguide-3_b.C: New test. > * g++.dg/modules/dguide-3_c.C: New test. > > Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com> > --- > gcc/cp/error.cc | 1 + > gcc/cp/module.cc | 60 +++++++++++++++++++++++ > gcc/cp/pt.cc | 2 +- > gcc/testsuite/g++.dg/modules/dguide-1_a.C | 44 +++++++++++++++++ > gcc/testsuite/g++.dg/modules/dguide-1_b.C | 20 ++++++++ > gcc/testsuite/g++.dg/modules/dguide-2_a.C | 24 +++++++++ > gcc/testsuite/g++.dg/modules/dguide-2_b.C | 19 +++++++ > gcc/testsuite/g++.dg/modules/dguide-3_a.C | 10 ++++ > gcc/testsuite/g++.dg/modules/dguide-3_b.C | 10 ++++ > gcc/testsuite/g++.dg/modules/dguide-3_c.C | 22 +++++++++ > 10 files changed, 211 insertions(+), 1 deletion(-) > create mode 100644 gcc/testsuite/g++.dg/modules/dguide-1_a.C > create mode 100644 gcc/testsuite/g++.dg/modules/dguide-1_b.C > create mode 100644 gcc/testsuite/g++.dg/modules/dguide-2_a.C > create mode 100644 gcc/testsuite/g++.dg/modules/dguide-2_b.C > create mode 100644 gcc/testsuite/g++.dg/modules/dguide-3_a.C > create mode 100644 gcc/testsuite/g++.dg/modules/dguide-3_b.C > create mode 100644 gcc/testsuite/g++.dg/modules/dguide-3_c.C > > diff --git a/gcc/cp/error.cc b/gcc/cp/error.cc > index 171a352c85f..2fb5084320e 100644 > --- a/gcc/cp/error.cc > +++ b/gcc/cp/error.cc > @@ -1866,6 +1866,7 @@ dump_function_decl (cxx_pretty_printer *pp, tree t, int flags) > dump_type_suffix (pp, ret, flags); > else if (deduction_guide_p (t)) > { > + pp->set_padding (pp_before); > pp_cxx_ws_string (pp, "->"); > dump_type (pp, TREE_TYPE (TREE_TYPE (t)), flags); > } > diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc > index 6d6044af199..a2c9e151fd5 100644 > --- a/gcc/cp/module.cc > +++ b/gcc/cp/module.cc > @@ -2589,6 +2589,9 @@ public: > void add_partial_entities (vec<tree, va_gc> *); > void add_class_entities (vec<tree, va_gc> *); > > + private: > + void add_deduction_guides (tree decl); > + > public: > void find_dependencies (module_state *); > bool finalize_dependencies (); > @@ -13127,6 +13130,11 @@ depset::hash::add_binding_entity (tree decl, WMB_Flags flags, void *data_) > { > tree inner = decl; > > + if (deduction_guide_p (inner)) > + /* Ignore deduction guides here, they'll be handled within > + find_dependencies for a class template. */ > + return false; > + > if (TREE_CODE (inner) == CONST_DECL > && TREE_CODE (DECL_CONTEXT (inner)) == ENUMERAL_TYPE) > inner = TYPE_NAME (DECL_CONTEXT (inner)); > @@ -13590,6 +13598,50 @@ find_pending_key (tree decl, tree *decl_p = nullptr) > return ns; > } > > +/* Creates bindings and dependencies for all deduction guides of > + the given class template DECL as needed. */ > + > +void > +depset::hash::add_deduction_guides (tree decl) > +{ > + /* Alias templates never have deduction guides. */ > + if (DECL_ALIAS_TEMPLATE_P (decl)) > + return; > + > + /* We don't need to do anything for class-scope deduction guides, > + as they will be added as members anyway. */ > + if (!DECL_NAMESPACE_SCOPE_P (decl)) > + return; > + > + tree ns = CP_DECL_CONTEXT (decl); > + tree name = dguide_name (decl); > + > + /* We always add all deduction guides with a given name at once, > + so if there's already a binding there's nothing to do. */ > + if (find_binding (ns, name)) > + return; > + > + tree guides = lookup_qualified_name (ns, name, LOOK_want::NORMAL, > + /*complain=*/false); > + if (guides == error_mark_node) > + return; > + > + /* We have bindings to add. */ > + depset *binding = make_binding (ns, name); > + add_namespace_context (binding, ns); > + > + depset **slot = binding_slot (ns, name, /*insert=*/true); > + *slot = binding; > + > + for (lkp_iterator it (guides); it; ++it) > + { > + gcc_checking_assert (!TREE_VISITED (*it)); > + depset *dep = make_dependency (*it, EK_FOR_BINDING); > + binding->deps.safe_push (dep); > + dep->deps.safe_push (binding); > + } > +} > + > /* Iteratively find dependencies. During the walk we may find more > entries on the same binding that need walking. */ > > @@ -13649,6 +13701,10 @@ depset::hash::find_dependencies (module_state *module) > } > walker.end (); > > + if (!walker.is_key_order () > + && DECL_CLASS_TEMPLATE_P (decl)) > + add_deduction_guides (decl); > + > if (!walker.is_key_order () > && TREE_CODE (decl) == TEMPLATE_DECL > && !DECL_UNINSTANTIATED_TEMPLATE_FRIEND_P (decl)) > @@ -15145,6 +15201,10 @@ 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 > + reachable whenever their class template is. */ > + flags |= cbf_export; > } > > gcc_checking_assert (DECL_P (bound)); > diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc > index 607753ae6b7..8e007a571a5 100644 > --- a/gcc/cp/pt.cc > +++ b/gcc/cp/pt.cc > @@ -30784,7 +30784,7 @@ deduction_guides_for (tree tmpl, bool &any_dguides_p, tsubst_flags_t complain) > else > { > cands = ctor_deduction_guides_for (tmpl, complain); > - for (ovl_iterator it (guides); it; ++it) > + for (lkp_iterator it (guides); it; ++it) > cands = lookup_add (*it, cands); > } > > diff --git a/gcc/testsuite/g++.dg/modules/dguide-1_a.C b/gcc/testsuite/g++.dg/modules/dguide-1_a.C > new file mode 100644 > index 00000000000..834e033eae3 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/modules/dguide-1_a.C > @@ -0,0 +1,44 @@ > +// PR c++/115231 > +// { dg-additional-options "-fmodules-ts -Wno-global-module" } > +// { dg-module-cmi M } > + > +module; > + > +template <typename T> > +struct A { > + template <typename U> A(U); > +}; > + > +template <typename T> A(T) -> A<T>; > + > +export module M; > + > +// Exporting a GMF entity should make the deduction guides reachable. > +export using ::A; > + > + > +export template <typename T> > +struct B { > + template <typename U> B(U); > +}; > + > +// Not exported, but should still be reachable by [temp.deduct.guide] p1. > +B(int) -> B<double>; > + > + > +// Class-scope deduction guides should be reachable as well, even if > +// the class body was not exported. > +export template <typename T> struct C; > + > +template <typename T> > +struct C { > + template <typename U> > + struct I { > + template <typename V> I(V); > + }; > + > + I(int) -> I<int>; > + > + template <typename P> > + I(const P*) -> I<P>; > +}; > diff --git a/gcc/testsuite/g++.dg/modules/dguide-1_b.C b/gcc/testsuite/g++.dg/modules/dguide-1_b.C > new file mode 100644 > index 00000000000..97266986d8f > --- /dev/null > +++ b/gcc/testsuite/g++.dg/modules/dguide-1_b.C > @@ -0,0 +1,20 @@ > +// PR c++/115231 > +// { dg-additional-options "-fmodules-ts" } > + > +import M; > + > +int main() { > + // Check that deduction guides are reachable, > + // and that they declared the right type. > + A a(1); > + A<int> a2 = a; > + > + B b(2); > + B<double> b2 = b; > + > + C<int>::I x(10); > + C<int>::I<int> x2 = x; > + > + C<int>::I y("xyz"); > + C<int>::I<char> y2 = y; > +} > diff --git a/gcc/testsuite/g++.dg/modules/dguide-2_a.C b/gcc/testsuite/g++.dg/modules/dguide-2_a.C > new file mode 100644 > index 00000000000..fcd6c579813 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/modules/dguide-2_a.C > @@ -0,0 +1,24 @@ > +// PR c++/115231 > +// { dg-additional-options "-fmodules-ts -Wno-global-module" } > +// { dg-module-cmi M } > + > +module; > + > +template <typename T> > +struct A { > + template <typename U> A(U); > +}; > +template <typename T> A(T) -> A<T>; > + > +export module M; > + > +template <typename T> > +struct B { > + template <typename U> B(U); > +}; > +B(int) -> B<int>; > + > +// Accessing deduction guides should be possible, > +// even if we can't name the type directly. > +export A<void> f(); > +export B<void> g(); > diff --git a/gcc/testsuite/g++.dg/modules/dguide-2_b.C b/gcc/testsuite/g++.dg/modules/dguide-2_b.C > new file mode 100644 > index 00000000000..ca31306aea3 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/modules/dguide-2_b.C > @@ -0,0 +1,19 @@ > +// PR c++/115231 > +// { dg-additional-options "-fmodules-ts" } > + > +import M; > + > +template <typename> > +struct U; > + > +template <template <typename> typename TT, typename Inner> > +struct U<TT<Inner>> { > + void go() { > + TT t(10); > + } > +}; > + > +int main() { > + U<decltype(f())>{}.go(); > + U<decltype(g())>{}.go(); > +} > diff --git a/gcc/testsuite/g++.dg/modules/dguide-3_a.C b/gcc/testsuite/g++.dg/modules/dguide-3_a.C > new file mode 100644 > index 00000000000..33350ce9804 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/modules/dguide-3_a.C > @@ -0,0 +1,10 @@ > +// { dg-additional-options "-fmodules-ts" } > +// { dg-module-cmi A } > + > +export module A; > + > +extern "C++" { > + template <typename T> struct S; > + S(int) -> S<int>; > + S(double) -> S<double>; > +} > diff --git a/gcc/testsuite/g++.dg/modules/dguide-3_b.C b/gcc/testsuite/g++.dg/modules/dguide-3_b.C > new file mode 100644 > index 00000000000..d23696c74bd > --- /dev/null > +++ b/gcc/testsuite/g++.dg/modules/dguide-3_b.C > @@ -0,0 +1,10 @@ > +// { dg-additional-options "-fmodules-ts" } > +// { dg-module-cmi B } > + > +export module B; > + > +extern "C++" { > + template <typename T> struct S; > + S(int) -> S<int>; > + S(char) -> S<char>; > +} > diff --git a/gcc/testsuite/g++.dg/modules/dguide-3_c.C b/gcc/testsuite/g++.dg/modules/dguide-3_c.C > new file mode 100644 > index 00000000000..39ae8f4aa58 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/modules/dguide-3_c.C > @@ -0,0 +1,22 @@ > +// { dg-additional-options "-fmodules-ts" } > +// Test merging deduction guides. > + > +import A; > +import B; > + > +template <typename T> struct S { > + template <typename U> S(U); > +}; > + > +int main() { > + S x(123); // { dg-bogus "incomplete" "" { xfail *-*-* } } > + S<int> x2 = x; > + > + S y('c'); // { dg-bogus "incomplete" "" { xfail *-*-* } } > + S<char> y2 = y; > + > + S z(0.5); // { dg-bogus "incomplete" "" { xfail *-*-* } } > + S<double> z2 = z; > +} > + > +S(char) -> S<double>; // { dg-error "ambiguating" } > -- > 2.43.2 > I just realised I forgot to explain these xfails in the above commit: this is because the return types declare a new "specialisation" that is treated as a separate type on stream-in, rather than merging with the existing template on instantiation. A simplified example of this error is: // a.cpp export module A; extern "C++" template <typename T> struct S; export S<int> foo(); // main.cpp import A; template <typename T> struct S {}; int main() { foo(); } I suspect this is related to PR c++/113814. I'm pretty sure this should be valid code ([temp.inst] p2 doesn't seem to require instantiation in A because a function return type doesn't require a completely-defined object type and completeness won't affect the semantics of the program) but I haven't looked much into how to fix this yet. Nathaniel
Ping for https://gcc.gnu.org/pipermail/gcc-patches/2024-June/654792.html On Sun, Jun 16, 2024 at 3:41 PM Nathaniel Shead <nathanieloshead@gmail.com> wrote: > > On Sun, Jun 16, 2024 at 12:29:23PM +1000, Nathaniel Shead wrote: > > Bootstrapped and regtested on x86_64-pc-linux-gnu, OK for trunk? > > > > This probably isn't the most efficient approach, since we need to do > > name lookup to find deduction guides for a type which will also > > potentially do a bunch of pointless lazy loading from imported modules, > > but I wasn't able to work out a better approach without completely > > reworking how deduction guides are stored and represented. This way at > > least is correct (I believe), and we can maybe revisit this in the > > future. > > > > -- >8 -- > > > > Deduction guides are represented as 'normal' functions currently, and > > have no special handling in modules. However, this causes some issues; > > by [temp.deduct.guide] a deduction guide is not found by normal name > > lookup and instead all reachable deduction guides for a class template > > should be considered, but this does not happen currently. > > > > To solve this, this patch ensures that all deduction guides are > > considered exported to ensure that they are always visible to importers > > if they are reachable. Another alternative here would be to add a new > > kind of "all reachable" flag to name lookup, but that is complicated by > > some difficulties in handling GM entities; this may be a better way to > > go if more kinds of entities end up needing this handling, however. > > > > Another issue here is that because deduction guides are "unrelated" > > functions, they will usually get discarded from the GMF, so this patch > > ensures that when finding dependencies, GMF deduction guides will also > > have bindings created. We do this in find_dependencies so that we don't > > unnecessarily create bindings for GMF deduction guides that are never > > reached; for consistency we do this for *all* deduction guides, not just > > GM ones. > > > > Finally, when merging deduction guides from multiple modules, the name > > lookup code may now return two-dimensional overload sets, so update > > callers to match. > > > > As a small drive-by improvement this patch also updates the error pretty > > printing code to add a space before the '->' when printing a deduction > > guide, so we get 'S(int) -> S<int>' instead of 'S(int)-> S<int>'. > > > > PR c++/115231 > > > > gcc/cp/ChangeLog: > > > > * error.cc (dump_function_decl): Add a space before '->' when > > printing deduction guides. > > * module.cc (depset::hash::add_binding_entity): Skip deduction > > guides here. > > (depset::hash::add_deduction_guides): New. > > (depset::hash::find_dependencies): Add deduction guide > > dependencies for a class template. > > (module_state::write_cluster): Always consider deduction guides > > as exported. > > * pt.cc (deduction_guides_for): Use 'lkp_iterator' instead of > > 'ovl_iterator'. > > > > gcc/testsuite/ChangeLog: > > > > * g++.dg/modules/dguide-1_a.C: New test. > > * g++.dg/modules/dguide-1_b.C: New test. > > * g++.dg/modules/dguide-2_a.C: New test. > > * g++.dg/modules/dguide-2_b.C: New test. > > * g++.dg/modules/dguide-3_a.C: New test. > > * g++.dg/modules/dguide-3_b.C: New test. > > * g++.dg/modules/dguide-3_c.C: New test. > > > > Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com> > > --- > > gcc/cp/error.cc | 1 + > > gcc/cp/module.cc | 60 +++++++++++++++++++++++ > > gcc/cp/pt.cc | 2 +- > > gcc/testsuite/g++.dg/modules/dguide-1_a.C | 44 +++++++++++++++++ > > gcc/testsuite/g++.dg/modules/dguide-1_b.C | 20 ++++++++ > > gcc/testsuite/g++.dg/modules/dguide-2_a.C | 24 +++++++++ > > gcc/testsuite/g++.dg/modules/dguide-2_b.C | 19 +++++++ > > gcc/testsuite/g++.dg/modules/dguide-3_a.C | 10 ++++ > > gcc/testsuite/g++.dg/modules/dguide-3_b.C | 10 ++++ > > gcc/testsuite/g++.dg/modules/dguide-3_c.C | 22 +++++++++ > > 10 files changed, 211 insertions(+), 1 deletion(-) > > create mode 100644 gcc/testsuite/g++.dg/modules/dguide-1_a.C > > create mode 100644 gcc/testsuite/g++.dg/modules/dguide-1_b.C > > create mode 100644 gcc/testsuite/g++.dg/modules/dguide-2_a.C > > create mode 100644 gcc/testsuite/g++.dg/modules/dguide-2_b.C > > create mode 100644 gcc/testsuite/g++.dg/modules/dguide-3_a.C > > create mode 100644 gcc/testsuite/g++.dg/modules/dguide-3_b.C > > create mode 100644 gcc/testsuite/g++.dg/modules/dguide-3_c.C > > > > diff --git a/gcc/cp/error.cc b/gcc/cp/error.cc > > index 171a352c85f..2fb5084320e 100644 > > --- a/gcc/cp/error.cc > > +++ b/gcc/cp/error.cc > > @@ -1866,6 +1866,7 @@ dump_function_decl (cxx_pretty_printer *pp, tree t, int flags) > > dump_type_suffix (pp, ret, flags); > > else if (deduction_guide_p (t)) > > { > > + pp->set_padding (pp_before); > > pp_cxx_ws_string (pp, "->"); > > dump_type (pp, TREE_TYPE (TREE_TYPE (t)), flags); > > } > > diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc > > index 6d6044af199..a2c9e151fd5 100644 > > --- a/gcc/cp/module.cc > > +++ b/gcc/cp/module.cc > > @@ -2589,6 +2589,9 @@ public: > > void add_partial_entities (vec<tree, va_gc> *); > > void add_class_entities (vec<tree, va_gc> *); > > > > + private: > > + void add_deduction_guides (tree decl); > > + > > public: > > void find_dependencies (module_state *); > > bool finalize_dependencies (); > > @@ -13127,6 +13130,11 @@ depset::hash::add_binding_entity (tree decl, WMB_Flags flags, void *data_) > > { > > tree inner = decl; > > > > + if (deduction_guide_p (inner)) > > + /* Ignore deduction guides here, they'll be handled within > > + find_dependencies for a class template. */ > > + return false; > > + > > if (TREE_CODE (inner) == CONST_DECL > > && TREE_CODE (DECL_CONTEXT (inner)) == ENUMERAL_TYPE) > > inner = TYPE_NAME (DECL_CONTEXT (inner)); > > @@ -13590,6 +13598,50 @@ find_pending_key (tree decl, tree *decl_p = nullptr) > > return ns; > > } > > > > +/* Creates bindings and dependencies for all deduction guides of > > + the given class template DECL as needed. */ > > + > > +void > > +depset::hash::add_deduction_guides (tree decl) > > +{ > > + /* Alias templates never have deduction guides. */ > > + if (DECL_ALIAS_TEMPLATE_P (decl)) > > + return; > > + > > + /* We don't need to do anything for class-scope deduction guides, > > + as they will be added as members anyway. */ > > + if (!DECL_NAMESPACE_SCOPE_P (decl)) > > + return; > > + > > + tree ns = CP_DECL_CONTEXT (decl); > > + tree name = dguide_name (decl); > > + > > + /* We always add all deduction guides with a given name at once, > > + so if there's already a binding there's nothing to do. */ > > + if (find_binding (ns, name)) > > + return; > > + > > + tree guides = lookup_qualified_name (ns, name, LOOK_want::NORMAL, > > + /*complain=*/false); > > + if (guides == error_mark_node) > > + return; > > + > > + /* We have bindings to add. */ > > + depset *binding = make_binding (ns, name); > > + add_namespace_context (binding, ns); > > + > > + depset **slot = binding_slot (ns, name, /*insert=*/true); > > + *slot = binding; > > + > > + for (lkp_iterator it (guides); it; ++it) > > + { > > + gcc_checking_assert (!TREE_VISITED (*it)); > > + depset *dep = make_dependency (*it, EK_FOR_BINDING); > > + binding->deps.safe_push (dep); > > + dep->deps.safe_push (binding); > > + } > > +} > > + > > /* Iteratively find dependencies. During the walk we may find more > > entries on the same binding that need walking. */ > > > > @@ -13649,6 +13701,10 @@ depset::hash::find_dependencies (module_state *module) > > } > > walker.end (); > > > > + if (!walker.is_key_order () > > + && DECL_CLASS_TEMPLATE_P (decl)) > > + add_deduction_guides (decl); > > + > > if (!walker.is_key_order () > > && TREE_CODE (decl) == TEMPLATE_DECL > > && !DECL_UNINSTANTIATED_TEMPLATE_FRIEND_P (decl)) > > @@ -15145,6 +15201,10 @@ 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 > > + reachable whenever their class template is. */ > > + flags |= cbf_export; > > } > > > > gcc_checking_assert (DECL_P (bound)); > > diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc > > index 607753ae6b7..8e007a571a5 100644 > > --- a/gcc/cp/pt.cc > > +++ b/gcc/cp/pt.cc > > @@ -30784,7 +30784,7 @@ deduction_guides_for (tree tmpl, bool &any_dguides_p, tsubst_flags_t complain) > > else > > { > > cands = ctor_deduction_guides_for (tmpl, complain); > > - for (ovl_iterator it (guides); it; ++it) > > + for (lkp_iterator it (guides); it; ++it) > > cands = lookup_add (*it, cands); > > } > > > > diff --git a/gcc/testsuite/g++.dg/modules/dguide-1_a.C b/gcc/testsuite/g++.dg/modules/dguide-1_a.C > > new file mode 100644 > > index 00000000000..834e033eae3 > > --- /dev/null > > +++ b/gcc/testsuite/g++.dg/modules/dguide-1_a.C > > @@ -0,0 +1,44 @@ > > +// PR c++/115231 > > +// { dg-additional-options "-fmodules-ts -Wno-global-module" } > > +// { dg-module-cmi M } > > + > > +module; > > + > > +template <typename T> > > +struct A { > > + template <typename U> A(U); > > +}; > > + > > +template <typename T> A(T) -> A<T>; > > + > > +export module M; > > + > > +// Exporting a GMF entity should make the deduction guides reachable. > > +export using ::A; > > + > > + > > +export template <typename T> > > +struct B { > > + template <typename U> B(U); > > +}; > > + > > +// Not exported, but should still be reachable by [temp.deduct.guide] p1. > > +B(int) -> B<double>; > > + > > + > > +// Class-scope deduction guides should be reachable as well, even if > > +// the class body was not exported. > > +export template <typename T> struct C; > > + > > +template <typename T> > > +struct C { > > + template <typename U> > > + struct I { > > + template <typename V> I(V); > > + }; > > + > > + I(int) -> I<int>; > > + > > + template <typename P> > > + I(const P*) -> I<P>; > > +}; > > diff --git a/gcc/testsuite/g++.dg/modules/dguide-1_b.C b/gcc/testsuite/g++.dg/modules/dguide-1_b.C > > new file mode 100644 > > index 00000000000..97266986d8f > > --- /dev/null > > +++ b/gcc/testsuite/g++.dg/modules/dguide-1_b.C > > @@ -0,0 +1,20 @@ > > +// PR c++/115231 > > +// { dg-additional-options "-fmodules-ts" } > > + > > +import M; > > + > > +int main() { > > + // Check that deduction guides are reachable, > > + // and that they declared the right type. > > + A a(1); > > + A<int> a2 = a; > > + > > + B b(2); > > + B<double> b2 = b; > > + > > + C<int>::I x(10); > > + C<int>::I<int> x2 = x; > > + > > + C<int>::I y("xyz"); > > + C<int>::I<char> y2 = y; > > +} > > diff --git a/gcc/testsuite/g++.dg/modules/dguide-2_a.C b/gcc/testsuite/g++.dg/modules/dguide-2_a.C > > new file mode 100644 > > index 00000000000..fcd6c579813 > > --- /dev/null > > +++ b/gcc/testsuite/g++.dg/modules/dguide-2_a.C > > @@ -0,0 +1,24 @@ > > +// PR c++/115231 > > +// { dg-additional-options "-fmodules-ts -Wno-global-module" } > > +// { dg-module-cmi M } > > + > > +module; > > + > > +template <typename T> > > +struct A { > > + template <typename U> A(U); > > +}; > > +template <typename T> A(T) -> A<T>; > > + > > +export module M; > > + > > +template <typename T> > > +struct B { > > + template <typename U> B(U); > > +}; > > +B(int) -> B<int>; > > + > > +// Accessing deduction guides should be possible, > > +// even if we can't name the type directly. > > +export A<void> f(); > > +export B<void> g(); > > diff --git a/gcc/testsuite/g++.dg/modules/dguide-2_b.C b/gcc/testsuite/g++.dg/modules/dguide-2_b.C > > new file mode 100644 > > index 00000000000..ca31306aea3 > > --- /dev/null > > +++ b/gcc/testsuite/g++.dg/modules/dguide-2_b.C > > @@ -0,0 +1,19 @@ > > +// PR c++/115231 > > +// { dg-additional-options "-fmodules-ts" } > > + > > +import M; > > + > > +template <typename> > > +struct U; > > + > > +template <template <typename> typename TT, typename Inner> > > +struct U<TT<Inner>> { > > + void go() { > > + TT t(10); > > + } > > +}; > > + > > +int main() { > > + U<decltype(f())>{}.go(); > > + U<decltype(g())>{}.go(); > > +} > > diff --git a/gcc/testsuite/g++.dg/modules/dguide-3_a.C b/gcc/testsuite/g++.dg/modules/dguide-3_a.C > > new file mode 100644 > > index 00000000000..33350ce9804 > > --- /dev/null > > +++ b/gcc/testsuite/g++.dg/modules/dguide-3_a.C > > @@ -0,0 +1,10 @@ > > +// { dg-additional-options "-fmodules-ts" } > > +// { dg-module-cmi A } > > + > > +export module A; > > + > > +extern "C++" { > > + template <typename T> struct S; > > + S(int) -> S<int>; > > + S(double) -> S<double>; > > +} > > diff --git a/gcc/testsuite/g++.dg/modules/dguide-3_b.C b/gcc/testsuite/g++.dg/modules/dguide-3_b.C > > new file mode 100644 > > index 00000000000..d23696c74bd > > --- /dev/null > > +++ b/gcc/testsuite/g++.dg/modules/dguide-3_b.C > > @@ -0,0 +1,10 @@ > > +// { dg-additional-options "-fmodules-ts" } > > +// { dg-module-cmi B } > > + > > +export module B; > > + > > +extern "C++" { > > + template <typename T> struct S; > > + S(int) -> S<int>; > > + S(char) -> S<char>; > > +} > > diff --git a/gcc/testsuite/g++.dg/modules/dguide-3_c.C b/gcc/testsuite/g++.dg/modules/dguide-3_c.C > > new file mode 100644 > > index 00000000000..39ae8f4aa58 > > --- /dev/null > > +++ b/gcc/testsuite/g++.dg/modules/dguide-3_c.C > > @@ -0,0 +1,22 @@ > > +// { dg-additional-options "-fmodules-ts" } > > +// Test merging deduction guides. > > + > > +import A; > > +import B; > > + > > +template <typename T> struct S { > > + template <typename U> S(U); > > +}; > > + > > +int main() { > > + S x(123); // { dg-bogus "incomplete" "" { xfail *-*-* } } > > + S<int> x2 = x; > > + > > + S y('c'); // { dg-bogus "incomplete" "" { xfail *-*-* } } > > + S<char> y2 = y; > > + > > + S z(0.5); // { dg-bogus "incomplete" "" { xfail *-*-* } } > > + S<double> z2 = z; > > +} > > + > > +S(char) -> S<double>; // { dg-error "ambiguating" } > > -- > > 2.43.2 > > > > I just realised I forgot to explain these xfails in the above commit: > this is because the return types declare a new "specialisation" that is > treated as a separate type on stream-in, rather than merging with the > existing template on instantiation. > > A simplified example of this error is: > > // a.cpp > export module A; > extern "C++" template <typename T> struct S; > export S<int> foo(); > > // main.cpp > import A; > template <typename T> struct S {}; > int main() { foo(); } > > I suspect this is related to PR c++/113814. I'm pretty sure this should > be valid code ([temp.inst] p2 doesn't seem to require instantiation in A > because a function return type doesn't require a completely-defined > object type and completeness won't affect the semantics of the program) > but I haven't looked much into how to fix this yet. > > Nathaniel
On 6/15/24 10:29 PM, Nathaniel Shead wrote: > Bootstrapped and regtested on x86_64-pc-linux-gnu, OK for trunk? > > This probably isn't the most efficient approach, since we need to do > name lookup to find deduction guides for a type which will also > potentially do a bunch of pointless lazy loading from imported modules, > but I wasn't able to work out a better approach without completely > reworking how deduction guides are stored and represented. Indeed. We likely want to find them more directly from the template; it's not clear to me that DECL_INITIAL is used for TEMPLATE_DECL, or we could put them in an internal attribute or a separate hash table. > -- >8 -- > > Deduction guides are represented as 'normal' functions currently, and > have no special handling in modules. However, this causes some issues; > by [temp.deduct.guide] a deduction guide is not found by normal name > lookup and instead all reachable deduction guides for a class template > should be considered, but this does not happen currently. > > To solve this, this patch ensures that all deduction guides are > considered exported to ensure that they are always visible to importers > if they are reachable. Another alternative here would be to add a new > kind of "all reachable" flag to name lookup, but that is complicated by > some difficulties in handling GM entities; this may be a better way to > go if more kinds of entities end up needing this handling, however. > > Another issue here is that because deduction guides are "unrelated" > functions, they will usually get discarded from the GMF, so this patch > ensures that when finding dependencies, GMF deduction guides will also > have bindings created. We do this in find_dependencies so that we don't > unnecessarily create bindings for GMF deduction guides that are never > reached; for consistency we do this for *all* deduction guides, not just > GM ones. If you fixed the dependency calculation, why do they also need to be exported? Jason
On Tue, Jul 23, 2024 at 04:17:22PM -0400, Jason Merrill wrote: > On 6/15/24 10:29 PM, Nathaniel Shead wrote: > > Bootstrapped and regtested on x86_64-pc-linux-gnu, OK for trunk? > > > > This probably isn't the most efficient approach, since we need to do > > name lookup to find deduction guides for a type which will also > > potentially do a bunch of pointless lazy loading from imported modules, > > but I wasn't able to work out a better approach without completely > > reworking how deduction guides are stored and represented. > > Indeed. We likely want to find them more directly from the template; it's > not clear to me that DECL_INITIAL is used for TEMPLATE_DECL, or we could put > them in an internal attribute or a separate hash table. > > > -- >8 -- > > > > Deduction guides are represented as 'normal' functions currently, and > > have no special handling in modules. However, this causes some issues; > > by [temp.deduct.guide] a deduction guide is not found by normal name > > lookup and instead all reachable deduction guides for a class template > > should be considered, but this does not happen currently. > > > > To solve this, this patch ensures that all deduction guides are > > considered exported to ensure that they are always visible to importers > > if they are reachable. Another alternative here would be to add a new > > kind of "all reachable" flag to name lookup, but that is complicated by > > some difficulties in handling GM entities; this may be a better way to > > go if more kinds of entities end up needing this handling, however. > > > > Another issue here is that because deduction guides are "unrelated" > > functions, they will usually get discarded from the GMF, so this patch > > ensures that when finding dependencies, GMF deduction guides will also > > have bindings created. We do this in find_dependencies so that we don't > > unnecessarily create bindings for GMF deduction guides that are never > > reached; for consistency we do this for *all* deduction guides, not just > > GM ones. > > If you fixed the dependency calculation, why do they also need to be > exported? > > Jason > Deduction guides aren't found using normal name lookup, but any reachable deduction guide must be considered. This means that even if the module interface exports no declarations whatsoever, a deduction guide declared in the module purview must still be considered by importers. The other option I've considered is adding a new "ANY_REACHABLE" flag to name lookup which would also consider non-exported reachable decls. On further consideration I might actually go this way; I've been thinking about how to resolve some issues adjacent to supporting textual redefinitions that I believe this will be necessary for anyway, and we can probably use this in tsubst_friend_class as well rather than the current relatively ad-hoc solution. That said, I've realised that this patch isn't completely sufficient anyway; consider: // m.cpp module; template <typename T> struct S; export module M; S(int) -> S<double>; // x.cpp template <typename T> struct S { S(int); }; import M; int main() { S s(10); // should be S<double> s; } This patch doesn't correctly handle this case yet, we need to also consider cases where only the deduction guide is in purview. Nathaniel
On 7/26/24 12:52 AM, Nathaniel Shead wrote: > On Tue, Jul 23, 2024 at 04:17:22PM -0400, Jason Merrill wrote: >> On 6/15/24 10:29 PM, Nathaniel Shead wrote: >>> Bootstrapped and regtested on x86_64-pc-linux-gnu, OK for trunk? >>> >>> This probably isn't the most efficient approach, since we need to do >>> name lookup to find deduction guides for a type which will also >>> potentially do a bunch of pointless lazy loading from imported modules, >>> but I wasn't able to work out a better approach without completely >>> reworking how deduction guides are stored and represented. >> >> Indeed. We likely want to find them more directly from the template; it's >> not clear to me that DECL_INITIAL is used for TEMPLATE_DECL, or we could put >> them in an internal attribute or a separate hash table. >> >>> -- >8 -- >>> >>> Deduction guides are represented as 'normal' functions currently, and >>> have no special handling in modules. However, this causes some issues; >>> by [temp.deduct.guide] a deduction guide is not found by normal name >>> lookup and instead all reachable deduction guides for a class template >>> should be considered, but this does not happen currently. >>> >>> To solve this, this patch ensures that all deduction guides are >>> considered exported to ensure that they are always visible to importers >>> if they are reachable. Another alternative here would be to add a new >>> kind of "all reachable" flag to name lookup, but that is complicated by >>> some difficulties in handling GM entities; this may be a better way to >>> go if more kinds of entities end up needing this handling, however. >>> >>> Another issue here is that because deduction guides are "unrelated" >>> functions, they will usually get discarded from the GMF, so this patch >>> ensures that when finding dependencies, GMF deduction guides will also >>> have bindings created. We do this in find_dependencies so that we don't >>> unnecessarily create bindings for GMF deduction guides that are never >>> reached; for consistency we do this for *all* deduction guides, not just >>> GM ones. >> >> If you fixed the dependency calculation, why do they also need to be >> exported? > > Deduction guides aren't found using normal name lookup, but any > reachable deduction guide must be considered. This means that even if > the module interface exports no declarations whatsoever, a deduction > guide declared in the module purview must still be considered by > importers. Ah, I was missing the name lookup issue. > The other option I've considered is adding a new "ANY_REACHABLE" flag to > name lookup which would also consider non-exported reachable decls. On > further consideration I might actually go this way; I've been thinking > about how to resolve some issues adjacent to supporting textual > redefinitions that I believe this will be necessary for anyway, and we > can probably use this in tsubst_friend_class as well rather than the > current relatively ad-hoc solution. There's also my hack in lookup_elaborated_type for ABI namespace types. I'm not sure that it should be necessary to do this for redefinitions, though; what's the advantage over merging in check_module_override (apart from that needing to be fixed)? > That said, I've realised that this patch isn't completely sufficient > anyway; consider: > > // m.cpp > module; > template <typename T> struct S; > export module M; > S(int) -> S<double>; > > // x.cpp > template <typename T> struct S { S(int); }; > import M; > int main() { > S s(10); // should be S<double> s; > } > > This patch doesn't correctly handle this case yet, we need to also > consider cases where only the deduction guide is in purview. Indeed. Jason
On Fri, Jul 26, 2024 at 01:17:57PM -0400, Jason Merrill wrote: > On 7/26/24 12:52 AM, Nathaniel Shead wrote: > > On Tue, Jul 23, 2024 at 04:17:22PM -0400, Jason Merrill wrote: > > > On 6/15/24 10:29 PM, Nathaniel Shead wrote: > > > > Bootstrapped and regtested on x86_64-pc-linux-gnu, OK for trunk? > > > > > > > > This probably isn't the most efficient approach, since we need to do > > > > name lookup to find deduction guides for a type which will also > > > > potentially do a bunch of pointless lazy loading from imported modules, > > > > but I wasn't able to work out a better approach without completely > > > > reworking how deduction guides are stored and represented. > > > > > > Indeed. We likely want to find them more directly from the template; it's > > > not clear to me that DECL_INITIAL is used for TEMPLATE_DECL, or we could put > > > them in an internal attribute or a separate hash table. > > > > > > > -- >8 -- > > > > > > > > Deduction guides are represented as 'normal' functions currently, and > > > > have no special handling in modules. However, this causes some issues; > > > > by [temp.deduct.guide] a deduction guide is not found by normal name > > > > lookup and instead all reachable deduction guides for a class template > > > > should be considered, but this does not happen currently. > > > > > > > > To solve this, this patch ensures that all deduction guides are > > > > considered exported to ensure that they are always visible to importers > > > > if they are reachable. Another alternative here would be to add a new > > > > kind of "all reachable" flag to name lookup, but that is complicated by > > > > some difficulties in handling GM entities; this may be a better way to > > > > go if more kinds of entities end up needing this handling, however. > > > > > > > > Another issue here is that because deduction guides are "unrelated" > > > > functions, they will usually get discarded from the GMF, so this patch > > > > ensures that when finding dependencies, GMF deduction guides will also > > > > have bindings created. We do this in find_dependencies so that we don't > > > > unnecessarily create bindings for GMF deduction guides that are never > > > > reached; for consistency we do this for *all* deduction guides, not just > > > > GM ones. > > > > > > If you fixed the dependency calculation, why do they also need to be > > > exported? > > > > Deduction guides aren't found using normal name lookup, but any > > reachable deduction guide must be considered. This means that even if > > the module interface exports no declarations whatsoever, a deduction > > guide declared in the module purview must still be considered by > > importers. > > Ah, I was missing the name lookup issue. > > > The other option I've considered is adding a new "ANY_REACHABLE" flag to > > name lookup which would also consider non-exported reachable decls. On > > further consideration I might actually go this way; I've been thinking > > about how to resolve some issues adjacent to supporting textual > > redefinitions that I believe this will be necessary for anyway, and we > > can probably use this in tsubst_friend_class as well rather than the > > current relatively ad-hoc solution. > > There's also my hack in lookup_elaborated_type for ABI namespace types. > > I'm not sure that it should be necessary to do this for redefinitions, > though; what's the advantage over merging in check_module_override (apart > from that needing to be fixed)? > My thought had been because currently type redefinitions don't go through 'check_module_override' at all, if the existing type name is visible, and so I was thinking to fix it at that end instead. This was also to fix things that aren't strictly redefinitions but also fail currently, e.g. module; template <typename T> struct S; export module M; export S<int> foo(); // declares a specialisation of S // ... import M; template <typename T> struct S {}; // definition of template int main() { foo(); // error: invalid use of incomplete type, because // we don't ever go through redeclare_class_template in xref_tag } But on further thought maybe it would be more consistent to ensure that check_module_override handles this, since I suppose we still need to handle things like the following anyway: export module M; struct S {}; // not exported // ... import M; template <typename T> struct S {}; Though the names correspond ([basic.scope.scope] p4), they don't declare the same entity ([basic.link] p8) since they have different attachment, and they don't potentially conflict ([basic.scope.scope] p6) because S@M doesn't precede the template decl because it's not visible to name lookup. So an "any reachable" flag would be incorrect here regardless. (Personally, I now even wonder whether it'd be make sense to be more consistent here, by type declarations always being a new type that is then merged with an existing one where necessary, rather than xref_tag always returning an existing type if it finds one, which would help with compiler errors in the presence of using-decls and help avoid the duplication of checks for redefining existing names spread across various places in parser.cc, decl.cc, and name-lookup.cc?) > > That said, I've realised that this patch isn't completely sufficient > > anyway; consider: > > > > // m.cpp > > module; > > template <typename T> struct S; > > export module M; > > S(int) -> S<double>; > > > > // x.cpp > > template <typename T> struct S { S(int); }; > > import M; > > int main() { > > S s(10); // should be S<double> s; > > } > > > > This patch doesn't correctly handle this case yet, we need to also > > consider cases where only the deduction guide is in purview. > > Indeed. > > Jason >
diff --git a/gcc/cp/error.cc b/gcc/cp/error.cc index 171a352c85f..2fb5084320e 100644 --- a/gcc/cp/error.cc +++ b/gcc/cp/error.cc @@ -1866,6 +1866,7 @@ dump_function_decl (cxx_pretty_printer *pp, tree t, int flags) dump_type_suffix (pp, ret, flags); else if (deduction_guide_p (t)) { + pp->set_padding (pp_before); pp_cxx_ws_string (pp, "->"); dump_type (pp, TREE_TYPE (TREE_TYPE (t)), flags); } diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc index 6d6044af199..a2c9e151fd5 100644 --- a/gcc/cp/module.cc +++ b/gcc/cp/module.cc @@ -2589,6 +2589,9 @@ public: void add_partial_entities (vec<tree, va_gc> *); void add_class_entities (vec<tree, va_gc> *); + private: + void add_deduction_guides (tree decl); + public: void find_dependencies (module_state *); bool finalize_dependencies (); @@ -13127,6 +13130,11 @@ depset::hash::add_binding_entity (tree decl, WMB_Flags flags, void *data_) { tree inner = decl; + if (deduction_guide_p (inner)) + /* Ignore deduction guides here, they'll be handled within + find_dependencies for a class template. */ + return false; + if (TREE_CODE (inner) == CONST_DECL && TREE_CODE (DECL_CONTEXT (inner)) == ENUMERAL_TYPE) inner = TYPE_NAME (DECL_CONTEXT (inner)); @@ -13590,6 +13598,50 @@ find_pending_key (tree decl, tree *decl_p = nullptr) return ns; } +/* Creates bindings and dependencies for all deduction guides of + the given class template DECL as needed. */ + +void +depset::hash::add_deduction_guides (tree decl) +{ + /* Alias templates never have deduction guides. */ + if (DECL_ALIAS_TEMPLATE_P (decl)) + return; + + /* We don't need to do anything for class-scope deduction guides, + as they will be added as members anyway. */ + if (!DECL_NAMESPACE_SCOPE_P (decl)) + return; + + tree ns = CP_DECL_CONTEXT (decl); + tree name = dguide_name (decl); + + /* We always add all deduction guides with a given name at once, + so if there's already a binding there's nothing to do. */ + if (find_binding (ns, name)) + return; + + tree guides = lookup_qualified_name (ns, name, LOOK_want::NORMAL, + /*complain=*/false); + if (guides == error_mark_node) + return; + + /* We have bindings to add. */ + depset *binding = make_binding (ns, name); + add_namespace_context (binding, ns); + + depset **slot = binding_slot (ns, name, /*insert=*/true); + *slot = binding; + + for (lkp_iterator it (guides); it; ++it) + { + gcc_checking_assert (!TREE_VISITED (*it)); + depset *dep = make_dependency (*it, EK_FOR_BINDING); + binding->deps.safe_push (dep); + dep->deps.safe_push (binding); + } +} + /* Iteratively find dependencies. During the walk we may find more entries on the same binding that need walking. */ @@ -13649,6 +13701,10 @@ depset::hash::find_dependencies (module_state *module) } walker.end (); + if (!walker.is_key_order () + && DECL_CLASS_TEMPLATE_P (decl)) + add_deduction_guides (decl); + if (!walker.is_key_order () && TREE_CODE (decl) == TEMPLATE_DECL && !DECL_UNINSTANTIATED_TEMPLATE_FRIEND_P (decl)) @@ -15145,6 +15201,10 @@ 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 + reachable whenever their class template is. */ + flags |= cbf_export; } gcc_checking_assert (DECL_P (bound)); diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc index 607753ae6b7..8e007a571a5 100644 --- a/gcc/cp/pt.cc +++ b/gcc/cp/pt.cc @@ -30784,7 +30784,7 @@ deduction_guides_for (tree tmpl, bool &any_dguides_p, tsubst_flags_t complain) else { cands = ctor_deduction_guides_for (tmpl, complain); - for (ovl_iterator it (guides); it; ++it) + for (lkp_iterator it (guides); it; ++it) cands = lookup_add (*it, cands); } diff --git a/gcc/testsuite/g++.dg/modules/dguide-1_a.C b/gcc/testsuite/g++.dg/modules/dguide-1_a.C new file mode 100644 index 00000000000..834e033eae3 --- /dev/null +++ b/gcc/testsuite/g++.dg/modules/dguide-1_a.C @@ -0,0 +1,44 @@ +// PR c++/115231 +// { dg-additional-options "-fmodules-ts -Wno-global-module" } +// { dg-module-cmi M } + +module; + +template <typename T> +struct A { + template <typename U> A(U); +}; + +template <typename T> A(T) -> A<T>; + +export module M; + +// Exporting a GMF entity should make the deduction guides reachable. +export using ::A; + + +export template <typename T> +struct B { + template <typename U> B(U); +}; + +// Not exported, but should still be reachable by [temp.deduct.guide] p1. +B(int) -> B<double>; + + +// Class-scope deduction guides should be reachable as well, even if +// the class body was not exported. +export template <typename T> struct C; + +template <typename T> +struct C { + template <typename U> + struct I { + template <typename V> I(V); + }; + + I(int) -> I<int>; + + template <typename P> + I(const P*) -> I<P>; +}; diff --git a/gcc/testsuite/g++.dg/modules/dguide-1_b.C b/gcc/testsuite/g++.dg/modules/dguide-1_b.C new file mode 100644 index 00000000000..97266986d8f --- /dev/null +++ b/gcc/testsuite/g++.dg/modules/dguide-1_b.C @@ -0,0 +1,20 @@ +// PR c++/115231 +// { dg-additional-options "-fmodules-ts" } + +import M; + +int main() { + // Check that deduction guides are reachable, + // and that they declared the right type. + A a(1); + A<int> a2 = a; + + B b(2); + B<double> b2 = b; + + C<int>::I x(10); + C<int>::I<int> x2 = x; + + C<int>::I y("xyz"); + C<int>::I<char> y2 = y; +} diff --git a/gcc/testsuite/g++.dg/modules/dguide-2_a.C b/gcc/testsuite/g++.dg/modules/dguide-2_a.C new file mode 100644 index 00000000000..fcd6c579813 --- /dev/null +++ b/gcc/testsuite/g++.dg/modules/dguide-2_a.C @@ -0,0 +1,24 @@ +// PR c++/115231 +// { dg-additional-options "-fmodules-ts -Wno-global-module" } +// { dg-module-cmi M } + +module; + +template <typename T> +struct A { + template <typename U> A(U); +}; +template <typename T> A(T) -> A<T>; + +export module M; + +template <typename T> +struct B { + template <typename U> B(U); +}; +B(int) -> B<int>; + +// Accessing deduction guides should be possible, +// even if we can't name the type directly. +export A<void> f(); +export B<void> g(); diff --git a/gcc/testsuite/g++.dg/modules/dguide-2_b.C b/gcc/testsuite/g++.dg/modules/dguide-2_b.C new file mode 100644 index 00000000000..ca31306aea3 --- /dev/null +++ b/gcc/testsuite/g++.dg/modules/dguide-2_b.C @@ -0,0 +1,19 @@ +// PR c++/115231 +// { dg-additional-options "-fmodules-ts" } + +import M; + +template <typename> +struct U; + +template <template <typename> typename TT, typename Inner> +struct U<TT<Inner>> { + void go() { + TT t(10); + } +}; + +int main() { + U<decltype(f())>{}.go(); + U<decltype(g())>{}.go(); +} diff --git a/gcc/testsuite/g++.dg/modules/dguide-3_a.C b/gcc/testsuite/g++.dg/modules/dguide-3_a.C new file mode 100644 index 00000000000..33350ce9804 --- /dev/null +++ b/gcc/testsuite/g++.dg/modules/dguide-3_a.C @@ -0,0 +1,10 @@ +// { dg-additional-options "-fmodules-ts" } +// { dg-module-cmi A } + +export module A; + +extern "C++" { + template <typename T> struct S; + S(int) -> S<int>; + S(double) -> S<double>; +} diff --git a/gcc/testsuite/g++.dg/modules/dguide-3_b.C b/gcc/testsuite/g++.dg/modules/dguide-3_b.C new file mode 100644 index 00000000000..d23696c74bd --- /dev/null +++ b/gcc/testsuite/g++.dg/modules/dguide-3_b.C @@ -0,0 +1,10 @@ +// { dg-additional-options "-fmodules-ts" } +// { dg-module-cmi B } + +export module B; + +extern "C++" { + template <typename T> struct S; + S(int) -> S<int>; + S(char) -> S<char>; +} diff --git a/gcc/testsuite/g++.dg/modules/dguide-3_c.C b/gcc/testsuite/g++.dg/modules/dguide-3_c.C new file mode 100644 index 00000000000..39ae8f4aa58 --- /dev/null +++ b/gcc/testsuite/g++.dg/modules/dguide-3_c.C @@ -0,0 +1,22 @@ +// { dg-additional-options "-fmodules-ts" } +// Test merging deduction guides. + +import A; +import B; + +template <typename T> struct S { + template <typename U> S(U); +}; + +int main() { + S x(123); // { dg-bogus "incomplete" "" { xfail *-*-* } } + S<int> x2 = x; + + S y('c'); // { dg-bogus "incomplete" "" { xfail *-*-* } } + S<char> y2 = y; + + S z(0.5); // { dg-bogus "incomplete" "" { xfail *-*-* } } + S<double> z2 = z; +} + +S(char) -> S<double>; // { dg-error "ambiguating" }
Bootstrapped and regtested on x86_64-pc-linux-gnu, OK for trunk? This probably isn't the most efficient approach, since we need to do name lookup to find deduction guides for a type which will also potentially do a bunch of pointless lazy loading from imported modules, but I wasn't able to work out a better approach without completely reworking how deduction guides are stored and represented. This way at least is correct (I believe), and we can maybe revisit this in the future. -- >8 -- Deduction guides are represented as 'normal' functions currently, and have no special handling in modules. However, this causes some issues; by [temp.deduct.guide] a deduction guide is not found by normal name lookup and instead all reachable deduction guides for a class template should be considered, but this does not happen currently. To solve this, this patch ensures that all deduction guides are considered exported to ensure that they are always visible to importers if they are reachable. Another alternative here would be to add a new kind of "all reachable" flag to name lookup, but that is complicated by some difficulties in handling GM entities; this may be a better way to go if more kinds of entities end up needing this handling, however. Another issue here is that because deduction guides are "unrelated" functions, they will usually get discarded from the GMF, so this patch ensures that when finding dependencies, GMF deduction guides will also have bindings created. We do this in find_dependencies so that we don't unnecessarily create bindings for GMF deduction guides that are never reached; for consistency we do this for *all* deduction guides, not just GM ones. Finally, when merging deduction guides from multiple modules, the name lookup code may now return two-dimensional overload sets, so update callers to match. As a small drive-by improvement this patch also updates the error pretty printing code to add a space before the '->' when printing a deduction guide, so we get 'S(int) -> S<int>' instead of 'S(int)-> S<int>'. PR c++/115231 gcc/cp/ChangeLog: * error.cc (dump_function_decl): Add a space before '->' when printing deduction guides. * module.cc (depset::hash::add_binding_entity): Skip deduction guides here. (depset::hash::add_deduction_guides): New. (depset::hash::find_dependencies): Add deduction guide dependencies for a class template. (module_state::write_cluster): Always consider deduction guides as exported. * pt.cc (deduction_guides_for): Use 'lkp_iterator' instead of 'ovl_iterator'. gcc/testsuite/ChangeLog: * g++.dg/modules/dguide-1_a.C: New test. * g++.dg/modules/dguide-1_b.C: New test. * g++.dg/modules/dguide-2_a.C: New test. * g++.dg/modules/dguide-2_b.C: New test. * g++.dg/modules/dguide-3_a.C: New test. * g++.dg/modules/dguide-3_b.C: New test. * g++.dg/modules/dguide-3_c.C: New test. Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com> --- gcc/cp/error.cc | 1 + gcc/cp/module.cc | 60 +++++++++++++++++++++++ gcc/cp/pt.cc | 2 +- gcc/testsuite/g++.dg/modules/dguide-1_a.C | 44 +++++++++++++++++ gcc/testsuite/g++.dg/modules/dguide-1_b.C | 20 ++++++++ gcc/testsuite/g++.dg/modules/dguide-2_a.C | 24 +++++++++ gcc/testsuite/g++.dg/modules/dguide-2_b.C | 19 +++++++ gcc/testsuite/g++.dg/modules/dguide-3_a.C | 10 ++++ gcc/testsuite/g++.dg/modules/dguide-3_b.C | 10 ++++ gcc/testsuite/g++.dg/modules/dguide-3_c.C | 22 +++++++++ 10 files changed, 211 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/g++.dg/modules/dguide-1_a.C create mode 100644 gcc/testsuite/g++.dg/modules/dguide-1_b.C create mode 100644 gcc/testsuite/g++.dg/modules/dguide-2_a.C create mode 100644 gcc/testsuite/g++.dg/modules/dguide-2_b.C create mode 100644 gcc/testsuite/g++.dg/modules/dguide-3_a.C create mode 100644 gcc/testsuite/g++.dg/modules/dguide-3_b.C create mode 100644 gcc/testsuite/g++.dg/modules/dguide-3_c.C