cpplib.h (struct cpp_options): Add new boolean flag warn_builtin_macro_redefined.

	* include/cpplib.h (struct cpp_options): Add new boolean flag
	warn_builtin_macro_redefined.
	* init.c (cpp_create_reader): Initialize warn_builtin_macro_redefined.
	* (struct builtin_operator): Split out from previous struct builtin,
	enhance extra const correctness.
	* (struct builtin_macro): Split out from previous struct builtin, add
	new always_warn_if_redefined flag, enhance const correctness.
	* (mark_named_operators): Use struct builtin_operator.
	* (cpp_init_special_builtins): Use struct builtin_macro, add NODE_WARN
	to builtins selectively.
	* macro.c (warn_of_redefinition): Return false if a builtin macro
	is not flagged with NODE_WARN.

	* c-opts.c (c_common_handle_option): Add handling for
	-Wbuiltin-macro-redefined command line option.
	* c.opt: Added builtin-macro-redefined option.
	* doc/invoke.texi (Warning Options): Add -Wbuiltin-macro-redefined
	documentation.

	* gcc.dg/builtin-redefine.c: New.

From-SVN: r140461

6 files changed, 108 insertions, 1 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9f9ddde..99b34c5 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2008-09-18  Simon Baldwin  <simonb@google.com>
+
+	* c-opts.c (c_common_handle_option): Add handling for
+	-Wbuiltin-macro-redefined command line option.
+	* c.opt: Added builtin-macro-redefined option.
+	* doc/invoke.texi (Warning Options): Add -Wbuiltin-macro-redefined
+	documentation.
+
 2008-09-18  Richard Guenther  <rguenther@suse.de>
 
 	PR tree-optimization/37258
diff --git a/gcc/c-opts.c b/gcc/c-opts.c
index 164ca4a..589b05b 100644
--- a/gcc/c-opts.c
+++ b/gcc/c-opts.c
@@ -426,6 +426,10 @@ c_common_handle_option (size_t scode, const char *arg, int value)
 	warn_pointer_sign = 1;
       break;
 
+    case OPT_Wbuiltin_macro_redefined:
+      cpp_opts->warn_builtin_macro_redefined = value;
+      break;
+
     case OPT_Wcomment:
     case OPT_Wcomments:
       cpp_opts->warn_comments = value;
diff --git a/gcc/c.opt b/gcc/c.opt
index d33fa46..94d6047 100644
--- a/gcc/c.opt
+++ b/gcc/c.opt
@@ -131,6 +131,10 @@ Wbad-function-cast
 C ObjC Var(warn_bad_function_cast) Warning
 Warn about casting functions to incompatible types
 
+Wbuiltin-macro-redefined
+C ObjC C++ ObjC++ Warning
+Warn when a built-in preprocessor macro is undefined or redefined
+
 Wc++-compat
 C ObjC Var(warn_cxx_compat) Warning
 Warn about C constructs that are not in the common subset of C and C++
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index e9aae02..05fc091 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -228,7 +228,8 @@ Objective-C and Objective-C++ Dialects}.
 @xref{Warning Options,,Options to Request or Suppress Warnings}.
 @gccoptlist{-fsyntax-only  -pedantic  -pedantic-errors @gol
 -w  -Wextra  -Wall  -Waddress  -Waggregate-return  -Warray-bounds @gol
--Wno-attributes -Wc++-compat -Wc++0x-compat -Wcast-align  -Wcast-qual  @gol
+-Wno-attributes -Wno-builtin-macro-redefined @gol
+-Wc++-compat -Wc++0x-compat -Wcast-align  -Wcast-qual  @gol
 -Wchar-subscripts -Wclobbered  -Wcomment @gol
 -Wconversion  -Wcoverage-mismatch  -Wno-deprecated  @gol
 -Wno-deprecated-declarations -Wdisabled-optimization  @gol
@@ -3731,6 +3732,13 @@ unrecognized attributes, function attributes applied to variables,
 etc.  This will not stop errors for incorrect use of supported
 attributes.
 
+@item -Wno-builtin-macro-redefined
+@opindex Wno-builtin-macro-redefined
+@opindex Wbuiltin-macro-redefined
+Do not warn if certain built-in macros are redefined.  This suppresses
+warnings for redefinition of @code{__TIMESTAMP__}, @code{__TIME__},
+@code{__DATE__}, @code{__FILE__}, and @code{__BASE_FILE__}.
+
 @item -Wstrict-prototypes @r{(C and Objective-C only)}
 @opindex Wstrict-prototypes
 @opindex Wno-strict-prototypes
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index e8d9846..dbeb7e6 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2008-09-18  Simon Baldwin  <simonb@google.com>
+
+	* gcc.dg/builtin-redefine.c: New.
+
 2008-09-18  Richard Guenther  <rguenther@suse.de>
 
 	PR tree-optimization/37258
diff --git a/gcc/testsuite/gcc.dg/builtin-redefine.c b/gcc/testsuite/gcc.dg/builtin-redefine.c
new file mode 100644
index 0000000..f94d3f3
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/builtin-redefine.c
@@ -0,0 +1,79 @@
+/* Test -Wno-builtin-macro-redefined warnings.  */
+
+/* { dg-do compile } */
+/* { dg-options "-Wno-builtin-macro-redefined -U__DATE__ -D__TIME__=X" } */
+
+/* Check date, time, and datestamp built-ins warnings may be suppressed.  */
+
+#if defined(__DATE__)
+#error "__DATE__ is defined, but should not be (-U command line error)"
+/* { dg-bogus "__DATE__ is defined" "" { target *-*-* } 9 } */
+#endif
+
+#if __TIME__ != X
+#error "__TIME__ is not defined as expected (-D command line error)"
+/* { dg-bogus "__TIME__ is not defined" "" { target *-*-* } 14 } */
+#endif
+
+#if !defined(__TIMESTAMP__)
+#error "__TIMESTAMP__ is not defined (built-in macro expectation error)"
+/* { dg-bogus "__TIMESTAMP__ is not defined" "" { target *-*-* } 19 } */
+#endif
+
+
+#undef __TIME__              /* Undefine while defined.  */
+#undef __TIME__              /* Undefine while already undefined.  */
+
+#define __TIME__ "X"         /* Define while undefined.  */
+#define __TIME__ "X"         /* Re-define while defined.  */
+
+#define __TIME__ "Y"         /* { dg-warning "\"__TIME__\" redefined" } */
+/* { dg-warning "previous definition" "" { target *-*-* } 28 } */
+
+#undef __TIME__              /* Undefine while defined.  */
+
+
+#undef __DATE__              /* Undefine while already undefined.  */
+
+#define __DATE__ "X"         /* Define while undefined.  */
+#define __DATE__ "X"         /* Re-define while defined.  */
+
+#define __DATE__ "Y"         /* { dg-warning "\"__DATE__\" redefined" } */
+/* { dg-warning "previous definition" "" { target *-*-* } 39 } */
+
+#undef __DATE__              /* Undefine while defined.  */
+
+
+#define __TIMESTAMP__ "X"    /* Define while already defined.  */
+#define __TIMESTAMP__ "X"    /* Re-define while defined.  */
+
+#define __TIMESTAMP__ "Y"    /* { dg-warning "\"__TIMESTAMP__\" redefined" } */
+/* { dg-warning "previous definition" "" { target *-*-* } 48 } */
+
+#undef __TIMESTAMP__         /* Undefine while defined.  */
+
+
+/* Check other built-ins with warnings that may be suppressed.  */
+
+#if !defined(__FILE__) || !defined(__BASE_FILE__)
+#error "Expected built-in is not defined (built-in macro expectation error)"
+/* { dg-bogus "Expected built-in is not defined" "" { target *-*-* } 59 } */
+#endif
+
+#define __FILE__ "X"         /* Define while already defined.  */
+#define __BASE_FILE__ "X"    /* Define while already defined.  */
+
+
+/* Check selected built-ins not affected by warning suppression. */
+
+#if !defined(__LINE__) || !defined(__INCLUDE_LEVEL__) || !defined(__COUNTER__)
+#error "Expected built-in is not defined (built-in macro expectation error)"
+/* { dg-bogus "Expected built-in is not defined" "" { target *-*-* } 70 } */
+#endif
+
+#define __LINE__ 0           /* { dg-warning "\"__LINE__\" redef" } */
+#define __INCLUDE_LEVEL__ 0  /* { dg-warning "\"__INCLUDE_LEVEL__\" redef" } */
+#define __COUNTER__ 0        /* { dg-warning "\"__COUNTER__\" redef" } */
+
+
+int unused;  /* Silence `ISO C forbids an empty translation unit' warning.  */