c: remove __CHAR_UNSIGNED__

In C, `char`, `signed char`, and `unsigned char` are three separate,
distinct types, so just because `char` happens to be signed does not
mean it is interchangeable with `signed char`.

CMakeLists.txt

@@ -1186,20 +1186,6 @@ MARK_AS_ADVANCED(ENABLE_SHARED_LIBRARY_VERSION)
 # Option checks
 ################################
 
-####
-# Check to see if char is signed or unsigned.
-####
-
-SET(SIGNED_TEST_SOURCE "\n
-  #include <stdlib.h>\n
-  int main(void) {\n
-    char error_if_char_is_signed[((char)-1) < 0 ? -1 : 1];\n
-    error_if_char_is_signed[0] = 0;
-    return -;\n
-}\n")
-
-CHECK_C_SOURCE_COMPILES("${SIGNED_TEST_SOURCE}" __CHAR_UNSIGNED__)
-
 # Library include checks
 CHECK_INCLUDE_FILE("math.h"      HAVE_MATH_H)
 CHECK_INCLUDE_FILE("unistd.h"  HAVE_UNISTD_H)

config.h.cmake.in

@@ -553,11 +553,6 @@ are set when opening a binary file on Windows. */
 /* Define for large files, on AIX-style hosts. */
 #cmakedefine _LARGE_FILES ${_LARGE_FILES}
 
-/* Define to 1 if type `char' is unsigned and you are not using gcc.  */
-#ifndef __CHAR_UNSIGNED__
-#cmakedefine  __CHAR_UNSIGNED__
-#endif
-
 /* Define to `long int' if <sys/types.h> does not define. */
 #cmakedefine off_t long int
 

config.h.cmake.in.old-works

@@ -196,11 +196,6 @@ are set when opening a binary file on Windows. */
 #cmakedefine SIZEOF_ULONGLONG @SIZEOF_ULONGLONG@
 #cmakedefine SIZEOF_UNSIGNED_LONG_LONG @SIZEOF_UNSIGNED_LONG_LONG@
 
-/* Define whether char is signed by default. */
-#ifndef __CHAR_UNSIGNED__
-#cmakedefine __CHAR_UNSIGNED__
-#endif
-
 /* The size of `void*` as computed by sizeof. */
 #cmakedefine SIZEOF_VOIDSTAR @SIZEOF_VOIDSTAR@
 /* The size of `char` as computed by sizeof. */

configure.ac

@@ -808,7 +808,6 @@ AC_STRUCT_ST_BLKSIZE
 UD_CHECK_IEEE
 AC_CHECK_TYPES([size_t, ssize_t, schar, uchar, longlong, ushort, uint, int64, uint64])
 AC_TYPE_OFF_T
-AC_C_CHAR_UNSIGNED
 AC_C_BIGENDIAN
 
 ###

libsrc/posixio.c

@@ -740,11 +740,7 @@ px_get(ncio *const nciop, ncio_px *const pxp,
 	pxp->bf_rflags |= rflags;
 	pxp->bf_refcount++;
 
-#ifndef __CHAR_UNSIGNED__
-    *vpp = (void *)((char *)pxp->bf_base + diff);
-#else
     *vpp = (void *)((signed char*)pxp->bf_base + diff);
-#endif
 	return NC_NOERR;
 }
 

libsrc/putget.m4

@@ -1198,11 +1198,7 @@ readNCv(const NC3_INFO* ncp, const NC_var* varp, const size_t* start,
 
     case CASE(NC_CHAR,NC_CHAR):
     case CASE(NC_CHAR,NC_UBYTE):
-#ifndef __CHAR_UNSIGNED__
-       return getNCvx_char_char(ncp,varp,start,nelems,(char*)value);
-#else
     return getNCvx_schar_schar(ncp,varp,start,nelems,(signed char*)value);
-#endif
     break;
     case CASE(NC_BYTE,NC_BYTE):
         return getNCvx_schar_schar(ncp,varp,start,nelems, (schar*)value);

nc_test/util.c

@@ -342,11 +342,7 @@ int dbl2nc ( const double d, const nc_type xtype, void *p)
              * reporting it as a range error.
              */
             if ( r < X_CHAR_MIN || r > X_CHAR_MAX ) return 2;
-#if defined(__CHAR_UNSIGNED__) && __CHAR_UNSIGNED__ != 0
             *((signed char*) p) = (signed char)r;
-#else
-            *((char   *) p) = (char)r;
-#endif
             break;
         case NC_BYTE:
             r = floor(0.5+d);