cpphash.h (struct spec_nodes): Remove n__CHAR_UNSIGNED__.

	* cpphash.h (struct spec_nodes): Remove n__CHAR_UNSIGNED__.
	* cpphash.c (_cpp_init_hashtable): Similarly.
	* cppinit.c (cpp_create_reader): Default the signed_char flag.
	(init_builtins): Define __CHAR_UNSIGNED__ appropriately.
	(COMMAND_LINE_OPTIONS): Recognise -f{un,}signed-char.
	(cpp_handle_option): Handle the new options.
	* cpplex.c (cpp_interpret_charconst): Use new flag.
	* cpplib.h (struct cpp_options): New member signed_char.
	* gcc.c (cpp_unique_options): Remove %c spec and documentation.
	(cpp_options): Handle -fsigned-char and -funsigned-char.
	(static_specs): Remove signed_char_spec.
	(do_spec1): Don't handle %c.
	* system.h: Poison SIGNED_CHAR_SPEC.
	* tradcif.y (yylex): Use flag_signed_char.
	* tradcpp.h (flag_signed_char): New.
	* tradcpp.c (flag_signed_char): New.
	(main): Handle new command-line options.
	(initialize_builtins): Define __CHAR_UNSIGNED__ if appropriate.
config:
	* alpha/alpha.h (SIGNED_CHAR_SPEC): Remove.
	* avr/avr.h: Remove old comments.
	* i960/i960.h (CPP_SPEC): Pass -fsigned-char if -mic*.
	(CC1_SPEC): Pass -fsigned-char if -mic*.
	(SIGNED_CHAR_SPEC): Remove.
doc:
	* tm.texi (SIGNED_CHAR_SPEC): Remove documentation.
testsuite:
	* gcc.dg/cpp/uchar-1.c, uchar-2.c, uchar-3.c: New tests.

From-SVN: r49444

19 files changed, 116 insertions, 70 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 5279c56..5ad4904 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,32 @@
+2002-02-02  Neil Booth  <neil@daikokuya.demon.co.uk>
+
+	* cpphash.h (struct spec_nodes): Remove n__CHAR_UNSIGNED__.
+	* cpphash.c (_cpp_init_hashtable): Similarly.
+	* cppinit.c (cpp_create_reader): Default the signed_char flag.
+	(init_builtins): Define __CHAR_UNSIGNED__ appropriately.
+	(COMMAND_LINE_OPTIONS): Recognise -f{un,}signed-char.
+	(cpp_handle_option): Handle the new options.
+	* cpplex.c (cpp_interpret_charconst): Use new flag.
+	* cpplib.h (struct cpp_options): New member signed_char.
+	* gcc.c (cpp_unique_options): Remove %c spec and documentation.
+	(cpp_options): Handle -fsigned-char and -funsigned-char.
+	(static_specs): Remove signed_char_spec.
+	(do_spec1): Don't handle %c.
+	* system.h: Poison SIGNED_CHAR_SPEC.
+	* tradcif.y (yylex): Use flag_signed_char.
+	* tradcpp.h (flag_signed_char): New.
+	* tradcpp.c (flag_signed_char): New.
+	(main): Handle new command-line options.
+	(initialize_builtins): Define __CHAR_UNSIGNED__ if appropriate.
+config:
+	* alpha/alpha.h (SIGNED_CHAR_SPEC): Remove.
+	* avr/avr.h: Remove old comments.
+	* i960/i960.h (CPP_SPEC): Pass -fsigned-char if -mic*.
+	(CC1_SPEC): Pass -fsigned-char if -mic*.
+	(SIGNED_CHAR_SPEC): Remove.
+doc:
+	* tm.texi (SIGNED_CHAR_SPEC): Remove documentation.
+
 2002-02-01  Eric Christopher  <echristo@redhat.com>
 
 	From Daniel Jacobowitz <dmj+@andrew.cmu.edu>
diff --git a/gcc/config/alpha/alpha.h b/gcc/config/alpha/alpha.h
index dd8d820..4e676f2 100644
--- a/gcc/config/alpha/alpha.h
+++ b/gcc/config/alpha/alpha.h
@@ -43,12 +43,6 @@ Boston, MA 02111-1307, USA.  */
 #define CPP_SUBTARGET_SPEC ""
 #endif
 
-/* Set the spec to use for signed char.  The default tests the above macro
-   but DEC's compiler can't handle the conditional in a "constant"
-   operand.  */
-
-#define SIGNED_CHAR_SPEC "%{funsigned-char:-D__CHAR_UNSIGNED__}"
-
 #define WORD_SWITCH_TAKES_ARG(STR)		\
  (!strcmp (STR, "rpath") || DEFAULT_WORD_SWITCH_TAKES_ARG(STR))
 
diff --git a/gcc/config/avr/avr.h b/gcc/config/avr/avr.h
index 52cba88..742c811 100644
--- a/gcc/config/avr/avr.h
+++ b/gcc/config/avr/avr.h
@@ -2688,16 +2688,7 @@ extern int avr_case_values_threshold;
 
    This should be defined if `PTRDIFF_TYPE' depends on target
    dependent flags which are not accessible to the preprocessor.
-   Otherwise, it should not be defined.
-
-   `SIGNED_CHAR_SPEC'
-   A C string constant that tells the GNU CC driver program options to
-   pass to CPP.  By default, this macro is defined to pass the option
-   `-D__CHAR_UNSIGNED__' to CPP if `char' will be treated as
-   `unsigned char' by `cc1'.
-
-   Do not define this macro unless you need to override the default
-   definition.  */
+   Otherwise, it should not be defined.  */
 
 #define CC1_SPEC "%{profile:-p}"
 /* A C string constant that tells the GNU CC driver program options to
diff --git a/gcc/config/i960/i960.h b/gcc/config/i960/i960.h
index ec4b9d1..4df5a6f 100644
--- a/gcc/config/i960/i960.h
+++ b/gcc/config/i960/i960.h
@@ -30,8 +30,9 @@ Boston, MA 02111-1307, USA.  */
 /* Names to predefine in the preprocessor for this target machine.  */
 #define CPP_PREDEFINES "-Di960 -Di80960 -DI960 -DI80960 -Acpu=i960 -Amachine=i960"
 
-/* Name to predefine in the preprocessor for processor variations.  */
-#define	CPP_SPEC "%{mic*:-D__i960\
+/* Name to predefine in the preprocessor for processor variations.
+   -mic* options make characters signed by default.  */
+#define	CPP_SPEC "%{mic*:-D__i960 -fsigned-char\
 			%{mka:-D__i960KA}%{mkb:-D__i960KB}\
 			%{mja:-D__i960JA}%{mjd:-D__i960JD}%{mjf:-D__i960JF}\
 			%{mrp:-D__i960RP}\
@@ -52,20 +53,13 @@ Boston, MA 02111-1307, USA.  */
 		%{!mcc:%{!mcf:-D__i960_KB -D__i960KB__ %{mic*:-D__i960KB}}}}}}}}}\
 	%{mlong-double-64:-D__LONG_DOUBLE_64__}"
 
-/* -mic* options make characters signed by default.  */
-/* Use #if rather than ?: because MIPS C compiler rejects ?: in
-   initializers.  */
-#if DEFAULT_SIGNED_CHAR
-#define SIGNED_CHAR_SPEC "%{funsigned-char:-D__CHAR_UNSIGNED__}"
-#else
-#define SIGNED_CHAR_SPEC "%{!fsigned-char:%{!mic*:-D__CHAR_UNSIGNED__}}"
-#endif
-
 /* Specs for the compiler, to handle processor variations. 
    If the user gives an explicit -gstabs or -gcoff option, then do not
-   try to add an implicit one, as this will fail.  */
+   try to add an implicit one, as this will fail. 
+   -mic* options make characters signed by default.  */
 #define CC1_SPEC \
-	"%{!mka:%{!mkb:%{!msa:%{!msb:%{!mmc:%{!mca:%{!mcc:%{!mcf:%{!mja:%{!mjd:%{!mjf:%{!mrp:-mka}}}}}}}}}}}}\
+	"%{mic*:-fsigned-char}\
+%{!mka:%{!mkb:%{!msa:%{!msb:%{!mmc:%{!mca:%{!mcc:%{!mcf:%{!mja:%{!mjd:%{!mjf:%{!mrp:-mka}}}}}}}}}}}}\
 	 %{!gs*:%{!gc*:%{mbout:%{g*:-gstabs}}\
 		       %{mcoff:%{g*:-gcoff}}\
 		       %{!mbout:%{!mcoff:%{g*:-gstabs}}}}}"
diff --git a/gcc/cpphash.c b/gcc/cpphash.c
index 8be1b2f..69e1a23 100644
--- a/gcc/cpphash.c
+++ b/gcc/cpphash.c
@@ -73,7 +73,6 @@ _cpp_init_hashtable (pfile, table)
   s->n_true		= cpp_lookup (pfile, DSC("true"));
   s->n_false		= cpp_lookup (pfile, DSC("false"));
   s->n__STRICT_ANSI__   = cpp_lookup (pfile, DSC("__STRICT_ANSI__"));
-  s->n__CHAR_UNSIGNED__ = cpp_lookup (pfile, DSC("__CHAR_UNSIGNED__"));
   s->n__VA_ARGS__       = cpp_lookup (pfile, DSC("__VA_ARGS__"));
   s->n__VA_ARGS__->flags |= NODE_DIAGNOSTIC;
 }
diff --git a/gcc/cpphash.h b/gcc/cpphash.h
index be8d902..e06914a 100644
--- a/gcc/cpphash.h
+++ b/gcc/cpphash.h
@@ -164,7 +164,6 @@ struct spec_nodes
   cpp_hashnode *n_true;			/* C++ keyword true */
   cpp_hashnode *n_false;		/* C++ keyword false */
   cpp_hashnode *n__STRICT_ANSI__;	/* STDC_0_IN_SYSTEM_HEADERS */
-  cpp_hashnode *n__CHAR_UNSIGNED__;	/* plain char is unsigned */
   cpp_hashnode *n__VA_ARGS__;		/* C99 vararg macros */
 };
 
diff --git a/gcc/cppinit.c b/gcc/cppinit.c
index ab3dad7..717fb3f 100644
--- a/gcc/cppinit.c
+++ b/gcc/cppinit.c
@@ -490,6 +490,11 @@ cpp_create_reader (lang)
   CPP_OPTION (pfile, show_column) = 1;
   CPP_OPTION (pfile, tabstop) = 8;
   CPP_OPTION (pfile, operator_names) = 1;
+#if DEFAULT_SIGNED_CHAR
+  CPP_OPTION (pfile, signed_char) = 1;
+#else
+  CPP_OPTION (pfile, signed_char) = 0;
+#endif
 
   CPP_OPTION (pfile, pending) =
     (struct cpp_pending *) xcalloc (1, sizeof (struct cpp_pending));
@@ -761,6 +766,9 @@ init_builtins (pfile)
   else if (CPP_OPTION (pfile, c99))
     _cpp_define_builtin (pfile, "__STDC_VERSION__ 199901L");
 
+  if (CPP_OPTION (pfile, signed_char) == 0)
+    _cpp_define_builtin (pfile, "__CHAR_UNSIGNED__ 1");
+
   if (CPP_OPTION (pfile, lang) == CLK_STDC89
       || CPP_OPTION (pfile, lang) == CLK_STDC94
       || CPP_OPTION (pfile, lang) == CLK_STDC99)
@@ -1186,7 +1194,9 @@ new_pending_directive (pend, text, handler)
   DEF_OPT("fno-show-column",          0,      OPT_fno_show_column)            \
   DEF_OPT("fpreprocessed",            0,      OPT_fpreprocessed)              \
   DEF_OPT("fshow-column",             0,      OPT_fshow_column)               \
+  DEF_OPT("fsigned-char",             0,      OPT_fsigned_char)               \
   DEF_OPT("ftabstop=",                no_num, OPT_ftabstop)                   \
+  DEF_OPT("funsigned-char",           0,      OPT_funsigned_char)             \
   DEF_OPT("h",                        0,      OPT_h)                          \
   DEF_OPT("idirafter",                no_dir, OPT_idirafter)                  \
   DEF_OPT("imacros",                  no_fil, OPT_imacros)                    \
@@ -1395,6 +1405,12 @@ cpp_handle_option (pfile, argc, argv, ignore)
 	case OPT_fno_show_column:
 	  CPP_OPTION (pfile, show_column) = 0;
 	  break;
+	case OPT_fsigned_char:
+	  CPP_OPTION (pfile, signed_char) = 1;
+	  break;
+	case OPT_funsigned_char:
+	  CPP_OPTION (pfile, signed_char) = 0;
+	  break;
 	case OPT_ftabstop:
 	  /* Silently ignore empty string, non-longs and silly values.  */
 	  if (arg[0] != '\0')
diff --git a/gcc/cpplex.c b/gcc/cpplex.c
index 8465350..70e6280 100644
--- a/gcc/cpplex.c
+++ b/gcc/cpplex.c
@@ -1903,14 +1903,13 @@ cpp_interpret_charconst (pfile, token, warn_multi, traditional, pchars_seen)
   else if (chars_seen > 1 && !traditional && warn_multi)
     cpp_warning (pfile, "multi-character character constant");
 
-  /* If char type is signed, sign-extend the constant.  The
-     __CHAR_UNSIGNED__ macro is set by the driver if appropriate.  */
+  /* If char type is signed, sign-extend the constant.  */
   if (token->type == CPP_CHAR && chars_seen)
     {
       unsigned int nbits = chars_seen * width;
 
       mask = (unsigned HOST_WIDE_INT) ~0 >> (HOST_BITS_PER_WIDE_INT - nbits);
-      if (pfile->spec_nodes.n__CHAR_UNSIGNED__->type == NT_MACRO
+      if (CPP_OPTION (pfile, signed_char) == 0
 	  || ((result >> (nbits - 1)) & 1) == 0)
 	result &= mask;
       else
diff --git a/gcc/cpplib.h b/gcc/cpplib.h
index eeeecc0..47169dc 100644
--- a/gcc/cpplib.h
+++ b/gcc/cpplib.h
@@ -240,6 +240,9 @@ struct cpp_options
   /* Non-0 means -v, so print the full set of include dirs.  */
   unsigned char verbose;
 
+  /* Nonzero means chars are signed.  */
+  unsigned char signed_char;
+
   /* Nonzero means use extra default include directories for C++.  */
   unsigned char cplusplus;
 
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index e9797bf..c81cd26 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -216,16 +216,6 @@ This should be defined if @code{WINT_TYPE} depends on target dependent flags
 which are not accessible to the preprocessor.  Otherwise, it should not
 be defined.
 
-@findex SIGNED_CHAR_SPEC
-@item SIGNED_CHAR_SPEC
-A C string constant that tells the GCC driver program options to
-pass to CPP@.  By default, this macro is defined to pass the option
-@option{-D__CHAR_UNSIGNED__} to CPP if @code{char} will be treated as
-@code{unsigned char} by @code{cc1}.
-
-Do not define this macro unless you need to override the default
-definition.
-
 @findex CC1_SPEC
 @item CC1_SPEC
 A C string constant that tells the GCC driver program options to
diff --git a/gcc/gcc.c b/gcc/gcc.c
index 8968af6..41c62a9 100644
--- a/gcc/gcc.c
+++ b/gcc/gcc.c
@@ -445,7 +445,6 @@ or with constant text in a single argument.
 	if multilib_dir is not set or is ".", output "".
  %S     process STARTFILE_SPEC as a spec.  A capital S is actually used here.
  %E     process ENDFILE_SPEC as a spec.  A capital E is actually used here.
- %c	process SIGNED_CHAR_SPEC as a spec.
  %C     process CPP_SPEC as a spec.
  %1	process CC1_SPEC as a spec.
  %2	process CC1PLUS_SPEC as a spec.
@@ -511,7 +510,7 @@ CC also knows implicitly that arguments starting in `-l' are to be
 treated as compiler output files, and passed to the linker in their
 proper position among the other output files.  */
 
-/* Define the macros used for specs %a, %l, %L, %S, %c, %C, %1.  */
+/* Define the macros used for specs %a, %l, %L, %S, %C, %1.  */
 
 /* config.h can define ASM_SPEC to provide extra args to the assembler
    or extra switch-translations.  */
@@ -582,17 +581,6 @@ proper position among the other output files.  */
 #define ENDFILE_SPEC ""
 #endif
 
-/* This spec is used for telling cpp whether char is signed or not.  */
-#ifndef SIGNED_CHAR_SPEC
-/* Use #if rather than ?:
-   because MIPS C compiler rejects like ?: in initializers.  */
-#if DEFAULT_SIGNED_CHAR
-#define SIGNED_CHAR_SPEC "%{funsigned-char:-D__CHAR_UNSIGNED__}"
-#else
-#define SIGNED_CHAR_SPEC "%{!fsigned-char:-D__CHAR_UNSIGNED__}"
-#endif
-#endif
-
 #ifndef LINKER_NAME
 #define LINKER_NAME "collect2"
 #endif
@@ -651,7 +639,6 @@ static const char *cpp_spec = CPP_SPEC;
 static const char *cpp_predefines = CPP_PREDEFINES;
 static const char *cc1_spec = CC1_SPEC;
 static const char *cc1plus_spec = CC1PLUS_SPEC;
-static const char *signed_char_spec = SIGNED_CHAR_SPEC;
 static const char *asm_spec = ASM_SPEC;
 static const char *asm_final_spec = ASM_FINAL_SPEC;
 static const char *link_spec = LINK_SPEC;
@@ -681,7 +668,7 @@ static const char *cpp_unique_options =
  %{M} %{MM} %W{MF*} %{MG} %{MP} %{MQ*} %{MT*} %{M|MD|MM|MMD:%{o*:-MQ %*}}\
  %{!no-gcc:-D__GNUC__=%v1 -D__GNUC_MINOR__=%v2 -D__GNUC_PATCHLEVEL__=%v3}\
  %{!undef:%{!ansi:%{!std=*:%p}%{std=gnu*:%p}} %P} %{trigraphs}\
- %c %{Os:-D__OPTIMIZE_SIZE__} %{O*:%{!O0:-D__OPTIMIZE__}}\
+ %{Os:-D__OPTIMIZE_SIZE__} %{O*:%{!O0:-D__OPTIMIZE__}}\
  %{fno-inline|O0|!O*:-D__NO_INLINE__} %{ffast-math:-D__FAST_MATH__}\
  %{fshort-wchar:-U__WCHAR_TYPE__ -D__WCHAR_TYPE__=short\\ unsigned\\ int}\
  %{ffreestanding:-D__STDC_HOSTED__=0} %{fno-hosted:-D__STDC_HOSTED__=0}\
@@ -694,6 +681,7 @@ static const char *cpp_unique_options =
 static const char *cpp_options =
 "%(cpp_unique_options) %{std*} %{d*} %{W*} %{w} %{pedantic*}\
  %{fshow-column} %{fno-show-column}\
+ %{fsigned-char&funsigned-char}\
  %{fleading-underscore} %{fno-leading-underscore}\
  %{fno-operator-names} %{ftabstop=*}";
 
@@ -1382,7 +1370,6 @@ static struct spec_list static_specs[] =
   INIT_STATIC_SPEC ("libgcc",			&libgcc_spec),
   INIT_STATIC_SPEC ("startfile",		&startfile_spec),
   INIT_STATIC_SPEC ("switches_need_spaces",	&switches_need_spaces),
-  INIT_STATIC_SPEC ("signed_char",		&signed_char_spec),
   INIT_STATIC_SPEC ("predefines",		&cpp_predefines),
   INIT_STATIC_SPEC ("cross_compile",		&cross_compile),
   INIT_STATIC_SPEC ("version",			&compiler_version),
@@ -1785,7 +1772,7 @@ load_specs (filename)
 
    A suffix which starts with `*' is a definition for
    one of the machine-specific sub-specs.  The "suffix" should be
-   *asm, *cc1, *cpp, *link, *startfile, *signed_char, etc.
+   *asm, *cc1, *cpp, *link, *startfile, etc.
    The corresponding spec is stored in asm_spec, etc.,
    rather than in the `compilers' vector.
 
@@ -4783,12 +4770,6 @@ do_spec_1 (spec, inswitch, soft_matched_part)
 	      return value;
 	    break;
 
-	  case 'c':
-	    value = do_spec_1 (signed_char_spec, 0, NULL);
-	    if (value != 0)
-	      return value;
-	    break;
-
 	  case 'C':
 	    {
 	      const char *const spec
diff --git a/gcc/system.h b/gcc/system.h
index 9bd0599..25e9549 100644
--- a/gcc/system.h
+++ b/gcc/system.h
@@ -594,7 +594,7 @@ typedef char _Bool;
 	SET_DEFAULT_TYPE_ATTRIBUTES SET_DEFAULT_DECL_ATTRIBUTES		\
 	MERGE_MACHINE_TYPE_ATTRIBUTES MERGE_MACHINE_DECL_ATTRIBUTES	\
 	MD_INIT_BUILTINS MD_EXPAND_BUILTIN ASM_OUTPUT_CONSTRUCTOR	\
-	ASM_OUTPUT_DESTRUCTOR
+	ASM_OUTPUT_DESTRUCTOR SIGNED_CHAR_SPEC
 
 /* And other obsolete target macros, or macros that used to be in target
    headers and were not used, and may be obsolete or may never have
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 35d019f..199f6ca 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2002-02-02  Neil Booth  <neil@daikokuya.demon.co.uk>
+
+	* gcc.dg/cpp/uchar-1.c, uchar-2.c, uchar-3.c: New tests.
+
 2002-02-02  Richard Henderson  <rth@redhat.com>
 
 	* gcc.c-torture/execute/991118-1.c: Revert 2002-01-29 change.
diff --git a/gcc/testsuite/gcc.dg/cpp/uchar-1.c b/gcc/testsuite/gcc.dg/cpp/uchar-1.c
new file mode 100644
index 0000000..3483e328
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/cpp/uchar-1.c
@@ -0,0 +1,8 @@
+/* Copyright (C) 2002 Free Software Foundation, Inc.  */
+
+/* { dg-do preprocess } */
+/* { dg-options "-funsigned-char -fsigned-char" } */
+
+#if defined (__CHAR_UNSIGNED__)
+# error __CHAR_UNSIGNED__ defined
+#endif
diff --git a/gcc/testsuite/gcc.dg/cpp/uchar-2.c b/gcc/testsuite/gcc.dg/cpp/uchar-2.c
new file mode 100644
index 0000000..739573c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/cpp/uchar-2.c
@@ -0,0 +1,8 @@
+/* Copyright (C) 2002 Free Software Foundation, Inc.  */
+
+/* { dg-do preprocess } */
+/* { dg-options "-funsigned-char -fsigned-char -traditional" } */
+
+#if defined (__CHAR_UNSIGNED__)
+# error __CHAR_UNSIGNED__ defined
+#endif
diff --git a/gcc/testsuite/gcc.dg/cpp/uchar-3.c b/gcc/testsuite/gcc.dg/cpp/uchar-3.c
new file mode 100644
index 0000000..41b987f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/cpp/uchar-3.c
@@ -0,0 +1,17 @@
+/* Copyright (C) 2002 Free Software Foundation, Inc.  */
+
+/* { dg-do compile } */
+/* { dg-options "-funsigned-char -fpreprocessed" } */
+
+/* Source: Ziemowit Laski.  -fpreprocessed doesn't define macros, but
+   CPP would interpret charconsts based upon whether __CHAR_UNSIGNED__
+   was defined.  */
+
+int foo()
+{
+  char f = 0x83;
+  if (f == '\x83')		/* { dg-bogus "always false" } */
+    f = 0;
+
+  return 0;
+}
diff --git a/gcc/tradcif.y b/gcc/tradcif.y
index 4598d61..953e2d6 100644
--- a/gcc/tradcif.y
+++ b/gcc/tradcif.y
@@ -344,8 +344,7 @@ yylex ()
 
     /* Sign-extend the constant if chars are signed on target machine.  */
     {
-      if (lookup ((const unsigned char *)"__CHAR_UNSIGNED__",
-		   sizeof ("__CHAR_UNSIGNED__")-1, -1)
+      if (flag_signed_char == 0
 	  || ((c >> (CHAR_TYPE_SIZE - 1)) & 1) == 0)
 	yylval.integer.value = c & ((1 << CHAR_TYPE_SIZE) - 1);
       else
diff --git a/gcc/tradcpp.c b/gcc/tradcpp.c
index 11c5fd3..3cff998 100644
--- a/gcc/tradcpp.c
+++ b/gcc/tradcpp.c
@@ -86,6 +86,13 @@ int inhibit_warnings = 0;
 /* Non-0 means don't output the preprocessed program.  */
 int inhibit_output = 0;
 
+/* Nonzero means chars are signed.  */
+#if DEFAULT_SIGNED_CHAR
+int flag_signed_char = 1;
+#else
+int flag_signed_char = 0;
+#endif
+
 /* Nonzero means warn if slash-star appears in a comment.  */
 
 int warn_comments;
@@ -627,6 +634,10 @@ main (argc, argv)
 	  user_label_prefix = "_";
 	else if (!strcmp (argv[i], "-fno-leading-underscore"))
 	  user_label_prefix = "";
+	else if (!strcmp (argv[i], "-fsigned-char"))
+	  flag_signed_char = 1;
+	else if (!strcmp (argv[i], "-funsigned-char"))
+	  flag_signed_char = 0;
 	break;
 
       case 'M':
@@ -5105,6 +5116,9 @@ initialize_builtins ()
 #endif
   install_value ("__REGISTER_PREFIX__",   REGISTER_PREFIX);
   install_value ("__USER_LABEL_PREFIX__", user_label_prefix);
+
+  if (flag_signed_char == 0)
+    install_value ("__CHAR_UNSIGNED__", "1");
 }
 #undef DSC
 #undef install_spec
diff --git a/gcc/tradcpp.h b/gcc/tradcpp.h
index 0c16cfa..89940d0 100644
--- a/gcc/tradcpp.h
+++ b/gcc/tradcpp.h
@@ -35,6 +35,7 @@ extern void fancy_abort PARAMS ((int, const char *)) ATTRIBUTE_NORETURN;
 extern struct hashnode *lookup PARAMS ((const unsigned char *, int, int));
 extern int parse_c_expression PARAMS ((const char *));  /* in tradcif.y */
 extern int test_assertion PARAMS ((unsigned char **));
+extern int flag_signed_char;
 
 #define is_idchar(x)	ISIDNUM(x)
 #define is_idstart(x)	ISIDST(x)