From a5ca022376fcedc2a67988726a9c5f9c84837c1b Mon Sep 17 00:00:00 2001 From: Nathaniel Shead Date: Wed, 17 Jan 2024 16:50:39 +1100 Subject: [PATCH] c++: Fix handling of extern templates in modules [PR112820] Currently, extern templates are detected by looking for the DECL_EXTERNAL flag on a TYPE_DECL. However, this is incorrect: TYPE_DECLs don't actually set this flag, and it happens to work by coincidence due to TYPE_DECL_SUPPRESS_DEBUG happening to use the same underlying bit. This however causes issues with other TYPE_DECLs that also happen to have suppressed debug information. Instead, this patch reworks the logic so CLASSTYPE_INTERFACE_ONLY is always emitted into the module BMI and can then be used to check for an extern template correctly. Otherwise, for other declarations we always want to redetermine this: even for declarations from the GMF, we may change our mind on whether to import or export depending on decisions made later in the TU after importing so we shouldn't decide this now, or necessarily reuse what the module we'd imported had decided. Some of this may need to change in the future to account for https://github.com/itanium-cxx-abi/cxx-abi/issues/170. PR c++/112820 PR c++/102607 gcc/cp/ChangeLog: * module.cc (trees_out::lang_type_bools): Write interface_only and interface_unknown. (trees_in::lang_type_bools): Read the above flags. (trees_in::decl_value): Reset CLASSTYPE_INTERFACE_* except for extern templates. (trees_in::read_class_def): Remove buggy extern template handling. gcc/testsuite/ChangeLog: * g++.dg/modules/debug-2_a.C: New test. * g++.dg/modules/debug-2_b.C: New test. * g++.dg/modules/debug-2_c.C: New test. * g++.dg/modules/debug-3_a.C: New test. * g++.dg/modules/debug-3_b.C: New test. Signed-off-by: Nathaniel Shead --- gcc/cp/module.cc | 37 ++++++++++++++---------- gcc/testsuite/g++.dg/modules/debug-2_a.C | 9 ++++++ gcc/testsuite/g++.dg/modules/debug-2_b.C | 8 +++++ gcc/testsuite/g++.dg/modules/debug-2_c.C | 9 ++++++ gcc/testsuite/g++.dg/modules/debug-3_a.C | 8 +++++ gcc/testsuite/g++.dg/modules/debug-3_b.C | 9 ++++++ 6 files changed, 64 insertions(+), 16 deletions(-) create mode 100644 gcc/testsuite/g++.dg/modules/debug-2_a.C create mode 100644 gcc/testsuite/g++.dg/modules/debug-2_b.C create mode 100644 gcc/testsuite/g++.dg/modules/debug-2_c.C create mode 100644 gcc/testsuite/g++.dg/modules/debug-3_a.C create mode 100644 gcc/testsuite/g++.dg/modules/debug-3_b.C diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc index 8db662c0267..70785493561 100644 --- a/gcc/cp/module.cc +++ b/gcc/cp/module.cc @@ -5806,10 +5806,8 @@ trees_out::lang_type_bools (tree t) WB ((lang->gets_delete >> 0) & 1); WB ((lang->gets_delete >> 1) & 1); - // Interfaceness is recalculated upon reading. May have to revisit? - // How do dllexport and dllimport interact across a module? - // lang->interface_only - // lang->interface_unknown + WB (lang->interface_only); + WB (lang->interface_unknown); WB (lang->contains_empty_class_p); WB (lang->anon_aggr); WB (lang->non_zero_init); @@ -5877,9 +5875,8 @@ trees_in::lang_type_bools (tree t) v = b () << 0; v |= b () << 1; lang->gets_delete = v; - // lang->interface_only - // lang->interface_unknown - lang->interface_unknown = true; // Redetermine interface + RB (lang->interface_only); + RB (lang->interface_unknown); RB (lang->contains_empty_class_p); RB (lang->anon_aggr); RB (lang->non_zero_init); @@ -8246,6 +8243,23 @@ trees_in::decl_value () /* Set the TEMPLATE_DECL's type. */ TREE_TYPE (decl) = TREE_TYPE (inner); + /* Redetermine whether we need to import or export this declaration + for this TU. But for extern templates we know we must import: + they'll be defined in a different TU. + FIXME: How do dllexport and dllimport interact across a module? + See also https://github.com/itanium-cxx-abi/cxx-abi/issues/170. + May have to revisit? */ + if (type + && CLASS_TYPE_P (type) + && TYPE_LANG_SPECIFIC (type) + && !(CLASSTYPE_EXPLICIT_INSTANTIATION (type) + && CLASSTYPE_INTERFACE_KNOWN (type) + && CLASSTYPE_INTERFACE_ONLY (type))) + { + CLASSTYPE_INTERFACE_ONLY (type) = false; + CLASSTYPE_INTERFACE_UNKNOWN (type) = true; + } + /* Add to specialization tables now that constraints etc are added. */ if (mk == MK_partial) @@ -12068,15 +12082,6 @@ trees_in::read_class_def (tree defn, tree maybe_template) bool installing = maybe_dup && !TYPE_SIZE (type); if (installing) { - if (DECL_EXTERNAL (defn) && TYPE_LANG_SPECIFIC (type)) - { - /* We don't deal with not-really-extern, because, for a - module you want the import to be the interface, and for a - header-unit, you're doing it wrong. */ - CLASSTYPE_INTERFACE_UNKNOWN (type) = false; - CLASSTYPE_INTERFACE_ONLY (type) = true; - } - if (maybe_dup != defn) { // FIXME: This is needed on other defns too, almost diff --git a/gcc/testsuite/g++.dg/modules/debug-2_a.C b/gcc/testsuite/g++.dg/modules/debug-2_a.C new file mode 100644 index 00000000000..eed0905542b --- /dev/null +++ b/gcc/testsuite/g++.dg/modules/debug-2_a.C @@ -0,0 +1,9 @@ +// PR c++/112820 +// { dg-additional-options "-fmodules-ts -g" } +// { dg-module-cmi io } + +export module io; + +export struct error { + virtual const char* what() const noexcept; +}; diff --git a/gcc/testsuite/g++.dg/modules/debug-2_b.C b/gcc/testsuite/g++.dg/modules/debug-2_b.C new file mode 100644 index 00000000000..fc9afbc02e0 --- /dev/null +++ b/gcc/testsuite/g++.dg/modules/debug-2_b.C @@ -0,0 +1,8 @@ +// PR c++/112820 +// { dg-additional-options "-fmodules-ts -g" } + +module io; + +const char* error::what() const noexcept { + return "bla"; +} diff --git a/gcc/testsuite/g++.dg/modules/debug-2_c.C b/gcc/testsuite/g++.dg/modules/debug-2_c.C new file mode 100644 index 00000000000..37117f69dcd --- /dev/null +++ b/gcc/testsuite/g++.dg/modules/debug-2_c.C @@ -0,0 +1,9 @@ +// PR c++/112820 +// { dg-module-do link } +// { dg-additional-options "-fmodules-ts -g" } + +import io; + +int main() { + error{}; +} diff --git a/gcc/testsuite/g++.dg/modules/debug-3_a.C b/gcc/testsuite/g++.dg/modules/debug-3_a.C new file mode 100644 index 00000000000..9e33d8260fd --- /dev/null +++ b/gcc/testsuite/g++.dg/modules/debug-3_a.C @@ -0,0 +1,8 @@ +// PR c++/102607 +// { dg-additional-options "-fmodules-ts -g" } +// { dg-module-cmi mod } + +export module mod; +export struct B { + virtual ~B() = default; +}; diff --git a/gcc/testsuite/g++.dg/modules/debug-3_b.C b/gcc/testsuite/g++.dg/modules/debug-3_b.C new file mode 100644 index 00000000000..03c78b71b5d --- /dev/null +++ b/gcc/testsuite/g++.dg/modules/debug-3_b.C @@ -0,0 +1,9 @@ +// PR c++/102607 +// { dg-module-do link } +// { dg-additional-options "-fmodules-ts -g" } + +import mod; +int main() { + struct D : B {}; + (void)D{}; +}