fatalarrayindex in ctype_isvalidsymbol

[d-torrance]

On autotools build, development branch, I get the following error in debug mode, which looks related to this.

/opt/homebrew/bin/ginstall -c M2 /Users/mike/src/M2-current-branches/M2-development/M2/BUILD/mike/builds.tmp/debug-arm64-appleclang/usr-dist/aarch64-Darwin-MacOS-15.5/bin/M2
: : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : :
: Macaulay2 executable location:
:    "/Users/mike/src/M2-current-branches/M2-development/M2/BUILD/mike/builds.tmp/debug-arm64-appleclang/usr-dist/aarch64-Darwin-MacOS-15.5/bin/M2-binary"
: : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : :
gmake[2]: Leaving directory '/Users/mike/src/M2-current-branches/M2-development/M2/BUILD/mike/builds.tmp/debug-arm64-appleclang/Macaulay2/bin'
gmake -C m2 all 
gmake[2]: Entering directory '/Users/mike/src/M2-current-branches/M2-development/M2/BUILD/mike/builds.tmp/debug-arm64-appleclang/Macaulay2/m2'
echo '# -*- sh -*-' >.gdb-directories
/bin/echo 'echo -- loading .gdb-directories\n' >>.gdb-directories
for i in \
	../../libraries/*/build/*/. \
	../../libraries/ntl/build/*/src/. \
	../../libraries/libfac/build/*/factor/. \
	../../libraries/libfac/build/*/charset/. \
	;\
do if [ -d $i ] ;\
   then echo directory $i >>.gdb-directories ;\
   fi ;\
done
/bin/echo 'echo -- loaded .gdb-directories\n' >>.gdb-directories
cp ../../../../../../Macaulay2/m2/.gdbinit.mike .gdbinit
echo '# -*- sh -*-' >.gdb-files
/bin/echo 'echo -- loading .gdb-files\n' >>.gdb-files
echo 'set environment LD_LIBRARY_PATH /Users/mike/src/M2-current-branches/M2-development/M2/BUILD/mike/builds.tmp/debug-arm64-appleclang/usr-host/lib:/Users/mike/src/M2-current-branches/M2-development/M2/BUILD/mike/builds.tmp/cmake-appleclang/installed/lib' >>.gdb-files
echo 'file /Users/mike/src/M2-current-branches/M2-development/M2/BUILD/mike/builds.tmp/debug-arm64-appleclang/usr-dist/aarch64-Darwin-MacOS-15.5/bin/M2-binary' >>.gdb-files
/bin/echo 'echo -- loaded .gdb-files\n' >>.gdb-files
touch .Macaulay2-made
/opt/homebrew/bin/ginstall -c -d /Users/mike/src/M2-current-branches/M2-development/M2/BUILD/mike/builds.tmp/debug-arm64-appleclang/usr-dist/common/share/Macaulay2/Core
rm -f /Users/mike/src/M2-current-branches/M2-development/M2/BUILD/mike/builds.tmp/debug-arm64-appleclang/usr-dist/common/share/Macaulay2/Core/tvalues.m2 && /Users/mike/src/M2-current-branches/M2-development/M2/BUILD/mike/builds.tmp/debug-arm64-appleclang/usr-dist/aarch64-Darwin-MacOS-15.5/bin/M2 -q --silent --stop -e errorDepth=0 --no-preload -e 'exit 0'
../../../../../../Macaulay2/d/ctype.d:74:54: error: array index 12 out of bounds 0 .. 11
-* stack trace, pid: 84449
 0# profiler_stacktrace(std::__1::basic_ostream<char, std::__1::char_traits<char>>&, int) in /Users/mike/src/M2-current-branches/M2-development/M2/BUILD/mike/builds.tmp/debug-arm64-appleclang/usr-dist/aarch64-Darwin-MacOS-15.5/bin/M2-binary
 1# profiler_stacktrace in /Users/mike/src/M2-current-branches/M2-development/M2/BUILD/mike/builds.tmp/debug-arm64-appleclang/usr-dist/aarch64-Darwin-MacOS-15.5/bin/M2-binary
 2# fatal in /Users/mike/src/M2-current-branches/M2-development/M2/BUILD/mike/builds.tmp/debug-arm64-appleclang/usr-dist/aarch64-Darwin-MacOS-15.5/bin/M2-binary
 3# fatalarrayindex in /Users/mike/src/M2-current-branches/M2-development/M2/BUILD/mike/builds.tmp/debug-arm64-appleclang/usr-dist/aarch64-Darwin-MacOS-15.5/bin/M2-binary
 4# ctype_isvalidsymbol in /Users/mike/src/M2-current-branches/M2-development/M2/BUILD/mike/builds.tmp/debug-arm64-appleclang/usr-dist/aarch64-Darwin-MacOS-15.5/bin/M2-binary
 5# binding_makeSymbol in /Users/mike/src/M2-current-branches/M2-development/M2/BUILD/mike/builds.tmp/debug-arm64-appleclang/usr-dist/aarch64-Darwin-MacOS-15.5/bin/M2-binary
 6# binding_makeSymbol_1 in /Users/mike/src/M2-current-branches/M2-development/M2/BUILD/mike/builds.tmp/debug-arm64-appleclang/usr-dist/aarch64-Darwin-MacOS-15.5/bin/M2-binary
 7# binding_makeSymbol_2 in /Users/mike/src/M2-current-branches/M2-development/M2/BUILD/mike/builds.tmp/debug-arm64-appleclang/usr-dist/aarch64-Darwin-MacOS-15.5/bin/M2-binary
 8# binding_makeProtectedSymbolClosure in /Users/mike/src/M2-current-branches/M2-development/M2/BUILD/mike/builds.tmp/debug-arm64-appleclang/usr-dist/aarch64-Darwin-MacOS-15.5/bin/M2-binary
 9# binding_makeProtectedSymbolClosure_1 in /Users/mike/src/M2-current-branches/M2-development/M2/BUILD/mike/builds.tmp/debug-arm64-appleclang/usr-dist/aarch64-Darwin-MacOS-15.5/bin/M2-binary
10# binding__prepare in /Users/mike/src/M2-current-branches/M2-development/M2/BUILD/mike/builds.tmp/debug-arm64-appleclang/usr-dist/aarch64-Darwin-MacOS-15.5/bin/M2-binary
-- end stack trace *-
gmake[2]: *** [Makefile:34: /Users/mike/src/M2-current-branches/M2-development/M2/BUILD/mike/builds.tmp/debug-arm64-appleclang/usr-dist/common/share/Macaulay2/Core/tvalues.m2] Error 1

Originally posted by @mikestillman in #3932 (comment)