BUG: Post-increment in lvalue for assignment operator

sdcc incorrectly compiles code that has a
post-increment operator (eg. i++) used to compute the
lvalue for an assignment-operator statement.

For example, the following code:

a[i++] |= value;

may be compiled incorrectly. The output code will
correctly store its result in a[i] but will read one of
its operands from a[i+1] rather than a[i].

I have seen this bug with the following version of sdcc:

$ sdcc --version

SDCC
mcs51/gbz80/z80/avr/ds390/pic14/pic16/TININative/xa51/ds400
2.3.5 (Aug 1 2003)\ (UNIX)

The attached file demonstrates the bug in a simple C
program. It also includes a comment showing the
generated .asm file and the bug it contains.

Thanks,

-Carl

Carl Worth <cwort@isi.edu>