Q69413: C1001: Internal Compiler Error: regMD.c, Lines 3101 and 3074

Article: Q69413
Product(s): See article
Version(s): 6.00 6.00a | 6.00 6.00a
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | buglist6.00 buglist6.00a | mspl13_c
Last Modified: 25-FEB-1991

The Microsoft C Compiler versions 6.00 and 6.00a produce the following
internal compiler errors when the sample program below is compiled
with default optimization:

With C 6.00a
------------

   file.c(5) : fatal error C1001: Internal Compiler Error
               (compiler file '@(#)regMD.c:1.110', line 3101)
               Contact Microsoft Product Support Services

With C 6.00
-----------

   file.c(5) : fatal error C1001: Internal Compiler Error
               (compiler file '@(#)regMD.c:1.100', line 3074)
               Contact Microsoft Product Support Services

These errors will occur under any memory model when using any one of
the following optimizations (although the errors may not occur when
some of these options are combined):

   /Oa, /Oc, /Od, /Oi, /On, /Op, /Or, /Os, /Ot, /Ow, or /Oz

There are several possible ways to work around these errors:

1. Do not use any of the above options and do not use the default
   optimization for the module where the error occurs.

2. Add /Oe or /Og; one of these combined with other optimizations
   may eliminate the problem.

3. Selectively disable optimizations for the particular function that
   is producing the error through use of the optimize pragma.

4. Rewrite the statement to use an if-else construct instead of the
   ternary operator.

Microsoft has confirmed this to be a problem in C versions 6.00 and
6.00a. We are researching this problem and will post new information
here as it becomes available.

Sample Code
-----------

/* Compile options needed: none
*/

void func(unsigned char uch1, unsigned char uch2)
{
    uch2 = uch1 ? (unsigned char)'0' : (unsigned char)(uch1 % 24);
}

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