Test cases for c++ comments and endif labels in system headers.

I made them up all by myself.

From-SVN: r31653

gcc/testsuite/gcc.dg/cxx-comments-1.c

+/* { dg-do preprocess } */
+/* { dg-options "-pedantic -std=gnu89" } */
+
+/* You can't do this in your own code... */
+// C++ comment is not in C89  { dg-warning "style comment|reported only once" "good warning" }
+
+/* ...but we don't bitch about it more than once.  */
+// C++ comment is not in C89  { dg-bogus "style comment" "bad warning" }
+
+/*
+   { dg-final { if ![file exists cxx-comments-1.i] { return }		} }
+   { dg-final { set tmp [grep cxx-comments-1.i "is not in C89" line]	} }
+   { dg-final { # send_user "$tmp\n"					} }
+   { dg-final { if [regexp "is not in C89" $tmp] \{			} }
+   { dg-final {     fail "cxx-comments-1: comment strip check"		} }
+   { dg-final { \} else \{						} }
+   { dg-final {     pass "cxx-comments-1: comment strip check"		} }
+   { dg-final { \}							} }
+*/
+

gcc/testsuite/gcc.dg/cxx-comments-2.c

+/* { dg-do preprocess } */
+/* { dg-options "-pedantic -std=c89" } */
+
+/* This is an extension and therefore gets a warning.  */
+#line 5 "cxx-comments-2.c" 3  /* { dg-warning "garbage at end" "#line extension" } */
+
+/* A system header may contain C++ comments irrespective of mode.  */
+// C++ comment is not in C89  { dg-bogus "style comment" "bad warning" }
+
+/*
+   { dg-final { if ![file exists cxx-comments-2.i] { return }		} }
+   { dg-final { set tmp [grep cxx-comments-2.i "is not in C89" line]	} }
+   { dg-final { # send_user "$tmp\n"					} }
+   { dg-final { if [regexp "is not in C89" $tmp] \{			} }
+   { dg-final {     fail "cxx-comments-2: comment strip check"		} }
+   { dg-final { \} else \{						} }
+   { dg-final {     pass "cxx-comments-2: comment strip check"		} }
+   { dg-final { \}							} }
+*/
+

gcc/testsuite/gcc.dg/endif-label.c

+/* { dg-do preprocess } */
+/* { dg-options "-pedantic -Wall" } */
+
+/* You can't get away with this in your own code... */
+#ifdef KERNEL
+#define foo
+#endif KERNEL  /* { dg-warning "text following" "good warning" } */
+
+/* This will provoke a warning because the '3' is an extension.  */
+#line 10 "endif-label.c" 3 /* { dg-warning "garbage at end" "#line extension" } */
+
+/* ... but in a system header, it's acceptable.  */
+#ifdef KERNEL
+#define foo
+#endif KERNEL  /* { dg-bogus "text following" "bad warning" } */