/* Handle parameterized types (templates) for GNU -*- C++ -*-. Copyright (C) 1992-2022 Free Software Foundation, Inc. Written by Ken Raeburn (raeburn@cygnus.com) while at Watchmaker Computing. Rewritten by Jason Merrill (jason@cygnus.com). This file is part of GCC. GCC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version. GCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GCC; see the file COPYING3. If not see . */ /* Known bugs or deficiencies include: all methods must be provided in header files; can't use a source file that contains only the method templates and "just win". Fixed by: C++20 modules. */ #include "config.h" #include "system.h" #include "coretypes.h" #include "cp-tree.h" #include "timevar.h" #include "stringpool.h" #include "varasm.h" #include "attribs.h" #include "stor-layout.h" #include "intl.h" #include "c-family/c-objc.h" #include "cp-objcp-common.h" #include "toplev.h" #include "tree-iterator.h" #include "type-utils.h" #include "gimplify.h" #include "gcc-rich-location.h" #include "selftest.h" #include "target.h" /* The type of functions taking a tree, and some additional data, and returning an int. */ typedef int (*tree_fn_t) (tree, void*); /* The PENDING_TEMPLATES is a list of templates whose instantiations have been deferred, either because their definitions were not yet available, or because we were putting off doing the work. */ struct GTY ((chain_next ("%h.next"))) pending_template { struct pending_template *next; struct tinst_level *tinst; }; static GTY(()) struct pending_template *pending_templates; static GTY(()) struct pending_template *last_pending_template; int processing_template_parmlist; static int template_header_count; static vec inline_parm_levels; static GTY(()) struct tinst_level *current_tinst_level; static GTY(()) vec *saved_access_scope; /* Live only within one (recursive) call to tsubst_expr. We use this to pass the statement expression node from the STMT_EXPR to the EXPR_STMT that is its result. */ static tree cur_stmt_expr; // -------------------------------------------------------------------------- // // Local Specialization Stack // // Implementation of the RAII helper for creating new local // specializations. local_specialization_stack::local_specialization_stack (lss_policy policy) : saved (local_specializations) { if (policy == lss_nop) ; else if (policy == lss_blank || !saved) local_specializations = new hash_map; else local_specializations = new hash_map(*saved); } local_specialization_stack::~local_specialization_stack () { if (local_specializations != saved) { delete local_specializations; local_specializations = saved; } } /* True if we've recursed into fn_type_unification too many times. */ static bool excessive_deduction_depth; struct spec_hasher : ggc_ptr_hash { static hashval_t hash (spec_entry *); static bool equal (spec_entry *, spec_entry *); }; /* The general template is not in these tables. */ typedef hash_table spec_hash_table; static GTY (()) spec_hash_table *decl_specializations; static GTY (()) spec_hash_table *type_specializations; /* Contains canonical template parameter types. The vector is indexed by the TEMPLATE_TYPE_IDX of the template parameter. Each element is a TREE_LIST, whose TREE_VALUEs contain the canonical template parameters of various types and levels. */ static GTY(()) vec *canonical_template_parms; #define UNIFY_ALLOW_NONE 0 #define UNIFY_ALLOW_MORE_CV_QUAL 1 #define UNIFY_ALLOW_LESS_CV_QUAL 2 #define UNIFY_ALLOW_DERIVED 4 #define UNIFY_ALLOW_INTEGER 8 #define UNIFY_ALLOW_OUTER_LEVEL 16 #define UNIFY_ALLOW_OUTER_MORE_CV_QUAL 32 #define UNIFY_ALLOW_OUTER_LESS_CV_QUAL 64 enum template_base_result { tbr_incomplete_type, tbr_ambiguous_baseclass, tbr_success }; static bool resolve_overloaded_unification (tree, tree, tree, tree, unification_kind_t, int, bool); static int try_one_overload (tree, tree, tree, tree, tree, unification_kind_t, int, bool, bool); static int unify (tree, tree, tree, tree, int, bool); static void add_pending_template (tree); static tree reopen_tinst_level (struct tinst_level *); static tree tsubst_initializer_list (tree, tree); static tree get_partial_spec_bindings (tree, tree, tree); static tree coerce_template_parms (tree, tree, tree, tsubst_flags_t, bool, bool); static tree coerce_innermost_template_parms (tree, tree, tree, tsubst_flags_t, bool, bool); static void tsubst_enum (tree, tree, tree); static bool check_instantiated_args (tree, tree, tsubst_flags_t); static int check_non_deducible_conversion (tree, tree, int, int, struct conversion **, bool); static int maybe_adjust_types_for_deduction (tree, unification_kind_t, tree*, tree*, tree); static int type_unification_real (tree, tree, tree, const tree *, unsigned int, int, unification_kind_t, vec **, bool); static void note_template_header (int); static tree convert_nontype_argument_function (tree, tree, tsubst_flags_t); static tree convert_nontype_argument (tree, tree, tsubst_flags_t); static tree convert_template_argument (tree, tree, tree, tsubst_flags_t, int, tree); static tree for_each_template_parm (tree, tree_fn_t, void*, hash_set *, bool, tree_fn_t = NULL); static tree expand_template_argument_pack (tree); static tree build_template_parm_index (int, int, int, tree, tree); static bool inline_needs_template_parms (tree, bool); static void push_inline_template_parms_recursive (tree, int); static tree reduce_template_parm_level (tree, tree, int, tree, tsubst_flags_t); static int mark_template_parm (tree, void *); static int template_parm_this_level_p (tree, void *); static tree tsubst_friend_function (tree, tree); static tree tsubst_friend_class (tree, tree); static int can_complete_type_without_circularity (tree); static tree get_bindings (tree, tree, tree, bool); static int template_decl_level (tree); static int check_cv_quals_for_unify (int, tree, tree); static int unify_pack_expansion (tree, tree, tree, tree, unification_kind_t, bool, bool); static tree copy_template_args (tree); static tree tsubst_template_parms (tree, tree, tsubst_flags_t); tree most_specialized_partial_spec (tree, tsubst_flags_t); static tree tsubst_aggr_type (tree, tree, tsubst_flags_t, tree, int); static tree tsubst_arg_types (tree, tree, tree, tsubst_flags_t, tree); static tree tsubst_function_type (tree, tree, tsubst_flags_t, tree); static bool check_specialization_scope (void); static tree process_partial_specialization (tree); static enum template_base_result get_template_base (tree, tree, tree, tree, bool , tree *); static tree try_class_unification (tree, tree, tree, tree, bool); static bool class_nttp_const_wrapper_p (tree t); static int coerce_template_template_parms (tree, tree, tsubst_flags_t, tree, tree); static bool template_template_parm_bindings_ok_p (tree, tree); static void tsubst_default_arguments (tree, tsubst_flags_t); static tree for_each_template_parm_r (tree *, int *, void *); static tree copy_default_args_to_explicit_spec_1 (tree, tree); static void copy_default_args_to_explicit_spec (tree); static bool invalid_nontype_parm_type_p (tree, tsubst_flags_t); static bool dependent_template_arg_p (tree); static bool any_template_arguments_need_structural_equality_p (tree); static bool dependent_type_p_r (tree); static tree tsubst_copy (tree, tree, tsubst_flags_t, tree); static tree tsubst_decl (tree, tree, tsubst_flags_t); static void perform_instantiation_time_access_checks (tree, tree); static tree listify (tree); static tree listify_autos (tree, tree); static tree tsubst_template_parm (tree, tree, tsubst_flags_t); static tree instantiate_alias_template (tree, tree, tsubst_flags_t); static bool complex_alias_template_p (const_tree tmpl); static tree get_underlying_template (tree); static tree tsubst_attributes (tree, tree, tsubst_flags_t, tree); static tree canonicalize_expr_argument (tree, tsubst_flags_t); static tree make_argument_pack (tree); static void register_parameter_specializations (tree, tree); static tree enclosing_instantiation_of (tree tctx); static void instantiate_body (tree pattern, tree args, tree d, bool nested); /* Make the current scope suitable for access checking when we are processing T. T can be FUNCTION_DECL for instantiated function template, VAR_DECL for static member variable, or TYPE_DECL for for a class or alias template (needed by instantiate_decl). */ void push_access_scope (tree t) { gcc_assert (VAR_OR_FUNCTION_DECL_P (t) || TREE_CODE (t) == TYPE_DECL); if (DECL_FRIEND_CONTEXT (t)) push_nested_class (DECL_FRIEND_CONTEXT (t)); else if (DECL_IMPLICIT_TYPEDEF_P (t) && CLASS_TYPE_P (TREE_TYPE (t))) push_nested_class (TREE_TYPE (t)); else if (DECL_CLASS_SCOPE_P (t)) push_nested_class (DECL_CONTEXT (t)); else if (deduction_guide_p (t) && DECL_ARTIFICIAL (t)) /* An artificial deduction guide should have the same access as the constructor. */ push_nested_class (TREE_TYPE (TREE_TYPE (t))); else push_to_top_level (); if (TREE_CODE (t) == FUNCTION_DECL) { vec_safe_push (saved_access_scope, current_function_decl); current_function_decl = t; } } /* Restore the scope set up by push_access_scope. T is the node we are processing. */ void pop_access_scope (tree t) { if (TREE_CODE (t) == FUNCTION_DECL) current_function_decl = saved_access_scope->pop(); if (DECL_FRIEND_CONTEXT (t) || (DECL_IMPLICIT_TYPEDEF_P (t) && CLASS_TYPE_P (TREE_TYPE (t))) || DECL_CLASS_SCOPE_P (t) || (deduction_guide_p (t) && DECL_ARTIFICIAL (t))) pop_nested_class (); else pop_from_top_level (); } /* Do any processing required when DECL (a member template declaration) is finished. Returns the TEMPLATE_DECL corresponding to DECL, unless it is a specialization, in which case the DECL itself is returned. */ tree finish_member_template_decl (tree decl) { if (decl == error_mark_node) return error_mark_node; gcc_assert (DECL_P (decl)); if (TREE_CODE (decl) == TYPE_DECL) { tree type; type = TREE_TYPE (decl); if (type == error_mark_node) return error_mark_node; if (MAYBE_CLASS_TYPE_P (type) && CLASSTYPE_TEMPLATE_INFO (type) && !CLASSTYPE_TEMPLATE_SPECIALIZATION (type)) { tree tmpl = CLASSTYPE_TI_TEMPLATE (type); check_member_template (tmpl); return tmpl; } return NULL_TREE; } else if (TREE_CODE (decl) == FIELD_DECL) error_at (DECL_SOURCE_LOCATION (decl), "data member %qD cannot be a member template", decl); else if (DECL_TEMPLATE_INFO (decl)) { if (!DECL_TEMPLATE_SPECIALIZATION (decl)) { check_member_template (DECL_TI_TEMPLATE (decl)); return DECL_TI_TEMPLATE (decl); } else return decl; } else error_at (DECL_SOURCE_LOCATION (decl), "invalid member template declaration %qD", decl); return error_mark_node; } /* Create a template info node. */ tree build_template_info (tree template_decl, tree template_args) { tree result = make_node (TEMPLATE_INFO); TI_TEMPLATE (result) = template_decl; TI_ARGS (result) = template_args; return result; } /* Return the template info node corresponding to T, whatever T is. */ tree get_template_info (const_tree t) { tree tinfo = NULL_TREE; if (!t || t == error_mark_node) return NULL; if (TREE_CODE (t) == NAMESPACE_DECL || TREE_CODE (t) == PARM_DECL) return NULL; if (DECL_P (t) && DECL_LANG_SPECIFIC (t)) tinfo = DECL_TEMPLATE_INFO (t); if (!tinfo && DECL_IMPLICIT_TYPEDEF_P (t)) t = TREE_TYPE (t); if (OVERLOAD_TYPE_P (t)) tinfo = TYPE_TEMPLATE_INFO (t); else if (TREE_CODE (t) == BOUND_TEMPLATE_TEMPLATE_PARM) tinfo = TEMPLATE_TEMPLATE_PARM_TEMPLATE_INFO (t); return tinfo; } /* Returns the template nesting level of the indicated class TYPE. For example, in: template struct A { template struct B {}; }; A::B has depth two, while A has depth one. Both A::B and A::B have depth one, if they are instantiations, not specializations. This function is guaranteed to return 0 if passed NULL_TREE so that, for example, `template_class_depth (current_class_type)' is always safe. */ int template_class_depth (tree type) { int depth; for (depth = 0; type && TREE_CODE (type) != NAMESPACE_DECL; ) { tree tinfo = get_template_info (type); if (tinfo && PRIMARY_TEMPLATE_P (TI_TEMPLATE (tinfo)) && uses_template_parms (INNERMOST_TEMPLATE_ARGS (TI_ARGS (tinfo)))) ++depth; if (DECL_P (type)) { if (tree fctx = DECL_FRIEND_CONTEXT (type)) type = fctx; else type = CP_DECL_CONTEXT (type); } else if (LAMBDA_TYPE_P (type) && LAMBDA_TYPE_EXTRA_SCOPE (type)) type = LAMBDA_TYPE_EXTRA_SCOPE (type); else type = CP_TYPE_CONTEXT (type); } return depth; } /* Return TRUE if NODE instantiates a template that has arguments of its own, be it directly a primary template or indirectly through a partial specializations. */ static bool instantiates_primary_template_p (tree node) { tree tinfo = get_template_info (node); if (!tinfo) return false; tree tmpl = TI_TEMPLATE (tinfo); if (PRIMARY_TEMPLATE_P (tmpl)) return true; if (!DECL_TEMPLATE_SPECIALIZATION (tmpl)) return false; /* So now we know we have a specialization, but it could be a full or a partial specialization. To tell which, compare the depth of its template arguments with those of its context. */ tree ctxt = DECL_CONTEXT (tmpl); tree ctinfo = get_template_info (ctxt); if (!ctinfo) return true; return (TMPL_ARGS_DEPTH (TI_ARGS (tinfo)) > TMPL_ARGS_DEPTH (TI_ARGS (ctinfo))); } /* Subroutine of maybe_begin_member_template_processing. Returns true if processing DECL needs us to push template parms. */ static bool inline_needs_template_parms (tree decl, bool nsdmi) { if (!decl || (!nsdmi && ! DECL_TEMPLATE_INFO (decl))) return false; return (TMPL_PARMS_DEPTH (DECL_TEMPLATE_PARMS (most_general_template (decl))) > (current_template_depth + DECL_TEMPLATE_SPECIALIZATION (decl))); } /* Subroutine of maybe_begin_member_template_processing. Push the template parms in PARMS, starting from LEVELS steps into the chain, and ending at the beginning, since template parms are listed innermost first. */ static void push_inline_template_parms_recursive (tree parmlist, int levels) { tree parms = TREE_VALUE (parmlist); int i; if (levels > 1) push_inline_template_parms_recursive (TREE_CHAIN (parmlist), levels - 1); ++processing_template_decl; current_template_parms = tree_cons (size_int (current_template_depth + 1), parms, current_template_parms); TEMPLATE_PARMS_FOR_INLINE (current_template_parms) = 1; begin_scope (TREE_VEC_LENGTH (parms) ? sk_template_parms : sk_template_spec, NULL); for (i = 0; i < TREE_VEC_LENGTH (parms); ++i) { tree parm = TREE_VALUE (TREE_VEC_ELT (parms, i)); if (error_operand_p (parm)) continue; gcc_assert (DECL_P (parm)); switch (TREE_CODE (parm)) { case TYPE_DECL: case TEMPLATE_DECL: pushdecl (parm); break; case PARM_DECL: /* Push the CONST_DECL. */ pushdecl (TEMPLATE_PARM_DECL (DECL_INITIAL (parm))); break; default: gcc_unreachable (); } } } /* Restore the template parameter context for a member template, a friend template defined in a class definition, or a non-template member of template class. */ void maybe_begin_member_template_processing (tree decl) { tree parms; int levels = 0; bool nsdmi = TREE_CODE (decl) == FIELD_DECL; if (nsdmi) { tree ctx = DECL_CONTEXT (decl); decl = (CLASSTYPE_TEMPLATE_INFO (ctx) /* Disregard full specializations (c++/60999). */ && uses_template_parms (ctx) ? CLASSTYPE_TI_TEMPLATE (ctx) : NULL_TREE); } if (inline_needs_template_parms (decl, nsdmi)) { parms = DECL_TEMPLATE_PARMS (most_general_template (decl)); levels = TMPL_PARMS_DEPTH (parms) - current_template_depth; if (DECL_TEMPLATE_SPECIALIZATION (decl)) { --levels; parms = TREE_CHAIN (parms); } push_inline_template_parms_recursive (parms, levels); } /* Remember how many levels of template parameters we pushed so that we can pop them later. */ inline_parm_levels.safe_push (levels); } /* Undo the effects of maybe_begin_member_template_processing. */ void maybe_end_member_template_processing (void) { int i; int last; if (inline_parm_levels.length () == 0) return; last = inline_parm_levels.pop (); for (i = 0; i < last; ++i) { --processing_template_decl; current_template_parms = TREE_CHAIN (current_template_parms); poplevel (0, 0, 0); } } /* Return a new template argument vector which contains all of ARGS, but has as its innermost set of arguments the EXTRA_ARGS. */ tree add_to_template_args (tree args, tree extra_args) { tree new_args; int extra_depth; int i; int j; if (args == NULL_TREE || extra_args == error_mark_node) return extra_args; extra_depth = TMPL_ARGS_DEPTH (extra_args); new_args = make_tree_vec (TMPL_ARGS_DEPTH (args) + extra_depth); for (i = 1; i <= TMPL_ARGS_DEPTH (args); ++i) SET_TMPL_ARGS_LEVEL (new_args, i, TMPL_ARGS_LEVEL (args, i)); for (j = 1; j <= extra_depth; ++j, ++i) SET_TMPL_ARGS_LEVEL (new_args, i, TMPL_ARGS_LEVEL (extra_args, j)); return new_args; } /* Like add_to_template_args, but only the outermost ARGS are added to the EXTRA_ARGS. In particular, all but TMPL_ARGS_DEPTH (EXTRA_ARGS) levels are added. This function is used to combine the template arguments from a partial instantiation with the template arguments used to attain the full instantiation from the partial instantiation. If ARGS is a TEMPLATE_DECL, use its parameters as args. */ tree add_outermost_template_args (tree args, tree extra_args) { tree new_args; if (!args) return extra_args; if (TREE_CODE (args) == TEMPLATE_DECL) { tree ti = get_template_info (DECL_TEMPLATE_RESULT (args)); args = TI_ARGS (ti); } /* If there are more levels of EXTRA_ARGS than there are ARGS, something very fishy is going on. */ gcc_assert (TMPL_ARGS_DEPTH (args) >= TMPL_ARGS_DEPTH (extra_args)); /* If *all* the new arguments will be the EXTRA_ARGS, just return them. */ if (TMPL_ARGS_DEPTH (args) == TMPL_ARGS_DEPTH (extra_args)) return extra_args; /* For the moment, we make ARGS look like it contains fewer levels. */ TREE_VEC_LENGTH (args) -= TMPL_ARGS_DEPTH (extra_args); new_args = add_to_template_args (args, extra_args); /* Now, we restore ARGS to its full dimensions. */ TREE_VEC_LENGTH (args) += TMPL_ARGS_DEPTH (extra_args); return new_args; } /* Return the N levels of innermost template arguments from the ARGS. */ tree get_innermost_template_args (tree args, int n) { tree new_args; int extra_levels; int i; gcc_assert (n >= 0); /* If N is 1, just return the innermost set of template arguments. */ if (n == 1) return TMPL_ARGS_LEVEL (args, TMPL_ARGS_DEPTH (args)); /* If we're not removing anything, just return the arguments we were given. */ extra_levels = TMPL_ARGS_DEPTH (args) - n; gcc_assert (extra_levels >= 0); if (extra_levels == 0) return args; /* Make a new set of arguments, not containing the outer arguments. */ new_args = make_tree_vec (n); for (i = 1; i <= n; ++i) SET_TMPL_ARGS_LEVEL (new_args, i, TMPL_ARGS_LEVEL (args, i + extra_levels)); return new_args; } /* The inverse of get_innermost_template_args: Return all but the innermost EXTRA_LEVELS levels of template arguments from the ARGS. */ static tree strip_innermost_template_args (tree args, int extra_levels) { tree new_args; int n = TMPL_ARGS_DEPTH (args) - extra_levels; int i; gcc_assert (n >= 0); /* If N is 1, just return the outermost set of template arguments. */ if (n == 1) return TMPL_ARGS_LEVEL (args, 1); /* If we're not removing anything, just return the arguments we were given. */ gcc_assert (extra_levels >= 0); if (extra_levels == 0) return args; /* Make a new set of arguments, not containing the inner arguments. */ new_args = make_tree_vec (n); for (i = 1; i <= n; ++i) SET_TMPL_ARGS_LEVEL (new_args, i, TMPL_ARGS_LEVEL (args, i)); return new_args; } /* We've got a template header coming up; push to a new level for storing the parms. */ void begin_template_parm_list (void) { /* We use a non-tag-transparent scope here, which causes pushtag to put tags in this scope, rather than in the enclosing class or namespace scope. This is the right thing, since we want TEMPLATE_DECLS, and not TYPE_DECLS for template classes. For a global template class, push_template_decl handles putting the TEMPLATE_DECL into top-level scope. For a nested template class, e.g.: template struct S1 { template struct S2 {}; }; pushtag contains special code to insert the TEMPLATE_DECL for S2 at the right scope. */ begin_scope (sk_template_parms, NULL); ++processing_template_decl; ++processing_template_parmlist; note_template_header (0); /* Add a dummy parameter level while we process the parameter list. */ current_template_parms = tree_cons (size_int (current_template_depth + 1), make_tree_vec (0), current_template_parms); } /* This routine is called when a specialization is declared. If it is invalid to declare a specialization here, an error is reported and false is returned, otherwise this routine will return true. */ static bool check_specialization_scope (void) { tree scope = current_scope (); /* [temp.expl.spec] An explicit specialization shall be declared in the namespace of which the template is a member, or, for member templates, in the namespace of which the enclosing class or enclosing class template is a member. An explicit specialization of a member function, member class or static data member of a class template shall be declared in the namespace of which the class template is a member. */ if (scope && TREE_CODE (scope) != NAMESPACE_DECL) { error ("explicit specialization in non-namespace scope %qD", scope); return false; } /* [temp.expl.spec] In an explicit specialization declaration for a member of a class template or a member template that appears in namespace scope, the member template and some of its enclosing class templates may remain unspecialized, except that the declaration shall not explicitly specialize a class member template if its enclosing class templates are not explicitly specialized as well. */ if (current_template_parms) { error ("enclosing class templates are not explicitly specialized"); return false; } return true; } /* We've just seen template <>. */ bool begin_specialization (void) { begin_scope (sk_template_spec, NULL); note_template_header (1); return check_specialization_scope (); } /* Called at then end of processing a declaration preceded by template<>. */ void end_specialization (void) { finish_scope (); reset_specialization (); } /* Any template <>'s that we have seen thus far are not referring to a function specialization. */ void reset_specialization (void) { processing_specialization = 0; template_header_count = 0; } /* We've just seen a template header. If SPECIALIZATION is nonzero, it was of the form template <>. */ static void note_template_header (int specialization) { processing_specialization = specialization; template_header_count++; } /* We're beginning an explicit instantiation. */ void begin_explicit_instantiation (void) { gcc_assert (!processing_explicit_instantiation); processing_explicit_instantiation = true; } void end_explicit_instantiation (void) { gcc_assert (processing_explicit_instantiation); processing_explicit_instantiation = false; } /* An explicit specialization or partial specialization of TMPL is being declared. Check that the namespace in which the specialization is occurring is permissible. Returns false iff it is invalid to specialize TMPL in the current namespace. */ static bool check_specialization_namespace (tree tmpl) { tree tpl_ns = decl_namespace_context (tmpl); /* [tmpl.expl.spec] An explicit specialization shall be declared in a namespace enclosing the specialized template. An explicit specialization whose declarator-id is not qualified shall be declared in the nearest enclosing namespace of the template, or, if the namespace is inline (7.3.1), any namespace from its enclosing namespace set. */ if (current_scope() != DECL_CONTEXT (tmpl) && !at_namespace_scope_p ()) { error ("specialization of %qD must appear at namespace scope", tmpl); return false; } if (is_nested_namespace (current_namespace, tpl_ns, cxx_dialect < cxx11)) /* Same or enclosing namespace. */ return true; else { auto_diagnostic_group d; if (permerror (input_location, "specialization of %qD in different namespace", tmpl)) inform (DECL_SOURCE_LOCATION (tmpl), " from definition of %q#D", tmpl); return false; } } /* SPEC is an explicit instantiation. Check that it is valid to perform this explicit instantiation in the current namespace. */ static void check_explicit_instantiation_namespace (tree spec) { tree ns; /* DR 275: An explicit instantiation shall appear in an enclosing namespace of its template. */ ns = decl_namespace_context (spec); if (!is_nested_namespace (current_namespace, ns)) permerror (input_location, "explicit instantiation of %qD in namespace %qD " "(which does not enclose namespace %qD)", spec, current_namespace, ns); } /* Returns the type of a template specialization only if that specialization needs to be defined. Otherwise (e.g., if the type has already been defined), the function returns NULL_TREE. */ static tree maybe_new_partial_specialization (tree type) { /* An implicit instantiation of an incomplete type implies the definition of a new class template. template struct S; template struct S; Here, S is an implicit instantiation of S whose type is incomplete. */ if (CLASSTYPE_IMPLICIT_INSTANTIATION (type) && !COMPLETE_TYPE_P (type)) return type; /* It can also be the case that TYPE is a completed specialization. Continuing the previous example, suppose we also declare: template requires Integral struct S; Here, S refers to the specialization S defined above. However, we need to differentiate definitions because we intend to define a new partial specialization. In this case, we rely on the fact that the constraints are different for this declaration than that above. Note that we also get here for injected class names and late-parsed template definitions. We must ensure that we do not create new type declarations for those cases. */ if (flag_concepts && CLASSTYPE_TEMPLATE_SPECIALIZATION (type)) { tree tmpl = CLASSTYPE_TI_TEMPLATE (type); tree args = CLASSTYPE_TI_ARGS (type); /* If there are no template parameters, this cannot be a new partial template specialization? */ if (!current_template_parms) return NULL_TREE; /* The injected-class-name is not a new partial specialization. */ if (DECL_SELF_REFERENCE_P (TYPE_NAME (type))) return NULL_TREE; /* If the constraints are not the same as those of the primary then, we can probably create a new specialization. */ tree type_constr = current_template_constraints (); if (type == TREE_TYPE (tmpl)) { tree main_constr = get_constraints (tmpl); if (equivalent_constraints (type_constr, main_constr)) return NULL_TREE; } /* Also, if there's a pre-existing specialization with matching constraints, then this also isn't new. */ tree specs = DECL_TEMPLATE_SPECIALIZATIONS (tmpl); while (specs) { tree spec_tmpl = TREE_VALUE (specs); tree spec_args = TREE_PURPOSE (specs); tree spec_constr = get_constraints (spec_tmpl); if (comp_template_args (args, spec_args) && equivalent_constraints (type_constr, spec_constr)) return NULL_TREE; specs = TREE_CHAIN (specs); } /* Create a new type node (and corresponding type decl) for the newly declared specialization. */ tree t = make_class_type (TREE_CODE (type)); CLASSTYPE_DECLARED_CLASS (t) = CLASSTYPE_DECLARED_CLASS (type); SET_TYPE_TEMPLATE_INFO (t, build_template_info (tmpl, args)); /* We only need a separate type node for storing the definition of this partial specialization; uses of S are unconstrained, so all are equivalent. So keep TYPE_CANONICAL the same. */ TYPE_CANONICAL (t) = TYPE_CANONICAL (type); /* Build the corresponding type decl. */ tree d = create_implicit_typedef (DECL_NAME (tmpl), t); DECL_CONTEXT (d) = TYPE_CONTEXT (t); DECL_SOURCE_LOCATION (d) = input_location; TREE_PRIVATE (d) = (current_access_specifier == access_private_node); TREE_PROTECTED (d) = (current_access_specifier == access_protected_node); set_instantiating_module (d); DECL_MODULE_EXPORT_P (d) = DECL_MODULE_EXPORT_P (tmpl); return t; } return NULL_TREE; } /* The TYPE is being declared. If it is a template type, that means it is a partial specialization. Do appropriate error-checking. */ tree maybe_process_partial_specialization (tree type) { tree context; if (type == error_mark_node) return error_mark_node; /* A lambda that appears in specialization context is not itself a specialization. */ if (CLASS_TYPE_P (type) && CLASSTYPE_LAMBDA_EXPR (type)) return type; /* An injected-class-name is not a specialization. */ if (DECL_SELF_REFERENCE_P (TYPE_NAME (type))) return type; if (TREE_CODE (type) == BOUND_TEMPLATE_TEMPLATE_PARM) { error ("name of class shadows template template parameter %qD", TYPE_NAME (type)); return error_mark_node; } context = TYPE_CONTEXT (type); if (TYPE_ALIAS_P (type)) { tree tinfo = TYPE_ALIAS_TEMPLATE_INFO (type); if (tinfo && DECL_ALIAS_TEMPLATE_P (TI_TEMPLATE (tinfo))) error ("specialization of alias template %qD", TI_TEMPLATE (tinfo)); else error ("explicit specialization of non-template %qT", type); return error_mark_node; } else if (CLASS_TYPE_P (type) && CLASSTYPE_USE_TEMPLATE (type)) { /* This is for ordinary explicit specialization and partial specialization of a template class such as: template <> class C; or: template class C; Make sure that `C' and `C' are implicit instantiations. */ if (tree t = maybe_new_partial_specialization (type)) { if (!check_specialization_namespace (CLASSTYPE_TI_TEMPLATE (t)) && !at_namespace_scope_p ()) return error_mark_node; SET_CLASSTYPE_TEMPLATE_SPECIALIZATION (t); DECL_SOURCE_LOCATION (TYPE_MAIN_DECL (t)) = input_location; if (processing_template_decl) { tree decl = push_template_decl (TYPE_MAIN_DECL (t)); if (decl == error_mark_node) return error_mark_node; return TREE_TYPE (decl); } } else if (CLASSTYPE_TEMPLATE_INSTANTIATION (type)) error ("specialization of %qT after instantiation", type); else if (errorcount && !processing_specialization && CLASSTYPE_TEMPLATE_SPECIALIZATION (type) && !uses_template_parms (CLASSTYPE_TI_ARGS (type))) /* Trying to define a specialization either without a template<> header or in an inappropriate place. We've already given an error, so just bail now so we don't actually define the specialization. */ return error_mark_node; } else if (CLASS_TYPE_P (type) && !CLASSTYPE_USE_TEMPLATE (type) && CLASSTYPE_TEMPLATE_INFO (type) && context && CLASS_TYPE_P (context) && CLASSTYPE_TEMPLATE_INFO (context)) { /* This is for an explicit specialization of member class template according to [temp.expl.spec/18]: template <> template class C::D; The context `C' must be an implicit instantiation. Otherwise this is just a member class template declared earlier like: template <> class C { template class D; }; template <> template class C::D; In the first case, `C::D' is a specialization of `C::D' while in the second case, `C::D' is a primary template and `C::D' may not exist. */ if (CLASSTYPE_IMPLICIT_INSTANTIATION (context) && !COMPLETE_TYPE_P (type)) { tree t; tree tmpl = CLASSTYPE_TI_TEMPLATE (type); if (current_namespace != decl_namespace_context (tmpl)) { if (permerror (input_location, "specialization of %qD in different namespace", type)) inform (DECL_SOURCE_LOCATION (tmpl), "from definition of %q#D", tmpl); } /* Check for invalid specialization after instantiation: template <> template <> class C::D; template <> template class C::D; */ for (t = DECL_TEMPLATE_INSTANTIATIONS (tmpl); t; t = TREE_CHAIN (t)) { tree inst = TREE_VALUE (t); if (CLASSTYPE_TEMPLATE_SPECIALIZATION (inst) || !COMPLETE_OR_OPEN_TYPE_P (inst)) { /* We already have a full specialization of this partial instantiation, or a full specialization has been looked up but not instantiated. Reassign it to the new member specialization template. */ spec_entry elt; spec_entry *entry; elt.tmpl = most_general_template (tmpl); elt.args = CLASSTYPE_TI_ARGS (inst); elt.spec = inst; type_specializations->remove_elt (&elt); elt.tmpl = tmpl; CLASSTYPE_TI_ARGS (inst) = elt.args = INNERMOST_TEMPLATE_ARGS (elt.args); spec_entry **slot = type_specializations->find_slot (&elt, INSERT); entry = ggc_alloc (); *entry = elt; *slot = entry; } else /* But if we've had an implicit instantiation, that's a problem ([temp.expl.spec]/6). */ error ("specialization %qT after instantiation %qT", type, inst); } /* Mark TYPE as a specialization. And as a result, we only have one level of template argument for the innermost class template. */ SET_CLASSTYPE_TEMPLATE_SPECIALIZATION (type); DECL_SOURCE_LOCATION (TYPE_MAIN_DECL (type)) = input_location; CLASSTYPE_TI_ARGS (type) = INNERMOST_TEMPLATE_ARGS (CLASSTYPE_TI_ARGS (type)); } } else if (processing_specialization) { /* Someday C++0x may allow for enum template specialization. */ if (cxx_dialect > cxx98 && TREE_CODE (type) == ENUMERAL_TYPE && CLASS_TYPE_P (context) && CLASSTYPE_USE_TEMPLATE (context)) pedwarn (input_location, OPT_Wpedantic, "template specialization " "of %qD not allowed by ISO C++", type); else { error ("explicit specialization of non-template %qT", type); return error_mark_node; } } return type; } /* Returns nonzero if we can optimize the retrieval of specializations for TMPL, a TEMPLATE_DECL. In particular, for such a template, we do not use DECL_TEMPLATE_SPECIALIZATIONS at all. */ static inline bool optimize_specialization_lookup_p (tree tmpl) { return (DECL_FUNCTION_TEMPLATE_P (tmpl) && DECL_CLASS_SCOPE_P (tmpl) /* DECL_CLASS_SCOPE_P holds of T::f even if T is a template parameter. */ && CLASS_TYPE_P (DECL_CONTEXT (tmpl)) /* The optimized lookup depends on the fact that the template arguments for the member function template apply purely to the containing class, which is not true if the containing class is an explicit or partial specialization. */ && !CLASSTYPE_TEMPLATE_SPECIALIZATION (DECL_CONTEXT (tmpl)) && !DECL_MEMBER_TEMPLATE_P (tmpl) && !DECL_CONV_FN_P (tmpl) /* It is possible to have a template that is not a member template and is not a member of a template class: template struct S { friend A::f(); }; Here, the friend function is a template, but the context does not have template information. The optimized lookup relies on having ARGS be the template arguments for both the class and the function template. */ && !DECL_UNIQUE_FRIEND_P (DECL_TEMPLATE_RESULT (tmpl))); } /* Make sure ARGS doesn't use any inappropriate typedefs; we should have gone through coerce_template_parms by now. */ static void verify_unstripped_args_1 (tree inner) { for (int i = 0; i < TREE_VEC_LENGTH (inner); ++i) { tree arg = TREE_VEC_ELT (inner, i); if (TREE_CODE (arg) == TEMPLATE_DECL) /* OK */; else if (TYPE_P (arg)) gcc_assert (strip_typedefs (arg, NULL) == arg); else if (ARGUMENT_PACK_P (arg)) verify_unstripped_args_1 (ARGUMENT_PACK_ARGS (arg)); else if (strip_typedefs (TREE_TYPE (arg), NULL) != TREE_TYPE (arg)) /* Allow typedefs on the type of a non-type argument, since a parameter can have them. */; else gcc_assert (strip_typedefs_expr (arg, NULL) == arg); } } static void verify_unstripped_args (tree args) { ++processing_template_decl; if (!any_dependent_template_arguments_p (args)) verify_unstripped_args_1 (INNERMOST_TEMPLATE_ARGS (args)); --processing_template_decl; } /* Retrieve the specialization (in the sense of [temp.spec] - a specialization is either an instantiation or an explicit specialization) of TMPL for the given template ARGS. If there is no such specialization, return NULL_TREE. The ARGS are a vector of arguments, or a vector of vectors of arguments, in the case of templates with more than one level of parameters. If TMPL is a type template and CLASS_SPECIALIZATIONS_P is true, then we search for a partial specialization matching ARGS. This parameter is ignored if TMPL is not a class template. We can also look up a FIELD_DECL, if it is a lambda capture pack; the result is a NONTYPE_ARGUMENT_PACK. */ static tree retrieve_specialization (tree tmpl, tree args, hashval_t hash) { if (tmpl == NULL_TREE) return NULL_TREE; if (args == error_mark_node) return NULL_TREE; gcc_assert (TREE_CODE (tmpl) == TEMPLATE_DECL || TREE_CODE (tmpl) == FIELD_DECL); /* There should be as many levels of arguments as there are levels of parameters. */ gcc_assert (TMPL_ARGS_DEPTH (args) == (TREE_CODE (tmpl) == TEMPLATE_DECL ? TMPL_PARMS_DEPTH (DECL_TEMPLATE_PARMS (tmpl)) : template_class_depth (DECL_CONTEXT (tmpl)))); if (flag_checking) verify_unstripped_args (args); /* Lambda functions in templates aren't instantiated normally, but through tsubst_lambda_expr. */ if (lambda_fn_in_template_p (tmpl)) return NULL_TREE; if (optimize_specialization_lookup_p (tmpl)) { /* The template arguments actually apply to the containing class. Find the class specialization with those arguments. */ tree class_template = CLASSTYPE_TI_TEMPLATE (DECL_CONTEXT (tmpl)); tree class_specialization = retrieve_specialization (class_template, args, 0); if (!class_specialization) return NULL_TREE; /* Find the instance of TMPL. */ tree fns = get_class_binding (class_specialization, DECL_NAME (tmpl)); for (ovl_iterator iter (fns); iter; ++iter) { tree fn = *iter; if (tree ti = get_template_info (fn)) if (TI_TEMPLATE (ti) == tmpl /* using-declarations can bring in a different instantiation of tmpl as a member of a different instantiation of tmpl's class. We don't want those here. */ && DECL_CONTEXT (fn) == class_specialization) return fn; } return NULL_TREE; } else { spec_entry *found; spec_entry elt; spec_hash_table *specializations; elt.tmpl = tmpl; elt.args = args; elt.spec = NULL_TREE; if (DECL_CLASS_TEMPLATE_P (tmpl)) specializations = type_specializations; else specializations = decl_specializations; if (hash == 0) hash = spec_hasher::hash (&elt); found = specializations->find_with_hash (&elt, hash); if (found) return found->spec; } return NULL_TREE; } /* Like retrieve_specialization, but for local declarations. */ tree retrieve_local_specialization (tree tmpl) { if (local_specializations == NULL) return NULL_TREE; tree *slot = local_specializations->get (tmpl); return slot ? *slot : NULL_TREE; } /* Returns nonzero iff DECL is a specialization of TMPL. */ int is_specialization_of (tree decl, tree tmpl) { tree t; if (TREE_CODE (decl) == FUNCTION_DECL) { for (t = decl; t != NULL_TREE; t = DECL_TEMPLATE_INFO (t) ? DECL_TI_TEMPLATE (t) : NULL_TREE) if (t == tmpl) return 1; } else { gcc_assert (TREE_CODE (decl) == TYPE_DECL); for (t = TREE_TYPE (decl); t != NULL_TREE; t = CLASSTYPE_USE_TEMPLATE (t) ? TREE_TYPE (CLASSTYPE_TI_TEMPLATE (t)) : NULL_TREE) if (same_type_ignoring_top_level_qualifiers_p (t, TREE_TYPE (tmpl))) return 1; } return 0; } /* Returns nonzero iff DECL is a specialization of friend declaration FRIEND_DECL according to [temp.friend]. */ bool is_specialization_of_friend (tree decl, tree friend_decl) { bool need_template = true; int template_depth; gcc_assert (TREE_CODE (decl) == FUNCTION_DECL || TREE_CODE (decl) == TYPE_DECL); /* For [temp.friend/6] when FRIEND_DECL is an ordinary member function of a template class, we want to check if DECL is a specialization if this. */ if (TREE_CODE (friend_decl) == FUNCTION_DECL && DECL_TEMPLATE_INFO (friend_decl) && !DECL_USE_TEMPLATE (friend_decl)) { /* We want a TEMPLATE_DECL for `is_specialization_of'. */ friend_decl = DECL_TI_TEMPLATE (friend_decl); need_template = false; } else if (TREE_CODE (friend_decl) == TEMPLATE_DECL && !PRIMARY_TEMPLATE_P (friend_decl)) need_template = false; /* There is nothing to do if this is not a template friend. */ if (TREE_CODE (friend_decl) != TEMPLATE_DECL) return false; if (is_specialization_of (decl, friend_decl)) return true; /* [temp.friend/6] A member of a class template may be declared to be a friend of a non-template class. In this case, the corresponding member of every specialization of the class template is a friend of the class granting friendship. For example, given a template friend declaration template friend void A::f(); the member function below is considered a friend template <> struct A { void f(); }; For this type of template friend, TEMPLATE_DEPTH below will be nonzero. To determine if DECL is a friend of FRIEND, we first check if the enclosing class is a specialization of another. */ template_depth = template_class_depth (CP_DECL_CONTEXT (friend_decl)); if (template_depth && DECL_CLASS_SCOPE_P (decl) && is_specialization_of (TYPE_NAME (DECL_CONTEXT (decl)), CLASSTYPE_TI_TEMPLATE (DECL_CONTEXT (friend_decl)))) { /* Next, we check the members themselves. In order to handle a few tricky cases, such as when FRIEND_DECL's are template friend void A::g(T t); template template friend void A::h(); and DECL's are void A::g(int); template void A::h(); we need to figure out ARGS, the template arguments from the context of DECL. This is required for template substitution of `T' in the function parameter of `g' and template parameter of `h' in the above examples. Here ARGS corresponds to `int'. */ tree context = DECL_CONTEXT (decl); tree args = NULL_TREE; int current_depth = 0; while (current_depth < template_depth) { if (CLASSTYPE_TEMPLATE_INFO (context)) { if (current_depth == 0) args = TYPE_TI_ARGS (context); else args = add_to_template_args (TYPE_TI_ARGS (context), args); current_depth++; } context = TYPE_CONTEXT (context); } if (TREE_CODE (decl) == FUNCTION_DECL) { bool is_template; tree friend_type; tree decl_type; tree friend_args_type; tree decl_args_type; /* Make sure that both DECL and FRIEND_DECL are templates or non-templates. */ is_template = DECL_TEMPLATE_INFO (decl) && PRIMARY_TEMPLATE_P (DECL_TI_TEMPLATE (decl)); if (need_template ^ is_template) return false; else if (is_template) { /* If both are templates, check template parameter list. */ tree friend_parms = tsubst_template_parms (DECL_TEMPLATE_PARMS (friend_decl), args, tf_none); if (!comp_template_parms (DECL_TEMPLATE_PARMS (DECL_TI_TEMPLATE (decl)), friend_parms)) return false; decl_type = TREE_TYPE (DECL_TI_TEMPLATE (decl)); } else decl_type = TREE_TYPE (decl); friend_type = tsubst_function_type (TREE_TYPE (friend_decl), args, tf_none, NULL_TREE); if (friend_type == error_mark_node) return false; /* Check if return types match. */ if (!same_type_p (TREE_TYPE (decl_type), TREE_TYPE (friend_type))) return false; /* Check if function parameter types match, ignoring the `this' parameter. */ friend_args_type = TYPE_ARG_TYPES (friend_type); decl_args_type = TYPE_ARG_TYPES (decl_type); if (DECL_NONSTATIC_MEMBER_FUNCTION_P (friend_decl)) friend_args_type = TREE_CHAIN (friend_args_type); if (DECL_NONSTATIC_MEMBER_FUNCTION_P (decl)) decl_args_type = TREE_CHAIN (decl_args_type); return compparms (decl_args_type, friend_args_type); } else { /* DECL is a TYPE_DECL */ bool is_template; tree decl_type = TREE_TYPE (decl); /* Make sure that both DECL and FRIEND_DECL are templates or non-templates. */ is_template = CLASSTYPE_TEMPLATE_INFO (decl_type) && PRIMARY_TEMPLATE_P (CLASSTYPE_TI_TEMPLATE (decl_type)); if (need_template ^ is_template) return false; else if (is_template) { tree friend_parms; /* If both are templates, check the name of the two TEMPLATE_DECL's first because is_friend didn't. */ if (DECL_NAME (CLASSTYPE_TI_TEMPLATE (decl_type)) != DECL_NAME (friend_decl)) return false; /* Now check template parameter list. */ friend_parms = tsubst_template_parms (DECL_TEMPLATE_PARMS (friend_decl), args, tf_none); return comp_template_parms (DECL_TEMPLATE_PARMS (CLASSTYPE_TI_TEMPLATE (decl_type)), friend_parms); } else return (DECL_NAME (decl) == DECL_NAME (friend_decl)); } } return false; } /* Register the specialization SPEC as a specialization of TMPL with the indicated ARGS. IS_FRIEND indicates whether the specialization is actually just a friend declaration. ATTRLIST is the list of attributes that the specialization is declared with or NULL when it isn't. Returns SPEC, or an equivalent prior declaration, if available. We also store instantiations of field packs in the hash table, even though they are not themselves templates, to make lookup easier. */ static tree register_specialization (tree spec, tree tmpl, tree args, bool is_friend, hashval_t hash) { tree fn; spec_entry **slot = NULL; spec_entry elt; gcc_assert ((TREE_CODE (tmpl) == TEMPLATE_DECL && DECL_P (spec)) || (TREE_CODE (tmpl) == FIELD_DECL && TREE_CODE (spec) == NONTYPE_ARGUMENT_PACK)); if (TREE_CODE (spec) == FUNCTION_DECL && uses_template_parms (DECL_TI_ARGS (spec))) /* This is the FUNCTION_DECL for a partial instantiation. Don't register it; we want the corresponding TEMPLATE_DECL instead. We use `uses_template_parms (DECL_TI_ARGS (spec))' rather than the more obvious `uses_template_parms (spec)' to avoid problems with default function arguments. In particular, given something like this: template void f(T t1, T t = T()) the default argument expression is not substituted for in an instantiation unless and until it is actually needed. */ return spec; if (optimize_specialization_lookup_p (tmpl)) /* We don't put these specializations in the hash table, but we might want to give an error about a mismatch. */ fn = retrieve_specialization (tmpl, args, 0); else { elt.tmpl = tmpl; elt.args = args; elt.spec = spec; if (hash == 0) hash = spec_hasher::hash (&elt); slot = decl_specializations->find_slot_with_hash (&elt, hash, INSERT); if (*slot) fn = (*slot)->spec; else fn = NULL_TREE; } /* We can sometimes try to re-register a specialization that we've already got. In particular, regenerate_decl_from_template calls duplicate_decls which will update the specialization list. But, we'll still get called again here anyhow. It's more convenient to simply allow this than to try to prevent it. */ if (fn == spec) return spec; else if (fn && DECL_TEMPLATE_SPECIALIZATION (spec)) { if (DECL_TEMPLATE_INSTANTIATION (fn)) { if (DECL_ODR_USED (fn) || DECL_EXPLICIT_INSTANTIATION (fn)) { error ("specialization of %qD after instantiation", fn); return error_mark_node; } else { tree clone; /* This situation should occur only if the first specialization is an implicit instantiation, the second is an explicit specialization, and the implicit instantiation has not yet been used. That situation can occur if we have implicitly instantiated a member function and then specialized it later. We can also wind up here if a friend declaration that looked like an instantiation turns out to be a specialization: template void foo(T); class S { friend void foo<>(int) }; template <> void foo(int); We transform the existing DECL in place so that any pointers to it become pointers to the updated declaration. If there was a definition for the template, but not for the specialization, we want this to look as if there were no definition, and vice versa. */ DECL_INITIAL (fn) = NULL_TREE; duplicate_decls (spec, fn, /*hiding=*/is_friend); /* The call to duplicate_decls will have applied [temp.expl.spec]: An explicit specialization of a function template is inline only if it is explicitly declared to be, and independently of whether its function template is. to the primary function; now copy the inline bits to the various clones. */ FOR_EACH_CLONE (clone, fn) { DECL_DECLARED_INLINE_P (clone) = DECL_DECLARED_INLINE_P (fn); DECL_SOURCE_LOCATION (clone) = DECL_SOURCE_LOCATION (fn); DECL_DELETED_FN (clone) = DECL_DELETED_FN (fn); } check_specialization_namespace (tmpl); return fn; } } else if (DECL_TEMPLATE_SPECIALIZATION (fn)) { tree dd = duplicate_decls (spec, fn, /*hiding=*/is_friend); if (dd == error_mark_node) /* We've already complained in duplicate_decls. */ return error_mark_node; if (dd == NULL_TREE && DECL_INITIAL (spec)) /* Dup decl failed, but this is a new definition. Set the line number so any errors match this new definition. */ DECL_SOURCE_LOCATION (fn) = DECL_SOURCE_LOCATION (spec); return fn; } } else if (fn) return duplicate_decls (spec, fn, /*hiding=*/is_friend); /* A specialization must be declared in the same namespace as the template it is specializing. */ if (DECL_P (spec) && DECL_TEMPLATE_SPECIALIZATION (spec) && !check_specialization_namespace (tmpl)) DECL_CONTEXT (spec) = DECL_CONTEXT (tmpl); if (slot != NULL /* !optimize_specialization_lookup_p (tmpl) */) { spec_entry *entry = ggc_alloc (); gcc_assert (tmpl && args && spec); *entry = elt; *slot = entry; if ((TREE_CODE (spec) == FUNCTION_DECL && DECL_NAMESPACE_SCOPE_P (spec) && PRIMARY_TEMPLATE_P (tmpl) && DECL_SAVED_TREE (DECL_TEMPLATE_RESULT (tmpl)) == NULL_TREE) || variable_template_p (tmpl)) /* If TMPL is a forward declaration of a template function, keep a list of all specializations in case we need to reassign them to a friend template later in tsubst_friend_function. Also keep a list of all variable template instantiations so that process_partial_specialization can check whether a later partial specialization would have used it. */ DECL_TEMPLATE_INSTANTIATIONS (tmpl) = tree_cons (args, spec, DECL_TEMPLATE_INSTANTIATIONS (tmpl)); } return spec; } /* Restricts tree and type comparisons. */ int comparing_specializations; int comparing_dependent_aliases; /* Returns true iff two spec_entry nodes are equivalent. */ bool spec_hasher::equal (spec_entry *e1, spec_entry *e2) { int equal; ++comparing_specializations; ++comparing_dependent_aliases; ++processing_template_decl; equal = (e1->tmpl == e2->tmpl && comp_template_args (e1->args, e2->args)); if (equal && flag_concepts /* tmpl could be a FIELD_DECL for a capture pack. */ && TREE_CODE (e1->tmpl) == TEMPLATE_DECL && VAR_P (DECL_TEMPLATE_RESULT (e1->tmpl)) && uses_template_parms (e1->args)) { /* Partial specializations of a variable template can be distinguished by constraints. */ tree c1 = e1->spec ? get_constraints (e1->spec) : NULL_TREE; tree c2 = e2->spec ? get_constraints (e2->spec) : NULL_TREE; equal = equivalent_constraints (c1, c2); } --processing_template_decl; --comparing_dependent_aliases; --comparing_specializations; return equal; } /* Returns a hash for a template TMPL and template arguments ARGS. */ static hashval_t hash_tmpl_and_args (tree tmpl, tree args) { hashval_t val = iterative_hash_object (DECL_UID (tmpl), 0); return iterative_hash_template_arg (args, val); } /* Returns a hash for a spec_entry node based on the TMPL and ARGS members, ignoring SPEC. */ hashval_t spec_hasher::hash (spec_entry *e) { return hash_tmpl_and_args (e->tmpl, e->args); } /* Recursively calculate a hash value for a template argument ARG, for use in the hash tables of template specializations. We must be careful to (at least) skip the same entities template_args_equal does. */ hashval_t iterative_hash_template_arg (tree arg, hashval_t val) { if (arg == NULL_TREE) return iterative_hash_object (arg, val); if (!TYPE_P (arg)) /* Strip nop-like things, but not the same as STRIP_NOPS. */ while (CONVERT_EXPR_P (arg) || TREE_CODE (arg) == NON_LVALUE_EXPR || class_nttp_const_wrapper_p (arg)) arg = TREE_OPERAND (arg, 0); enum tree_code code = TREE_CODE (arg); val = iterative_hash_object (code, val); switch (code) { case ARGUMENT_PACK_SELECT: gcc_unreachable (); case ERROR_MARK: return val; case IDENTIFIER_NODE: return iterative_hash_object (IDENTIFIER_HASH_VALUE (arg), val); case TREE_VEC: for (int i = 0, len = TREE_VEC_LENGTH (arg); i < len; ++i) val = iterative_hash_template_arg (TREE_VEC_ELT (arg, i), val); return val; case TYPE_PACK_EXPANSION: case EXPR_PACK_EXPANSION: val = iterative_hash_template_arg (PACK_EXPANSION_PATTERN (arg), val); return iterative_hash_template_arg (PACK_EXPANSION_EXTRA_ARGS (arg), val); case TYPE_ARGUMENT_PACK: case NONTYPE_ARGUMENT_PACK: return iterative_hash_template_arg (ARGUMENT_PACK_ARGS (arg), val); case TREE_LIST: for (; arg; arg = TREE_CHAIN (arg)) val = iterative_hash_template_arg (TREE_VALUE (arg), val); return val; case OVERLOAD: for (lkp_iterator iter (arg); iter; ++iter) val = iterative_hash_template_arg (*iter, val); return val; case CONSTRUCTOR: { iterative_hash_template_arg (TREE_TYPE (arg), val); for (auto &e: CONSTRUCTOR_ELTS (arg)) { val = iterative_hash_template_arg (e.index, val); val = iterative_hash_template_arg (e.value, val); } return val; } case PARM_DECL: if (!DECL_ARTIFICIAL (arg)) { val = iterative_hash_object (DECL_PARM_INDEX (arg), val); val = iterative_hash_object (DECL_PARM_LEVEL (arg), val); } return iterative_hash_template_arg (TREE_TYPE (arg), val); case TARGET_EXPR: return iterative_hash_template_arg (TARGET_EXPR_INITIAL (arg), val); case PTRMEM_CST: val = iterative_hash_template_arg (PTRMEM_CST_CLASS (arg), val); return iterative_hash_template_arg (PTRMEM_CST_MEMBER (arg), val); case TEMPLATE_PARM_INDEX: val = iterative_hash_template_arg (TREE_TYPE (TEMPLATE_PARM_DECL (arg)), val); val = iterative_hash_object (TEMPLATE_PARM_LEVEL (arg), val); return iterative_hash_object (TEMPLATE_PARM_IDX (arg), val); case TRAIT_EXPR: val = iterative_hash_object (TRAIT_EXPR_KIND (arg), val); val = iterative_hash_template_arg (TRAIT_EXPR_TYPE1 (arg), val); return iterative_hash_template_arg (TRAIT_EXPR_TYPE2 (arg), val); case BASELINK: val = iterative_hash_template_arg (BINFO_TYPE (BASELINK_BINFO (arg)), val); return iterative_hash_template_arg (DECL_NAME (get_first_fn (arg)), val); case MODOP_EXPR: val = iterative_hash_template_arg (TREE_OPERAND (arg, 0), val); code = TREE_CODE (TREE_OPERAND (arg, 1)); val = iterative_hash_object (code, val); return iterative_hash_template_arg (TREE_OPERAND (arg, 2), val); case LAMBDA_EXPR: /* [temp.over.link] Two lambda-expressions are never considered equivalent. So just hash the closure type. */ return iterative_hash_template_arg (TREE_TYPE (arg), val); case CAST_EXPR: case IMPLICIT_CONV_EXPR: case STATIC_CAST_EXPR: case REINTERPRET_CAST_EXPR: case CONST_CAST_EXPR: case DYNAMIC_CAST_EXPR: case NEW_EXPR: val = iterative_hash_template_arg (TREE_TYPE (arg), val); /* Now hash operands as usual. */ break; case CALL_EXPR: { tree fn = CALL_EXPR_FN (arg); if (tree name = dependent_name (fn)) { if (TREE_CODE (fn) == TEMPLATE_ID_EXPR) val = iterative_hash_template_arg (TREE_OPERAND (fn, 1), val); fn = name; } val = iterative_hash_template_arg (fn, val); call_expr_arg_iterator ai; for (tree x = first_call_expr_arg (arg, &ai); x; x = next_call_expr_arg (&ai)) val = iterative_hash_template_arg (x, val); return val; } default: break; } char tclass = TREE_CODE_CLASS (code); switch (tclass) { case tcc_type: if (tree ats = alias_template_specialization_p (arg, nt_transparent)) { // We want an alias specialization that survived strip_typedefs // to hash differently from its TYPE_CANONICAL, to avoid hash // collisions that compare as different in template_args_equal. // These could be dependent specializations that strip_typedefs // left alone, or untouched specializations because // coerce_template_parms returns the unconverted template // arguments if it sees incomplete argument packs. tree ti = TYPE_ALIAS_TEMPLATE_INFO (ats); return hash_tmpl_and_args (TI_TEMPLATE (ti), TI_ARGS (ti)); } switch (TREE_CODE (arg)) { case TEMPLATE_TEMPLATE_PARM: { tree tpi = TEMPLATE_TYPE_PARM_INDEX (arg); /* Do not recurse with TPI directly, as that is unbounded recursion. */ val = iterative_hash_object (TEMPLATE_PARM_LEVEL (tpi), val); val = iterative_hash_object (TEMPLATE_PARM_IDX (tpi), val); } break; case DECLTYPE_TYPE: val = iterative_hash_template_arg (DECLTYPE_TYPE_EXPR (arg), val); break; default: if (tree canonical = TYPE_CANONICAL (arg)) val = iterative_hash_object (TYPE_HASH (canonical), val); break; } return val; case tcc_declaration: case tcc_constant: return iterative_hash_expr (arg, val); default: gcc_assert (IS_EXPR_CODE_CLASS (tclass)); for (int i = 0, n = cp_tree_operand_length (arg); i < n; ++i) val = iterative_hash_template_arg (TREE_OPERAND (arg, i), val); return val; } } /* Unregister the specialization SPEC as a specialization of TMPL. Replace it with NEW_SPEC, if NEW_SPEC is non-NULL. Returns true if the SPEC was listed as a specialization of TMPL. Note that SPEC has been ggc_freed, so we can't look inside it. */ bool reregister_specialization (tree spec, tree tinfo, tree new_spec) { spec_entry *entry; spec_entry elt; elt.tmpl = most_general_template (TI_TEMPLATE (tinfo)); elt.args = TI_ARGS (tinfo); elt.spec = NULL_TREE; entry = decl_specializations->find (&elt); if (entry != NULL) { gcc_assert (entry->spec == spec || entry->spec == new_spec); gcc_assert (new_spec != NULL_TREE); entry->spec = new_spec; return 1; } return 0; } /* Like register_specialization, but for local declarations. We are registering SPEC, an instantiation of TMPL. */ void register_local_specialization (tree spec, tree tmpl) { gcc_assert (tmpl != spec); local_specializations->put (tmpl, spec); } /* TYPE is a class type. Returns true if TYPE is an explicitly specialized class. */ bool explicit_class_specialization_p (tree type) { if (!CLASSTYPE_TEMPLATE_SPECIALIZATION (type)) return false; return !uses_template_parms (CLASSTYPE_TI_ARGS (type)); } /* Print the list of functions at FNS, going through all the overloads for each element of the list. Alternatively, FNS cannot be a TREE_LIST, in which case it will be printed together with all the overloads. MORE and *STR should respectively be FALSE and NULL when the function is called from the outside. They are used internally on recursive calls. print_candidates manages the two parameters and leaves NULL in *STR when it ends. */ static void print_candidates_1 (tree fns, char **str, bool more = false) { if (TREE_CODE (fns) == TREE_LIST) for (; fns; fns = TREE_CHAIN (fns)) print_candidates_1 (TREE_VALUE (fns), str, more || TREE_CHAIN (fns)); else for (lkp_iterator iter (fns); iter;) { tree cand = *iter; ++iter; const char *pfx = *str; if (!pfx) { if (more || iter) pfx = _("candidates are:"); else pfx = _("candidate is:"); *str = get_spaces (pfx); } inform (DECL_SOURCE_LOCATION (cand), "%s %#qD", pfx, cand); } } /* Print the list of candidate FNS in an error message. FNS can also be a TREE_LIST of non-functions in the case of an ambiguous lookup. */ void print_candidates (tree fns) { char *str = NULL; print_candidates_1 (fns, &str); free (str); } /* Get a (possibly) constrained template declaration for the purpose of ordering candidates. */ static tree get_template_for_ordering (tree list) { gcc_assert (TREE_CODE (list) == TREE_LIST); tree f = TREE_VALUE (list); if (tree ti = DECL_TEMPLATE_INFO (f)) return TI_TEMPLATE (ti); return f; } /* Among candidates having the same signature, return the most constrained or NULL_TREE if there is no best candidate. If the signatures of candidates vary (e.g., template specialization vs. member function), then there can be no most constrained. Note that we don't compare constraints on the functions themselves, but rather those of their templates. */ static tree most_constrained_function (tree candidates) { // Try to find the best candidate in a first pass. tree champ = candidates; for (tree c = TREE_CHAIN (champ); c; c = TREE_CHAIN (c)) { int winner = more_constrained (get_template_for_ordering (champ), get_template_for_ordering (c)); if (winner == -1) champ = c; // The candidate is more constrained else if (winner == 0) return NULL_TREE; // Neither is more constrained } // Verify that the champ is better than previous candidates. for (tree c = candidates; c != champ; c = TREE_CHAIN (c)) { if (!more_constrained (get_template_for_ordering (champ), get_template_for_ordering (c))) return NULL_TREE; } return champ; } /* Returns the template (one of the functions given by TEMPLATE_ID) which can be specialized to match the indicated DECL with the explicit template args given in TEMPLATE_ID. The DECL may be NULL_TREE if none is available. In that case, the functions in TEMPLATE_ID are non-members. If NEED_MEMBER_TEMPLATE is nonzero the function is known to be a specialization of a member template. The TEMPLATE_COUNT is the number of references to qualifying template classes that appeared in the name of the function. See check_explicit_specialization for a more accurate description. TSK indicates what kind of template declaration (if any) is being declared. TSK_TEMPLATE indicates that the declaration given by DECL, though a FUNCTION_DECL, has template parameters, and is therefore a template function. The template args (those explicitly specified and those deduced) are output in a newly created vector *TARGS_OUT. If it is impossible to determine the result, an error message is issued. The error_mark_node is returned to indicate failure. */ static tree determine_specialization (tree template_id, tree decl, tree* targs_out, int need_member_template, int template_count, tmpl_spec_kind tsk) { tree fns; tree targs; tree explicit_targs; tree candidates = NULL_TREE; /* A TREE_LIST of templates of which DECL may be a specialization. The TREE_VALUE of each node is a TEMPLATE_DECL. The corresponding TREE_PURPOSE is the set of template arguments that, when used to instantiate the template, would produce a function with the signature of DECL. */ tree templates = NULL_TREE; int header_count; cp_binding_level *b; *targs_out = NULL_TREE; if (template_id == error_mark_node || decl == error_mark_node) return error_mark_node; /* We shouldn't be specializing a member template of an unspecialized class template; we already gave an error in check_specialization_scope, now avoid crashing. */ if (!VAR_P (decl) && template_count && DECL_CLASS_SCOPE_P (decl) && template_class_depth (DECL_CONTEXT (decl)) > 0) { gcc_assert (errorcount); return error_mark_node; } fns = TREE_OPERAND (template_id, 0); explicit_targs = TREE_OPERAND (template_id, 1); if (fns == error_mark_node) return error_mark_node; /* Check for baselinks. */ if (BASELINK_P (fns)) fns = BASELINK_FUNCTIONS (fns); if (TREE_CODE (decl) == FUNCTION_DECL && !is_overloaded_fn (fns)) { error_at (DECL_SOURCE_LOCATION (decl), "%qD is not a function template", fns); return error_mark_node; } else if (VAR_P (decl) && !variable_template_p (fns)) { error ("%qD is not a variable template", fns); return error_mark_node; } /* Count the number of template headers specified for this specialization. */ header_count = 0; for (b = current_binding_level; b->kind == sk_template_parms; b = b->level_chain) ++header_count; tree orig_fns = fns; bool header_mismatch = false; if (variable_template_p (fns)) { tree parms = INNERMOST_TEMPLATE_PARMS (DECL_TEMPLATE_PARMS (fns)); targs = coerce_template_parms (parms, explicit_targs, fns, tf_warning_or_error, /*req_all*/true, /*use_defarg*/true); if (targs != error_mark_node && constraints_satisfied_p (fns, targs)) templates = tree_cons (targs, fns, templates); } else for (lkp_iterator iter (fns); iter; ++iter) { tree fn = *iter; if (TREE_CODE (fn) == TEMPLATE_DECL) { tree decl_arg_types; tree fn_arg_types; /* In case of explicit specialization, we need to check if the number of template headers appearing in the specialization is correct. This is usually done in check_explicit_specialization, but the check done there cannot be exhaustive when specializing member functions. Consider the following code: template <> void A::f(int); template <> template <> void A::f(int); Assuming that A is not itself an explicit specialization already, the first line specializes "f" which is a non-template member function, whilst the second line specializes "f" which is a template member function. So both lines are syntactically correct, and check_explicit_specialization does not reject them. Here, we can do better, as we are matching the specialization against the declarations. We count the number of template headers, and we check if they match TEMPLATE_COUNT + 1 (TEMPLATE_COUNT is the number of qualifying template classes, plus there must be another header for the member template itself). Notice that if header_count is zero, this is not a specialization but rather a template instantiation, so there is no check we can perform here. */ if (header_count && header_count != template_count + 1) { header_mismatch = true; continue; } /* Check that the number of template arguments at the innermost level for DECL is the same as for FN. */ if (current_binding_level->kind == sk_template_parms && !current_binding_level->explicit_spec_p && (TREE_VEC_LENGTH (DECL_INNERMOST_TEMPLATE_PARMS (fn)) != TREE_VEC_LENGTH (INNERMOST_TEMPLATE_PARMS (current_template_parms)))) continue; /* DECL might be a specialization of FN. */ decl_arg_types = TYPE_ARG_TYPES (TREE_TYPE (decl)); fn_arg_types = TYPE_ARG_TYPES (TREE_TYPE (fn)); /* For a non-static member function, we need to make sure that the const qualification is the same. Since get_bindings does not try to merge the "this" parameter, we must do the comparison explicitly. */ if (DECL_NONSTATIC_MEMBER_FUNCTION_P (fn)) { if (!same_type_p (TREE_VALUE (fn_arg_types), TREE_VALUE (decl_arg_types))) continue; /* And the ref-qualification. */ if (type_memfn_rqual (TREE_TYPE (decl)) != type_memfn_rqual (TREE_TYPE (fn))) continue; } /* Skip the "this" parameter and, for constructors of classes with virtual bases, the VTT parameter. A full specialization of a constructor will have a VTT parameter, but a template never will. */ decl_arg_types = skip_artificial_parms_for (decl, decl_arg_types); fn_arg_types = skip_artificial_parms_for (fn, fn_arg_types); /* Function templates cannot be specializations; there are no partial specializations of functions. Therefore, if the type of DECL does not match FN, there is no match. Note that it should never be the case that we have both candidates added here, and for regular member functions below. */ if (tsk == tsk_template) { if (!comp_template_parms (DECL_TEMPLATE_PARMS (fn), current_template_parms)) continue; if (!same_type_p (TREE_TYPE (TREE_TYPE (decl)), TREE_TYPE (TREE_TYPE (fn)))) continue; if (!compparms (fn_arg_types, decl_arg_types)) continue; tree freq = get_trailing_function_requirements (fn); tree dreq = get_trailing_function_requirements (decl); if (!freq != !dreq) continue; if (freq) { tree fargs = DECL_TI_ARGS (fn); tsubst_flags_t complain = tf_none; freq = tsubst_constraint (freq, fargs, complain, fn); if (!cp_tree_equal (freq, dreq)) continue; } candidates = tree_cons (NULL_TREE, fn, candidates); continue; } /* See whether this function might be a specialization of this template. Suppress access control because we might be trying to make this specialization a friend, and we have already done access control for the declaration of the specialization. */ push_deferring_access_checks (dk_no_check); targs = get_bindings (fn, decl, explicit_targs, /*check_ret=*/true); pop_deferring_access_checks (); if (!targs) /* We cannot deduce template arguments that when used to specialize TMPL will produce DECL. */ continue; if (uses_template_parms (targs)) /* We deduced something involving 'auto', which isn't a valid template argument. */ continue; /* Save this template, and the arguments deduced. */ templates = tree_cons (targs, fn, templates); } else if (need_member_template) /* FN is an ordinary member function, and we need a specialization of a member template. */ ; else if (TREE_CODE (fn) != FUNCTION_DECL) /* We can get IDENTIFIER_NODEs here in certain erroneous cases. */ ; else if (!DECL_FUNCTION_MEMBER_P (fn)) /* This is just an ordinary non-member function. Nothing can be a specialization of that. */ ; else if (DECL_ARTIFICIAL (fn)) /* Cannot specialize functions that are created implicitly. */ ; else { tree decl_arg_types; /* This is an ordinary member function. However, since we're here, we can assume its enclosing class is a template class. For example, template struct S { void f(); }; template <> void S::f() {} Here, S::f is a non-template, but S is a template class. If FN has the same type as DECL, we might be in business. */ if (!DECL_TEMPLATE_INFO (fn)) /* Its enclosing class is an explicit specialization of a template class. This is not a candidate. */ continue; if (!same_type_p (TREE_TYPE (TREE_TYPE (decl)), TREE_TYPE (TREE_TYPE (fn)))) /* The return types differ. */ continue; /* Adjust the type of DECL in case FN is a static member. */ decl_arg_types = TYPE_ARG_TYPES (TREE_TYPE (decl)); if (DECL_STATIC_FUNCTION_P (fn) && DECL_NONSTATIC_MEMBER_FUNCTION_P (decl)) decl_arg_types = TREE_CHAIN (decl_arg_types); if (!compparms (TYPE_ARG_TYPES (TREE_TYPE (fn)), decl_arg_types)) continue; if (DECL_NONSTATIC_MEMBER_FUNCTION_P (fn) && (type_memfn_rqual (TREE_TYPE (decl)) != type_memfn_rqual (TREE_TYPE (fn)))) continue; // If the deduced arguments do not satisfy the constraints, // this is not a candidate. if (flag_concepts && !constraints_satisfied_p (fn)) continue; // Add the candidate. candidates = tree_cons (NULL_TREE, fn, candidates); } } if (templates && TREE_CHAIN (templates)) { /* We have: [temp.expl.spec] It is possible for a specialization with a given function signature to be instantiated from more than one function template. In such cases, explicit specification of the template arguments must be used to uniquely identify the function template specialization being specialized. Note that here, there's no suggestion that we're supposed to determine which of the candidate templates is most specialized. However, we, also have: [temp.func.order] Partial ordering of overloaded function template declarations is used in the following contexts to select the function template to which a function template specialization refers: -- when an explicit specialization refers to a function template. So, we do use the partial ordering rules, at least for now. This extension can only serve to make invalid programs valid, so it's safe. And, there is strong anecdotal evidence that the committee intended the partial ordering rules to apply; the EDG front end has that behavior, and John Spicer claims that the committee simply forgot to delete the wording in [temp.expl.spec]. */ tree tmpl = most_specialized_instantiation (templates); if (tmpl != error_mark_node) { templates = tmpl; TREE_CHAIN (templates) = NULL_TREE; } } // Concepts allows multiple declarations of member functions // with the same signature. Like above, we need to rely on // on the partial ordering of those candidates to determine which // is the best. if (flag_concepts && candidates && TREE_CHAIN (candidates)) { if (tree cand = most_constrained_function (candidates)) { candidates = cand; TREE_CHAIN (cand) = NULL_TREE; } } if (templates == NULL_TREE && candidates == NULL_TREE) { error ("template-id %qD for %q+D does not match any template " "declaration", template_id, decl); if (header_mismatch) inform (DECL_SOURCE_LOCATION (decl), "saw %d %%>, need %d for " "specializing a member function template", header_count, template_count + 1); print_candidates (orig_fns); return error_mark_node; } else if ((templates && TREE_CHAIN (templates)) || (candidates && TREE_CHAIN (candidates)) || (templates && candidates)) { error ("ambiguous template specialization %qD for %q+D", template_id, decl); candidates = chainon (candidates, templates); print_candidates (candidates); return error_mark_node; } /* We have one, and exactly one, match. */ if (candidates) { tree fn = TREE_VALUE (candidates); *targs_out = copy_node (DECL_TI_ARGS (fn)); /* Propagate the candidate's constraints to the declaration. */ if (tsk != tsk_template) set_constraints (decl, get_constraints (fn)); /* DECL is a re-declaration or partial instantiation of a template function. */ if (TREE_CODE (fn) == TEMPLATE_DECL) return fn; /* It was a specialization of an ordinary member function in a template class. */ return DECL_TI_TEMPLATE (fn); } /* It was a specialization of a template. */ targs = DECL_TI_ARGS (DECL_TEMPLATE_RESULT (TREE_VALUE (templates))); if (TMPL_ARGS_HAVE_MULTIPLE_LEVELS (targs)) { *targs_out = copy_node (targs); SET_TMPL_ARGS_LEVEL (*targs_out, TMPL_ARGS_DEPTH (*targs_out), TREE_PURPOSE (templates)); } else *targs_out = TREE_PURPOSE (templates); return TREE_VALUE (templates); } /* Returns a chain of parameter types, exactly like the SPEC_TYPES, but with the default argument values filled in from those in the TMPL_TYPES. */ static tree copy_default_args_to_explicit_spec_1 (tree spec_types, tree tmpl_types) { tree new_spec_types; if (!spec_types) return NULL_TREE; if (spec_types == void_list_node) return void_list_node; /* Substitute into the rest of the list. */ new_spec_types = copy_default_args_to_explicit_spec_1 (TREE_CHAIN (spec_types), TREE_CHAIN (tmpl_types)); /* Add the default argument for this parameter. */ return hash_tree_cons (TREE_PURPOSE (tmpl_types), TREE_VALUE (spec_types), new_spec_types); } /* DECL is an explicit specialization. Replicate default arguments from the template it specializes. (That way, code like: template void f(T = 3); template <> void f(double); void g () { f (); } works, as required.) An alternative approach would be to look up the correct default arguments at the call-site, but this approach is consistent with how implicit instantiations are handled. */ static void copy_default_args_to_explicit_spec (tree decl) { tree tmpl; tree spec_types; tree tmpl_types; tree new_spec_types; tree old_type; tree new_type; tree t; tree object_type = NULL_TREE; tree in_charge = NULL_TREE; tree vtt = NULL_TREE; /* See if there's anything we need to do. */ tmpl = DECL_TI_TEMPLATE (decl); tmpl_types = TYPE_ARG_TYPES (TREE_TYPE (DECL_TEMPLATE_RESULT (tmpl))); for (t = tmpl_types; t; t = TREE_CHAIN (t)) if (TREE_PURPOSE (t)) break; if (!t) return; old_type = TREE_TYPE (decl); spec_types = TYPE_ARG_TYPES (old_type); if (DECL_NONSTATIC_MEMBER_FUNCTION_P (decl)) { /* Remove the this pointer, but remember the object's type for CV quals. */ object_type = TREE_TYPE (TREE_VALUE (spec_types)); spec_types = TREE_CHAIN (spec_types); tmpl_types = TREE_CHAIN (tmpl_types); if (DECL_HAS_IN_CHARGE_PARM_P (decl)) { /* DECL may contain more parameters than TMPL due to the extra in-charge parameter in constructors and destructors. */ in_charge = spec_types; spec_types = TREE_CHAIN (spec_types); } if (DECL_HAS_VTT_PARM_P (decl)) { vtt = spec_types; spec_types = TREE_CHAIN (spec_types); } } /* Compute the merged default arguments. */ new_spec_types = copy_default_args_to_explicit_spec_1 (spec_types, tmpl_types); /* Compute the new FUNCTION_TYPE. */ if (object_type) { if (vtt) new_spec_types = hash_tree_cons (TREE_PURPOSE (vtt), TREE_VALUE (vtt), new_spec_types); if (in_charge) /* Put the in-charge parameter back. */ new_spec_types = hash_tree_cons (TREE_PURPOSE (in_charge), TREE_VALUE (in_charge), new_spec_types); new_type = build_method_type_directly (object_type, TREE_TYPE (old_type), new_spec_types); } else new_type = build_function_type (TREE_TYPE (old_type), new_spec_types); new_type = cp_build_type_attribute_variant (new_type, TYPE_ATTRIBUTES (old_type)); new_type = cxx_copy_lang_qualifiers (new_type, old_type); TREE_TYPE (decl) = new_type; } /* Return the number of template headers we expect to see for a definition or specialization of CTYPE or one of its non-template members. */ int num_template_headers_for_class (tree ctype) { int num_templates = 0; while (ctype && CLASS_TYPE_P (ctype)) { /* You're supposed to have one `template <...>' for every template class, but you don't need one for a full specialization. For example: template struct S{}; template <> struct S { void f(); }; void S::f () {} is correct; there shouldn't be a `template <>' for the definition of `S::f'. */ if (!CLASSTYPE_TEMPLATE_INFO (ctype)) /* If CTYPE does not have template information of any kind, then it is not a template, nor is it nested within a template. */ break; if (explicit_class_specialization_p (ctype)) break; if (PRIMARY_TEMPLATE_P (CLASSTYPE_TI_TEMPLATE (ctype))) ++num_templates; ctype = TYPE_CONTEXT (ctype); } return num_templates; } /* Do a simple sanity check on the template headers that precede the variable declaration DECL. */ void check_template_variable (tree decl) { tree ctx = CP_DECL_CONTEXT (decl); int wanted = num_template_headers_for_class (ctx); if (DECL_LANG_SPECIFIC (decl) && DECL_TEMPLATE_INFO (decl) && PRIMARY_TEMPLATE_P (DECL_TI_TEMPLATE (decl))) { if (cxx_dialect < cxx14) pedwarn (DECL_SOURCE_LOCATION (decl), OPT_Wc__14_extensions, "variable templates only available with " "%<-std=c++14%> or %<-std=gnu++14%>"); // Namespace-scope variable templates should have a template header. ++wanted; } if (template_header_count > wanted) { auto_diagnostic_group d; bool warned = pedwarn (DECL_SOURCE_LOCATION (decl), 0, "too many template headers for %qD " "(should be %d)", decl, wanted); if (warned && CLASS_TYPE_P (ctx) && CLASSTYPE_TEMPLATE_SPECIALIZATION (ctx)) inform (DECL_SOURCE_LOCATION (decl), "members of an explicitly specialized class are defined " "without a template header"); } } /* An explicit specialization whose declarator-id or class-head-name is not qualified shall be declared in the nearest enclosing namespace of the template, or, if the namespace is inline (7.3.1), any namespace from its enclosing namespace set. If the name declared in the explicit instantiation is an unqualified name, the explicit instantiation shall appear in the namespace where its template is declared or, if that namespace is inline (7.3.1), any namespace from its enclosing namespace set. */ void check_unqualified_spec_or_inst (tree t, location_t loc) { tree tmpl = most_general_template (t); if (DECL_NAMESPACE_SCOPE_P (tmpl) && !is_nested_namespace (current_namespace, CP_DECL_CONTEXT (tmpl), true)) { if (processing_specialization) permerror (loc, "explicit specialization of %qD outside its " "namespace must use a nested-name-specifier", tmpl); else if (processing_explicit_instantiation && cxx_dialect >= cxx11) /* This was allowed in C++98, so only pedwarn. */ pedwarn (loc, OPT_Wpedantic, "explicit instantiation of %qD " "outside its namespace must use a nested-name-" "specifier", tmpl); } } /* Warn for a template specialization SPEC that is missing some of a set of function or type attributes that the template TEMPL is declared with. ATTRLIST is a list of additional attributes that SPEC should be taken to ultimately be declared with. */ static void warn_spec_missing_attributes (tree tmpl, tree spec, tree attrlist) { if (DECL_FUNCTION_TEMPLATE_P (tmpl)) tmpl = DECL_TEMPLATE_RESULT (tmpl); /* Avoid warning if the difference between the primary and the specialization is not in one of the attributes below. */ const char* const blacklist[] = { "alloc_align", "alloc_size", "assume_aligned", "format", "format_arg", "malloc", "nonnull", NULL }; /* Put together a list of the black listed attributes that the primary template is declared with that the specialization is not, in case it's not apparent from the most recent declaration of the primary. */ pretty_printer str; unsigned nattrs = decls_mismatched_attributes (tmpl, spec, attrlist, blacklist, &str); if (!nattrs) return; auto_diagnostic_group d; if (warning_at (DECL_SOURCE_LOCATION (spec), OPT_Wmissing_attributes, "explicit specialization %q#D may be missing attributes", spec)) inform (DECL_SOURCE_LOCATION (tmpl), nattrs > 1 ? G_("missing primary template attributes %s") : G_("missing primary template attribute %s"), pp_formatted_text (&str)); } /* Check to see if the function just declared, as indicated in DECLARATOR, and in DECL, is a specialization of a function template. We may also discover that the declaration is an explicit instantiation at this point. Returns DECL, or an equivalent declaration that should be used instead if all goes well. Issues an error message if something is amiss. Returns error_mark_node if the error is not easily recoverable. FLAGS is a bitmask consisting of the following flags: 2: The function has a definition. 4: The function is a friend. The TEMPLATE_COUNT is the number of references to qualifying template classes that appeared in the name of the function. For example, in template struct S { void f(); }; void S::f(); the TEMPLATE_COUNT would be 1. However, explicitly specialized classes are not counted in the TEMPLATE_COUNT, so that in template struct S {}; template <> struct S { void f(); } template <> void S::f(); the TEMPLATE_COUNT would be 0. (Note that this declaration is invalid; there should be no template <>.) If the function is a specialization, it is marked as such via DECL_TEMPLATE_SPECIALIZATION. Furthermore, its DECL_TEMPLATE_INFO is set up correctly, and it is added to the list of specializations for that template. */ tree check_explicit_specialization (tree declarator, tree decl, int template_count, int flags, tree attrlist) { int have_def = flags & 2; int is_friend = flags & 4; bool is_concept = flags & 8; int specialization = 0; int explicit_instantiation = 0; int member_specialization = 0; tree ctype = DECL_CLASS_CONTEXT (decl); tree dname = DECL_NAME (decl); tmpl_spec_kind tsk; if (is_friend) { if (!processing_specialization) tsk = tsk_none; else tsk = tsk_excessive_parms; } else tsk = current_tmpl_spec_kind (template_count); switch (tsk) { case tsk_none: if (processing_specialization && !VAR_P (decl)) { specialization = 1; SET_DECL_TEMPLATE_SPECIALIZATION (decl); } else if (TREE_CODE (declarator) == TEMPLATE_ID_EXPR) { if (is_friend) /* This could be something like: template void f(T); class S { friend void f<>(int); } */ specialization = 1; else { /* This case handles bogus declarations like template <> template void f(); */ error_at (cp_expr_loc_or_input_loc (declarator), "template-id %qE in declaration of primary template", declarator); return decl; } } break; case tsk_invalid_member_spec: /* The error has already been reported in check_specialization_scope. */ return error_mark_node; case tsk_invalid_expl_inst: error ("template parameter list used in explicit instantiation"); /* Fall through. */ case tsk_expl_inst: if (have_def) error ("definition provided for explicit instantiation"); explicit_instantiation = 1; break; case tsk_excessive_parms: case tsk_insufficient_parms: if (tsk == tsk_excessive_parms) error ("too many template parameter lists in declaration of %qD", decl); else if (template_header_count) error("too few template parameter lists in declaration of %qD", decl); else error("explicit specialization of %qD must be introduced by " "%