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1.4 Compatibility with previous versions

Newer versions have usually numerous bug fixes compared with the previous version. But we also sometimes introduce some incompatibilities with older versions. Not just for the fun of it, but to make the compiler more stable, efficient and ANSI compliant (see section 8.2 for ANSI-Compliance).

- short is now equivalent to int (16 bits), it used to be equivalent to char (8 bits) which is not ANSI compliant. To maintain compatibility, old programs may be compiled using the --short-is-8bits commandline option (see lyx:-short-is-8bits).
- the default directory for gcc-builds where include, library and documentation files are stored is now in /usr/local/share.
- char type parameters to vararg functions are casted to int unless explicitly casted and --std-c89 and --std-c99 command line option are not defined, e.g.:
  `char a=3;`
  `printf (%d %c\n, a, (char)a);`
  will push a as an int and as a char resp if --std-c89 and --std-c99 command line options are not defined,
  will push a as two ints if --std-c89 or --std-c99 command line option is defined.
- pointer type parameters to vararg functions are casted to generic pointers on harvard architectures (e.g. mcs51, ds390) unless explicitly casted and --std-c89 and --std-c99 command line option are not defined.
- option --regextend has been removed.
- option --noregparms has been removed.
- option --stack-after-data has been removed.
- bit and sbit types now consistently behave like the C99 _Bool type with respect to type conversion. The most common incompatibility resulting from this change is related to bit toggling idioms, e.g.:
  `bit b;`
  `b = ~b; /* equivalent to b=1 instead of toggling b */`
  `b = !b; /* toggles b */`
  In previous versions, both forms would have toggled the bit.
- in older versions, the preprocessor was always called with --std-c99 regardless of the --std-xxx setting. This is no longer true, and can cause compilation failures on code built with --std-c89 but using c99 preprocessor features, such as one-line (//) comments
- in versions older than 2.8.4 the pic16 *printf() and printf_tiny() library functions supported undocumented and not standard compliant 'b' binary format specifier (%b, %hb and %lb). The 'b' specifier is now disabled by default. It can be enabled by defining BINARY_SPECIFIER macro in files device/lib/pic16/libc/stdio/vfprintf.c and device/lib/pic16/libc/stdio/printf_tiny.c and recompiling the library.
- in versions older then 2.8.5 the unnamed bitfield structure members participated in initialization, which is not conforming with ISO/IEC 9899:1999 standard (see section Section 6.7.8 Initialization, clause 9)
  Old behavior, before version 2.8.5:
  `struct {`
  `int a : 2;`
  `char : 2;`
  `int b : 2;`
  `} s = {1, 2, 3};`
  `/* s.a = 1, s.b = 3 */`
  New behavior:
  `struct {`
  `int a : 2;`
  `char : 2;`
  `int b : 2;`
  `} s = {1, 2};`
  `/* s.a = 1, s.b = 2 */`
- libraries, included in sdcc packages, are in ar format in sdcc version 2.9.0 and higher. See section 3.1.6.
- special sdcc keywords which are not preceded by a double underscore are deprecated in version 3.0 and higher. See section 8.2 ANSI-Compliance.
- targets for xa51 and avr are disabled by default in version 3.0 and higher.
- in sdcc version 3.0 and higher sdldgb and sdldz80 don't support generation of GameBoy binary image format. The makebin utility can be used to convert Intel Hex format to GameBoy binary image format.
- in sdcc version 3.0 and higher sdldgb and sdldz80 don't support generation of rrgb (GameBoy simulator) map file and no$gmb symbol file formats. The as2gbmap utility can be used to convert sdld map format to rrgb and no$gmb file formats.

Next: 1.5 System Requirements Up: 1. Introduction Previous: 1.3 Typographic conventions Contents Index