User:Pkmnfrk/Mystery SIGTRAPs in FreeBasic

Program received signal SIGTRAP, Trace/breakpoint trap.
0x7c901231 in _C__prg_code_bas_FreeBASIC_lib_win32_def____libmsvcrt_dll_a_iname()

Uh oh. Everything seems fine when you run your program, but when debugging in GDB, you get mystery "Trace/breakpoint trap" errors. Worse, they point to the bowels of the native runtime library, which doesn't have any symbols! And, if you grab a backtrace, the last line you wrote was something harmless, like:

return -1

What's going on here?!

Don't Panic

I've run in to these before, and now I am putting digital pen to paper and writing down my experiences for others to use. Read on, and we'll figure out what's going on!

/redim foo(ubound(foo) + 1)

Signs this is your problem:

• Your backtrace looks like this:

(gdb) bt
#0  0x7c901231 in _C__prg_code_bas_FreeBASIC_lib_win32_def____libmsvcrt_dll_a_iname ()
' snip
#6  0x77c2c2de in _C__prg_code_bas_FreeBASIC_lib_win32_def____libmsvcrt_dll_a_iname ()
#7  0x00401582 in hRedim ()
#8  0x0040161c in fb_ArrayRedimEx ()
#9  0x004012f5 in DOSOMETHING (FOO=
      {data = 0x12ff80, ptr = 0x12ff80, size = 12, elen = 4, dims = 1, dim1_elemns = 3,
       dim1_lbound = 0, dim1_ubound = 2}) at crash1.bas:3
#10 0x004013b6 in main (__FB_ARGC__=1, __FB_ARGV__=0x323da8) at crash1.bas:11

• You get a warning just before the SIGTRAP:

warning: HEAP[crash1.exe]:
warning: Invalid Address specified to RtlFreeHeap( 00320000, 0012FF80 )