Hi Jakub, On Tue, Feb 11, 2025 at 07:04:31PM +0100, Jakub Jelinek wrote: > The following testcase IMO in violation of the P2552R3 paper doesn't > pedwarn on alignas applying to dependent types or alignas with dependent > argument. > > tsubst was just ignoring TYPE_ATTRIBUTES. > > The following patch fixes it for the POINTER/REFERENCE_TYPE and > ARRAY_TYPE cases, but perhaps we need to do the same also for other > types (INTEGER_TYPE/REAL_TYPE and the like). I guess I'll need to > construct more testcases. > > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? > > 2025-02-11 Jakub Jelinek <ja...@redhat.com> > > PR c++/118787 > * pt.cc (tsubst) <case ARRAY_TYPE>: Use return t; only if it doesn't > have any TYPE_ATTRIBUTES. Call apply_late_template_attributes. > <case POINTER_TYPE, case REFERENCE_TYPE>: Likewise. Formatting fix. > > * g++.dg/cpp0x/alignas22.C: New test.
This seems to have broken the gcc-fedora-mingw build: https://builder.sourceware.org/buildbot/#/builders/262/builds/11014 In file included from /home/builder/shared/bb2-1/worker/gcc-fedora-mingw/gcc-build/x86_64-w64-mingw32/libstdc++-v3/include/bits/basic_string.h:4230, from /home/builder/shared/bb2-1/worker/gcc-fedora-mingw/gcc-build/x86_64-w64-mingw32/libstdc++-v3/include/string:56, from /home/builder/shared/bb2-1/worker/gcc-fedora-mingw/gcc-build/x86_64-w64-mingw32/libstdc++-v3/include/bits/locale_classes.h:42, from /home/builder/shared/bb2-1/worker/gcc-fedora-mingw/gcc-build/x86_64-w64-mingw32/libstdc++-v3/include/codecvt:42, from ../../../../../gcc/libstdc++-v3/src/c++11/codecvt.cc:25: /home/builder/shared/bb2-1/worker/gcc-fedora-mingw/gcc-build/x86_64-w64-mingw32/libstdc++-v3/include/ext/string_conversions.h: In substitution of 'template<class _String, class _CharT> _String __gnu_cxx::__to_xstring(int (*)(_CharT*, std::size_t, const _CharT*, char*), std::size_t, const _CharT*, ...) [with _String = std::__cxx11::basic_string<char>; _CharT = char]': /home/builder/shared/bb2-1/worker/gcc-fedora-mingw/gcc-build/x86_64-w64-mingw32/libstdc++-v3/include/bits/basic_string.h:4483:43: required from here 4483 | return __gnu_cxx::__to_xstring<string>(&std::vsnprintf, __n, | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~ 4484 | "%f", __val); | ~~~~~~~~~~~~ /home/builder/shared/bb2-1/worker/gcc-fedora-mingw/gcc-build/x86_64-w64-mingw32/libstdc++-v3/include/ext/string_conversions.h:103:5: internal compiler error: in apply_late_template_attributes, at cp/pt.cc:12403 103 | __to_xstring(int (*__convf) (_CharT*, std::size_t, const _CharT*, | ^~~~~~~~~~~~ 0x2529c91 internal_error(char const*, ...) ../../gcc/gcc/diagnostic-global-context.cc:517 0x715e09 fancy_abort(char const*, int, char const*) ../../gcc/gcc/diagnostic.cc:1722 0x4a4034 apply_late_template_attributes ../../gcc/gcc/cp/pt.cc:12403 0x95be8d tsubst(tree_node*, tree_node*, int, tree_node*) ../../gcc/gcc/cp/pt.cc:16951 0x9741c4 tsubst_arg_types ../../gcc/gcc/cp/pt.cc:16022 0x9740e9 tsubst_arg_types ../../gcc/gcc/cp/pt.cc:15999 0x9740e9 tsubst_arg_types ../../gcc/gcc/cp/pt.cc:16058 0x9740e9 tsubst_arg_types ../../gcc/gcc/cp/pt.cc:15999 0x9740e9 tsubst_arg_types ../../gcc/gcc/cp/pt.cc:16058 0x9740e9 tsubst_arg_types ../../gcc/gcc/cp/pt.cc:15999 0x9740e9 tsubst_arg_types ../../gcc/gcc/cp/pt.cc:16058 0x974561 tsubst_arg_types ../../gcc/gcc/cp/pt.cc:15999 0x974561 tsubst_function_type ../../gcc/gcc/cp/pt.cc:16176 0x95bd6a tsubst(tree_node*, tree_node*, int, tree_node*) ../../gcc/gcc/cp/pt.cc:17009 0x95afd7 tsubst(tree_node*, tree_node*, int, tree_node*) ../../gcc/gcc/cp/pt.cc:16521 0x9741c4 tsubst_arg_types ../../gcc/gcc/cp/pt.cc:16022 0x974561 tsubst_arg_types ../../gcc/gcc/cp/pt.cc:15999 0x974561 tsubst_function_type ../../gcc/gcc/cp/pt.cc:16176 0x95bd6a tsubst(tree_node*, tree_node*, int, tree_node*) ../../gcc/gcc/cp/pt.cc:17009 0x96a866 tsubst_function_decl ../../gcc/gcc/cp/pt.cc:14834 Please submit a full bug report, with preprocessed source (by using -freport-bug). Please include the complete backtrace with any bug report. See <https://gcc.gnu.org/bugs/> for instructions. make[5]: *** [Makefile:883: codecvt.lo] Error 1 > --- gcc/cp/pt.cc.jj 2025-02-07 17:03:13.560227281 +0100 > +++ gcc/cp/pt.cc 2025-02-10 17:17:47.651313333 +0100 > @@ -16854,7 +16854,9 @@ tsubst (tree t, tree args, tsubst_flags_ > case POINTER_TYPE: > case REFERENCE_TYPE: > { > - if (type == TREE_TYPE (t) && TREE_CODE (type) != METHOD_TYPE) > + if (type == TREE_TYPE (t) > + && TREE_CODE (type) != METHOD_TYPE > + && TYPE_ATTRIBUTES (t) == NULL_TREE) > return t; > > /* [temp.deduct] > @@ -16924,9 +16926,9 @@ tsubst (tree t, tree args, tsubst_flags_ > A,' while an attempt to create the type type rvalue reference to > cv T' creates the type T" > */ > - r = cp_build_reference_type > - (TREE_TYPE (type), > - TYPE_REF_IS_RVALUE (t) && TYPE_REF_IS_RVALUE (type)); > + r = cp_build_reference_type (TREE_TYPE (type), > + TYPE_REF_IS_RVALUE (t) > + && TYPE_REF_IS_RVALUE (type)); > else > r = cp_build_reference_type (type, TYPE_REF_IS_RVALUE (t)); > r = cp_build_qualified_type (r, cp_type_quals (t), complain); > @@ -16935,6 +16937,11 @@ tsubst (tree t, tree args, tsubst_flags_ > /* Will this ever be needed for TYPE_..._TO values? */ > layout_type (r); > > + if (!apply_late_template_attributes (&r, TYPE_ATTRIBUTES (t), > + /*flags=*/0, > + args, complain, in_decl)) > + return error_mark_node; > + > return r; > } > case OFFSET_TYPE: > @@ -17009,7 +17016,9 @@ tsubst (tree t, tree args, tsubst_flags_ > > /* As an optimization, we avoid regenerating the array type if > it will obviously be the same as T. */ > - if (type == TREE_TYPE (t) && domain == TYPE_DOMAIN (t)) > + if (type == TREE_TYPE (t) > + && domain == TYPE_DOMAIN (t) > + && TYPE_ATTRIBUTES (t) == NULL_TREE) > return t; > > /* These checks should match the ones in create_array_type_for_decl. > @@ -17048,6 +17057,11 @@ tsubst (tree t, tree args, tsubst_flags_ > TYPE_USER_ALIGN (r) = 1; > } > > + if (!apply_late_template_attributes (&r, TYPE_ATTRIBUTES (t), > + /*flags=*/0, > + args, complain, in_decl)) > + return error_mark_node; > + > return r; > } > > --- gcc/testsuite/g++.dg/cpp0x/alignas22.C.jj 2025-02-10 17:33:16.242452750 > +0100 > +++ gcc/testsuite/g++.dg/cpp0x/alignas22.C 2025-02-10 17:36:28.739046629 > +0100 > @@ -0,0 +1,23 @@ > +// PR c++/118787 > +// { dg-do compile { target c++11 } } > +// { dg-options "-pedantic" } > + > +template <typename T, int N> > +void foo (T & alignas (N)); // { dg-warning "'alignas' on a type > other than class" } > +template <typename T, int N> > +void bar (T (&)[N] alignas (N)); // { dg-warning "'alignas' on a type > other than class" } > +template <typename T, int N> > +using U = T * alignas (N); // { dg-warning "'alignas' on a type > other than class" } > +template <typename T, int N> > +using V = T[N] alignas (N); // { dg-warning "'alignas' on a type > other than class" } > + > +void > +baz () > +{ > + int x alignas (4) = 0; > + foo <int, 4> (x); > + int y alignas (4) [4]; > + bar <int, 4> (y); > + U <int, 4> u; > + V <int, 4> v; > +} > > Jakub >
