[Sdcc-user] Arguments on Stack Throws '78: incompatible types' [mcs51]

[George O. <G.O...@lb...>]

Hi all

While playing around with the Contiki OS, I came across something that left
me scratching my head for a while... I stripped it down to something small
that will still exhibit the same behaviour. I was about to file a bug report
but thought I'd double check that it's not bad code for some reason that
I've failed to spot

The attached will compile just fine with:
sdcc -c foo.c

However, if we compile with --stack-auto, we get the following error:

geo@lin-geo:~/workspace/test-proj$ sdcc --stack-auto -c foo.c
foo.c:19: error 78: incompatible types
from type 'unsigned-char generic* auto'
to type 'struct ip6_addr generic* fixed'

As anticipated, if we add __reentrant to foo's prototype and compile
without --stack-auto we get the same error. --model-xyz does not make any
difference that I've noticed (tried small, large, huge)

However, if we make any of the following changes (demonstrated in the
attached), --stack-auto works
- If foo returns void *
- If we cast its return value to (void *)
- If it takes only a single argument
- If it takes two arguments but neither of type struct xyz *

I tried with the following versions:
SDCC : mcs51 3.0.4 #6748 (Aug 17 2011) (Linux)
SDCC : mcs51 3.0.4 #6726 (Aug  8 2011) (Mac OS X x86_64)
SDCC : mcs51 3.0.1 #6188 (Feb  3 2011) (CYGWIN)
(can you tell how often I use cygwin???):

As ever, folks, thanks a lot for your time reading this and even more so for
all the efforts maintaining SDCC
geo