add type-safe MIN() and MAX() macros (#2112)

* add type-safe MIN() and MAX() macros

https://stackoverflow.com/questions/3437404/min-and-max-in-c

* add a CMake check for __typeof__() availability

* extend CMake check for statement expressions

* Revert "extend CMake check for statement expressions"

This reverts commit 52a24bc.

* Revert "add a CMake check for __typeof__() availability"

This reverts commit 24d14f5.

Author: fabiangreffrath

src/doomtype.h

@@ -74,11 +74,25 @@ typedef byte lighttable_t;
 
 #define arrlen(array) (sizeof(array) / sizeof(*array))
 
-#define MIN(a, b) (((a) < (b)) ? (a) : (b))
-
-#define MAX(a, b) (((a) > (b)) ? (a) : (b))
+#if defined(__GNUC__) || defined(__clang__)
+ #define MIN(a,b)             \
+ ({                           \
+     __typeof__ (a) _a = (a); \
+     __typeof__ (b) _b = (b); \
+     _a < _b ? _a : _b;       \
+ })
+ #define MAX(a,b)             \
+ ({                           \
+     __typeof__ (a) _a = (a); \
+     __typeof__ (b) _b = (b); \
+     _a > _b ? _a : _b;       \
+ })
+#else
+ #define MIN(a, b) (((a) < (b)) ? (a) : (b))
+ #define MAX(a, b) (((a) > (b)) ? (a) : (b))
+#endif
 
-#define BETWEEN(l, u, x) ((l) > (x) ? (l) : (x) > (u) ? (u) : (x))
+#define BETWEEN(l, u, x) (MAX((l), (MIN((u), (x)))))
 
 #define DIV_ROUND_FLOOR(n, d) (((n) - (d) / 2) / (d))