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Fix Ada overloading with 'null'

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Currently, the Ada expression parser treats 'null' as an integer 0.
However, this causes overloading to fail in certain cases.

This patch changes the Ada expression parser to use a special type for
'null'.  I chose pointer-to-int0, because I think that's not likely to
be needed for any other Ada expression.  Note this works because a
"mod 1" type has an underlying non-zero byte size; the test includes a
check for this.

The output is changed so that "print null", by default, shows "null".
And, ada_type_match is changed both to recognize the special null type
and to remove a bit of weird code related to how pointers are treated
for overload type matching.

Tested on x86-64 Fedora 32.  Because this only touches Ada, and Joel
already approved it internally at AdaCore, I am checking it in.

gdb/ChangeLog
2021-04-28  Tom Tromey  <tromey@adacore.com>

	* ada-exp.y (primary): Use new type for null pointer.
	* ada-lang.c (ada_type_match): Remove "may_deref"
	parameter.  Handle null pointer.
	(ada_args_match): Update.
	* ada-valprint.c (ada_value_print_ptr, ada_value_print):
	Handle null pointer.

gdb/testsuite/ChangeLog
2021-04-28  Tom Tromey  <tromey@adacore.com>

	* gdb.ada/null_overload.exp: New file.
	* gdb.ada/null_overload/foo.adb: New file.
This commit is contained in:
Tom Tromey 2021-04-27 07:35:23 -06:00
parent e43c3e2a74
commit db2534b704
7 changed files with 121 additions and 16 deletions
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23
gdb/ada-lang.c
View file

@ -95,8 +95,6 @@ static struct type *desc_index_type (struct type *, int);
static int desc_arity (struct type *);
static int ada_type_match (struct type *, struct type *, int);
static int ada_args_match (struct symbol *, struct value **, int);
static struct value *make_array_descriptor (struct type *, struct value *);
@ -3492,14 +3490,12 @@ ada_resolve_variable (struct symbol *sym, const struct block *block,
return candidates[i];
}
/* Return non-zero if formal type FTYPE matches actual type ATYPE. If
MAY_DEREF is non-zero, the formal may be a pointer and the actual
a non-pointer. */
/* Return non-zero if formal type FTYPE matches actual type ATYPE. */
/* The term "match" here is rather loose. The match is heuristic and
liberal. */
static int
ada_type_match (struct type *ftype, struct type *atype, int may_deref)
ada_type_match (struct type *ftype, struct type *atype)
{
ftype = ada_check_typedef (ftype);
atype = ada_check_typedef (atype);
@ -3514,12 +3510,13 @@ ada_type_match (struct type *ftype, struct type *atype, int may_deref)
default:
return ftype->code () == atype->code ();
case TYPE_CODE_PTR:
if (atype->code () == TYPE_CODE_PTR)
return ada_type_match (TYPE_TARGET_TYPE (ftype),
TYPE_TARGET_TYPE (atype), 0);
else
return (may_deref
&& ada_type_match (TYPE_TARGET_TYPE (ftype), atype, 0));
if (atype->code () != TYPE_CODE_PTR)
return 0;
atype = TYPE_TARGET_TYPE (atype);
/* This can only happen if the actual argument is 'null'. */
if (atype->code () == TYPE_CODE_INT && TYPE_LENGTH (atype) == 0)
return 1;
return ada_type_match (TYPE_TARGET_TYPE (ftype), atype);
case TYPE_CODE_INT:
case TYPE_CODE_ENUM:
case TYPE_CODE_RANGE:
@ -3580,7 +3577,7 @@ ada_args_match (struct symbol *func, struct value **actuals, int n_actuals)
struct type *ftype = ada_check_typedef (func_type->field (i).type ());
struct type *atype = ada_check_typedef (value_type (actuals[i]));
if (!ada_type_match (ftype, atype, 1))
if (!ada_type_match (ftype, atype))
return 0;
}
}