[C++ PATCH] Fix decomp ICEs in templates (PR c++/80370, take 3)

Jason Merrill jason@redhat.com
Tue Apr 11 18:40:00 GMT 2017


OK.

On Tue, Apr 11, 2017 at 1:13 PM, Jakub Jelinek <jakub@redhat.com> wrote:
> On Tue, Apr 11, 2017 at 03:41:39PM +0200, Jakub Jelinek wrote:
>> So like this?  Or just type_dependent_expression_p check rather than
>> both?
>
> To answer myself, testing there both type_dependent_expression_p
> and value_dependent_expression_p for value_expr breaks
> the lambda-generic-const2.C testcase.  So I'll test this instead:
>
> 2017-04-11  Jakub Jelinek  <jakub@redhat.com>
>
>         PR c++/80370
>         * decl.c (cp_finish_decomp): If processing_template_decl on
>         non-dependent decl, only set TREE_TYPE on the v[i] decls, but don't
>         change their DECL_VALUE_EXPR nor cp_finish_decl them.  Instead make
>         sure DECL_VALUE_EXPR is the canonical NULL type ARRAY_REF for tsubst
>         processing.
>         * pt.c (value_dependent_expression_p) <case VAR_DECL>: For variables
>         with DECL_VALUE_EXPR, return true if DECL_VALUE_EXPR is type
>         dependent.
>
>         * g++.dg/cpp1z/decomp28.C: New test.
>
> --- gcc/cp/decl.c.jj    2017-04-10 22:26:56.441388051 +0200
> +++ gcc/cp/decl.c       2017-04-11 15:21:24.473163169 +0200
> @@ -7473,6 +7473,8 @@ cp_finish_decomp (tree decl, tree first,
>         {
>           TREE_TYPE (v[i]) = eltype;
>           layout_decl (v[i], 0);
> +         if (processing_template_decl)
> +           continue;
>           tree t = unshare_expr (dexp);
>           t = build4_loc (DECL_SOURCE_LOCATION (v[i]), ARRAY_REF,
>                           eltype, t, size_int (i), NULL_TREE,
> @@ -7492,6 +7494,8 @@ cp_finish_decomp (tree decl, tree first,
>         {
>           TREE_TYPE (v[i]) = eltype;
>           layout_decl (v[i], 0);
> +         if (processing_template_decl)
> +           continue;
>           tree t = unshare_expr (dexp);
>           t = build1_loc (DECL_SOURCE_LOCATION (v[i]),
>                           i ? IMAGPART_EXPR : REALPART_EXPR, eltype,
> @@ -7510,6 +7514,8 @@ cp_finish_decomp (tree decl, tree first,
>         {
>           TREE_TYPE (v[i]) = eltype;
>           layout_decl (v[i], 0);
> +         if (processing_template_decl)
> +           continue;
>           tree t = unshare_expr (dexp);
>           convert_vector_to_array_for_subscript (DECL_SOURCE_LOCATION (v[i]),
>                                                  &t, size_int (i));
> @@ -7559,8 +7565,9 @@ cp_finish_decomp (tree decl, tree first,
>               SET_DECL_VALUE_EXPR (v[i], NULL_TREE);
>               DECL_HAS_VALUE_EXPR_P (v[i]) = 0;
>             }
> -         cp_finish_decl (v[i], init, /*constexpr*/false,
> -                         /*asm*/NULL_TREE, LOOKUP_NORMAL);
> +         if (!processing_template_decl)
> +           cp_finish_decl (v[i], init, /*constexpr*/false,
> +                           /*asm*/NULL_TREE, LOOKUP_NORMAL);
>         }
>      }
>    else if (TREE_CODE (type) == UNION_TYPE)
> @@ -7615,12 +7622,26 @@ cp_finish_decomp (tree decl, tree first,
>               tt = TREE_OPERAND (tt, 0);
>             TREE_TYPE (v[i]) = TREE_TYPE (tt);
>             layout_decl (v[i], 0);
> -           SET_DECL_VALUE_EXPR (v[i], tt);
> -           DECL_HAS_VALUE_EXPR_P (v[i]) = 1;
> +           if (!processing_template_decl)
> +             {
> +               SET_DECL_VALUE_EXPR (v[i], tt);
> +               DECL_HAS_VALUE_EXPR_P (v[i]) = 1;
> +             }
>             i++;
>           }
>      }
> -  if (DECL_NAMESPACE_SCOPE_P (decl))
> +  if (processing_template_decl)
> +    {
> +      for (unsigned int i = 0; i < count; i++)
> +       if (!DECL_HAS_VALUE_EXPR_P (v[i]))
> +         {
> +           tree a = build_nt (ARRAY_REF, decl, size_int (i),
> +                              NULL_TREE, NULL_TREE);
> +           SET_DECL_VALUE_EXPR (v[i], a);
> +           DECL_HAS_VALUE_EXPR_P (v[i]) = 1;
> +         }
> +    }
> +  else if (DECL_NAMESPACE_SCOPE_P (decl))
>      SET_DECL_ASSEMBLER_NAME (decl, mangle_decomp (decl, v));
>  }
>
> --- gcc/cp/pt.c.jj      2017-04-11 19:06:52.871624849 +0200
> +++ gcc/cp/pt.c 2017-04-11 19:10:39.795803274 +0200
> @@ -23576,6 +23576,12 @@ value_dependent_expression_p (tree expre
>               || type_dependent_expression_p (DECL_INITIAL (expression))
>               || value_dependent_expression_p (DECL_INITIAL (expression))))
>         return true;
> +      if (DECL_HAS_VALUE_EXPR_P (expression))
> +       {
> +         tree value_expr = DECL_VALUE_EXPR (expression);
> +         if (type_dependent_expression_p (value_expr))
> +           return true;
> +       }
>        return false;
>
>      case DYNAMIC_CAST_EXPR:
> --- gcc/testsuite/g++.dg/cpp1z/decomp28.C.jj    2017-04-11 15:21:24.473163169 +0200
> +++ gcc/testsuite/g++.dg/cpp1z/decomp28.C       2017-04-11 15:21:24.473163169 +0200
> @@ -0,0 +1,39 @@
> +// PR c++/80370
> +// { dg-do compile { target c++14 } }
> +// { dg-options "" }
> +
> +namespace std {
> +  template <typename> struct tuple_size;
> +  template <long, typename> struct tuple_element;
> +  template <typename...> struct tuple {};
> +  template <typename... T> struct tuple_size<tuple<T...>> { static constexpr int value = 1; };
> +  template <typename T, typename... U> struct tuple_element<0, tuple<T, U...>> { typedef T type; };
> +  template <int, typename... T> int& get (tuple<T...>);
> +}
> +
> +template <int N>
> +void
> +foo (std::tuple<int> b)
> +{
> +  auto [c] = b;                // { dg-warning "decomposition declaration only available with" "" { target c++14_down } }
> +}
> +
> +template <typename T>
> +void
> +bar (std::tuple<T> b)
> +{
> +  auto [c] = b;                // { dg-warning "decomposition declaration only available with" "" { target c++14_down } }
> +}
> +
> +void
> +baz (std::tuple<int> b)
> +{
> +  foo <5> (b);
> +  bar (b);
> +}
> +
> +int
> +main ()
> +{
> +  [](auto) { [](std::tuple<int> b) { auto[c] = b; }; } (0); // { dg-warning "decomposition declaration only available with" "" { target c++14_down } }
> +}
>
>
>         Jakub



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