invoke.texi (Warning Options): Document that -Wempty-body also checks for and…

invoke.texi (Warning Options): Document that -Wempty-body also checks for and while statements in C++.

	* doc/invoke.texi (Warning Options): Document that -Wempty-body
	also checks for and while statements in C++.

cp:
	* parser.c (check_empty_body): Add.
	(cp_parser_iteration_statement): Add call to check_empty_body.

testsuite:
	* g++.old-deja/g++.mike/empty.C: Add.

From-SVN: r124534

gcc/ChangeLog

+2007-05-07  Mike Stump  <mrs@apple.com>
+
+	* doc/invoke.texi (Warning Options): Document that -Wempty-body
+	also checks for and while statements in C++.
+
 2007-05-07  Nathan Froyd  <froydnj@codesourcery.com>
 
 	* gcc.c (at_file_supplied): New variable.

gcc/cp/ChangeLog

+2007-05-07  Mike Stump  <mrs@apple.com>
+
+	* parser.c (check_empty_body): Add.
+	(cp_parser_iteration_statement): Add call to check_empty_body.
+
 2007-05-05  Geoffrey Keating  <geoffk@apple.com>
 
 	PR 31775

gcc/cp/parser.c

@@ -7065,6 +7065,51 @@ cp_parser_condition (cp_parser* parser)
   return cp_parser_expression (parser, /*cast_p=*/false);
 }
 
+/* We check for a ) immediately followed by ; with no whitespacing
+   between.  This is used to issue a warning for:
+
+     while (...);
+
+   and:
+
+     for (...);
+
+   as the semicolon is probably extraneous.
+
+   On parse errors, the next token might not be a ), so do nothing in
+   that case. */
+
+static void
+check_empty_body (cp_parser* parser, const char* type)
+{
+  cp_token *token;
+  cp_token *close_paren;
+  expanded_location close_loc;
+  expanded_location semi_loc;
+  
+  close_paren = cp_lexer_peek_token (parser->lexer);
+  if (close_paren->type != CPP_CLOSE_PAREN)
+    return;
+
+  close_loc = expand_location (close_paren->location);
+  token = cp_lexer_peek_nth_token (parser->lexer, 2);
+
+  if (token->type != CPP_SEMICOLON
+      || (token->flags & PREV_WHITE))
+    return;
+
+  semi_loc =  expand_location (token->location);
+  if (close_loc.line == semi_loc.line
+#ifdef USE_MAPPED_LOCATION
+      && close_loc.column+1 == semi_loc.column
+#endif
+      )
+    warning (OPT_Wempty_body,
+	     "suggest a space before %<;%> or explicit braces around empty "
+	     "body in %<%s%> statement",
+	     type);
+}
+
 /* Parse an iteration-statement.
 
    iteration-statement:
@@ -7107,6 +7152,7 @@ cp_parser_iteration_statement (cp_parser* parser)
 	/* Parse the condition.  */
 	condition = cp_parser_condition (parser);
 	finish_while_stmt_cond (condition, statement);
+	check_empty_body (parser, "while");
 	/* Look for the `)'.  */
 	cp_parser_require (parser, CPP_CLOSE_PAREN, "`)'");
 	/* Parse the dependent statement.  */
@@ -7168,6 +7214,7 @@ cp_parser_iteration_statement (cp_parser* parser)
 	if (cp_lexer_next_token_is_not (parser->lexer, CPP_CLOSE_PAREN))
 	  expression = cp_parser_expression (parser, /*cast_p=*/false);
 	finish_for_expr (expression, statement);
+	check_empty_body (parser, "for");
 	/* Look for the `)'.  */
 	cp_parser_require (parser, CPP_CLOSE_PAREN, "`)'");
 

gcc/doc/invoke.texi

@@ -3157,6 +3157,11 @@ An empty body occurs in an @samp{if}, @samp{else} or
 @samp{do while} statement. This warning can be independently
 controlled by @option{-Wempty-body}.
 
+@item @r{(C++ only)}
+An empty body occurs in a @samp{while} or @samp{for} statement with no
+whitespacing before the semicolon. This warning can be independently
+controlled by @option{-Wempty-body}.
+
 @item
 A pointer is compared against integer zero with @samp{<}, @samp{<=},
 @samp{>}, or @samp{>=}.
@@ -3421,8 +3426,10 @@ to them.
 
 @item -Wempty-body
 @opindex Wempty-body
-An empty body occurs in an @samp{if}, @samp{else} or @samp{do while}
-statement.  This warning is also enabled by @option{-Wextra}.
+Warn if an empty body occurs in an @samp{if}, @samp{else} or @samp{do
+while} statement.  Additionally, in C++, warn when an empty body occurs
+in a @samp{while} or @samp{for} statement with no whitespacing before
+the semicolon.  This warning is also enabled by @option{-Wextra}.
 
 @item -Wsign-compare
 @opindex Wsign-compare

gcc/testsuite/ChangeLog

+2007-05-07  Mike Stump  <mrs@apple.com>
+
+	* g++.old-deja/g++.mike/empty.C: Add.
+
 2007-05-07  Eric Christopher  <echristo@apple.com>
 
 	* gcc.dg/invalid-call-1.c: Fix options for 32-bit x86.

gcc/testsuite/g++.old-deja/g++.mike/empty.C

+// { dg-options "-W" }
+
+#define NOPE
+
+void foo() {
+  while (1); /* { dg-error "suggest a space before " } */
+    {
+    }
+  for (;;); /* { dg-error "suggest a space before " } */
+    {
+    }
+  while (1)
+    ;
+  for (;;)
+    ;
+  while (1) ;
+  for (;;) ;
+  /* These two work when using mapped locations */
+  while (1) NOPE; /* { dg-bogus "suggest a space before " "suggest" { xfail *-*-* } } */
+  for (;;) NOPE; /* { dg-bogus "suggest a space before " "suggest" { xfail *-*-* } } */
+  while (1)
+    NOPE;
+  for (;;)
+    NOPE;
+}