OpenMP: Fix ICE and other issues in C/C++ metadirective error recovery.

The new testcase included in this patch used to ICE in gcc after
diagnosing the first error, and in g++ it only diagnosed the error in
the first metadirective, ignoring the second one.  The solution is to
make error recovery in the C front end more like that in the C++ front
end, and remove the code in both front ends that previously tried to
skip all the way over the following statement (instead of just to the
end of the metadirective pragma) after an error.

gcc/c/ChangeLog
	* c-parser.cc (c_parser_skip_to_closing_brace): New, copied from
	the equivalent function in the C++ front end.
	(c_parser_skip_to_end_of_block_or_statement): Pass false to
	the error flag.
	(c_parser_omp_context_selector): Immediately return error_mark_node
	after giving an error that the integer trait property is invalid,
	similarly to C++ front end.
	(c_parser_omp_context_selector_specification): Likewise handle
	error return from c_parser_omp_context_selector similarly to C++.
	(c_parser_omp_metadirective): Do not call
	c_parser_skip_to_end_of_block_or_statement after an error.

gcc/cp/ChangeLog
	* parser.cc (cp_parser_omp_metadirective): Do not call
	cp_parser_skip_to_end_of_block_or_statement after an error.

gcc/testsuite/ChangeLog
	* c-c++-common/gomp/declare-variant-2.c: Adjust patterns now that
	C and C++ now behave similarly.
	* c-c++-common/gomp/metadirective-error-recovery.c: New.

(cherry picked from commit 33b65e4d1c83808b54cd6b3fc97ebacc522b125d)

1 files changed, 62 insertions, 20 deletions

diff --git a/gcc/c/c-parser.cc b/gcc/c/c-parser.cc
index d825e05..93cc7b0 100644
--- a/gcc/c/c-parser.cc
+++ b/gcc/c/c-parser.cc
@@ -1418,6 +1418,51 @@ c_parser_skip_to_end_of_parameter (c_parser *parser)
   parser->error = false;
 }
 
+/* Skip tokens until a non-nested closing curly brace is the next
+   token, or there are no more tokens. Return true in the first case,
+   false otherwise.  */
+
+static bool
+c_parser_skip_to_closing_brace (c_parser *parser)
+{
+  unsigned nesting_depth = 0;
+
+  while (true)
+    {
+      c_token *token = c_parser_peek_token (parser);
+
+      switch (token->type)
+	{
+	case CPP_PRAGMA_EOL:
+	  if (!parser->in_pragma)
+	    break;
+	  /* FALLTHRU */
+	case CPP_EOF:
+	  /* If we've run out of tokens, stop.  */
+	  return false;
+
+	case CPP_CLOSE_BRACE:
+	  /* If the next token is a non-nested `}', then we have reached
+	     the end of the current block.  */
+	  if (nesting_depth-- == 0)
+	    return true;
+	  break;
+
+	case CPP_OPEN_BRACE:
+	  /* If it the next token is a `{', then we are entering a new
+	     block.  Consume the entire block.  */
+	  ++nesting_depth;
+	  break;
+
+	default:
+	  break;
+	}
+
+      /* Consume the token.  */
+      c_parser_consume_token (parser);
+    }
+}
+
 /* Expect to be at the end of the pragma directive and consume an
    end of line marker.  */
 
@@ -1533,7 +1578,7 @@ c_parser_skip_to_end_of_block_or_statement (c_parser *parser,
 	     here for secondary error recovery, after parser->error has
 	     been cleared.  */
 	  c_parser_consume_pragma (parser);
-	  c_parser_skip_to_pragma_eol (parser);
+	  c_parser_skip_to_pragma_eol (parser, false);
 	  parser->error = save_error;
 	  continue;
 
@@ -26772,19 +26817,17 @@ c_parser_omp_context_selector (c_parser *parser, enum omp_tss_code set,
 	    case OMP_TRAIT_PROPERTY_DEV_NUM_EXPR:
 	    case OMP_TRAIT_PROPERTY_BOOL_EXPR:
 	      t = c_parser_expr_no_commas (parser, NULL).value;
-	      if (t != error_mark_node)
+	      if (t == error_mark_node)
+		return error_mark_node;
+	      mark_exp_read (t);
+	      t = c_fully_fold (t, false, NULL);
+	      if (!INTEGRAL_TYPE_P (TREE_TYPE (t)))
 		{
-		  mark_exp_read (t);
-		  t = c_fully_fold (t, false, NULL);
-		  if (!INTEGRAL_TYPE_P (TREE_TYPE (t)))
-		    error_at (token->location,
-			      "property must be integer expression");
-		  else
-		    properties = make_trait_property (NULL_TREE, t,
-						      properties);
+		  error_at (token->location,
+			    "property must be integer expression");
+		  return error_mark_node;
 		}
-	      else
-		return error_mark_node;
+	      properties = make_trait_property (NULL_TREE, t, properties);
 	      break;
 	    case OMP_TRAIT_PROPERTY_CLAUSE_LIST:
 	      if (sel == OMP_TRAIT_CONSTRUCT_SIMD)
@@ -26886,11 +26929,14 @@ c_parser_omp_context_selector_specification (c_parser *parser, tree parms)
 
       tree selectors = c_parser_omp_context_selector (parser, set, parms);
       if (selectors == error_mark_node)
-	ret = error_mark_node;
+	{
+	  c_parser_skip_to_closing_brace (parser);
+	  ret = error_mark_node;
+	}
       else if (ret != error_mark_node)
 	ret = make_trait_set_selector (set, selectors, ret);
 
-      braces.skip_until_found_close (parser);
+      braces.require_close (parser);
 
       if (c_parser_next_token_is (parser, CPP_COMMA))
 	c_parser_consume_token (parser);
@@ -29095,7 +29141,6 @@ c_parser_omp_metadirective (c_parser *parser, bool *if_p)
 	    {
 	      error_at (match_loc, "too many %<otherwise%> or %<default%> "
 			"clauses in %<metadirective%>");
-	      c_parser_skip_to_end_of_block_or_statement (parser, true);
 	      goto error;
 	    }
 	  default_seen = true;
@@ -29104,14 +29149,12 @@ c_parser_omp_metadirective (c_parser *parser, bool *if_p)
 	{
 	  error_at (match_loc, "%<otherwise%> or %<default%> clause "
 		    "must appear last in %<metadirective%>");
-	  c_parser_skip_to_end_of_block_or_statement (parser, true);
 	  goto error;
 	}
       if (!default_p && strcmp (p, "when") != 0)
 	{
 	  error_at (match_loc, "%qs is not valid for %qs",
 		    p, "metadirective");
-	  c_parser_skip_to_end_of_block_or_statement (parser, true);
 	  goto error;
 	}
 
@@ -29179,7 +29222,6 @@ c_parser_omp_metadirective (c_parser *parser, bool *if_p)
       if (i == 0)
 	{
 	  error_at (loc, "expected directive name");
-	  c_parser_skip_to_end_of_block_or_statement (parser, true);
 	  goto error;
 	}
 
@@ -29388,9 +29430,9 @@ c_parser_omp_metadirective (c_parser *parser, bool *if_p)
   return;
 
 error:
+  /* Skip the metadirective pragma.  Do not skip the metadirective body.  */
   if (parser->in_pragma)
-    c_parser_skip_to_pragma_eol (parser);
-  c_parser_skip_to_end_of_block_or_statement (parser, true);
+    c_parser_skip_to_pragma_eol (parser, false);
 }
 
 /* Main entry point to parsing most OpenMP pragmas.  */