Preprocessor endless loop eat all memory

[mingodad]

While trying to figure out this issue #203 and attempting to dump the preprocessed source I found that circle seems to enter an endless loop and eat all memory.

g++-9.4
0.08user 0.01system 0:00.11elapsed 85%CPU (0avgtext+0avgdata 21992maxresident)k
0inputs+0outputs (0major+2499minor)pagefaults 0swaps

clang++-18
0.07user 0.01system 0:00.11elapsed 78%CPU (0avgtext+0avgdata 63860maxresident)k
328inputs+0outputs (1major+4108minor)pagefaults 0swaps

Script to test:

# run gcc compiler in freestanding mode
optim=-O2
#CXX=g++
#CXX="clang-18-env clang++"
#CXX="circle -DCIRCLE_SAFETY_ON"
CXX=circle

/usr/bin/time $CXX $optim  -E -fno-rtti -Wall \
	-DNDEBUG -DONLY_ASCII -DNO_ABSTRACT_METHOD -DCUSTOM_DELETE_OPERATOR -DSQ_USE_MKSTEMP  -DSQ_ENABLE_INCLUDES -DSQ_SUBLATIN -DNEED_SUBLATIN_C -DSQUSEDOUBLE \
	-D__SQAMALGAMATION__ -D_SQ64 -DMAKE_SQ_CMD am-squilu.cpp #-o am-squilu-circle

Sources : https://github.com/user-attachments/files/15526008/am-squilu.cpp.zip

[sanbei101]

This is an extremely serious problem！