https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68746
--- Comment #12 from dave.anglin at bell dot net ---
On 2018-01-31 3:17 AM, tkoenig at gcc dot gnu.org wrote:
> Is there anything than can be done to debug this?
> What happens if you compile the test with -g and
> run it under a debgger?
It's not easy. It turns out the "system" call causes gdb to crash.
Working around that,
we have at the end of data_transfer_init:
Breakpoint 34, data_transfer_init (dtp=0x800003fffdff0ad0,
read_flag=<optimized out>) at
../../../gcc/libgfortran/io/transfer.c:3201
3201 if ((cf & (IOPARM_DT_LIST_FORMAT |
IOPARM_DT_HAS_NAMELIST_NAME)) == 0
(gdb) p cf
$7 = 128
(gdb) p *dtp
$8 = {common = {flags = 128, unit = 6,
filename = 0x4000000000001860 "read_dir.f90", line = 10,
iomsg_len = 9223376434867631712, iomsg = 0x800003fffdfedbf8 "\200",
iostat = 0x800003fffdff0acc}, rec = 0, size = 0x9,
iolength = 0x4000000000001870, internal_unit_desc = 0x0,
format = 0x40000000000018a0 <options.4> "", format_len = 6,
advance_len = 4611686018427394176,
advance = 0x1 <error: Cannot access memory at address 0x1>,
internal_unit = 0x0, internal_unit_len = 9223376434866410515,
namelist_name_len = 9223376434866047520,
namelist_name = 0x4 <error: Cannot access memory at address 0x4>, id
= 0x0,
pos = 4, asynchronous = 0x4000000000001888 "read", asynchronous_len = 0,
blank_len = 0, blank = 0x800003fffdff07b0 "\200",
decimal = 0x800003fffde64a20 "\200", decimal_len = 3,
delim_len = 9223376434866032944, delim = 0x800003fffdff0b10 "@",
pad = 0x318 <error: Cannot access memory at address 0x318>, pad_len = 1,
round_len = 0, round = 0x0,
sign = 0x800003fffdda4293 <signal+136> "\301\210\034
\030S\302>\241S\334?\001\350@\320", sign_len = 281479271677959, u = {p = {
transfer = 0x800003fffde62260, current_unit = 0x800000010000a518,
item_count = 0, mode = WRITING, blank_status = BLANK_NULL,
sign_status = SIGN_UNSPECIFIED, scale_factor = 0, max_pos = 0,
skips = 0, pending_spaces = 0, sf_seen_eor = 0,
---Type <return> to continue, or q <return> to quit---
advance_status = ADVANCE_YES, reversion_flag = 0, first_item = 1,
seen_dollar = 0, eor_condition = 0, no_leading_blank = 0,
char_flag = 0,
input_complete = 0, at_eol = 0, comma_flag = 0, namelist_mode = 0,
nml_read_error = 0, sf_read_comma = 0, line_buffer_enabled = 0,
unit_is_internal = 0, at_eof = 0, g0_no_blanks = 0,
format_not_saved = 0, expanded_read = 0, child_saved_iostat = 0,
nml_delim = 0, repeat_count = 0, saved_length = 0, saved_used = 0,
saved_type = BT_UNKNOWN, saved_string = 0x0, scratch = 0x0,
line_buffer = 0x0, fmt = 0x0, ionml = 0x0, line_buffer_pos = 0,
value = '\000' <repeats 31 times>, not_used = 0, fdtio_ptr = 0x0,
ufdtio_ptr = 0x0, cc = {type = 0, len = 0, u = {start = 0 '\000',
end = 0 '\000'}}},
pad =
"\200\000\003\377\375\346\"`\200\000\000\001\000\000\245\030\000\000\000\000\000\000\000\001\000\000\000\000\000\000\000\003",
'\000' <repeats 24 times>, "@", '\000' <repeats 151 times>...}}
