* cpphash.h (struct spec_nodes): Add n_true and n_false.

	* cppinit.c (cpp_create_reader): Initialize them.
	(append_include_chain): cxx_aware arg might be unused.
	* cppexp.c (lex): In C++ mode, recognize 'true' and 'false'
	keywords and give them their phase 7 meaning.  Pedwarn about
	this unless '__bool_true_false_are_defined' is defined.

	* g++.dg/stdbool-if.C: New test.


git-svn-id: https://gcc.gnu.org/svn/gcc/trunk@39523 138bc75d-0d04-0410-961f-82ee72b054a4

5 files changed, 77 insertions, 11 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index bbfc2fe9b30..2f385b7ccae 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2001-02-07  Zack Weinberg  <zack@wolery.stanford.edu>
+
+	* cpphash.h (struct spec_nodes): Add n_true and n_false.
+	* cppinit.c (cpp_create_reader): Initialize them.
+	(append_include_chain): cxx_aware arg might be unused.
+	* cppexp.c (lex): In C++ mode, recognize 'true' and 'false'
+	keywords and give them their phase 7 meaning.  Pedwarn about
+	this unless '__bool_true_false_are_defined' is defined.
+
 2001-02-07  Alexandre Oliva  <aoliva@redhat.com>
 
 	* lcm.c (optimize_mode_switching): Emit mode_set before the
diff --git a/gcc/cppexp.c b/gcc/cppexp.c
index bea20a22ce5..11cde7066e1 100644
--- a/gcc/cppexp.c
+++ b/gcc/cppexp.c
@@ -426,18 +426,36 @@ lex (pfile, skip_evaluation, token)
 
 	  return parse_defined (pfile);
 	}
-      /* Controlling #if expressions cannot contain identifiers (they
-	 could become macros in the future).  */
-      pfile->mi_state = MI_FAILED;
-
-      op.op = CPP_INT;
-      op.unsignedp = 0;
-      op.value = 0;
+      else if (CPP_OPTION (pfile, cplusplus)
+	       && (token->val.node == pfile->spec_nodes.n_true
+		   || token->val.node == pfile->spec_nodes.n_false))
+	{
+	  op.op = CPP_INT;
+	  op.unsignedp = 0;
+	  op.value = (token->val.node == pfile->spec_nodes.n_true);
+
+	  /* Warn about use of true or false in #if when pedantic
+	     and stdbool.h has not been included.  */
+	  if (CPP_PEDANTIC (pfile)
+	      && ! cpp_defined (pfile, DSC("__bool_true_false_are_defined")))
+	    cpp_pedwarn (pfile, "ISO C++ does not permit \"%s\" in #if",
+			 token->val.node->name);
+	  return op;
+	}
+      else
+	{
+	  /* Controlling #if expressions cannot contain identifiers (they
+	     could become macros in the future).  */
+	  pfile->mi_state = MI_FAILED;
 
-      if (CPP_OPTION (pfile, warn_undef) && !skip_evaluation)
-	cpp_warning (pfile, "\"%s\" is not defined", token->val.node->name);
+	  op.op = CPP_INT;
+	  op.unsignedp = 0;
+	  op.value = 0;
 
-      return op;
+	  if (CPP_OPTION (pfile, warn_undef) && !skip_evaluation)
+	    cpp_warning (pfile, "\"%s\" is not defined", token->val.node->name);
+	  return op;
+	}
 
     case CPP_HASH:
       {
diff --git a/gcc/cppinit.c b/gcc/cppinit.c
index 845d35b7fd1..539366660b1 100644
--- a/gcc/cppinit.c
+++ b/gcc/cppinit.c
@@ -203,7 +203,7 @@ append_include_chain (pfile, dir, path, cxx_aware)
      cpp_reader *pfile;
      char *dir;
      int path;
-     int cxx_aware;
+     int cxx_aware ATTRIBUTE_UNUSED;
 {
   struct cpp_pending *pend = CPP_OPTION (pfile, pending);
   struct file_name_list *new;
@@ -554,6 +554,8 @@ cpp_create_reader (lang)
   s = &pfile->spec_nodes;
   s->n_L                = cpp_lookup (pfile, DSC("L"));
   s->n_defined		= cpp_lookup (pfile, DSC("defined"));
+  s->n_true		= cpp_lookup (pfile, DSC("true"));
+  s->n_false		= cpp_lookup (pfile, DSC("false"));
   s->n__Pragma		= cpp_lookup (pfile, DSC("_Pragma"));
   s->n__STRICT_ANSI__   = cpp_lookup (pfile, DSC("__STRICT_ANSI__"));
   s->n__CHAR_UNSIGNED__ = cpp_lookup (pfile, DSC("__CHAR_UNSIGNED__"));
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 3e77bda33fa..b40f2d5c627 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2001-02-07  Zack Weinberg  <zack@wolery.stanford.edu>
+
+	* g++.dg/stdbool-if.C: New test.
+
 Wed Feb  7 09:54:47 2001  Ovidiu Predescu  <ovidiu@cup.hp.com>
 
 	* objc/execute/fdecl.m: Added main().
diff --git a/gcc/testsuite/g++.dg/stdbool-if.C b/gcc/testsuite/g++.dg/stdbool-if.C
new file mode 100644
index 00000000000..e9800bf160d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/stdbool-if.C
@@ -0,0 +1,33 @@
+/* { dg-do compile } */
+/* { dg-options -pedantic } */
+
+/* test of 'true' and 'false' in #if.  this is accepted with a pedwarn
+   before stdbool.h is included, silently afterward.  */
+
+/* Make sure they're viable keywords.  */
+bool a = true;
+bool b = false;
+
+#if true		/* { dg-warning "true" "true in #if pedwarn" } */
+#else
+#error true is false	/* { dg-bogus "true" "true is false" } */
+#endif
+
+#if false		/* { dg-warning "false" "false in #if pedwarn" } */
+#error false is true	/* { dg-bogus "false" "false is true" } */
+#endif
+
+#include <stdbool.h>
+
+/* Must still be viable keywords.  */
+bool c = true;
+bool d = false;
+
+#if true		/* { dg-bogus "true" "true in #if with stdbool.h" } */
+#else
+#error true is false	/* { dg-bogus "true" "true is false" } */
+#endif
+
+#if false		/* { dg-bogus "false" "false in #if with stdbool.h" } */
+#error false is true	/* { dg-bogus "false" "false is true" } */
+#endif