Split tdesc_type into multiple classes

This patch makes tdesc_type an abstract base class and creates three
subclasses:

- tdesc_type_builtin, for builtin types
- tdesc_type_vector, for vector types
- tdesc_type_with_fields, for struct, union, flag and enum types

This allows getting rid of the union in tdesc_type and to not allow the
std::vector separately.  I tried to go further and create separate
classes for struct, union, flag and enum, but it proved too difficult.
One problem is that from the point of the of the target description
code, the types tdesc_type_* are opaque (only forward-declared).
Therefore, it doesn't know about inheritance relationship between those
classes.  This makes it impossible to make functions that accept a
pointer to a base class and pass a pointer to a derived class, for
example.  I think this patch here is a good compromise, and if somebody
wants to improve things further, the door is open.

A make_gdb_type virtual pure method is added to tdesc_type, which
replaces the current tdesc_gdb_type function.  Calling this method on a
tdesc_type returns the corresponding built gdb type.

gdb/ChangeLog:

	* target-descriptions.c (struct tdesc_type): Use default
	destructor.
	<u>: Remove.
	<accept>: Remove.
	(struct tdesc_type_builtin): New.
	(struct tdesc_type_vector): New.
	(struct tdesc_type_with_fields): New.
	(tdesc_predefined_types): Change type to tdesc_type_builtin[].
	(tdesc_gdb_type): Remove.
	(tdesc_register_type): Adjust.
	(tdesc_create_vector): Create tdesc_type_vector.
	(tdesc_create_struct): Create tdesc_type_with_fields.
	(tdesc_set_struct_size): Change parameter type.
	(tdesc_create_union): Create tdesc_type_with_fields.
	(tdesc_create_flags): Likewise.
	(tdesc_create_enum): Likewise.
	(tdesc_add_field): Change parameter type.
	(tdesc_add_typed_bitfield): Likewise.
	(tdesc_add_bitfield): Likewise.
	(tdesc_add_flag): Likewise.
	(tdesc_add_enum_value): Likewise.
	(print_c_tdesc) <visit>: Remove overload with tdesc_type
	parameter, add overloads for tdesc_type_builtin,
	tdesc_type_with_fields and tdesc_type_vector.
	<m_printed_type>: Remove.
	<m_printed_element_type, m_printed_type_with_fields>: Add.
	* target-descriptions.h (tdesc_create_enum): Change return type.
	(tdesc_add_typed_bitfield): Change parameter type.
	(tdesc_add_enum_value): Change parameter type.
	* xml-tdesc.c (struct tdesc_parsing_data) <current_type>: Change
	type to tdesc_type_with_fields.
	(tdesc_start_struct): Adjust.
	(tdesc_start_flags): Adjust.
	(tdesc_start_enum): Adjust.
	(tdesc_start_field): Adjust.
	* arch/tdesc.h (struct tdesc_type_builtin): Forward-declare.
	(struct tdesc_type_vector): Forward-declare.
	(struct tdesc_type_with_fields): Forward-declare.
	(tdesc_create_struct): Change return type.
	(tdesc_create_union): Likewise.
	(tdesc_create_flags): Likewise.
	(tdesc_add_field): Change parameter type.
	(tdesc_set_struct_size): Likewise.
	(tdesc_add_bitfield): Likewise.
	(tdesc_add_flag): Likewise.
	* features: Re-generate C files.

gdb/gdbserver/ChangeLog:

	* tdesc.c (struct tdesc_type): Change return type.
	(tdesc_add_flag): Change parameter type.
	(tdesc_add_bitfield): Likewise.
	(tdesc_add_field): Likewise.
	(tdesc_set_struct_size): Likewise.

1 files changed, 14 insertions, 11 deletions

diff --git a/gdb/arch/tdesc.h b/gdb/arch/tdesc.h
index 78bb0fb..2240df6 100644
--- a/gdb/arch/tdesc.h
+++ b/gdb/arch/tdesc.h
@@ -20,6 +20,9 @@
 
 struct tdesc_feature;
 struct tdesc_type;
+struct tdesc_type_builtin;
+struct tdesc_type_vector;
+struct tdesc_type_with_fields;
 struct tdesc_reg;
 struct target_desc;
 
@@ -51,37 +54,37 @@ struct tdesc_type *tdesc_create_vector (struct tdesc_feature *feature,
 					int count);
 
 /* Return the created struct tdesc_type named NAME in FEATURE.  */
-struct tdesc_type *tdesc_create_struct (struct tdesc_feature *feature,
-					const char *name);
+tdesc_type_with_fields *tdesc_create_struct (struct tdesc_feature *feature,
+					     const char *name);
 
 /* Return the created union tdesc_type named NAME in FEATURE.  */
-struct tdesc_type *tdesc_create_union (struct tdesc_feature *feature,
-				       const char *name);
+tdesc_type_with_fields *tdesc_create_union (struct tdesc_feature *feature,
+					    const char *name);
 
 /* Return the created flags tdesc_type named NAME in FEATURE.  */
-struct tdesc_type *tdesc_create_flags (struct tdesc_feature *feature,
-				       const char *name,
-				       int size);
+tdesc_type_with_fields *tdesc_create_flags (struct tdesc_feature *feature,
+					    const char *name,
+					    int size);
 
 /* Add a new field to TYPE.  FIELD_NAME is its name, and FIELD_TYPE is
    its type.  */
-void tdesc_add_field (struct tdesc_type *type, const char *field_name,
+void tdesc_add_field (tdesc_type_with_fields *type, const char *field_name,
 		      struct tdesc_type *field_type);
 
 /* Set the total length of TYPE.  Structs which contain bitfields may
    omit the reserved bits, so the end of the last field may not
    suffice.  */
-void tdesc_set_struct_size (struct tdesc_type *type, int size);
+void tdesc_set_struct_size (tdesc_type_with_fields *type, int size);
 
 /* Add a new untyped bitfield to TYPE.
    Untyped bitfields become either uint32 or uint64 depending on the size
    of the underlying type.  */
-void tdesc_add_bitfield (struct tdesc_type *type, const char *field_name,
+void tdesc_add_bitfield (tdesc_type_with_fields *type, const char *field_name,
 			 int start, int end);
 
 /* A flag is just a typed(bool) single-bit bitfield.
    This function is kept to minimize changes in generated files.  */
-void tdesc_add_flag (struct tdesc_type *type, int start,
+void tdesc_add_flag (tdesc_type_with_fields *type, int start,
 		     const char *flag_name);
 
 /* Create a register in feature FEATURE.  */