| Summary: | Strange behaviour of gdb.Type.fields | ||
|---|---|---|---|
| Product: | gdb | Reporter: | Andre' <andre.poenitz> |
| Component: | python | Assignee: | Not yet assigned to anyone <unassigned> |
| Status: | RESOLVED DUPLICATE | ||
| Severity: | normal | CC: | gdb-prs, tromey |
| Priority: | P2 | ||
| Version: | 7.1 | ||
| Target Milestone: | 7.1 | ||
| Host: | i486-linux-gnu | Target: | i486-linux-gnu |
| Build: | i486-linux-gnu | Last reconfirmed: | |
To reproduce:
mkdir x && cd x
echo -e "#include <QRegion>\nint main() { QRegion r; }" > 1.cpp
qmake -project && qmake && make
gdb -ex "b main" -ex "run" -ex "python import gdb" -ex 'python print
gdb.parse_and_eval("r")["d"].dereference()["qt_rgn"].dereference().type.fields()' -ex
'python print
gdb.lookup_type(str(gdb.parse_and_eval("r")["d"].dereference()["qt_rgn"].dereference().type)).fields()'
./x
To reproduce without Qt:
------------------------- snip ------------------------
mkdir x && cd x
echo -e "struct P { P(); int a, b, c, d; }; " > p.h
echo -e "#include \"p.h\"\n P::P() {} " > p.cpp
echo -e "class P; struct X { X(); P *p; };" > x.h
echo -e " #include \"x.h\"\n X::X() {} " > x.cpp
echo -e "#include \"x.h\"\n int main() { X x; }" > main.cpp
g++ -g -shared -o libxp.so x.cpp p.cpp
g++ -g -o x -L. -lxp main.cpp -Wl,-rpath,`pwd`
gdb -ex "b main" -ex "run" -ex "python import gdb" \
-ex 'set confirm off' \
-ex 'python print gdb.parse_and_eval("x")["p"].dereference().type.fields()' \
-ex 'python print
gdb.lookup_type(str(gdb.parse_and_eval("x")["p"].dereference().type)).fields()' \
-ex q \
./x
------------------------- snip ------------------------
(In reply to comment #2) > -ex 'python print gdb.parse_and_eval("x")["p"].dereference().type.fields()' \ I can make this work by adding a call to strip_typedefs: (gdb) python print gdb.parse_and_eval ('x')['p'].dereference().type.fields() [] (gdb) python print gdb.parse_and_eval ('x')['p'].dereference().type.strip_typedefs().fields() [<gdb.Field object at 0xb7dbc220>, <gdb.Field object at 0xb7dbc250>, <gdb.Field object at 0xb7dbc280>, <gdb.Field object at 0xb7dbc2b0>] Arguably the Python API should be doing this for you. It seems useless to get the fields of a stub type. |
I sometimes cannot get a proper list of members from structures that do have members: This accesses a "real" QRegionPrivate object in a 'QRegion region;': python print gdb.parse_and_eval(\"region\")[\"d\"].dereference()[\"qt_rgn\"].dereference().type -> struct myns::QRegionPrivate python print gdb.parse_and_eval(\"region\")[\"d\"].dereference()[\"qt_rgn\"].dereference().type.fields() -> [] If I "create" the type manually I get: python print gdb.parse_and_eval(\"('myns::QRegionPrivate'*)0\").dereference().type -> myns::QRegionPrivate python print gdb.parse_and_eval(\"('myns::QRegionPrivate'*)0 \").dereference().type.fields() -> [<gdb.Field object at 0xb7764ac0>, <gdb.Field object at 0xb7764af0>, <gdb.Field object at 0xb7764b20>, <gdb.Field object at 0xb7764b50>, <gdb.Field object at 0xb7764b80>] Note the extra "struct " in the 'type' output in the first case. The problem also disappears when I use type = gdb.lookup_type(str(type)) before accessing fields().