Message ID | 65aba461.a70a0220.7fd5c.ad24@mx.google.com |
---|---|
State | New |
Headers | show |
Series | [v3] c++/modules: Emit definitions of ODR-used static members imported from modules [PR112899] | expand |
On 1/20/24 05:45, Nathaniel Shead wrote: > On Fri, Jan 19, 2024 at 01:57:18PM -0500, Patrick Palka wrote: >> On Wed, 3 Jan 2024, Nathaniel Shead wrote: >>> + if (DECL_CONTEXT (decl) >>> + && RECORD_OR_UNION_TYPE_P (DECL_CONTEXT (decl)) >>> + && !DECL_TEMPLATE_INFO (decl)) >>> + note_static_storage_variable (decl); >> >> It seems this should also handle templated inlines via >> >> && (!DECL_TEMPLATE_INFO (decl) >> || DECL_IMPLICIT_INSTANTIATION (decl)) >> >> otherwise the following fails to link: >> >> $ cat init-5_a.H >> template<bool _DecOnly> >> struct __from_chars_alnum_to_val_table { >> static inline int value = 42; >> }; >> >> inline unsigned char >> __from_chars_alnum_to_val() { >> return __from_chars_alnum_to_val_table<false>::value; >> } >> >> $ cat init-6_b.C >> import "init-5_a.H"; >> >> int main() { >> __from_chars_alnum_to_val(); >> } >> >> $ g++ -fmodules-ts -std=c++20 init-5_a.H init-5_b.C >> /usr/bin/ld: /tmp/ccNRaads.o: in function `__from_chars_alnum_to_val()': >> init-6_b.C:(.text._Z25__from_chars_alnum_to_valv[_Z25__from_chars_alnum_to_valv]+0x6): undefined reference to `__from_chars_alnum_to_val_table<false>::value' > > Ah yes, of course, since that's the other context where declarations are > added to 'pending_statics'. > >> By the way I ran into this when testing out std::print with modules: >> >> $ cat std.C >> export module std; >> export import <bits/stdc++.h>; >> >> $ cat hello.C >> import std; >> >> int main() { >> std::print("Hello {}!", "World"); >> } >> >> $ g++ -fmodules-ts -std=c++26 -x c++-system-header bits/stdc++.h >> $ g++ -fmodules-ts -std=c++26 std.C hello.C && ./a.out # before >> /usr/bin/ld: /tmp/ccqNgOM1.o: in function `unsigned char std::__detail::__from_chars_alnum_to_val<false>(unsigned char)': >> hello.C:(.text._ZNSt8__detail25__from_chars_alnum_to_valILb0EEEhh[_ZNSt8__detail25__from_chars_alnum_to_valILb0EEEhh]+0x12): undefined reference to `std::__detail::__from_chars_alnum_to_val_table<false>::value' >> $ g++ -fmodules-ts -std=c++26 std.C hello.C && ./a.out # after >> Hello World! >> >> It's great that this is so close to working! > > That's great! > > Here's a new version of the patch with the above fixed. > I also included > your change to only add class variable templates to 'pending_statics' > (and the normal 'static_decl's for non-class otherwise) as otherwise I > could imagine that they would cause issues with this later too. That seems wrong; the 'static_decls' vec is just for checking that static/inline variables got defined. pending_statics has been used for template instantiations for a long time, for non-module code; let's not mess with that in a modules patch. > I know that there's been discussion about the correct ABI for inline > declarations, but personally I'd like to have this fixed for normal uses > in GCC14 at least, and we can revisit the specific cases where various > kinds of declarations are emitted in stage 1. Makes sense. > P.S. As I go to send this, I wonder if maybe something like > 'note_static_member_variable' would be a clearer choice of name than > 'note_static_storage_variable'? Let's call it note_vague_linkage_variable, to go with _fn just above. > -- >8 -- > > Static data members marked 'inline' should be emitted in TUs where they > are ODR-used. We need to make sure that statics imported from modules > are correctly added to the 'pending_statics' map so that they get > emitted if needed, otherwise the attached testcase fails to link. What about non-member variables marked inline, and non-member variable template instantiations? Jason
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h index d9b14d7c4f5..ac7531c5a73 100644 --- a/gcc/cp/cp-tree.h +++ b/gcc/cp/cp-tree.h @@ -7146,7 +7146,7 @@ extern tree maybe_get_tls_wrapper_call (tree); extern void mark_needed (tree); extern bool decl_needed_p (tree); extern void note_vague_linkage_fn (tree); -extern void note_variable_template_instantiation (tree); +extern void note_static_storage_variable (tree); extern tree build_artificial_parm (tree, tree, tree); extern bool possibly_inlined_p (tree); extern int parm_index (tree); diff --git a/gcc/cp/decl2.cc b/gcc/cp/decl2.cc index 91d4e2e5ea4..5d270bf2cdc 100644 --- a/gcc/cp/decl2.cc +++ b/gcc/cp/decl2.cc @@ -947,10 +947,10 @@ note_vague_linkage_fn (tree decl) vec_safe_push (deferred_fns, decl); } -/* As above, but for variable template instantiations. */ +/* As above, but for variables with static storage duration. */ void -note_variable_template_instantiation (tree decl) +note_static_storage_variable (tree decl) { vec_safe_push (pending_statics, decl); } diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc index 8db662c0267..b68407a3499 100644 --- a/gcc/cp/module.cc +++ b/gcc/cp/module.cc @@ -11775,6 +11775,11 @@ trees_in::read_var_def (tree decl, tree maybe_template) DECL_INITIALIZED_P (decl) = true; if (maybe_dup && DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (maybe_dup)) DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (decl) = true; + if (DECL_CLASS_SCOPE_P (decl) + && !DECL_VTABLE_OR_VTT_P (decl) + && (!DECL_TEMPLATE_INFO (decl) + || DECL_IMPLICIT_INSTANTIATION (decl))) + note_static_storage_variable (decl); } DECL_INITIAL (decl) = init; if (!dyn_init) diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc index f82d018c981..7c38594b82d 100644 --- a/gcc/cp/pt.cc +++ b/gcc/cp/pt.cc @@ -27256,7 +27256,12 @@ instantiate_decl (tree d, bool defer_ok, bool expl_inst_class_mem_p) { set_instantiating_module (d); if (variable_template_p (gen_tmpl)) - note_variable_template_instantiation (d); + { + if (DECL_CLASS_SCOPE_P (d)) + note_static_storage_variable (d); + else + vec_safe_push (static_decls, d); + } instantiate_body (td, args, d, false); } diff --git a/gcc/testsuite/g++.dg/modules/init-4_a.C b/gcc/testsuite/g++.dg/modules/init-4_a.C new file mode 100644 index 00000000000..e0eb97b474e --- /dev/null +++ b/gcc/testsuite/g++.dg/modules/init-4_a.C @@ -0,0 +1,9 @@ +// PR c++/112899 +// { dg-additional-options "-fmodules-ts" } +// { dg-module-cmi M } + +export module M; + +export struct A { + static constexpr int x = -1; +}; diff --git a/gcc/testsuite/g++.dg/modules/init-4_b.C b/gcc/testsuite/g++.dg/modules/init-4_b.C new file mode 100644 index 00000000000..d28017a1d14 --- /dev/null +++ b/gcc/testsuite/g++.dg/modules/init-4_b.C @@ -0,0 +1,11 @@ +// PR c++/112899 +// { dg-module-do run } +// { dg-additional-options "-fmodules-ts" } + +import M; + +int main() { + const int& x = A::x; + if (x != -1) + __builtin_abort(); +} diff --git a/gcc/testsuite/g++.dg/modules/init-6_a.H b/gcc/testsuite/g++.dg/modules/init-6_a.H new file mode 100644 index 00000000000..a48d90d7aa7 --- /dev/null +++ b/gcc/testsuite/g++.dg/modules/init-6_a.H @@ -0,0 +1,12 @@ +// { dg-additional-options "-fmodule-header" } +// { dg-module-cmi {} } + +template <bool _DecOnly> +struct __from_chars_alnum_to_val_table { + static inline int value = 42; +}; + +inline unsigned char +__from_chars_alnum_to_val() { + return __from_chars_alnum_to_val_table<false>::value; +} diff --git a/gcc/testsuite/g++.dg/modules/init-6_b.C b/gcc/testsuite/g++.dg/modules/init-6_b.C new file mode 100644 index 00000000000..6bb0e83c3ac --- /dev/null +++ b/gcc/testsuite/g++.dg/modules/init-6_b.C @@ -0,0 +1,8 @@ +// { dg-module-do link } +// { dg-additional-options "-fmodules-ts" } + +import "init-6_a.H"; + +int main() { + __from_chars_alnum_to_val(); +}