mirror of git://gcc.gnu.org/git/gcc.git
c3f281a0c1
Per https://github.com/itanium-cxx-abi/cxx-abi/issues/24 and https://github.com/itanium-cxx-abi/cxx-abi/pull/166 We need to mangle constraints to be able to distinguish between function templates that only differ in constraints. From the latter link, we want to use the template parameter mangling previously specified for lambdas to also make explicit the form of a template parameter where the argument is not a "natural" fit for it, such as when the parameter is constrained or deduced. I'm concerned about how the latter link changes the mangling for some C++98 and C++11 patterns, so I've limited template_parm_natural_p to avoid two cases found by running the testsuite with -Wabi forced on: template <class T, T V> T f() { return V; } int main() { return f<int,42>(); } template <int i> int max() { return i; } template <int i, int j, int... rest> int max() { int sub = max<j, rest...>(); return i > sub ? i : sub; } int main() { return max<1,2,3>(); } A third C++11 pattern is changed by this patch: template <template <typename...> class TT, typename... Ts> TT<Ts...> f(); template <typename> struct A { }; int main() { f<A,int>(); } I aim to resolve these with the ABI committee before GCC 14.1. We also need to resolve https://github.com/itanium-cxx-abi/cxx-abi/issues/38 (mangling references to dependent template-ids where the name is fully resolved) as references to concepts in std:: will consistently run into this area. This is why mangle-concepts1.C only refers to concepts in the global namespace so far. The library changes are to avoid trying to mangle builtins, which fails. Demangler support and test coverage is not complete yet. gcc/cp/ChangeLog: * cp-tree.h (TEMPLATE_ARGS_TYPE_CONSTRAINT_P): New. (get_concept_check_template): Declare. * constraint.cc (combine_constraint_expressions) (finish_shorthand_constraint): Use UNKNOWN_LOCATION. * pt.cc (convert_generic_types_to_packs): Likewise. * mangle.cc (write_constraint_expression) (write_tparms_constraints, write_type_constraint) (template_parm_natural_p, write_requirement) (write_requires_expr): New. (write_encoding): Mangle trailing requires-clause. (write_name): Pass parms to write_template_args. (write_template_param_decl): Factor out from... (write_closure_template_head): ...here. (write_template_args): Mangle non-natural parms and requires-clause. (write_expression): Handle REQUIRES_EXPR. include/ChangeLog: * demangle.h (enum demangle_component_type): Add DEMANGLE_COMPONENT_CONSTRAINTS. libiberty/ChangeLog: * cp-demangle.c (d_make_comp): Handle DEMANGLE_COMPONENT_CONSTRAINTS. (d_count_templates_scopes): Likewise. (d_print_comp_inner): Likewise. (d_maybe_constraints): New. (d_encoding, d_template_args_1): Call it. (d_parmlist): Handle 'Q'. * testsuite/demangle-expected: Add some constraint tests. libstdc++-v3/ChangeLog: * include/std/bit: Avoid builtins in requires-clauses. * include/std/variant: Likewise. gcc/testsuite/ChangeLog: * g++.dg/abi/mangle10.C: Disable compat aliases. * g++.dg/abi/mangle52.C: Specify ABI 18. * g++.dg/cpp2a/class-deduction-alias3.C * g++.dg/cpp2a/class-deduction-alias8.C: Avoid builtins in requires-clauses. * g++.dg/abi/mangle-concepts1.C: New test. * g++.dg/abi/mangle-ttp1.C: New test. |
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README
file: libstdc++-v3/README New users may wish to point their web browsers to the file index.html in the 'doc/html' subdirectory. It contains brief building instructions and notes on how to configure the library in interesting ways.