Hugs debuggers, I built the December 2001 distribution of Hugs on AIX using IBM's C compiler, and it required a few changes to the distribution to work. System: AIX 4.3.3 XL C 5.0.2 To build without error, I had to change the value of "CFLAGS". I could not do this with "configure" because it was hardwired to set "CFLAGS = -g". I modified "configure" as follows, commenting out the hardwired values. % diff configure.orig configure 4611,4612c4611,4612 < CFLAGS="-g" < OPTFLAGS="-O2" ---
#CFLAGS="-g" #OPTFLAGS="-O2"
Then I configured with the following command. The "-qalloca" is required. CC=cc CFLAGS="-g -qalloca" OPTFLAGS="-O -qmaxmem=-1" LDFLAGS="-bmaxdata:0x70000000" configure --prefix=$MYPREFIX The resulting Hugs executable hung while parsing the Prelude. (The distribution from February 2001 did not have this problem.) I eventually discovered the root of the problem in "input.c". I made the following change to fix it. % diff input.c.orig input.c 516c516 < if (lineBuffer[lineLength] == EOF) ---
if (lineBuffer[lineLength] == (char)EOF)
With AIX, "EOF" is a signed integer of value -1, but characters are unsigned. When the character variable "lineBuffer[lineLength]" is set to "EOF", its value becomes 255. Since 255 doesn't equal -1, the "if" statement is never true. Casting "EOF" to a character give it the needed value of 255. Section 2.7 of K&R's C book, 2nd edition, describes the machine dependence of the automatic conversion of characters "up" to signed integers. The explicit "downward" cast avoids this machine dependence. I humbly suggest incorporating this change to "input.c" in future Hugs distributions. -- James B. White III (Trey) Center for Computational Sciences Oak Ridge National Laboratory whitejbiii@ornl.gov