re PR c++/32121 (C++ front-end accepts invalid __label__ declarations)

PR c++/32121
	* parser.c (cp_parser_compound_statement): Handle label-declarations
	at the beginning of the compound statement.
	(cp_parser_block_declaration): Issue diagnostics about __label__
	not at the beginning of a block.

	* g++.dg/ext/label4.C: Adjust error regexp.
	* g++.dg/ext/label6.C: Adjust error regexp.
	* g++.dg/ext/label7.C: New test.
	* g++.dg/ext/label8.C: New test.
	* g++.dg/ext/label9.C: New test.

From-SVN: r129253

gcc/cp/ChangeLog

@@ -1,3 +1,11 @@
+2007-10-12  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/32121
+	* parser.c (cp_parser_compound_statement): Handle label-declarations
+	at the beginning of the compound statement.
+	(cp_parser_block_declaration): Issue diagnostics about __label__
+	not at the beginning of a block.
+
 2007-10-11  Paolo Carlini  <pcarlini@suse.de>
 
 	PR c++/33461

gcc/cp/parser.c

@@ -6821,6 +6821,15 @@ cp_parser_expression_statement (cp_parser* parser, tree in_statement_expr)
    compound-statement:
      { statement-seq [opt] }
 
+   GNU extension:
+
+   compound-statement:
+     { label-declaration-seq [opt] statement-seq [opt] }
+
+   label-declaration-seq:
+     label-declaration
+     label-declaration-seq label-declaration
+
    Returns a tree representing the statement.  */
 
 static tree
@@ -6834,6 +6843,9 @@ cp_parser_compound_statement (cp_parser *parser, tree in_statement_expr,
     return error_mark_node;
   /* Begin the compound-statement.  */
   compound_stmt = begin_compound_stmt (in_try ? BCS_TRY_BLOCK : 0);
+  /* If the next keyword is `__label__' we have a label declaration.  */
+  while (cp_lexer_next_token_is_keyword (parser->lexer, RID_LABEL))
+    cp_parser_label_declaration (parser);
   /* Parse an (optional) statement-seq.  */
   cp_parser_statement_seq_opt (parser, in_statement_expr);
   /* Finish the compound-statement.  */
@@ -7711,7 +7723,6 @@ cp_parser_declaration (cp_parser* parser)
 
    block-declaration:
      __extension__ block-declaration
-     label-declaration
 
    C++0x Extension:
 
@@ -7772,12 +7783,16 @@ cp_parser_block_declaration (cp_parser *parser,
 	cp_parser_using_declaration (parser,
 				     /*access_declaration_p=*/false);
     }
-  /* If the next keyword is `__label__' we have a label declaration.  */
+  /* If the next keyword is `__label__' we have a misplaced label
+     declaration.  */
   else if (token1->keyword == RID_LABEL)
     {
-      if (statement_p)
-	cp_parser_commit_to_tentative_parse (parser);
-      cp_parser_label_declaration (parser);
+      cp_lexer_consume_token (parser->lexer);
+      error ("%<__label__%> not at the beginning of a block");
+      cp_parser_skip_to_end_of_statement (parser);
+      /* If the next token is now a `;', consume it.  */
+      if (cp_lexer_next_token_is (parser->lexer, CPP_SEMICOLON))
+	cp_lexer_consume_token (parser->lexer);
     }
   /* If the next token is `static_assert' we have a static assertion.  */
   else if (token1->keyword == RID_STATIC_ASSERT)

gcc/testsuite/ChangeLog

@@ -1,3 +1,12 @@
+2007-10-12  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/32121
+	* g++.dg/ext/label4.C: Adjust error regexp.
+	* g++.dg/ext/label6.C: Adjust error regexp.
+	* g++.dg/ext/label7.C: New test.
+	* g++.dg/ext/label8.C: New test.
+	* g++.dg/ext/label9.C: New test.
+
 2007-10-11  Kenneth Zadeck <zadeck@naturalbridge.com>
 
 	PR middle-end/33676

gcc/testsuite/g++.dg/ext/label4.C

@@ -3,4 +3,4 @@
 
 // { dg-do compile }
 
-__label__ *l;  // { dg-error "before" }
+__label__ *l;  // { dg-error "not at the beginning of" }

gcc/testsuite/g++.dg/ext/label6.C

@@ -1,3 +1,3 @@
 // PR c++/32108
 
-__label__ L; // { dg-error "function scopes" }
+__label__ L; // { dg-error "not at the beginning" }

gcc/testsuite/g++.dg/ext/label7.C

@@ -0,0 +1,12 @@
+// PR c++/32121
+// { dg-do compile }
+
+int f (void)
+{
+  a:;
+  __label__ a;	// { dg-error "not at the beginning" }
+  int b;
+  __label__ c;	// { dg-error "not at the beginning" }
+  a:;		// { dg-error "duplicate label" }
+  c:;
+}

gcc/testsuite/g++.dg/ext/label8.C

@@ -0,0 +1,22 @@
+// PR c++/32121
+// { dg-do compile }
+
+int f (void)
+{
+  __label__ a, b;
+  __label__ c;
+  a:;
+  b:;
+  c:;
+  {
+    __label__ d;
+    d:;
+    if (0)
+      {
+	__label__ e;
+	__label__ f;
+	f:;
+	e:;
+      }
+  }
+}

gcc/testsuite/g++.dg/ext/label9.C

@@ -0,0 +1,10 @@
+// PR c++/32121
+// { dg-do compile }
+
+int f (void)
+{
+  while (1)
+    __label__ a;	// { dg-error "not at the beginning" }
+  for (;;)
+    __label__ b;	// { dg-error "not at the beginning" }
+}