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update portability guide 

From-SVN: r35041
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Michael Meissner 2000-07-15 04:18:47 +00:00 committed by Michael Meissner
parent 7de515541f
commit ae0e50e87b
2 changed files with 13 additions and 5 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
2000-07-15 Michael Meissner <meissner@redhat.com>
* README.Portability: Update integer suffixes and function
prototype sections.
2000-07-15 Neil Booth <NeilB@earthling.net>
* README.Portability: Small update.

13
gcc/README.Portability
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@ -155,6 +155,9 @@ ansidecl.h for the definitions of the above macros and more.
#define PARAMS(paramlist) () /* K+R C. */
#define VPARAMS(args) (va_alist) va_dcl
One aspect of using K+R style function declarations, is you cannot have
arguments whose types are char, short, or float, since without prototypes (ie,
K+R rules), these types are promoted to int, int, and double respectively.
Calling functions through pointers to functions
-----------------------------------------------
@ -230,10 +233,6 @@ int is done as an unsigned comparison in K+R (since unsigned char
promotes to unsigned) while it is signed in ISO (since all of the
values in unsigned char fit in an int, it promotes to int).
** Not having any argument whose type is a short type (char, short,
float of any flavor) and subject to promotion. **
Trigraphs
---------
@ -245,7 +244,11 @@ them.
Suffixes on Integer Constants
-----------------------------
**Using a 'u' suffix on integer constants.**
K+R C did not accept a 'u' suffix on integer constants. If you want to declare
a constant to be be unsigned, you must use an explicit cast.
You should never use a 'l' suffix on integer constants ('L' is fine), since it
can easily be confused with the number '1'.
Common Coding Pitfalls