[google,4_7] Backport r194909 (<:: is incorrectly treated as digraph ...) to google/gcc-4_7 branch (issue7028052)

Index: gcc/testsuite/g++.old-deja/g++.other/crash28.C
===================================================================
--- gcc/testsuite/g++.old-deja/g++.other/crash28.C	(revision 194909)
+++ gcc/testsuite/g++.old-deja/g++.other/crash28.C	(working copy)
@@ -31,5 +31,5 @@ 
 };
 void foo::x() throw(bar)
 {
-  if (!b) throw bar (static_cast<::N::X*>(this));	// { dg-error "lambda expressions|expected" } parse error
+  if (!b) throw bar (static_cast<::N::X*>(this));	// { dg-error "lambda expressions|expected|invalid" } parse error
 }
Index: gcc/testsuite/g++.dg/parse/error12.C
===================================================================
--- gcc/testsuite/g++.dg/parse/error12.C	(revision 194909)
+++ gcc/testsuite/g++.dg/parse/error12.C	(working copy)
@@ -8,6 +8,6 @@ 
 template <class A>
 struct Foo {};
 
-Foo<::B> foo;   // { dg-bogus "error" "error in place of warning" }
-// { dg-warning "4: '<::' cannot begin a template-argument list" "warning <::" { target *-*-* } 11 }
-// { dg-message "4:'<:' is an alternate spelling for '.'. Insert whitespace between '<' and '::'" "note <:" { target *-*-* } 11 }
+Foo<::B> foo;   // { dg-bogus "error" "error in place of warning" { target c++98 } }
+// { dg-warning "4: '<::' cannot begin a template-argument list" "warning <::" { target c++98 } 11 }
+// { dg-message "4:'<:' is an alternate spelling for '.'. Insert whitespace between '<' and '::'" "note <:" { target c++98 } 11 }
Index: gcc/testsuite/g++.dg/parse/error11.C
===================================================================
--- gcc/testsuite/g++.dg/parse/error11.C	(revision 194909)
+++ gcc/testsuite/g++.dg/parse/error11.C	(working copy)
@@ -16,22 +16,22 @@ 
   };
 
   void method(void) {
-    typename Foo<::B>::template Nested<::B> n; // { dg-error "17:'<::' cannot begin" "17-begin" }
-// { dg-message "17:'<:' is an alternate spelling" "17-alt" { target *-*-* } 19 }
-// { dg-error "39:'<::' cannot begin" "39-begin" { target *-*-* } 19 }
-// { dg-message "39:'<:' is an alternate spelling" "39-alt" { target *-*-* } 19 }
+    typename Foo<::B>::template Nested<::B> n; // { dg-error "17:'<::' cannot begin" "17-begin" { target c++98 } }
+// { dg-message "17:'<:' is an alternate spelling" "17-alt" { target c++98 } 19 }
+// { dg-error "39:'<::' cannot begin" "39-begin" { target c++98 } 19 }
+// { dg-message "39:'<:' is an alternate spelling" "39-alt" { target c++98 } 19 }
     n.template Nested<B>::method();
-    n.template Nested<::B>::method();  // { dg-error "22:'<::' cannot begin" "error" }
-// { dg-message "22:'<:' is an alternate" "note" { target *-*-* } 24 }
+    n.template Nested<::B>::method();  // { dg-error "22:'<::' cannot begin" "error" { target c++98 } }
+// { dg-message "22:'<:' is an alternate" "note" { target c++98 } 24 }
     Nested<B>::method();
-    Nested<::B>::method(); // { dg-error "11:'<::' cannot begin" "error" }
-// { dg-message "11:'<:' is an alternate" "note" { target *-*-* } 27 }
+    Nested<::B>::method(); // { dg-error "11:'<::' cannot begin" "error" { target c++98 } }
+// { dg-message "11:'<:' is an alternate" "note" { target c++98 } 27 }
   }
 };
 
 template <int N> struct Foo2 {};
-template struct Foo2<::B>;  // { dg-error "21:'<::' cannot begin" "begin" }
-// { dg-message "21:'<:' is an alternate" "alt" { target *-*-* } 33 }
+template struct Foo2<::B>;  // { dg-error "21:'<::' cannot begin" "begin" { target c++98 } }
+// { dg-message "21:'<:' is an alternate" "alt" { target c++98 } 33 }
 // { dg-message "25:type/value mismatch" "mismatch" { target *-*-* } 33 }
 // { dg-error "25:expected a constant" "const" { target *-*-* } 33 }
 
@@ -39,11 +39,11 @@ 
 
 void func(void)
 {
-  Foo<::B> f; // { dg-error "cannot begin" "begin" }
-// { dg-message "alternate spelling" "alt" { target *-*-* } 42 }
+  Foo<::B> f; // { dg-error "cannot begin" "begin" { target c++98 } }
+// { dg-message "alternate spelling" "alt" { target c++98 } 42 }
   f.Foo<B>::method();
-  f.Foo<::B>::method(); // { dg-error "8:cannot begin" "begin" }
-// { dg-message "8:alternate spelling" "alt" { target *-*-* } 45 }
+  f.Foo<::B>::method(); // { dg-error "8:cannot begin" "begin" { target c++98 } }
+// { dg-message "8:alternate spelling" "alt" { target c++98 } 45 }
 
   // Check cases where we the token sequence is the correct one, but there
   //  was no digraph or whitespaces in the middle, so we should not emit
@@ -63,9 +63,9 @@ 
   Foo[::value] = 0;
 }
 
-template struct Foo<::B>; // { dg-error "20:'<::' cannot begin" "begin" }
-// { dg-message "20:is an alternate" "alt" { target *-*-* } 66 }
+template struct Foo<::B>; // { dg-error "20:'<::' cannot begin" "begin" { target c++98 } }
+// { dg-message "20:is an alternate" "alt" { target c++98 } 66 }
 
 // On the first error message, an additional note about the use of 
 //  -fpermissive should be present
-// { dg-message "17:\\(if you use '-fpermissive' G\\+\\+ will accept your code\\)" "-fpermissive" { target *-*-* } 19 }
+// { dg-message "17:\\(if you use '-fpermissive' G\\+\\+ will accept your code\\)" "-fpermissive" { target c++98 } 19 }
Index: libcpp/lex.c
===================================================================
--- libcpp/lex.c	(revision 194909)
+++ libcpp/lex.c	(working copy)
@@ -2224,6 +2224,17 @@ 
 	{
 	  if (*buffer->cur == ':')
 	    {
+	      /* C++11 [2.5/3 lex.pptoken], "Otherwise, if the next
+		 three characters are <:: and the subsequent character
+		 is neither : nor >, the < is treated as a preprocessor
+		 token by itself".  */
+	      if (CPP_OPTION (pfile, cplusplus)
+		  && (CPP_OPTION (pfile, lang) == CLK_CXX11
+		      || CPP_OPTION (pfile, lang) == CLK_GNUCXX11)
+		  && buffer->cur[1] == ':'
+		  && buffer->cur[2] != ':' && buffer->cur[2] != '>')
+		break;
+
 	      buffer->cur++;
 	      result->flags |= DIGRAPH;
 	      result->type = CPP_OPEN_SQUARE;