generated string libraries & -Wformat

[Bruce Korb]

Hello,

I mess around with a lot of generated code.  That means I do automated
construction of libraries that use literal strings.  In order to
reduce address fixups, I often put all the literal strings into one long
string with each piece separated from the others with a NUL byte.
Unfortunately, I am then constrained from using ``-Wformat'' because
it fears I might accidentally be doing something wrong.

I believe the attached patch is sufficient to implement
   -Wno-format-contains-nul
(I am bootstrapping GCC and will be testing for a few hours.)

I'd like to hear any complaints about the change before I
spend too much time polishing it.  Thank you!

Regards, Bruce

patterned after usage of "format-nonliteral"

Index: c-format.c
===================================================================
--- c-format.c  (revision 123186)
+++ c-format.c  (working copy)
@@ -43,6 +43,7 @@
   if (setting != 1)
     {
       warn_format_nonliteral = setting;
+      warn_format_contains_nul = setting;
       warn_format_security = setting;
       warn_format_y2k = setting;
     }
@@ -1482,7 +1483,7 @@
       if (*format_chars == 0)
        {
          if (format_chars - orig_format_chars != format_length)
-           warning (OPT_Wformat, "embedded %<\\0%> in format");
+           warning (OPT_Wformat_contains_nul, "embedded %<\\0%> in format");
          if (info->first_arg_num != 0 && params != 0
              && has_operand_number <= 0)
            {
Index: c.opt
===================================================================
--- c.opt       (revision 123186)
+++ c.opt       (working copy)
@@ -216,6 +216,10 @@
 C ObjC C++ ObjC++ Var(warn_format_nonliteral) Warning
 Warn about format strings that are not literals

+Wformat-contains-nul
+C ObjC C++ ObjC++ Var(warn_format_contains_nul)
+Warn about format strings that contain NUL bytes
+
 Wformat-security
 C ObjC C++ ObjC++ Var(warn_format_security) Warning
 Warn about possible security problems with format functions
Index: c-opts.c
===================================================================
--- c-opts.c    (revision 123186)
+++ c-opts.c    (working copy)
@@ -1106,6 +1106,8 @@
               "-Wformat-zero-length ignored without -Wformat");
       warning (OPT_Wformat_nonliteral,
               "-Wformat-nonliteral ignored without -Wformat");
+      warning (OPT_Wformat_contains_nul,
+              "-Wformat-contains-nul ignored without -Wformat");
       warning (OPT_Wformat_security,
               "-Wformat-security ignored without -Wformat");
     }