c++: var tmpl w/ dependent constrained auto type [PR103341]
When deducing the type of a variable template (or templated static data member) with a constrained auto type, we might need its template arguments for satisfaction since the constraint could depend on them. PR c++/103341 gcc/cp/ChangeLog: * decl.cc (cp_finish_decl): Pass the template arguments of a variable template specialization or a templated static data member to do_auto_deduction when the auto is constrained. gcc/testsuite/ChangeLog: * g++.dg/cpp2a/concepts-class4.C: New test. * g++.dg/cpp2a/concepts-var-templ2.C: New test.
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@ -7958,9 +7958,19 @@ cp_finish_decl (tree decl, tree init, bool init_const_expr_p,
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enum auto_deduction_context adc = adc_variable_type;
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if (VAR_P (decl) && DECL_DECOMPOSITION_P (decl))
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adc = adc_decomp_type;
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tree outer_targs = NULL_TREE;
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if (PLACEHOLDER_TYPE_CONSTRAINTS_INFO (auto_node)
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&& VAR_P (decl)
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&& DECL_LANG_SPECIFIC (decl)
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&& DECL_TEMPLATE_INFO (decl)
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&& !DECL_FUNCTION_SCOPE_P (decl))
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/* The outer template arguments might be needed for satisfaction.
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(For function scope variables, do_auto_deduction will obtain the
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outer template arguments from current_function_decl.) */
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outer_targs = DECL_TI_ARGS (decl);
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type = TREE_TYPE (decl) = do_auto_deduction (type, d_init, auto_node,
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tf_warning_or_error, adc,
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NULL_TREE, flags);
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outer_targs, flags);
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if (type == error_mark_node)
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return;
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if (TREE_CODE (type) == FUNCTION_TYPE)
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@ -0,0 +1,11 @@
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// PR c++/103341
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// { dg-do compile { target c++20 } }
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template<class T, class U> concept same_as = __is_same(T, U);
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template<class T>
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struct A {
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static inline same_as<T> auto value = 0; // { dg-error "constraint" }
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};
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template struct A<int>; // { dg-bogus "" }
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template struct A<bool>; // { dg-message "required from here" }
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@ -0,0 +1,13 @@
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// PR c++/103341
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// { dg-do compile { target c++20 } }
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template<class T, class U> concept same_as = __is_same(T, U);
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template<class T> same_as<T> auto v1a = 1;
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template<class T> same_as<T> auto v1b = T();
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template<class T> same_as<T*> auto v2a = 1; // { dg-error "constraints" }
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template<class T> same_as<T*> auto v2b = T(); // { dg-error "constraints" }
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template int v1a<int>;
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template int v1b<int>;
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template int v2a<int>; // { dg-message "required from here" }
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template int v2b<int>; // { dg-message "required from here" }
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