🚀 go-pugleaf

In article <1064@tuewsd.lso.win.tue.nl>, wsinpdb@lso.win.tue.nl (Paul de Bra) writes:
> When compiling metafont on a 386, using the AT&T (development system 4.1.6)
> c-compiler, I get bogus errors like this:
> 
> "mf2.c", line 1811: illegal character: 043 (octal)
> "mf2.c", line 1811: cannot recover from earlier errors: goodbye!
> 
> I compiled the stuff with gcc without getting any errors.
> Also, when I say
> 
> cc -P -I.. mf2.c; cc -O -I.. -c mf2.i
> 
> I get no errors, so just by splitting the compilation in 2 supposedly
> equivalent parts the errors go away.

Well, 043 is '#', so it would seem that you have some
preprocessor directives that aren't getting interpreted by the
preprocessor but are instead making their way into the compiler
which is choking on them.  The place that I've seen this most
often is when the '#' isn't in column 1.  Since the problem goes
away when you run the file through the preprocessor twice (the
net result of your double cc), I would guess that there is a
comment before the '#' which gets removed by the first cpp so
that the '#' is in column 1 for the second pass.
----
Larry Jones                         UUCP: uunet!sdrc!scjones
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-Calvin

In article <1282@sdrc.UUCP> scjones@sdrc.UUCP (Larry Jones) writes:
>In article <1064@tuewsd.lso.win.tue.nl>, wsinpdb@lso.win.tue.nl (Paul de Bra) writes:
>> When compiling metafont on a 386, using the AT&T (development system 4.1.6)
>> c-compiler, I get bogus errors like this:
>> 
>> "mf2.c", line 1811: illegal character: 043 (octal)
>> "mf2.c", line 1811: cannot recover from earlier errors: goodbye!
> [ stuff deleted ]1
>... The place that I've seen this most
>often is when the '#' isn't in column 1.  Since the problem goes
>away when you run the file through the preprocessor twice...

Many people sent their comments (thanks folks), but nobody got it right
unfortunately. The source code had no comments, no # signs or anything
in the vincinity of the reported error. (The code is, as the name suggests,
the source for metafont (2.0), generated by web2c)

So I dug in a little deeper and this is what happened (I trimmed down the file):

The following source lines (18 to 21 in the file):
  if ( ! ( abs ( mem [ curedges + 2 ] .hhfield .lhfield + mem [ curedges + 3 ]
  .hhfield .lhfield - 8192 ) < 4096 ) || ! ( abs ( mem [ curedges + 2 ]
  .hhfield .v.RH + mem [ curedges + 3 ] .hhfield .lhfield - 8192 ) < 4096 ) )
  fixoffset () ;

are translated by the preprocessor to: (output from cc -E)
  if ( ! ( zabs((integer) ( mem [ curedges + 2 ] .hhfield .v.LH + mem [ curedges + 3 ]    .hhfield .v.LH - 8192 )) < 4096 ) || ! ( # 20 "mf2.c"
zabs((integer) ( mem [ curedges + 2 ]    .hhfield .v.RH + mem [ curedges + 3 ] .hhfield .v.LH - 8192 )) < 4096 ) )
# 21 "mf2.c"

Note that the required newline before the # 20 "mf2.c" is missing.
This is clearly a preprocessor bug.

The problem went away by performing cc -P first as it rearranges the
expression in a similar fashion but does not generate new
preprocessor commands, like the ones to remember source line numbers.

Now, since the piece of source code that triggered the preprocessor bug
is the source for Metafont, I wonder: who else has encountered this bug
when compiling metafont 2.0?

Paul.
(debra@research.att.com)

In article <1064@tuewsd.lso.win.tue.nl> wsinpdb@lso.win.tue.nl (Paul de Bra) writes:
>When compiling metafont on a 386, using the AT&T (development system 4.1.6)
>c-compiler, I get bogus errors like this:
>"mf2.c", line 1811: illegal character: 043 (octal)
>"mf2.c", line 1811: cannot recover from earlier errors: goodbye!

Since 043 is a '#' character, I suspect the source code is attempting
to use the ANSI-C stringizing or pasting features, which generally
aren't supported by older compilers.  Look on line 1811 of mf2.c and
see how it's trying to use the '#' character..