revert the Rboolean changes pending further testing

git-svn-id: https://svn.r-project.org/R/trunk@87679 00db46b3-68df-0310-9c12-caf00c1e9a41

doc/NEWS.Rd

@@ -306,6 +306,8 @@
 
       The macro \code{_R_RBOOLEAN_IS_BOOL_} is defined where
       \code{Rboolean} is implemented \emph{via} \code{bool}.
+
+      [Deferred pending further testing.]
     }
   }
 

src/include/R_ext/Boolean.h

@@ -1,6 +1,6 @@
 /*
  *  R : A Computer Language for Statistical Data Analysis
- *  Copyright (C) 2000, 2025 The R Core Team.
+ *  Copyright (C) 2000, 2001 The R Core Team.
  *
  *  This header file is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU Lesser General Public License as published by
@@ -21,51 +21,21 @@
  *  https://www.R-project.org/Licenses/
  */
 
-/* Included by R.h: Part of the API. */
+/* Included by R.h: API */
 
 #ifndef R_EXT_BOOLEAN_H_
 #define R_EXT_BOOLEAN_H_
 
 #undef FALSE
 #undef TRUE
 
-
-
 #ifdef  __cplusplus
-
 extern "C" {
-    /* once cpp11 is sorted
-typedef bool Rboolean;
-#define FALSE false
-#define TRUE true
-    */
-typedef enum { FALSE = 0, TRUE } Rboolean;
-}
-
-# else
-
-// Also include standard C boolean type
-#if defined __STDC_VERSION__ && __STDC_VERSION__ > 201710L
-// C23 so these are keywords
-#else
-// stdbool.h is C99, so available everywhere
-//# include <stdbool.h>
 #endif
+typedef enum { FALSE = 0, TRUE /*, MAYBE */ } Rboolean;
 
-/* 
-   __bool_true_false_are_defined is defined in stdbool.h, and C23, but
-   it and stdbool.h are declared obsolescent in C23.
-*/
-#ifdef __bool_true_false_are_defined
-typedef bool Rboolean;
-# define FALSE false
-# define TRUE true
-# define _R_RBOOLEAN_IS_BOOL_ 1
-#else
-typedef enum { FALSE = 0, TRUE } Rboolean;
-#endif //__bool_true_false_are_defined
-
-# endif // __cplusplus
-
+#ifdef  __cplusplus
+}
+#endif
 
 #endif /* R_EXT_BOOLEAN_H_ */