cppexp.c (parse_defined): Mark macro used.

	* cppexp.c (parse_defined): Mark macro used.
	* cpphash.h (struct cpp_macro): New member "used".
	(_cpp_mark_macro_used, _cpp_warn_if_unused_macro): New.
	(struct cpp_reader): New member.
	* cppinit.c (cpp_finish_options): Set first_unused_line.
	(cpp_finish): Warn of unused macros if requested.
	(OPT_TABLE): New switches.
	(cpp_handle_option): Handle them.
	* cpplib.c (do_undef): Warn if macro unused.
	(do_ifdef, do_ifndef): Mark macro used.
	* cpplib.h (struct cpp_options): New member.
	* cppmacro.c (_cpp_warn_if_unused_macro): New.
	(enter_macro_context): Mark macro used.
	(_cpp_create_definition): Mark macro unused; warn if unused
	when redefined.
	* cpptrad.c (scan_out_logcial_line, push_replacement_text):
	Mark macros used.
	* doc/cppopts.texi: Update.
testsuite:
	* gcc.dg/cpp/trad/Wunused.c, gcc.dg/cpp/trad/Wunused.h,
	gcc.dg/cpp/Wunused.c, gcc.dg/cpp/Wunused.h: New tests.

From-SVN: r55692

1 files changed, 29 insertions, 0 deletions

diff --git a/gcc/cppmacro.c b/gcc/cppmacro.c
index 4d807a2..c8e2410 100644
--- a/gcc/cppmacro.c
+++ b/gcc/cppmacro.c
@@ -74,6 +74,29 @@ static void check_trad_stringification PARAMS ((cpp_reader *,
 						const cpp_macro *,
 						const cpp_string *));
 
+/* Emits a warning if NODE is a macro defined in the main file that
+   has not been used.  */
+int
+_cpp_warn_if_unused_macro (pfile, node, v)
+     cpp_reader *pfile;
+     cpp_hashnode *node;
+     void *v ATTRIBUTE_UNUSED;
+{
+  if (node->type == NT_MACRO && !(node->flags & NODE_BUILTIN))
+    {
+      cpp_macro *macro = node->value.macro;
+
+      if (!macro->used
+	  /* Skip front-end built-ins and command line macros.  */
+	  && macro->line >= pfile->first_unused_line
+	  && MAIN_FILE_P (lookup_line (&pfile->line_maps, macro->line)))
+	cpp_error_with_line (pfile, DL_WARNING, macro->line, 0,
+			     "macro \"%s\" is not used", NODE_NAME (node));
+    }
+
+  return 1;
+}
+
 /* Allocates and returns a CPP_STRING token, containing TEXT of length
    LEN, after null-terminating it.  TEXT must be in permanent storage.  */
 static const cpp_token *
@@ -728,6 +751,8 @@ enter_macro_context (pfile, node)
       /* Disable the macro within its expansion.  */
       node->flags |= NODE_DISABLED;
 
+      macro->used = 1;
+
       if (macro->paramc == 0)
 	push_token_context (pfile, node, macro->exp.tokens, macro->count);
 
@@ -1488,6 +1513,7 @@ _cpp_create_definition (pfile, node)
   macro->params = 0;
   macro->paramc = 0;
   macro->variadic = 0;
+  macro->used = 0;
   macro->count = 0;
   macro->fun_like = 0;
   /* To suppress some diagnostics.  */
@@ -1523,6 +1549,9 @@ _cpp_create_definition (pfile, node)
 
   if (node->type != NT_VOID)
     {
+      if (CPP_OPTION (pfile, warn_unused_macros))
+	_cpp_warn_if_unused_macro (pfile, node, NULL);
+
       if (warn_of_redefinition (pfile, node, macro))
 	{
 	  cpp_error_with_line (pfile, DL_PEDWARN, pfile->directive_line, 0,