(Ref: https://sourceware.org/ml/gdb/2017-06/msg00020.html)
Assuming int_t is a typedef to int:
typedef int int_t;
gdb currently loses this expression's typedef:
(gdb) p (int_t) 0
$1 = 0
(gdb) whatis $1
type = int
or:
(gdb) whatis (int_t) 0
type = int
or, to get "whatis" out of the way:
(gdb) maint print type (int_t) 0
...
name 'int'
code 0x8 (TYPE_CODE_INT)
...
This prevents a type printer for "int_t" kicking in, with e.g.:
(gdb) p (int_t) 0
From the manual, we can see that that "whatis (int_t) 0" command
invocation should have printed "type = int_t":
If @var{arg} is a variable or an expression, @code{whatis} prints its
literal type as it is used in the source code. If the type was
defined using a @code{typedef}, @code{whatis} will @emph{not} print
the data type underlying the @code{typedef}.
(...)
If @var{arg} is a type name that was defined using @code{typedef},
@code{whatis} @dfn{unrolls} only one level of that @code{typedef}.
That one-level stripping is currently done here, in
gdb/eval.c:evaluate_subexp_standard, handling OP_TYPE:
...
else if (noside == EVAL_AVOID_SIDE_EFFECTS)
{
struct type *type = exp->elts[pc + 1].type;
/* If this is a typedef, then find its immediate target. We
use check_typedef to resolve stubs, but we ignore its
result because we do not want to dig past all
typedefs. */
check_typedef (type);
if (TYPE_CODE (type) == TYPE_CODE_TYPEDEF)
type = TYPE_TARGET_TYPE (type);
return allocate_value (type);
}
However, this stripping is reachable in both:
#1 - (gdb) whatis (int_t)0 # ARG is an expression with a cast to
# typedef type.
#2 - (gdb) whatis int_t # ARG is a type name.
while only case #2 should strip the typedef. Removing that code from
evaluate_subexp_standard is part of the fix. Instead, we make the
"whatis" command implementation itself strip one level of typedefs
when the command argument is a type name.
We then run into another problem, also fixed by this commit:
value_cast always drops any typedefs of the destination type.
With all that fixed, "whatis (int_t) 0" now works as expected:
(gdb) whatis int_t
type = int
(gdb) whatis (int_t)0
type = int_t
value_cast has many different exit/convertion paths, for handling many
different kinds of casts/conversions, and most of them had to be
tweaked to construct the value of the right "to" type. The new tests
try to exercise most of it, by trying castin of many different
combinations of types. With:
$ make check TESTS="*/whatis-ptype*.exp */gnu_vector.exp */dfp-test.exp"
... due to combinatorial explosion, the testsuite results for the
tests above alone grow like:
- # of expected passes 246
+ # of expected passes 3811
You'll note that the tests exposed one GCC buglet, filed here:
Missing DW_AT_type in DW_TAG_typedef of "typedef of typedef of void"
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81267
gdb/ChangeLog:
2017-08-21 Pedro Alves <palves@redhat.com>
* eval.c (evaluate_subexp_standard) <OP_TYPE>: Don't dig past
typedefs.
* typeprint.c (whatis_exp): If handling "whatis", and expression
is OP_TYPE, strip one typedef level. Otherwise don't strip
typedefs here.
* valops.c (value_cast): Save "to" type before resolving
stubs/typedefs. Use that type as resulting value's type.
gdb/testsuite/ChangeLog:
2017-08-21 Pedro Alves <palves@redhat.com>
* gdb.base/dfp-test.c
(d32_t, d64_t, d128_t, d32_t2, d64_t2, d128_t2, v_d32_t, v_d64_t)
(v_d128_t, v_d32_t2, v_d64_t2, v_d128_t2): New.
* gdb.base/dfp-test.exp: Add whatis/ptype/cast tests.
* gdb.base/gnu_vector.exp: Add whatis/ptype/cast tests.
* gdb.base/whatis-ptype-typedefs.c: New.
* gdb.base/whatis-ptype-typedefs.exp: New.
* gdb.python/py-prettyprint.c (int_type, int_type2): New typedefs.
(an_int, an_int_type, an_int_type2): New globals.
* gdb.python/py-prettyprint.exp (run_lang_tests): Add tests
involving typedefs and cast expressions.
* gdb.python/py-prettyprint.py (class pp_int_typedef): New.
(lookup_typedefs_function): New.
(typedefs_pretty_printers_dict): New.
(top level): Register lookup_typedefs_function in
gdb.pretty_printers.
This applies the second part of GDB's End of Year Procedure, which
updates the copyright year range in all of GDB's files.
gdb/ChangeLog:
Update copyright year range in all GDB files.
Two modifications:
1. The addition of 2013 to the copyright year range for every file;
2. The use of a single year range, instead of potentially multiple
year ranges, as approved by the FSF.
for expressions with decimal float values.
(test_dfp_conversions): New function to test casts to and from
decimal float types.
Call test_dfp_conversions.
* gdb.base/dfp-test.c (struct decstruct): Add float4 and double8
elements.
(main): Initialize ds.float4 and ds.double8 elements.
* gdb.base/dfp-test.exp (d32_set_tests): Fix typo. Adjust expect
string to new error message.
(d64_set_tests): Likewise.
(d128_set_tests): Likewise.
Add tests for expressions with decimal float variables. Add tests for
conversions to and from decimal float types.
Thiago Jung Bauermann <bauerman@br.ibm.com>
* gdb.base/dfp-exprs.exp: new file adding tests for Decimal
Floating Point expressions.
* gdb.base/dfp-test.exp: new file adding tests for Decimal
Floating Point variables.
* gdb.base/dfp-test.c: new file containing program with Decimal
Floating variables, used by gdb.base/dfp-test.exp.
Joel Brobecker
Pedro Alves
Joel Brobecker
Thiago Jung Bauermann
Daniel Jacobowitz