type-props: Suppress warnings in newer Clang and GCC.

Until now, Clang 3.7+ and sufficiently new versions of GCC complained about
TYPE_MAXIMUM(int), etc., because it shifts a negative value.  This commit
fixes the problem.

This commit also gives these macros sensible definitions for _Bool, and
documents all of them.

Reported-by: Joe Stringer <joestringer@nicira.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Joe Stringer <joestringer@nicira.com>

lib/type-props.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2011 Nicira, Inc.
+ * Copyright (c) 2008, 2011, 2015 Nicira, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,15 +19,31 @@
 
 #include <limits.h>
 
+/* True if TYPE is _Bool, false otherwise. */
+#define TYPE_IS_BOOL(TYPE) ((TYPE) 1 == (TYPE) 2)
+
+/* True if TYPE is an integer type (including _Bool), false if it is a
+ * floating-point type. */
 #define TYPE_IS_INTEGER(TYPE) ((TYPE) 1.5 == (TYPE) 1)
+
+/* True if TYPE is a signed integer or floating point type, otherwise false. */
 #define TYPE_IS_SIGNED(TYPE) ((TYPE) 1 > (TYPE) -1)
-#define TYPE_VALUE_BITS(TYPE) (sizeof(TYPE) * CHAR_BIT - TYPE_IS_SIGNED(TYPE))
-#define TYPE_MINIMUM(TYPE) (TYPE_IS_SIGNED(TYPE) \
-                            ? ~(TYPE)0 << (sizeof(TYPE) * 8 - 1) \
-                            : 0)
-#define TYPE_MAXIMUM(TYPE) (TYPE_IS_SIGNED(TYPE) \
-                            ? ~(~(TYPE)0 << (sizeof(TYPE) * 8 - 1)) \
-                            : (TYPE)-1)
+
+/* The number of value bits in an signed or unsigned integer TYPE:
+ *
+ *    - _Bool has 1 value bit.
+ *
+ *    - An N-bit unsigned integer type has N value bits.
+ *
+ *    - An N-bit signed integer type has N-1 value bits.
+ */
+#define TYPE_VALUE_BITS(TYPE) \
+    (TYPE_IS_BOOL(TYPE) ? 1 : sizeof(TYPE) * CHAR_BIT - TYPE_IS_SIGNED(TYPE))
+
+/* The minimum or maximum value of a signed or unsigned integer TYPE. */
+#define TYPE_MINIMUM(TYPE) (TYPE_IS_SIGNED(TYPE) ? -TYPE_MAXIMUM(TYPE) - 1 : 0)
+#define TYPE_MAXIMUM(TYPE) \
+    ((((TYPE)1 << (TYPE_VALUE_BITS(TYPE) - 1)) - 1) * 2 + 1)
 
 /* Number of decimal digits required to format an integer of the given TYPE.
  * Includes space for a sign, if TYPE is signed, but not for a null

tests/test-type-props.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2009, 2011 Nicira, Inc.
+ * Copyright (c) 2008, 2009, 2011, 2015 Nicira, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -44,6 +44,10 @@ main (void)
     char max_s[128];
     char min_s[128];
 
+#ifndef __CHECKER__             /* sparse hates sizeof(bool). */
+    TEST_TYPE(_Bool, 0, 1, 0);
+#endif
+
     TEST_TYPE(char, CHAR_MIN, CHAR_MAX, (CHAR_MIN < 0));
 
     TEST_TYPE(signed char, SCHAR_MIN, SCHAR_MAX, 1);