1 files changed, 317 insertions, 170 deletions

diff --git a/gcc/c/c-parser.cc b/gcc/c/c-parser.cc
index 4a13fc0..566ab1b 100644
--- a/gcc/c/c-parser.cc
+++ b/gcc/c/c-parser.cc
@@ -2822,7 +2822,7 @@ c_parser_declaration_or_fndef (c_parser *parser, bool fndef_ok,
 			      specs->constexpr_p, &richloc);
 		  /* A parameter is initialized, which is invalid.  Don't
 		     attempt to instrument the initializer.  */
-		  int flag_sanitize_save = flag_sanitize;
+		  sanitize_code_type flag_sanitize_save = flag_sanitize;
 		  if (nested && !empty_ok)
 		    flag_sanitize = 0;
 		  init = c_parser_expr_no_commas (parser, NULL);
@@ -2911,7 +2911,7 @@ c_parser_declaration_or_fndef (c_parser *parser, bool fndef_ok,
 			      specs->constexpr_p, &richloc);
 		  /* A parameter is initialized, which is invalid.  Don't
 		     attempt to instrument the initializer.  */
-		  int flag_sanitize_save = flag_sanitize;
+		  sanitize_code_type flag_sanitize_save = flag_sanitize;
 		  if (TREE_CODE (d) == PARM_DECL)
 		    flag_sanitize = 0;
 		  init = c_parser_initializer (parser, d);
@@ -11876,12 +11876,9 @@ c_parser_postfix_expression (c_parser *parser)
 	    if (c_parser_next_token_is (parser, CPP_NAME))
 	      {
 		c_token *comp_tok = c_parser_peek_token (parser);
-		/* Ignore the counted_by attribute for reference inside
-		   offsetof since the information is not useful at all.  */
 		offsetof_ref
 		  = build_component_ref (loc, offsetof_ref, comp_tok->value,
-					 comp_tok->location, UNKNOWN_LOCATION,
-					 false);
+					 comp_tok->location, UNKNOWN_LOCATION);
 		c_parser_consume_token (parser);
 		while (c_parser_next_token_is (parser, CPP_DOT)
 		       || c_parser_next_token_is (parser,
@@ -11908,14 +11905,11 @@ c_parser_postfix_expression (c_parser *parser)
 			    break;
 			  }
 			c_token *comp_tok = c_parser_peek_token (parser);
-			/* Ignore the counted_by attribute for reference inside
-			   offsetof since the information is not useful.  */
 			offsetof_ref
 			  = build_component_ref (loc, offsetof_ref,
 						 comp_tok->value,
 						 comp_tok->location,
-						 UNKNOWN_LOCATION,
-						 false);
+						 UNKNOWN_LOCATION);
 			c_parser_consume_token (parser);
 		      }
 		    else
@@ -12701,7 +12695,7 @@ c_parser_postfix_expression (c_parser *parser)
 	    /* If the array ref is inside TYPEOF or ALIGNOF, the call to
 	       .ACCESS_WITH_SIZE was not generated by the routine
 	       build_component_ref by default, we should generate it here.  */
-	    if ((in_typeof || in_alignof) && TREE_CODE (ref) == COMPONENT_REF)
+	    if (TREE_CODE (ref) == COMPONENT_REF)
 	      ref = handle_counted_by_for_component_ref (loc, ref);
 
 	    if (has_counted_by_object (ref))
@@ -16659,7 +16653,7 @@ c_parser_omp_variable_list (c_parser *parser,
 		   || CONVERT_EXPR_P (decl))
 	    decl = TREE_OPERAND (decl, 0);
 
-	  tree u = build_omp_clause (clause_loc, kind);
+	  tree u = build_omp_clause (loc, kind);
 	  OMP_CLAUSE_DECL (u) = decl;
 	  OMP_CLAUSE_CHAIN (u) = list;
 	  list = u;
@@ -20072,7 +20066,7 @@ c_parser_omp_clause_doacross (c_parser *parser, tree list)
    map ( [map-type-modifier[,] ...] map-kind: variable-list )
 
    map-type-modifier:
-     always | close */
+     always | close | present | iterator (iterators-definition)  */
 
 static tree
 c_parser_omp_clause_map (c_parser *parser, tree list, bool declare_mapper_p)
@@ -20087,15 +20081,35 @@ c_parser_omp_clause_map (c_parser *parser, tree list, bool declare_mapper_p)
 
   int pos = 1;
   int map_kind_pos = 0;
-  while (c_parser_peek_nth_token_raw (parser, pos)->type == CPP_NAME)
+  int iterator_length = 0;
+  for (;;)
     {
-      if (c_parser_peek_nth_token_raw (parser, pos + 1)->type == CPP_COLON)
+      c_token *tok = c_parser_peek_nth_token_raw (parser, pos);
+      if (tok->type != CPP_NAME)
+	break;
+
+      const char *p = IDENTIFIER_POINTER (tok->value);
+      c_token *next_tok = c_parser_peek_nth_token_raw (parser, pos + 1);
+      if (strcmp (p, "iterator") == 0 && next_tok->type == CPP_OPEN_PAREN)
+	{
+	  unsigned n = pos + 2;
+	  if (c_parser_check_balanced_raw_token_sequence (parser, &n)
+	      && c_parser_peek_nth_token_raw (parser, n)->type
+		 == CPP_CLOSE_PAREN)
+	    {
+	      iterator_length = n - pos + 1;
+	      pos = n;
+	      next_tok = c_parser_peek_nth_token_raw (parser, pos + 1);
+	    }
+	}
+
+      if (next_tok->type == CPP_COLON)
 	{
 	  map_kind_pos = pos;
 	  break;
 	}
 
-      if (c_parser_peek_nth_token_raw (parser, pos + 1)->type == CPP_COMMA)
+      if (next_tok->type == CPP_COMMA)
 	pos++;
       else if (c_parser_peek_nth_token_raw (parser, pos + 1)->type
 	       == CPP_OPEN_PAREN)
@@ -20117,6 +20131,7 @@ c_parser_omp_clause_map (c_parser *parser, tree list, bool declare_mapper_p)
   int present_modifier = 0;
   int mapper_modifier = 0;
   tree mapper_name = NULL_TREE;
+  tree iterators = NULL_TREE;
   for (int pos = 1; pos < map_kind_pos; ++pos)
     {
       c_token *tok = c_parser_peek_token (parser);
@@ -20150,6 +20165,17 @@ c_parser_omp_clause_map (c_parser *parser, tree list, bool declare_mapper_p)
 	  close_modifier++;
 	  c_parser_consume_token (parser);
 	}
+      else if (strcmp ("iterator", p) == 0)
+	{
+	  if (iterators)
+	    {
+	      c_parser_error (parser, "too many %<iterator%> modifiers");
+	      parens.skip_until_found_close (parser);
+	      return list;
+	    }
+	  iterators = c_parser_omp_iterators (parser);
+	  pos += iterator_length - 1;
+	}
       else if (strcmp ("mapper", p) == 0)
 	{
 	  c_parser_consume_token (parser);
@@ -20223,8 +20249,8 @@ c_parser_omp_clause_map (c_parser *parser, tree list, bool declare_mapper_p)
       else
 	{
 	  c_parser_error (parser, "%<map%> clause with map-type modifier other "
-				  "than %<always%>, %<close%>, %<mapper%> or "
-				  "%<present%>");
+				  "than %<always%>, %<close%>, %<iterator%>, "
+				  "%<mapper%> or %<present%>");
 	  parens.skip_until_found_close (parser);
 	  return list;
 	}
@@ -20273,9 +20299,19 @@ c_parser_omp_clause_map (c_parser *parser, tree list, bool declare_mapper_p)
 
   tree last_new = NULL_TREE;
 
+  if (iterators)
+    {
+      tree block = pop_scope ();
+      if (iterators == error_mark_node)
+	iterators = NULL_TREE;
+      else
+	TREE_VEC_ELT (iterators, 5) = block;
+    }
+
   for (c = nl; c != list; c = OMP_CLAUSE_CHAIN (c))
     {
       OMP_CLAUSE_SET_MAP_KIND (c, kind);
+      OMP_CLAUSE_ITERATORS (c) = iterators;
       last_new = c;
     }
 
@@ -20534,8 +20570,11 @@ c_parser_omp_clause_device_type (c_parser *parser, tree list)
    to ( variable-list )
 
    OpenMP 5.1:
-   from ( [present :] variable-list )
-   to ( [present :] variable-list ) */
+   from ( [motion-modifier[,] [motion-modifier[,]...]:] variable-list )
+   to ( [motion-modifier[,] [motion-modifier[,]...]:] variable-list )
+
+   motion-modifier:
+     present | iterator (iterators-definition)  */
 
 static tree
 c_parser_omp_clause_from_to (c_parser *parser, enum omp_clause_code kind,
@@ -20546,18 +20585,85 @@ c_parser_omp_clause_from_to (c_parser *parser, enum omp_clause_code kind,
   if (!parens.require_open (parser))
     return list;
 
+  int pos = 1, colon_pos = 0;
+  int iterator_length = 0;
+
+  while (c_parser_peek_nth_token_raw (parser, pos)->type == CPP_NAME)
+    {
+      const char *identifier =
+	IDENTIFIER_POINTER (c_parser_peek_nth_token_raw (parser, pos)->value);
+      if (c_parser_peek_nth_token_raw (parser, pos + 1)->type
+	  == CPP_OPEN_PAREN)
+	{
+	  unsigned int npos = pos + 2;
+	  if (c_parser_check_balanced_raw_token_sequence (parser, &npos)
+	      && (c_parser_peek_nth_token_raw (parser, npos)->type
+		  == CPP_CLOSE_PAREN))
+	    {
+	      if (strcmp (identifier, "iterator") == 0)
+		iterator_length = npos - pos + 1;
+	      pos = npos;
+	    }
+	}
+      if (c_parser_peek_nth_token_raw (parser, pos + 1)->type == CPP_COMMA)
+	pos += 2;
+      else
+	pos++;
+      if (c_parser_peek_nth_token_raw (parser, pos)->type == CPP_COLON)
+	{
+	  colon_pos = pos;
+	  break;
+	}
+    }
+
   bool present = false;
-  c_token *token = c_parser_peek_token (parser);
+  tree iterators = NULL_TREE;
 
-  if (token->type == CPP_NAME
-      && strcmp (IDENTIFIER_POINTER (token->value), "present") == 0
-      && c_parser_peek_2nd_token (parser)->type == CPP_COLON)
+  for (int pos = 1; pos < colon_pos; ++pos)
     {
-      present = true;
-      c_parser_consume_token (parser);
-      c_parser_consume_token (parser);
+      c_token *token = c_parser_peek_token (parser);
+      if (token->type == CPP_COMMA)
+	{
+	  c_parser_consume_token (parser);
+	  continue;
+	}
+      const char *p = IDENTIFIER_POINTER (token->value);
+      if (strcmp ("present", p) == 0)
+	{
+	  if (present)
+	    {
+	      c_parser_error (parser, "too many %<present%> modifiers");
+	      parens.skip_until_found_close (parser);
+	      return list;
+	    }
+	  present = true;
+	  c_parser_consume_token (parser);
+	}
+      else if (strcmp ("iterator", p) == 0)
+	{
+	  if (iterators)
+	    {
+	      c_parser_error (parser, "too many %<iterator%> modifiers");
+	      parens.skip_until_found_close (parser);
+	      return list;
+	    }
+	  iterators = c_parser_omp_iterators (parser);
+	  pos += iterator_length - 1;
+	}
+      else
+	{
+	  error_at (token->location,
+		    "%qs clause with modifier other than %<iterator%> or "
+		    "%<present%>",
+		    kind == OMP_CLAUSE_TO ? "to" : "from");
+	  parens.skip_until_found_close (parser);
+	  return list;
+	}
     }
 
+  if (colon_pos)
+    c_parser_require (parser, CPP_COLON, "expected %<:%>");
+
   tree nl = c_parser_omp_variable_list (parser, loc, kind, list);
   parens.skip_until_found_close (parser);
 
@@ -20565,6 +20671,19 @@ c_parser_omp_clause_from_to (c_parser *parser, enum omp_clause_code kind,
     for (tree c = nl; c != list; c = OMP_CLAUSE_CHAIN (c))
       OMP_CLAUSE_MOTION_PRESENT (c) = 1;
 
+  if (iterators)
+    {
+      tree block = pop_scope ();
+      if (iterators == error_mark_node)
+	iterators = NULL_TREE;
+      else
+	TREE_VEC_ELT (iterators, 5) = block;
+    }
+
+  if (iterators)
+    for (tree c = nl; c != list; c = OMP_CLAUSE_CHAIN (c))
+      OMP_CLAUSE_ITERATORS (c) = iterators;
+
   return nl;
 }
 
@@ -27185,6 +27304,30 @@ c_finish_omp_declare_variant (c_parser *parser, tree fndecl, tree parms)
       undeclared_variable (token->location, token->value);
       variant = error_mark_node;
     }
+  else if (TREE_CODE (variant) != FUNCTION_DECL)
+    {
+      error_at (token->location, "variant %qD is not a function",
+		variant);
+      variant = error_mark_node;
+    }
+  else if (fndecl_built_in_p (variant)
+	   && (strncmp (IDENTIFIER_POINTER (DECL_NAME (variant)),
+			"__builtin_", strlen ("__builtin_")) == 0
+	       || strncmp (IDENTIFIER_POINTER (DECL_NAME (variant)),
+			   "__sync_", strlen ("__sync_")) == 0
+	       || strncmp (IDENTIFIER_POINTER (DECL_NAME (variant)),
+			   "__atomic_", strlen ("__atomic_")) == 0))
+    {
+      error_at (token->location, "variant %qD is a built-in",
+		variant);
+      variant = error_mark_node;
+    }
+  else if (variant == fndecl)
+    {
+      error_at (token->location, "variant %qD is the same as base function",
+		variant);
+      variant = error_mark_node;
+    }
 
   c_parser_consume_token (parser);
 
@@ -27258,30 +27401,6 @@ c_finish_omp_declare_variant (c_parser *parser, tree fndecl, tree parms)
 	    goto fail;
 	  ctx = omp_check_context_selector (match_loc, ctx,
 					    OMP_CTX_DECLARE_VARIANT);
-	  if (ctx != error_mark_node && variant != error_mark_node)
-	    {
-	      if (TREE_CODE (variant) != FUNCTION_DECL)
-		{
-		  error_at (token->location, "variant %qD is not a function",
-			    variant);
-		  variant = error_mark_node;
-		}
-	      else if (fndecl_built_in_p (variant)
-		       && (strncmp (IDENTIFIER_POINTER (DECL_NAME (variant)),
-				    "__builtin_", strlen ("__builtin_"))
-			     == 0
-			   || strncmp (IDENTIFIER_POINTER (DECL_NAME (variant)),
-				       "__sync_", strlen ("__sync_"))
-				== 0
-			   || strncmp (IDENTIFIER_POINTER (DECL_NAME (variant)),
-				       "__atomic_", strlen ("__atomic_"))
-				== 0))
-		{
-		  error_at (token->location, "variant %qD is a built-in",
-			    variant);
-		  variant = error_mark_node;
-		}
-	    }
 	}
       else if (ccode == adjust_args)
 	{
@@ -27423,18 +27542,64 @@ c_finish_omp_declare_variant (c_parser *parser, tree fndecl, tree parms)
 
       parens.require_close (parser);
   } while (c_parser_next_token_is_not (parser, CPP_PRAGMA_EOL));
+  if (variant != error_mark_node && !has_match)
+    {
+      c_parser_error (parser, "expected %<match%> clause");
+      variant = error_mark_node;
+    }
   c_parser_skip_to_pragma_eol (parser);
 
-  if ((ctx != error_mark_node && variant != error_mark_node)
+  /* At this point, we have completed parsing of the pragma, now it's
+     on to error checking.  */
+  if (variant == error_mark_node || ctx == error_mark_node)
+    /* Previously diagnosed error.  */
+    return;
+
+  if ((has_adjust_args || append_args_tree)
       && !omp_get_context_selector (ctx, OMP_TRAIT_SET_CONSTRUCT,
-				    OMP_TRAIT_CONSTRUCT_SIMD))
+				    OMP_TRAIT_CONSTRUCT_DISPATCH))
     {
-      bool fail = false;
-      if (append_args_tree)
+      error_at (has_adjust_args ? adjust_args_loc : append_args_loc,
+		"an %qs clause can only be specified if the "
+		"%<dispatch%> selector of the %<construct%> selector "
+		"set appears in the %<match%> clause",
+		has_adjust_args ? "adjust_args" : "append_args");
+      return;
+    }
+
+  if (!omp_get_context_selector (ctx, OMP_TRAIT_SET_CONSTRUCT,
+				 OMP_TRAIT_CONSTRUCT_SIMD))
+    /* Check that the base and variant have compatible types.  */
+    {
+      tree base_type = TREE_TYPE (fndecl);
+      tree variant_type = TREE_TYPE (variant);
+      bool unprototyped_variant
+	= (TYPE_ARG_TYPES (variant_type) == NULL_TREE
+	   && !TYPE_NO_NAMED_ARGS_STDARG_P (variant_type));
+
+      if (append_args_tree
+	  && TYPE_ARG_TYPES (base_type) == NULL_TREE
+	  && !TYPE_NO_NAMED_ARGS_STDARG_P (base_type))
+	{
+	  /* The base function is a pre-C23 unprototyped function.  Without
+	     a prototype, we don't know the offset where the append_args go.
+	     That offset needs to be stored with the append_args in the
+	     variant function attributes, so we cannot presently handle
+	     this case.  */
+	  sorry_at (append_args_loc,
+		    "%<append_args%> with unprototyped base function "
+		    "is not supported yet");
+	  inform (DECL_SOURCE_LOCATION (fndecl),
+		  "base function %qD declared here", fndecl);
+	  return;
+	}
+      else if (append_args_tree)
 	{
+	  /* Find nbase_args, the number of fixed arguments in the base
+	     function.  */
 	  int nappend_args = 0;
 	  int nbase_args = 0;
-	  for (tree t = TYPE_ARG_TYPES (TREE_TYPE (fndecl));
+	  for (tree t = TYPE_ARG_TYPES (base_type);
 	       t && TREE_VALUE (t) != void_type_node; t = TREE_CHAIN (t))
 	    nbase_args++;
 	  for (tree t = append_args_tree; t; t = TREE_CHAIN (t))
@@ -27445,135 +27610,117 @@ c_finish_omp_declare_variant (c_parser *parser, tree fndecl, tree parms)
 	  append_args_tree = build_tree_list (build_int_cst (integer_type_node,
 							     nbase_args),
 					      append_args_tree);
-	  tree args, arg;
-	  args = arg = TYPE_ARG_TYPES (TREE_TYPE (variant));
-	  for (int j = 0; j < nbase_args && arg; j++, arg = TREE_CHAIN (arg))
-	    args = arg;
-	  for (int i = 0; i < nappend_args && arg; i++)
-	    arg = TREE_CHAIN (arg);
-	  tree saved_args;
-	  if (nbase_args && args)
-	    {
-	      saved_args = TREE_CHAIN (args);
-	      TREE_CHAIN (args) = arg;
+
+	  /* Give a specific diagnostic if the append_args parameters
+	     of the variant are of the wrong type, or missing.  The
+	     compatible types test below could fail to detect this if
+	     the variant is a varargs function.  */
+	  if (!unprototyped_variant)
+	    {
+	      tree args = TYPE_ARG_TYPES (variant_type);
+	      for (int i = 0; args && i < nbase_args;
+		   i++, args = TREE_CHAIN (args))
+		;
+	      for (int i = 0; i < nappend_args; i++, args = TREE_CHAIN (args))
+		if (!args || !c_omp_interop_t_p (TREE_VALUE (args)))
+		  {
+		    error_at (DECL_SOURCE_LOCATION (variant),
+			      "argument %d of %qD must be of "
+			      "%<omp_interop_t%>",
+			      nbase_args + i + 1, variant);
+		    inform (append_args_loc,
+			    "%<append_args%> specified here");
+		    return;
+		  }
 	    }
-	  else
+
+	  /* Perform the "implementation defined transformation" on the type
+	     of the base function to add the append_args before checking it
+	     for compatibility with the function variant's type.  */
+	  tree args = TYPE_ARG_TYPES (base_type);
+	  tree newargs = NULL_TREE;
+	  tree lastarg = NULL_TREE;
+	  for (int j = 0; j < nbase_args; j++, args = TREE_CHAIN (args))
 	    {
-	      saved_args = args;
-	      TYPE_ARG_TYPES (TREE_TYPE (variant)) = arg;
-	      TYPE_NO_NAMED_ARGS_STDARG_P (TREE_TYPE (variant)) = 1;
+	      tree t = tree_cons (TREE_PURPOSE (args),
+				  TREE_VALUE (args), NULL_TREE);
+	      if (lastarg)
+		TREE_CHAIN (lastarg) = t;
+	      else
+		newargs = t;
+	      lastarg = t;
 	    }
-	  if (!comptypes (TREE_TYPE (fndecl), TREE_TYPE (variant)))
-	    fail = true;
-	  if (nbase_args && args)
-	    TREE_CHAIN (args) = saved_args;
-	  else
+	  tree type = lookup_name (get_identifier ("omp_interop_t"));
+	  type = type ? TREE_TYPE (type) : pointer_sized_int_node;
+	  for (int j = 0; j < nappend_args; j++)
 	    {
-	      TYPE_ARG_TYPES (TREE_TYPE (variant)) = saved_args;
-	      TYPE_NO_NAMED_ARGS_STDARG_P (TREE_TYPE (variant)) = 0;
+	      tree t = tree_cons (NULL_TREE, type, NULL_TREE);
+	      if (lastarg)
+		TREE_CHAIN (lastarg) = t;
+	      else
+		newargs = t;
+	      lastarg = t;
 	    }
-	  arg = saved_args;
-	  if (!fail)
-	    for (int i = 0; i < nappend_args; i++, arg = TREE_CHAIN (arg))
-	      if (!arg || !c_omp_interop_t_p (TREE_VALUE (arg)))
-		{
-		  error_at (DECL_SOURCE_LOCATION (variant),
-			    "argument %d of %qD must be of %<omp_interop_t%>",
-			    nbase_args + i + 1, variant);
-		  inform (append_args_loc, "%<append_args%> specified here");
-		  break;
-		}
-	}
-      else
-	{
-	  if (comptypes (TREE_TYPE (fndecl), TREE_TYPE (variant)))
+	  TREE_CHAIN (lastarg) = args;
+
+	  /* Temporarily stuff newargs into the original base_type.  */
+	  tree saveargs = TYPE_ARG_TYPES (base_type);
+	  TYPE_ARG_TYPES (base_type) = newargs;
+	  bool fail = !comptypes (base_type, variant_type);
+	  TYPE_ARG_TYPES (base_type) = saveargs;
+
+	  if (fail)
 	    {
-	      if (TYPE_ARG_TYPES (TREE_TYPE (variant)) == NULL_TREE
-		  && TYPE_ARG_TYPES (TREE_TYPE (fndecl)) != NULL_TREE)
-		{
-		  if (!append_args_tree)
-		    TYPE_ARG_TYPES (TREE_TYPE (variant))
-		      = TYPE_ARG_TYPES (TREE_TYPE (fndecl));
-		  else
-		    {
-		      tree new_args = NULL_TREE;
-		      tree arg, last_arg = NULL_TREE;
-		      for (arg = TYPE_ARG_TYPES (TREE_TYPE (fndecl));
-			   arg && arg != void_type_node; arg = TREE_CHAIN (arg))
-			{
-			  if (new_args == NULL_TREE)
-			    new_args = last_arg = copy_node (arg);
-			  else
-			    {
-			      TREE_CHAIN (last_arg) = copy_node (arg);
-			      last_arg = TREE_CHAIN (last_arg);
-			    }
-			}
-		      for (tree t3 = append_args_tree; t3; t3 = TREE_CHAIN (t3))
-			{
-			  tree type = lookup_name (get_identifier ("omp_interop_t"));
-			  type = type ? TREE_TYPE (type) : ptr_type_node;
-			  last_arg = tree_cons (NULL_TREE, type, last_arg);
-			}
-		      TREE_CHAIN (last_arg) = arg;
-		      TYPE_ARG_TYPES (TREE_TYPE (variant)) = new_args;
-		    }
-		}
+	      error_at (token->location,
+			"variant %qD and base %qD have incompatible types "
+			"after %<append_args%> adjustment",
+			variant, fndecl);
+	      inform (DECL_SOURCE_LOCATION (variant),
+		      "%<declare variant%> candidate %qD declared here",
+		      variant);
+	      return;
 	    }
-	  else
-	    fail = true;
+	  else if (unprototyped_variant)
+	    /* If we've got an unprototyped variant, copy the transformed
+	       base arg types to the variant.  This is needed later by
+	       modify_call_for_omp_dispatch.  */
+	    TYPE_ARG_TYPES (variant_type) = newargs;
 	}
-      if (fail)
-	{
-	  error_at (token->location,
-		    "variant %qD and base %qD have incompatible types",
-		    variant, fndecl);
-	  variant = error_mark_node;
-	}
-    }
-  if (ctx != error_mark_node && variant != error_mark_node)
-    {
-      C_DECL_USED (variant) = 1;
-      tree construct = omp_get_context_selector_list (ctx,
-						      OMP_TRAIT_SET_CONSTRUCT);
-      omp_mark_declare_variant (match_loc, variant, construct);
-      if (omp_context_selector_matches (ctx, NULL_TREE, false))
+      else  /* No append_args present.  */
 	{
-	  tree attr = tree_cons (get_identifier ("omp declare variant base"),
-				 build_tree_list (variant, ctx),
-				 DECL_ATTRIBUTES (fndecl));
-	  DECL_ATTRIBUTES (fndecl) = attr;
+	  if (!comptypes (base_type, variant_type))
+	    {
+	      error_at (token->location,
+			"variant %qD and base %qD have incompatible types",
+			variant, fndecl);
+	      inform (DECL_SOURCE_LOCATION (variant),
+		      "%<declare variant%> candidate %qD declared here",
+		      variant);
+	      return;
+	    }
+	  else if (TYPE_ARG_TYPES (variant_type) == NULL_TREE
+		   && !TYPE_NO_NAMED_ARGS_STDARG_P (variant_type)
+		   && TYPE_ARG_TYPES (base_type) != NULL_TREE)
+	    /* If we've got an unprototyped variant but the base has
+	       a prototype, copy the base arg types to the variant.  */
+	    TYPE_ARG_TYPES (variant_type) = TYPE_ARG_TYPES (base_type);
 	}
     }
 
-  if (has_adjust_args || append_args_tree)
+  /* If we made it here, store the parsed information.  */
+  C_DECL_USED (variant) = 1;
+  tree construct = omp_get_context_selector_list (ctx,
+						  OMP_TRAIT_SET_CONSTRUCT);
+  omp_mark_declare_variant (match_loc, variant, construct);
+  if (omp_context_selector_matches (ctx, NULL_TREE, false))
     {
-      if (!has_match)
-	{
-	  error_at (has_adjust_args ? adjust_args_loc : append_args_loc,
-		    "an %qs clause requires a %<match%> clause",
-		    has_adjust_args ? "adjust_args" : "append_args");
-	}
-      else if (ctx != error_mark_node && variant != error_mark_node)
-	{
-	  tree attr = lookup_attribute ("omp declare variant base",
-					DECL_ATTRIBUTES (fndecl));
-	  if (attr != NULL_TREE)
-	    {
-	      tree ctx = TREE_VALUE (TREE_VALUE (attr));
-	      if (!omp_get_context_selector (ctx, OMP_TRAIT_SET_CONSTRUCT,
-					     OMP_TRAIT_CONSTRUCT_DISPATCH))
-		error_at (has_adjust_args ? adjust_args_loc : append_args_loc,
-			  "an %qs clause can only be specified if the "
-			  "%<dispatch%> selector of the %<construct%> selector "
-			  "set appears in the %<match%> clause",
-			  has_adjust_args ? "adjust_args" : "append_args");
-	    }
-	}
+      tree attr = tree_cons (get_identifier ("omp declare variant base"),
+			     build_tree_list (variant, ctx),
+			     DECL_ATTRIBUTES (fndecl));
+      DECL_ATTRIBUTES (fndecl) = attr;
     }
 
-  if ((ctx != error_mark_node && variant != error_mark_node)
-      && (need_device_ptr_list || append_args_tree))
+  if (need_device_ptr_list || append_args_tree)
     {
       tree variant_decl = tree_strip_nop_conversions (variant);
       tree t = build_tree_list (need_device_ptr_list,