gcc/README.TRAD

   1 This is a partial list of how `gcc -traditional' disagrees with
   2 traditional C compilers (perhaps only some of them).  Most of these
   3 differences are not bugs.
   4
   5 ---------------------------------------------------------------------------
   6 K&R-1 (2.4.3) says:
   7
   8         "If the character following a backslash is not one of those
   9         specified {in the table above}, the backslash is ignored."
  10
  11 Up until recently, `gcc -traditional' complained about \x \a and \v
  12 appearing in a character or string literal.  I believe however that
  13 this non-feature has been eliminated (recently).
  14
  15 ---------------------------------------------------------------------------
  16 When in -traditional mode, gcc allows the following erroneous pair of
  17 declarations to appear together in a given scope:
  18
  19         typedef int foo;
  20         typedef foo foo;
  21
  22 ---------------------------------------------------------------------------
  23 K&R-1 (8.5) says:
  24
  25         "No field may be wider than a word."
  26
  27 Gcc however allows:
  28
  29         struct S { int i:33; };
  30
  31 ---------------------------------------------------------------------------
  32 In K&R-1 there is no restriction against comments crossing include file
  33 boundaries.  Gcc however doesn't allow this, even when in -traditional mode.
  34
  35 ---------------------------------------------------------------------------
  36 Regarding the length of identifiers, K&R-1 (2.2) says:
  37
  38         "No more than the first eight characters are significant,
  39         although more may be used."
  40
  41 Gcc treats all characters of identifiers as significant, even when in
  42 -traditional mode.
  43
  44 ---------------------------------------------------------------------------
  45 K&R-1 (2.2) says:
  46
  47         "An identifier is a sequence of letters and digits; the first
  48         character must be a letter.  The underscore _ counts as a letter."
  49
  50 Gcc also allows dollar signs in identifiers.  (This may also be an issue
  51 for the -pedantic option.)
  52
  53 ---------------------------------------------------------------------------
  54
  55