[Bug modula2/108344] Many tests time out: isatty called in a tight loop

["ro at CeBiTec dot Uni-Bielefeld.DE" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108344

--- Comment #1 from ro at CeBiTec dot Uni-Bielefeld.DE <ro at CeBiTec dot Uni-Bielefeld.DE> ---
To gather more information, I've tried a -g3 -O0 build.  The failures
still occur, but the failure mode is slightly different: all the 64-bit
tests in gm2/iso/pass now SEGV in cc1gm2:

Core was generated by `/var/gcc/regression/master/11.4-gcc/build/gcc/cc1gm2
-fcpp-begin -E -lang-asm -'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x0b38d8cf in LINEMAPS_MACRO_USED (set=0xfaee1000) at
/vol/gcc/src/hg/master/local/gcc/../libcpp/include/line-map.h:1002
1002      return LINEMAPS_USED (set, true);

#1  0x0b38d902 in LINEMAPS_MACRO_LOWEST_LOCATION (set=0xfaee1000) at
/vol/gcc/src/hg/master/local/libcpp/include/line-map.h:1025
#2  0x0b3b3815 in linemap_location_from_macro_expansion_p (set=0xfaee1000,
location=223680) at /vol/gcc/src/hg/master/local/libcpp/line-map.cc:1360
#3  0x0b3b2f64 in linemap_lookup (set=0xfaee1000, line=223680) at
/vol/gcc/src/hg/master/local/libcpp/line-map.cc:1055
#4  0x0b3b1c5d in pure_location_p (set=0xfaee1000, loc=223680) at
/vol/gcc/src/hg/master/local/libcpp/line-map.cc:342
#5  0x0b3b1708 in get_combined_adhoc_loc (set=0xfaee1000, locus=223680,
src_range=..., data=0x0, discriminator=0) at
/vol/gcc/src/hg/master/local/libcpp/line-map.cc:190
#6  0x0a029d7e in COMBINE_LOCATION_DATA (set=0xfaee1000, loc=223680,
src_range=..., block=0x0, discriminator=0) at
/vol/gcc/src/hg/master/local/gcc/../libcpp/include/line-map.h:1067
#7  0x0b3822f8 in make_location (caret=223680, src_range=...) at
/vol/gcc/src/hg/master/local/gcc/input.cc:1194
#8  0x09491abc in m2linemap_GetLocationRange (start=2096540, end=2096540) at
/vol/gcc/src/hg/master/local/gcc/m2/gm2-gcc/m2linemap.cc:102
#9  0x094a044f in updatepos () at
/vol/gcc/src/hg/master/local/gcc/m2/m2.flex:521
#10 0x094a0968 in yywrap () at /vol/gcc/src/hg/master/local/gcc/m2/m2.flex:756
#11 0x0949e9e3 in yylex () at
/var/gcc/regression/master/11.4-gcc/build/gcc/<stdout>:1927
#12 0x094a07a7 in m2flex_GetToken () at
/vol/gcc/src/hg/master/local/gcc/m2/m2.flex:654
#13 0x094dea34 in M2LexBuf_GetToken () at m2/gm2-compiler-boot/M2LexBuf.c:958
#14 0x094dea39 in M2LexBuf_GetToken () at m2/gm2-compiler-boot/M2LexBuf.c:959
[...]
#2096552 0x094dea39 in M2LexBuf_GetToken () at
m2/gm2-compiler-boot/M2LexBuf.c:9
59
#2096553 0x094de8d7 in M2LexBuf_OpenSource (s=0xc0fa638) at
m2/gm2-compiler-boot
/M2LexBuf.c:855
#2096554 0x094bf342 in DoPass0 (s=0xc0f3550) at
m2/gm2-compiler-boot/M2Comp.c:304
#2096555 0x094befe1 in Compile (s=0xc0f3550) at
m2/gm2-compiler-boot/M2Comp.c:183
#2096556 0x094bfdae in M2Comp_compile (filename=0xfeffb441) at
m2/gm2-compiler-boot/M2Comp.c:760
#2096557 0x0949b9f5 in init_PerCompilationInit (filename=0xfeffb441
"/vol/gcc/src/hg/master/local/gcc/testsuite/gm2/iso/pass/ChanConsts.mod") at
/vol/gcc/src/hg/master/local/gcc/m2/gm2-gcc/init.cc:195
#2096558 0x09461457 in gm2_parse_input_files (filenames=0xc0907c0,
filename_count=2) at /vol/gcc/src/hg/master/local/gcc/m2/gm2-lang.cc:451
#2096559 0x09461485 in gm2_langhook_parse_file () at
/vol/gcc/src/hg/master/local/gcc/m2/gm2-lang.cc:458
#2096560 0x09c45c5c in compile_file () at
/vol/gcc/src/hg/master/local/gcc/toplev.cc:444
#2096561 0x09c48898 in do_compile (no_backend=false) at
/vol/gcc/src/hg/master/local/gcc/toplev.cc:2125
#2096562 0x09c48c11 in toplev::main (this=0xfeffa7aa, argc=79, argv=0xfeffa80c)
at /vol/gcc/src/hg/master/local/gcc/toplev.cc:2277
#2096563 0x0b328eee in main (argc=79, argv=0xfeffa80c) at
/vol/gcc/src/hg/master/local/gcc/main.cc:39

so we have unbounded recursion in M2LexBuf_GetToken.