Bug#408703: gnat-4.1.1-15: compilation hangs

[Ludovic Brenta <ludovic@ludovic-brenta.org>]

tags 408703 confirmed upstream
forwarded 408703 http://gcc.gnu.org/PR30618
thanks

The infinite loop takes place in sem_ch8.end_use_clauses, as evidenced
by running "gnat1 integer_indexed_io-debug.ads" under gdb:

#1  0x00000000005b0cc0 in sem_ch8.end_use_clauses ()
#2  0x00000000005b0e4d in sem_ch8.pop_scope ()
#3  0x0000000000560b4a in sem_ch10.remove_parents ()
#4  0x0000000000560c19 in sem_ch10.remove_context ()
#5  0x00000000005664f2 in sem_ch10.analyze_compilation_unit ()
#6  0x000000000054b4ac in sem.analyze ()
#7  0x000000000054b829 in sem.semantics.do_analyze ()
#8  0x000000000054ba66 in sem.semantics ()
#9  0x00000000004f1a30 in frontend ()
#10 0x000000000062bac6 in gnat1drv ()
#11 0x0000000000412dad in gnat_parse_file ()
#12 0x0000000000870138 in toplev_main ()
#13 0x00002ade5132c4ca in __libc_start_main () from /lib/libc.so.6
#14 0x0000000000402f0a in _start () at ../sysdeps/x86_64/elf/start.S:113

If you stop gnat1 at various times, the topmost frame (#0)
varies, but after executing the statements until you return to
sem_ch8.end_use_clauses and type n, the infinite loop resumes.

Memory usage remains constant in the infinite loop.

-- 
Ludovic Brenta.