Clarify and document the integer type configuration

doc/apiref.rst

@@ -296,9 +296,21 @@ Number
 
    Usually, you can safely use plain ``int`` in place of
    ``json_int_t``, and the implicit C integer conversion handles the
-   rest. Only when you know that you need a full 64-bit range, you
+   rest. Only when you know that you need the full 64-bit range, you
    should use ``json_int_t`` explicitly.
 
+``JSON_INTEGER_IS_LONG_LONG``
+
+   This is a preprocessor variable that holds the value 1 if
+   :ctype:`json_int_t` is ``long long``, and 0 if it's ``long``. It
+   can be used as follows::
+
+       #if JSON_INTEGER_IS_LONG_LONG
+       /* Code specific for long long */
+       #else
+       /* Code specific for long */
+       #endif
+
 ``JSON_INTEGER_FORMAT``
 
    This is a macro that expands to a :cfunc:`printf()` conversion

src/jansson_config.h.in

@@ -11,29 +11,24 @@
  *
  * The configure script copies this file to jansson_config.h and
  * replaces @var@ substitutions by values that fit your system. If you
- * cannot run the configure script, you can copy the file and do the
- * value substitution by hand.
- *
- * See below for explanations of each substitution variable.
+ * cannot run the configure script, you can do the value substitution
+ * by hand.
  */
 
 #ifndef JANSSON_CONFIG_H
 #define JANSSON_CONFIG_H
 
+/* If your compiler supports the inline keyword in C, JSON_INLINE is
+   defined to `inline', otherwise empty. In C++, the inline is always
+   supported. */
 #ifdef __cplusplus
 #define JSON_INLINE inline
 #else
-/* If your compiler supports the inline keyword, @json_inline@ is
-   replaced with `inline', otherwise empty. */
 #define JSON_INLINE @json_inline@
 #endif
 
 /* If your compiler supports the `long long` type,
-   @json_have_long_long@ is replaced with 1, otherwise with 0. */
-#if @json_have_long_long@
-#define JSON_INTEGER_IS_LONG_LONG 1
-#else
-#define JSON_INTEGER_IS_LONG 1
-#endif
+   JSON_INTEGER_IS_LONG_LONG is defined to 1, otherwise to 0. */
+#define JSON_INTEGER_IS_LONG_LONG @json_have_long_long@
 
 #endif

src/load.c

@@ -401,7 +401,7 @@ out:
     free(lex->value.string);
 }
 
-#ifdef JSON_INTEGER_IS_LONG_LONG
+#if JSON_INTEGER_IS_LONG_LONG
 #define json_strtoint     strtoll
 #else
 #define json_strtoint     strtol