gawk awking bug, version 3.1.5

[shioyai]

Dear GNU-awk;

I am processing the words in plain text files.
GNU Awk 3.1.5 dosn't work well. However,GNU Awk 3.1.3 is
fine well. So, I try to find the bug reports. But, none.
Sumary of my report is:
my program is ver simple:
------------------
{
 print "DEB", $0;
 str = "";
 for(i=1;i<=length($2);i++) {
   s = substr($2,i,1);
   if (s == "A") s = "a";
   else if (s == "B") s = "b";
   else if (s == "C") s = "c";
   else if (s == "D") s = "d";
   else if (s == "E") s = "e";
   else if (s == "F") s = "f";
   else if (s == "G") s = "g";
   else if (s == "H") s = "h";
   else if (s == "I") s = "i";
   else if (s == "J") s = "j";
   else if (s == "K") s = "k";
   else if (s == "L") s = "l";
   else if (s == "M") s = "m";
   else if (s == "N") s = "n";
   else if (s == "O") s = "o";
   else if (s == "P") s = "p";
   else if (s == "Q") s = "q";
   else if (s == "R") s = "r";
   else if (s == "S") s = "s";
   else if (s == "T") s = "t";
   else if (s == "U") s = "u";
   else if (s == "V") s = "v";
   else if (s == "W") s = "w";
   else if (s == "X") s = "x";
   else if (s == "Y") s = "y";
   else if (s == "Z") s = "z";
   str = str s;
 }
 print $1, str;
}

---------------------- data --------------------
1 THE
1 INDIAN
1 COUNCIL
1 OF
1 LIBRARY
1 AND
1 INFORMATION
1 SERVICES
1 RESEARCH
1 AND
1 A
1 PROPOSAL
1 FOR
1 CONSIDERATION
1 MISALLOCATION
1 AND
1 UNDERUTILISATION
1 OF
1 LIBRARY
1 RESOURCES
--------------------- end -------------------------------
gawk -f par3.awk w2.txt > w3.txt

*** glibc detected *** gawk: double free or corruption (fasttop): 0x098b6a58 ***
======= Backtrace: =========
/lib/libc.so.6[0x41fb8efd]
/lib/libc.so.6(cfree+0x90)[0x41fbc550]
gawk(str2wstr+0x42)[0x80700d2]
gawk(do_length+0xb5)[0x8058bb5]
gawk(r_tree_eval+0x52e)[0x80824ce]
gawk(r_tree_eval+0xc8)[0x8082068]
gawk[0x8083596]
gawk(interpret+0x5c8)[0x8080aa8]
gawk(interpret+0x3bd)[0x808089d]
gawk(interpret+0x1d6)[0x80806b6]
gawk(do_input+0x38)[0x806d128]
gawk(main+0x1063)[0x806f7a3]
/lib/libc.so.6(__libc_start_main+0xdc)[0x41f68f2c]
gawk[0x804c9a1]
======= Memory map: ========
00e04000-00e05000 r-xp 00e04000 00:00 0          [vdso]
08047000-08095000 r-xp 00000000 fd:00 34865229   /bin/gawk
08095000-08096000 rwxp 0004d000 fd:00 34865229   /bin/gawk
08096000-0809b000 rwxp 08096000 00:00 0
09623000-098d8000 rwxp 09623000 00:00 0
41584000-4159d000 r-xp 00000000 fd:00 24576077   /lib/ld-2.5.so
4159d000-4159e000 r-xp 00018000 fd:00 24576077   /lib/ld-2.5.so
4159e000-4159f000 rwxp 00019000 fd:00 24576077   /lib/ld-2.5.so
41f53000-4208a000 r-xp 00000000 fd:00 24576094   /lib/libc-2.5.so
4208a000-4208c000 r-xp 00137000 fd:00 24576094   /lib/libc-2.5.so
4208c000-4208d000 rwxp 00139000 fd:00 24576094   /lib/libc-2.5.so
4208d000-42090000 rwxp 4208d000 00:00 0
42092000-420b7000 r-xp 00000000 fd:00 24577601   /lib/libm-2.5.so
420b7000-420b8000 r-xp 00024000 fd:00 24577601   /lib/libm-2.5.so
420b8000-420b9000 rwxp 00025000 fd:00 24577601   /lib/libm-2.5.so
420bb000-420bd000 r-xp 00000000 fd:00 24576182   /lib/libdl-2.5.so
420bd000-420be000 r-xp 00001000 fd:00 24576182   /lib/libdl-2.5.so
420be000-420bf000 rwxp 00002000 fd:00 24576182   /lib/libdl-2.5.so
42ad8000-42ae3000 r-xp 00000000 fd:00 24577638
/lib/libgcc_s-4.1.1-20061011.so.1
42ae3000-42ae4000 rwxp 0000a000 fd:00 24577638
/lib/libgcc_s-4.1.1-20061011.so.1
b7b00000-b7b21000 rw-p b7b00000 00:00 0
b7b21000-b7c00000 ---p b7b21000 00:00 0
b7c74000-b7c75000 rw-p b7c74000 00:00 0
b7c75000-b7c7c000 r--s 00000000 fd:00 11535374
/usr/lib/gconv/gconv-modules.cache
b7c7c000-b7d66000 r--p 02bb1000 fd:00 11472521   /usr/lib/locale/locale-archive
b7d66000-b7f66000 r--p 00000000 fd:00 11472521   /usr/lib/locale/locale-archive
b7f66000-b7f67000 rw-p b7f66000 00:00 0
b7f78000-b7f79000 rw-p b7f78000 00:00 0
bf83f000-bf855000 rw-p bf83f000 00:00 0          [stack]
run: line 10:  9009 aborted(original message is japanese) gawk -f
par3.awk w2.txt >w3.txt