PR c/71171: Fix uninitialized source_range in c_parser_postfix_expression

A common way for a c_expr to have an uninitialized src_range is in
error-handling, where the "value" field is set to error_mark_node
without touching the src_range, leading to complaints from valgrind.

This patch introduces a new method c_expr::set_error which sets
the value to error_mark_node whilst initializing the src_range to
UNKNOWN_LOCATION.

This fixes the valgrind issue seen in PR c/71171, along with various
other related issues seen when running the testsuite using the
checker patch I posted here:
  https://gcc.gnu.org/ml/gcc-patches/2015-12/msg00887.html
(this checker still doesn't fully work yet, but it seems to be good
for easily detecting these issues without needing Valgrind).

gcc/c/ChangeLog:
	PR c/71171
	* c-parser.c (c_parser_generic_selection): Use c_expr::set_error
	in error-handling.
	(c_parser_postfix_expression): Likewise.
	* c-tree.h (c_expr::set_error): New method.
	* c-typeck.c (parser_build_binary_op): In error-handling, ensure
	that result's range is initialized.

From-SVN: r236488

diff --git a/gcc/c/ChangeLog b/gcc/c/ChangeLog
index 476718fa631a500a6fc9a01a3356a16e8430c0b9..5731048b087e2a1100a637659a0519c3b476d32e 100644 (file)
--- a/gcc/c/ChangeLog
+++ b/gcc/c/ChangeLog
@@ -1,3 +1,13 @@
+2016-05-19  David Malcolm  <dmalcolm@redhat.com>
+
+       PR c/71171
+       * c-parser.c (c_parser_generic_selection): Use c_expr::set_error
+       in error-handling.
+       (c_parser_postfix_expression): Likewise.
+       * c-tree.h (c_expr::set_error): New method.
+       * c-typeck.c (parser_build_binary_op): In error-handling, ensure
+       that result's range is initialized.
+
 2016-05-17  James Greenhalgh  <james.greenhalgh@arm.com>
 
        * c-typeck.c (parser_build_unary_op): Fix formatting.

diff --git a/gcc/c/c-parser.c b/gcc/c/c-parser.c
index 6523c08d63f0975c6f7bce2578a5ed7a9727f9e8..c2c83143c0518585b8350aa063f6c5de9a1ad16d 100644 (file)
--- a/gcc/c/c-parser.c
+++ b/gcc/c/c-parser.c
@@ -7194,7 +7194,7 @@ c_parser_generic_selection (c_parser *parser)
 
   error_expr.original_code = ERROR_MARK;
   error_expr.original_type = NULL;
-  error_expr.value = error_mark_node;
+  error_expr.set_error ();
   matched_assoc.type_location = UNKNOWN_LOCATION;
   matched_assoc.type = NULL_TREE;
   matched_assoc.expression = error_expr;
@@ -7505,13 +7505,13 @@ c_parser_postfix_expression (c_parser *parser)
            gcc_assert (c_dialect_objc ());
            if (!c_parser_require (parser, CPP_DOT, "expected %<.%>"))
              {
-               expr.value = error_mark_node;
+               expr.set_error ();
                break;
              }
            if (c_parser_next_token_is_not (parser, CPP_NAME))
              {
                c_parser_error (parser, "expected identifier");
-               expr.value = error_mark_node;
+               expr.set_error ();
                break;
              }
            c_token *component_tok = c_parser_peek_token (parser);
@@ -7525,7 +7525,7 @@ c_parser_postfix_expression (c_parser *parser)
          }
        default:
          c_parser_error (parser, "expected expression");
-         expr.value = error_mark_node;
+         expr.set_error ();
          break;
        }
       break;
@@ -7547,7 +7547,7 @@ c_parser_postfix_expression (c_parser *parser)
              parser->error = true;
              c_parser_skip_until_found (parser, CPP_CLOSE_BRACE, NULL);
              c_parser_skip_until_found (parser, CPP_CLOSE_PAREN, NULL);
-             expr.value = error_mark_node;
+             expr.set_error ();
              break;
            }
          stmt = c_begin_stmt_expr ();
@@ -7576,7 +7576,7 @@ c_parser_postfix_expression (c_parser *parser)
                                     "expected %<)%>");
          if (type_name == NULL)
            {
-             expr.value = error_mark_node;
+             expr.set_error ();
            }
          else
            expr = c_parser_postfix_expression_after_paren_type (parser,
@@ -7636,7 +7636,7 @@ c_parser_postfix_expression (c_parser *parser)
            c_parser_consume_token (parser);
            if (!c_parser_require (parser, CPP_OPEN_PAREN, "expected %<(%>"))
              {
-               expr.value = error_mark_node;
+               expr.set_error ();
                break;
              }
            e1 = c_parser_expr_no_commas (parser, NULL);
@@ -7645,7 +7645,7 @@ c_parser_postfix_expression (c_parser *parser)
            if (!c_parser_require (parser, CPP_COMMA, "expected %<,%>"))
              {
                c_parser_skip_until_found (parser, CPP_CLOSE_PAREN, NULL);
-               expr.value = error_mark_node;
+               expr.set_error ();
                break;
              }
            loc = c_parser_peek_token (parser)->location;
@@ -7655,7 +7655,7 @@ c_parser_postfix_expression (c_parser *parser)
                                       "expected %<)%>");
            if (t1 == NULL)
              {
-               expr.value = error_mark_node;
+               expr.set_error ();
              }
            else
              {
@@ -7677,7 +7677,7 @@ c_parser_postfix_expression (c_parser *parser)
          c_parser_consume_token (parser);
          if (!c_parser_require (parser, CPP_OPEN_PAREN, "expected %<(%>"))
            {
-             expr.value = error_mark_node;
+             expr.set_error ();
              break;
            }
          t1 = c_parser_type_name (parser);
@@ -7688,7 +7688,7 @@ c_parser_postfix_expression (c_parser *parser)
          if (parser->error)
            {
              c_parser_skip_until_found (parser, CPP_CLOSE_PAREN, NULL);
-             expr.value = error_mark_node;
+             expr.set_error ();
              break;
            }
 
@@ -7777,7 +7777,7 @@ c_parser_postfix_expression (c_parser *parser)
                                            &cexpr_list, true,
                                            &close_paren_loc))
              {
-               expr.value = error_mark_node;
+               expr.set_error ();
                break;
              }
 
@@ -7785,7 +7785,7 @@ c_parser_postfix_expression (c_parser *parser)
              {
                error_at (loc, "wrong number of arguments to "
                               "%<__builtin_choose_expr%>");
-               expr.value = error_mark_node;
+               expr.set_error ();
                break;
              }
 
@@ -7810,25 +7810,25 @@ c_parser_postfix_expression (c_parser *parser)
          c_parser_consume_token (parser);
          if (!c_parser_require (parser, CPP_OPEN_PAREN, "expected %<(%>"))
            {
-             expr.value = error_mark_node;
+             expr.set_error ();
              break;
            }
          t1 = c_parser_type_name (parser);
          if (t1 == NULL)
            {
-             expr.value = error_mark_node;
+             expr.set_error ();
              break;
            }
          if (!c_parser_require (parser, CPP_COMMA, "expected %<,%>"))
            {
              c_parser_skip_until_found (parser, CPP_CLOSE_PAREN, NULL);
-             expr.value = error_mark_node;
+             expr.set_error ();
              break;
            }
          t2 = c_parser_type_name (parser);
          if (t2 == NULL)
            {
-             expr.value = error_mark_node;
+             expr.set_error ();
              break;
            }
          {
@@ -7840,7 +7840,7 @@ c_parser_postfix_expression (c_parser *parser)
            e2 = groktypename (t2, NULL, NULL);
            if (e1 == error_mark_node || e2 == error_mark_node)
              {
-               expr.value = error_mark_node;
+               expr.set_error ();
                break;
              }
 
@@ -7865,14 +7865,14 @@ c_parser_postfix_expression (c_parser *parser)
                                            &cexpr_list, false,
                                            &close_paren_loc))
              {
-               expr.value = error_mark_node;
+               expr.set_error ();
                break;
              }
            if (vec_safe_length (cexpr_list) != 2)
              {
                error_at (loc, "wrong number of arguments to "
                               "%<__builtin_call_with_static_chain%>");
-               expr.value = error_mark_node;
+               expr.set_error ();
                break;
              }
 
@@ -7907,7 +7907,7 @@ c_parser_postfix_expression (c_parser *parser)
                                            &cexpr_list, false,
                                            &close_paren_loc))
              {
-               expr.value = error_mark_node;
+               expr.set_error ();
                break;
              }
 
@@ -7915,7 +7915,7 @@ c_parser_postfix_expression (c_parser *parser)
              {
                error_at (loc, "wrong number of arguments to "
                               "%<__builtin_complex%>");
-               expr.value = error_mark_node;
+               expr.set_error ();
                break;
              }
 
@@ -7937,7 +7937,7 @@ c_parser_postfix_expression (c_parser *parser)
              {
                error_at (loc, "%<__builtin_complex%> operand "
                          "not of real binary floating-point type");
-               expr.value = error_mark_node;
+               expr.set_error ();
                break;
              }
            if (TYPE_MAIN_VARIANT (TREE_TYPE (e1_p->value))
@@ -7945,7 +7945,7 @@ c_parser_postfix_expression (c_parser *parser)
              {
                error_at (loc,
                          "%<__builtin_complex%> operands of different types");
-               expr.value = error_mark_node;
+               expr.set_error ();
                break;
              }
            pedwarn_c90 (loc, OPT_Wpedantic,
@@ -7971,7 +7971,7 @@ c_parser_postfix_expression (c_parser *parser)
                                            &cexpr_list, false,
                                            &close_paren_loc))
              {
-               expr.value = error_mark_node;
+               expr.set_error ();
                break;
              }
 
@@ -7994,7 +7994,7 @@ c_parser_postfix_expression (c_parser *parser)
              {
                error_at (loc, "wrong number of arguments to "
                               "%<__builtin_shuffle%>");
-               expr.value = error_mark_node;
+               expr.set_error ();
              }
            set_c_expr_source_range (&expr, loc, close_paren_loc);
            break;
@@ -8004,7 +8004,7 @@ c_parser_postfix_expression (c_parser *parser)
          c_parser_consume_token (parser);
          if (!c_parser_require (parser, CPP_OPEN_PAREN, "expected %<(%>"))
            {
-             expr.value = error_mark_node;
+             expr.set_error ();
              break;
            }
          {
@@ -8021,14 +8021,14 @@ c_parser_postfix_expression (c_parser *parser)
          c_parser_consume_token (parser);
          if (!c_parser_require (parser, CPP_OPEN_PAREN, "expected %<(%>"))
            {
-             expr.value = error_mark_node;
+             expr.set_error ();
              break;
            }
          if (c_parser_next_token_is_not (parser, CPP_NAME))
            {
              c_parser_error (parser, "expected identifier");
              c_parser_skip_until_found (parser, CPP_CLOSE_PAREN, NULL);
-             expr.value = error_mark_node;
+             expr.set_error ();
              break;
            }
          {
@@ -8047,13 +8047,13 @@ c_parser_postfix_expression (c_parser *parser)
          c_parser_consume_token (parser);
          if (!c_parser_require (parser, CPP_OPEN_PAREN, "expected %<(%>"))
            {
-             expr.value = error_mark_node;
+             expr.set_error ();
              break;
            }
          t1 = c_parser_type_name (parser);
          if (t1 == NULL)
            {
-             expr.value = error_mark_node;
+             expr.set_error ();
              c_parser_skip_until_found (parser, CPP_CLOSE_PAREN, NULL);
              break;
            }
@@ -8076,7 +8076,7 @@ c_parser_postfix_expression (c_parser *parser)
              error_at (loc, "-fcilkplus must be enabled to use "
                        "%<_Cilk_spawn%>");
              expr = c_parser_cast_expression (parser, NULL);
-             expr.value = error_mark_node;
+             expr.set_error ();
            }
          else if (c_parser_peek_token (parser)->keyword == RID_CILK_SPAWN)
            {
@@ -8095,7 +8095,7 @@ c_parser_postfix_expression (c_parser *parser)
          break;
        default:
          c_parser_error (parser, "expected expression");
-         expr.value = error_mark_node;
+         expr.set_error ();
          break;
        }
       break;
@@ -8116,7 +8116,7 @@ c_parser_postfix_expression (c_parser *parser)
       /* Else fall through to report error.  */
     default:
       c_parser_error (parser, "expected expression");
-      expr.value = error_mark_node;
+      expr.set_error ();
       break;
     }
   return c_parser_postfix_expression_after_primary
@@ -8331,7 +8331,7 @@ c_parser_postfix_expression_after_primary (c_parser *parser,
          else
            {
              c_parser_error (parser, "expected identifier");
-             expr.value = error_mark_node;
+             expr.set_error ();
              expr.original_code = ERROR_MARK;
               expr.original_type = NULL;
              return expr;
@@ -8363,7 +8363,7 @@ c_parser_postfix_expression_after_primary (c_parser *parser,
          else
            {
              c_parser_error (parser, "expected identifier");
-             expr.value = error_mark_node;
+             expr.set_error ();
              expr.original_code = ERROR_MARK;
              expr.original_type = NULL;
              return expr;

diff --git a/gcc/c/c-tree.h b/gcc/c/c-tree.h
index 4a0236d87a9e3939d49dc93114734b50b751dea8..444e9a4777e8a7bfbac468f3e9a28ef846f8af1b 100644 (file)
--- a/gcc/c/c-tree.h
+++ b/gcc/c/c-tree.h
@@ -143,6 +143,15 @@ struct c_expr
      of this expression.  */
   location_t get_start () const { return src_range.m_start; }
   location_t get_finish () const { return src_range.m_finish; }
+
+  /* Set the value to error_mark_node whilst ensuring that src_range
+     is initialized.  */
+  void set_error ()
+  {
+    value = error_mark_node;
+    src_range.m_start = UNKNOWN_LOCATION;
+    src_range.m_finish = UNKNOWN_LOCATION;
+  }
 };
 
 /* Type alias for struct c_expr. This allows to use the structure

diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c
index 8297aae4bd848d11a0e690291427758185f7f727..30102404284295589e8f2ad70726aa4102ca9c42 100644 (file)
--- a/gcc/c/c-typeck.c
+++ b/gcc/c/c-typeck.c
@@ -3533,7 +3533,12 @@ parser_build_binary_op (location_t location, enum tree_code code,
   result.original_type = NULL;
 
   if (TREE_CODE (result.value) == ERROR_MARK)
-    return result;
+    {
+      set_c_expr_source_range (&result,
+                              arg1.get_start (),
+                              arg2.get_finish ());
+      return result;
+    }
 
   if (location != UNKNOWN_LOCATION)
     protected_set_expr_location (result.value, location);