c++: Substitute into function parms in lexical order [PR96560]
This makes tsubst_arg_types substitute into a function's parameter types in left-to-right instead of right-to-left order, in accordance with DR 1227. DR 1227 PR c++/96560 gcc/cp/ChangeLog: * pt.c (tsubst_arg_types): Rearrange so that we substitute into TYPE_ARG_TYPES in forward order while short circuiting appropriately. Adjust formatting. gcc/testsuite/ChangeLog: * g++.dg/template/sfinae-dr1227.C: New test.
This commit is contained in:
Patrick Palka
parent
1e690757d3
commit
b0d73a66ae
2 changed files with 83 additions and 55 deletions
115
gcc/cp/pt.c
115
gcc/cp/pt.c
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@ -14946,20 +14946,13 @@ tsubst_arg_types (tree arg_types,
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tsubst_flags_t complain,
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tree in_decl)
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{
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tree remaining_arg_types;
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tree type = NULL_TREE;
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int i = 1;
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int len = 1;
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tree expanded_args = NULL_TREE;
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tree default_arg;
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if (!arg_types || arg_types == void_list_node || arg_types == end)
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return arg_types;
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remaining_arg_types = tsubst_arg_types (TREE_CHAIN (arg_types),
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args, end, complain, in_decl);
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if (remaining_arg_types == error_mark_node)
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return error_mark_node;
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if (PACK_EXPANSION_P (TREE_VALUE (arg_types)))
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{
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/* For a pack expansion, perform substitution on the
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@ -14970,7 +14963,7 @@ tsubst_arg_types (tree arg_types,
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if (TREE_CODE (expanded_args) == TREE_VEC)
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/* So that we'll spin through the parameters, one by one. */
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i = TREE_VEC_LENGTH (expanded_args);
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len = TREE_VEC_LENGTH (expanded_args);
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else
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{
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/* We only partially substituted into the parameter
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@ -14979,59 +14972,71 @@ tsubst_arg_types (tree arg_types,
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expanded_args = NULL_TREE;
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}
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}
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else
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type = tsubst (TREE_VALUE (arg_types), args, complain, in_decl);
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while (i > 0) {
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--i;
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/* Check if a substituted type is erroneous before substituting into
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the rest of the chain. */
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for (int i = 0; i < len; i++)
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{
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if (expanded_args)
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type = TREE_VEC_ELT (expanded_args, i);
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if (expanded_args)
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type = TREE_VEC_ELT (expanded_args, i);
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else if (!type)
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type = tsubst (TREE_VALUE (arg_types), args, complain, in_decl);
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if (type == error_mark_node)
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return error_mark_node;
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if (VOID_TYPE_P (type))
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{
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if (complain & tf_error)
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{
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error ("invalid parameter type %qT", type);
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if (in_decl)
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error ("in declaration %q+D", in_decl);
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}
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return error_mark_node;
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if (type == error_mark_node)
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return error_mark_node;
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if (VOID_TYPE_P (type))
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{
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if (complain & tf_error)
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{
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error ("invalid parameter type %qT", type);
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if (in_decl)
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error ("in declaration %q+D", in_decl);
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}
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return error_mark_node;
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}
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}
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/* Do array-to-pointer, function-to-pointer conversion, and ignore
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top-level qualifiers as required. */
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type = cv_unqualified (type_decays_to (type));
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/* We do not substitute into default arguments here. The standard
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mandates that they be instantiated only when needed, which is
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done in build_over_call. */
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tree default_arg = TREE_PURPOSE (arg_types);
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/* We do not substitute into default arguments here. The standard
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mandates that they be instantiated only when needed, which is
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done in build_over_call. */
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default_arg = TREE_PURPOSE (arg_types);
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/* Except that we do substitute default arguments under tsubst_lambda_expr,
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since the new op() won't have any associated template arguments for us
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to refer to later. */
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if (lambda_fn_in_template_p (in_decl))
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default_arg = tsubst_copy_and_build (default_arg, args, complain, in_decl,
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false/*fn*/, false/*constexpr*/);
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/* Except that we do substitute default arguments under tsubst_lambda_expr,
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since the new op() won't have any associated template arguments for us
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to refer to later. */
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if (lambda_fn_in_template_p (in_decl))
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default_arg = tsubst_copy_and_build (default_arg, args, complain, in_decl,
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false/*fn*/, false/*constexpr*/);
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tree remaining_arg_types = tsubst_arg_types (TREE_CHAIN (arg_types),
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args, end, complain, in_decl);
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if (remaining_arg_types == error_mark_node)
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return error_mark_node;
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if (default_arg && TREE_CODE (default_arg) == DEFERRED_PARSE)
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{
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/* We've instantiated a template before its default arguments
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have been parsed. This can happen for a nested template
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class, and is not an error unless we require the default
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argument in a call of this function. */
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remaining_arg_types =
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tree_cons (default_arg, type, remaining_arg_types);
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vec_safe_push (DEFPARSE_INSTANTIATIONS (default_arg),
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remaining_arg_types);
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}
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else
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remaining_arg_types =
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hash_tree_cons (default_arg, type, remaining_arg_types);
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}
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for (int i = len-1; i >= 0; i--)
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{
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if (expanded_args)
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type = TREE_VEC_ELT (expanded_args, i);
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/* Do array-to-pointer, function-to-pointer conversion, and ignore
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top-level qualifiers as required. */
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type = cv_unqualified (type_decays_to (type));
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if (default_arg && TREE_CODE (default_arg) == DEFERRED_PARSE)
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{
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/* We've instantiated a template before its default arguments
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have been parsed. This can happen for a nested template
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class, and is not an error unless we require the default
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argument in a call of this function. */
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remaining_arg_types
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= tree_cons (default_arg, type, remaining_arg_types);
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vec_safe_push (DEFPARSE_INSTANTIATIONS (default_arg),
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remaining_arg_types);
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}
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else
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remaining_arg_types
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= hash_tree_cons (default_arg, type, remaining_arg_types);
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}
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return remaining_arg_types;
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}
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23
gcc/testsuite/g++.dg/template/sfinae-dr1227.C
Normal file
23
gcc/testsuite/g++.dg/template/sfinae-dr1227.C
Normal file
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@ -0,0 +1,23 @@
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// PR c++/96560
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// DR 1227
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// Test that we substitute function parameter types in lexical order.
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template <class T>
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struct A { typedef typename T::type type; }; // { dg-error "void" }
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template <class T> void f(typename T::type, typename A<T>::type);
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template <class T> long f(...);
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long x = f<int>(0, 0); // { dg-bogus "" } OK
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template <class T> void g(T, typename A<T>::type);
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template <class T> long g(...);
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long y = g<void>(0, 0); // { dg-bogus "" } OK
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template <class T> void h(typename A<T>::type, T);
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template <class T> long h(...);
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long z = h<void>(0, 0); // { dg-message "required from here" } hard error
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