Re: [PATCH] c++: Fix up handling of dependent (late) attributes on function/method types [PR116175]

[Jason Merrill]

On 8/1/24 2:39 PM, Jakub Jelinek wrote:

Hi!

When working on unsequenced/reproducible attributes, I've noticed that on
templates for some attributes decl_attributes isn't called at all, so they
are kept in TYPE_ATTRIBUTES without any verification/transformations and
also without argument substitution.

The following patch fixes that for FUNCTION/METHOD_TYPE attributes.
The included testcase ICEs without the pt.cc changes.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

OK.

2024-08-01  Jakub Jelinek  <ja...@redhat.com>

        PR c++/116175
        * pt.cc (apply_late_template_attributes): For function/method types
        call cp_build_type_attribute_variant on the non-dependent attributes.
        (rebuild_function_or_method_type): Add ARGS argument.  Use
        apply_late_template_attributes rather than
        cp_build_type_attribute_variant.
        (maybe_rebuild_function_decl_type): Add ARGS argument, pass it to
        rebuild_function_or_method_type.
        (tsubst_function_decl): Adjust caller.
        (tsubst_function_type): Adjust rebuild_function_or_method_type caller.

        * g++.dg/ext/attr-format4.C: New test.

--- gcc/cp/pt.cc.jj     2024-07-31 14:38:54.405628645 +0200
+++ gcc/cp/pt.cc        2024-08-01 16:29:59.671779469 +0200
@@ -12219,6 +12219,8 @@ apply_late_template_attributes (tree *de
           to our attributes parameter.  */
        gcc_assert (*p == attributes);
      }
+  else if (FUNC_OR_METHOD_TYPE_P (*decl_p))
+    p = NULL;
    else
      {
        p = &TYPE_ATTRIBUTES (*decl_p);
@@ -12237,7 +12239,10 @@ apply_late_template_attributes (tree *de
    tree nondep = t;

/* Apply any non-dependent attributes. */

-  *p = nondep;
+  if (p)
+    *p = nondep;
+  else if (nondep)
+    *decl_p = cp_build_type_attribute_variant (*decl_p, nondep);

if (nondep == attributes)

      return true;
@@ -14375,8 +14380,9 @@ lookup_explicit_specifier (tree v)
     identical to T.  */

static tree

-rebuild_function_or_method_type (tree t, tree return_type, tree arg_types,
-                                tree raises, tsubst_flags_t complain)
+rebuild_function_or_method_type (tree t, tree args, tree return_type,
+                                tree arg_types, tree raises,
+                                tsubst_flags_t complain)
  {
    gcc_assert (FUNC_OR_METHOD_TYPE_P (t));

@@ -14409,7 +14415,9 @@ rebuild_function_or_method_type (tree t,

        new_type = build_method_type_directly (r, return_type,
                                             TREE_CHAIN (arg_types));
      }
-  new_type = cp_build_type_attribute_variant (new_type, TYPE_ATTRIBUTES (t));
+  if (!apply_late_template_attributes (&new_type, TYPE_ATTRIBUTES (t), 0,
+                                      args, complain, NULL_TREE))
+    return error_mark_node;

cp_ref_qualifier rqual = type_memfn_rqual (t);

    bool late_return_type_p = TYPE_HAS_LATE_RETURN_TYPE (t);
@@ -14422,7 +14430,7 @@ rebuild_function_or_method_type (tree t,
     resolution for Core issues 1001/1322.  */

static void

-maybe_rebuild_function_decl_type (tree decl)
+maybe_rebuild_function_decl_type (tree decl, tree args)
  {
    bool function_type_needs_rebuilding = false;
    if (tree parm_list = FUNCTION_FIRST_USER_PARM (decl))
@@ -14474,7 +14482,7 @@ maybe_rebuild_function_decl_type (tree d
      *q = void_list_node;

TREE_TYPE (decl)

-    = rebuild_function_or_method_type (fntype,
+    = rebuild_function_or_method_type (fntype, args,
                                       TREE_TYPE (fntype), new_parm_type_list,
                                       TYPE_RAISES_EXCEPTIONS (fntype), 
tf_none);
  }
@@ -14657,7 +14665,7 @@ tsubst_function_decl (tree t, tree args,
    DECL_ARGUMENTS (r) = parms;
    DECL_RESULT (r) = NULL_TREE;

- maybe_rebuild_function_decl_type (r);

+  maybe_rebuild_function_decl_type (r, args);

TREE_STATIC (r) = 0;

    TREE_PUBLIC (r) = TREE_PUBLIC (t);
@@ -15925,7 +15933,7 @@ tsubst_function_type (tree t,
      }

/* Construct a new type node and return it. */

-  return rebuild_function_or_method_type (t, return_type, arg_types,
+  return rebuild_function_or_method_type (t, args, return_type, arg_types,
                                          /*raises=*/NULL_TREE, complain);
  }

--- gcc/testsuite/g++.dg/ext/attr-format4.C.jj 2024-08-01 17:44:35.492269816 +0200

+++ gcc/testsuite/g++.dg/ext/attr-format4.C     2024-08-01 17:43:27.340127120 
+0200
@@ -0,0 +1,12 @@
+// PR c++/116175
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wformat" }
+
+template <typename ...T>
+int foo (T ...args, const char *fmt, ...)
+[[gnu::format (printf, 1 + sizeof... (T), 2 + sizeof... (T))]];
+
+int a = foo <> ("%d", 1);
+int b = foo <int, int, int, int, int> (1, 2, 3, 4, 5, "%d", 1);
+int c = foo <> ("%f", 1);      // { dg-warning "format '%f' expects argument of 
type 'double', but argument 2 has type 'int'" }
+int d = foo <int, int, int, int, int> (1, 2, 3, 4, 5, "%f", 1);        // { dg-warning 
"format '%f' expects argument of type 'double', but argument 7 has type 'int'" }

        Jakub