[PATCH 121/203] Implement C++ cast operations

Tom Tromey
2021-01-01T21:48:53Z

This adds class cxx_cast_operation, which is used to implement the C++
dynamic_cast and reinterpret_cast operations.

gdb/ChangeLog
2021-01-01 Tom Tromey <tom@tromey.com>

* expop.h (cxx_cast_ftype): New typedef.
(cxx_cast_operation): New template.
(dynamic_cast_operation, reinterpret_cast_operation): New
typedefs.
---
gdb/ChangeLog | 7 +++++++
gdb/expop.h | 34 ++++++++++++++++++++++++++++++++++
2 files changed, 41 insertions(+)

diff --git a/gdb/expop.h b/gdb/expop.h
index 9102f2bb66d..53ff93c4b83 100644
--- a/gdb/expop.h
+++ b/gdb/expop.h
@@ -1884,6 +1884,40 @@ class unop_cast_type_operation
override;
};

+typedef value *cxx_cast_ftype (struct type *, value *);
+
+/* This implements dynamic_cast and reinterpret_cast. static_cast and
+ const_cast are handled by the ordinary case operations. */
+template<exp_opcode OP, cxx_cast_ftype FUNC>
+class cxx_cast_operation
+ : public maybe_constant_operation<operation_up, operation_up>
+{
+public:
+
+ using maybe_constant_operation::maybe_constant_operation;
+
+ value *evaluate (struct type *expect_type,
+ struct expression *exp,
+ enum noside noside) override
+ {
+ value *val = std::get<0> (m_storage)->evaluate (nullptr, exp,
+ EVAL_AVOID_SIDE_EFFECTS);
+ struct type *type = value_type (val);
+ value *rhs = std::get<1> (m_storage)->evaluate (type, exp, noside);
+ if (noside == EVAL_SKIP)
+ return eval_skip_value (exp);
+ return FUNC (type, rhs);
+ }
+
+ enum exp_opcode opcode () const override
+ { return OP; }
+};
+
+using dynamic_cast_operation = cxx_cast_operation<UNOP_DYNAMIC_CAST,
+ value_dynamic_cast>;
+using reinterpret_cast_operation = cxx_cast_operation<UNOP_REINTERPRET_CAST,
+ value_reinterpret_cast>;
+
} /* namespace expr */

#endif /* EXPOP_H */
--
2.26.2