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.