Add new option, -Wliteral-suffix.

This option, which is enabled by default, causes the preprocessor to warn
when a string or character literal is followed by a ud-suffix which does
not begin with an underscore.  According to [lex.ext]p10, this is
ill-formed.

Also modifies the preprocessor to treat such ill-formed suffixes as separate
preprocessing tokens.  This is consistent with the Clang front end (see
http://llvm.org/viewvc/llvm-project?view=rev&revision=152287), and enables
backwards compatibility with code that uses formatting macros from
<inttypes.h>, as in the following code block:

  int main() {
    int64_t i64 = 123;
    printf("My int64: %"PRId64"\n", i64);
  }

Google ref b/6377711.

2012-04-27   Ollie Wild  <aaw@google.com>

	PR c++/52538
	* gcc/c-family/c-common.c: Add CPP_W_LITERAL_SUFFIX mapping.
	* gcc/c-family/c-opts.c (c_common_handle_option): Handle
	OPT_Wliteral_suffix.
	* gcc/c-family/c.opt: Add Wliteral-suffix.
	* gcc/doc/invoke.texi (Wliteral-suffix): Document new option.
	* gcc/testsuite/g++.dg/cpp0x/Wliteral-suffix.c: New test.
	* libcpp/include/cpplib.h (struct cpp_options): Add new field,
	warn_literal_suffix.
	(CPP_W_LITERAL_SUFFIX): New enum.
	* libcpp/init.c (cpp_create_reader): Default initialization of
	warn_literal_suffix.
	* libcpp/lex.c (lex_raw_string): Treat user-defined literals which
	don't begin with '_' as separate tokens and produce a warning.
	(lex_string): Ditto.

From-SVN: r186909

8 files changed, 78 insertions, 2 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index aeda32c..7097f17 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,7 @@
+2012-04-27   Ollie Wild  <aaw@google.com>
+
+	* doc/invoke.texi (Wliteral-suffix): Document new option.
+
 2012-04-27  Tom Tromey  <tromey@redhat.com>
 
 	* dwarf2out.c (dwarf_stack_op_name): Use get_DW_OP_name.
diff --git a/gcc/c-family/ChangeLog b/gcc/c-family/ChangeLog
index fb89531..2082ff6 100644
--- a/gcc/c-family/ChangeLog
+++ b/gcc/c-family/ChangeLog
@@ -1,3 +1,9 @@
+2012-04-27   Ollie Wild  <aaw@google.com>
+
+	* c-common.c: Add CPP_W_LITERAL_SUFFIX mapping.
+	* c-opts.c (c_common_handle_option): Handle OPT_Wliteral_suffix.
+	* c.opt: Add Wliteral-suffix.
+
 2012-04-22  Manuel López-Ibáñez  <manu@gcc.gnu.org>
 
 	PR c/44774
diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index 4eacd19..bf5b034 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -8820,6 +8820,7 @@ static const struct reason_option_codes_t option_codes[] = {
   {CPP_W_NORMALIZE,			OPT_Wnormalized_},
   {CPP_W_INVALID_PCH,			OPT_Winvalid_pch},
   {CPP_W_WARNING_DIRECTIVE,		OPT_Wcpp},
+  {CPP_W_LITERAL_SUFFIX,		OPT_Wliteral_suffix},
   {CPP_W_NONE,				0}
 };
 
diff --git a/gcc/c-family/c-opts.c b/gcc/c-family/c-opts.c
index 17e1958..2510747 100644
--- a/gcc/c-family/c-opts.c
+++ b/gcc/c-family/c-opts.c
@@ -476,6 +476,10 @@ c_common_handle_option (size_t scode, const char *arg, int value,
       cpp_opts->warn_invalid_pch = value;
       break;
 
+    case OPT_Wliteral_suffix:
+      cpp_opts->warn_literal_suffix = value;
+      break;
+
     case OPT_Wlong_long:
       cpp_opts->cpp_warn_long_long = value;
       break;
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index d8c944d..db8ca81 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -449,6 +449,10 @@ Wjump-misses-init
 C ObjC Var(warn_jump_misses_init) Init(-1) Warning
 Warn when a jump misses a variable initialization
 
+Wliteral-suffix
+C++ ObjC++ Warning
+Warn when a string or character literal is followed by a ud-suffix which does not begin with an underscore.
+
 Wlogical-op
 C ObjC C++ ObjC++ Var(warn_logical_op) Init(0) Warning 
 Warn when a logical operator is suspiciously always evaluating to true or false
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index c6bf20d..280fac3 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -198,8 +198,8 @@ in the following sections.
 -fno-default-inline  -fvisibility-inlines-hidden @gol
 -fvisibility-ms-compat @gol
 -Wabi  -Wconversion-null  -Wctor-dtor-privacy @gol
--Wdelete-non-virtual-dtor -Wnarrowing -Wnoexcept @gol
--Wnon-virtual-dtor  -Wreorder @gol
+-Wdelete-non-virtual-dtor -Wliteral-suffix -Wnarrowing @gol
+-Wnoexcept -Wnon-virtual-dtor  -Wreorder @gol
 -Weffc++  -Wstrict-null-sentinel @gol
 -Wno-non-template-friend  -Wold-style-cast @gol
 -Woverloaded-virtual  -Wno-pmf-conversions @gol
@@ -2425,6 +2425,30 @@ an instance of a derived class through a pointer to a base class if the
 base class does not have a virtual destructor.  This warning is enabled
 by @option{-Wall}.
 
+@item -Wliteral-suffix @r{(C++ and Objective-C++ only)}
+@opindex Wliteral-suffix
+@opindex Wno-literal-suffix
+Warn when a string or character literal is followed by a ud-suffix which does
+not begin with an underscore.  As a conforming extension, GCC treats such
+suffixes as separate preprocessing tokens in order to maintain backwards
+compatibility with code that uses formatting macros from @code{<inttypes.h>}.
+For example:
+
+@smallexample
+#define __STDC_FORMAT_MACROS
+#include <inttypes.h>
+#include <stdio.h>
+
+int main() @{
+  int64_t i64 = 123;
+  printf("My int64: %"PRId64"\n", i64);
+@}
+@end smallexample
+
+In this case, @code{PRId64} is treated as a separate preprocessing token.
+
+This warning is enabled by default.
+
 @item -Wnarrowing @r{(C++ and Objective-C++ only)}
 @opindex Wnarrowing
 @opindex Wno-narrowing
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 72f1f46..54c616c 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2012-04-27   Ollie Wild  <aaw@google.com>
+
+	* g++.dg/cpp0x/Wliteral-suffix.c: New test.
+
 2012-04-27  Paolo Bonzini  <bonzini@gnu.org>
 
 	* gcc.c-torture/execute/20120427-2.c: New testcase.
diff --git a/gcc/testsuite/g++.dg/cpp0x/Wliteral-suffix.C b/gcc/testsuite/g++.dg/cpp0x/Wliteral-suffix.C
new file mode 100644
index 0000000..39a8353
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/Wliteral-suffix.C
@@ -0,0 +1,29 @@
+// { dg-do run }
+// { dg-options "-std=c++0x" }
+
+// Make sure -Wliteral-suffix is enabled by default and
+// triggers as expected.
+
+#define BAR "bar"
+#define PLUS_ONE + 1
+
+#include <cstdint>
+#include <cassert>
+
+
+void
+test()
+{
+  char c = '3'PLUS_ONE;	  // { dg-warning "invalid suffix on literal" }
+  char s[] = "foo"BAR;	  // { dg-warning "invalid suffix on literal" }
+
+  assert(c == '4');
+  assert(s[3] != '\0');
+  assert(s[3] == 'b');
+}
+
+int
+main()
+{
+  test();
+}