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binutils-gdb/gdb/testsuite/gdb.go/max-depth.exp

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gdb: Introduce 'print max-depth' feature Introduce a new print setting max-depth which can be set with 'set print max-depth DEPTH'. The default value of DEPTH is 20, but this can also be set to unlimited. When GDB is printing a value containing nested structures GDB will stop descending at depth DEPTH. Here is a small example: typedef struct s1 { int a; } s1; typedef struct s2 { s1 b; } s2; typedef struct s3 { s2 c; } s3; typedef struct s4 { s3 d; } s4; s4 var = { { { { 3 } } } }; The following table shows how various depth settings affect printing of 'var': | Depth Setting | Result of 'p var' | |---------------+--------------------------------| | Unlimited | $1 = {d = {c = {b = {a = 3}}}} | | 4 | $1 = {d = {c = {b = {a = 3}}}} | | 3 | $1 = {d = {c = {b = {...}}}} | | 2 | $1 = {d = {c = {...}}} | | 1 | $1 = {d = {...}} | | 0 | $1 = {...} | Only structures, unions, and arrays are replaced in this way, scalars and strings are not replaced. The replacement is counted from the level at which you print, not from the top level of the structure. So, consider the above example and this GDB session: (gdb) set print max-depth 2 (gdb) p var $1 = {d = {c = {...}}} (gdb) p var.d $2 = {c = {b = {...}}} (gdb) p var.d.c $3 = {b = {a = 3}} Setting the max-depth to 2 doesn't prevent the user from exploring deeper into 'var' by asking for specific sub-fields to be printed. The motivation behind this feature is to try and give the user more control over how much is printed when examining large, complex data structures. The default max-depth of 20 means that there is a change in GDB's default behaviour. Someone printing a data structure with 20 levels of nesting will now see '{...}' instead of their data, they would need to adjust the max depth, or call print again naming a specific field in order to dig deeper into their data structure. If this is considered a problem then we could increase the default, or even make the default unlimited. This commit relies on the previous commit, which added a new field to the language structure, this new field was a string that contained the pattern that should be used when a structure/union/array is replaced in the output, this allows languages to use a syntax that is more appropriate, mostly this will be selecting the correct types of bracket '(...)' or '{...}', both of which are currently in use. This commit should have no impact on MI output, expressions are printed through the MI using -var-create and then -var-list-children. As each use of -var-list-children only ever displays a single level of an expression then the max-depth setting will have no impact. This commit also adds the max-depth mechanism to the scripting language pretty printers following basically the same rules as for the built in value printing. One quirk is that when printing a value using the display hint 'map', if the keys of the map are structs then GDB will hide the keys one depth level after it hides the values, this ensures that GDB produces output like this: $1 = map_object = {[{key1}] = {...}, [{key2}] = {...}} Instead of this less helpful output: $1 = map_object = {[{...}] = {...}, [{...}] = {...}} This is covered by the new tests in gdb.python/py-nested-maps.exp. gdb/ChangeLog: * cp-valprint.c (cp_print_value_fields): Allow an additional level of depth when printing anonymous structs or unions. * guile/scm-pretty-print.c (gdbscm_apply_val_pretty_printer): Don't print either the top-level value, or the children if the max-depth is exceeded. (ppscm_print_children): When printing the key of a map, allow one extra level of depth. * python/py-prettyprint.c (gdbpy_apply_val_pretty_printer): Don't print either the top-level value, or the children if the max-depth is exceeded. (print_children): When printing the key of a map, allow one extra level of depth. * python/py-value.c (valpy_format_string): Add max_depth keyword. * valprint.c: (PRINT_MAX_DEPTH_DEFAULT): Define. (user_print_options): Initialise max_depth field. (val_print_scalar_or_string_type_p): New function. (val_print): Check to see if the max depth has been reached. (val_print_check_max_depth): Define new function. (show_print_max_depth): New function. (_initialize_valprint): Add 'print max-depth' option. * valprint.h (struct value_print_options) <max_depth>: New field. (val_print_check_max_depth): Declare new function. * NEWS: Document new feature. gdb/doc/ChangeLog: * gdb.texinfo (Print Settings): Document 'print max-depth'. * guile.texi (Guile Pretty Printing API): Document that 'print max-depth' can effect the display of a values children. * python.texi (Pretty Printing API): Likewise. (Values From Inferior): Document max_depth keyword. gdb/testsuite/ChangeLog: * gdb.base/max-depth.c: New file. * gdb.base/max-depth.exp: New file. * gdb.python/py-nested-maps.c: New file. * gdb.python/py-nested-maps.exp: New file. * gdb.python/py-nested-maps.py: New file. * gdb.python/py-format-string.exp (test_max_depth): New proc. (test_all_common): Call test_max_depth. * gdb.fortran/max-depth.exp: New file. * gdb.fortran/max-depth.f90: New file. * gdb.go/max-depth.exp: New file. * gdb.go/max-depth.go: New file. * gdb.modula2/max-depth.exp: New file. * gdb.modula2/max-depth.c: New file. * lib/gdb.exp (get_print_expr_at_depths): New proc.
2019-03-21 23:13:23 +08:00
# This testcase is part of GDB, the GNU debugger.
# Copyright 2019 Free Software Foundation, Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
# Test the use of 'set prinnt max-depth' when printing go structures.
load_lib "go.exp"
if { [skip_go_tests] } { continue }
standard_testfile .go
if { [prepare_for_testing "failed to prepare" ${testfile} ${srcfile} {debug go}] } {
return -1
}
if { [go_runto_main] < 0 } {
untested "could not run to main"
return -1
}
gdb_breakpoint [gdb_get_line_number "Break here"]
gdb_continue_to_breakpoint "run to breakpoint" ".*Break here.*"
gdb_print_expr_at_depths "s1" [list "{...}" \
"{m_struct = {...}, m_string = $hex \"hello world\"}" \
"{m_struct = {m_a = 3, m_b = 7}, m_string = $hex \"hello world\"}"]
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