* src/abg-ir.cc (decl_base_hash::operator()): Don't hash the
context for decls in general.
* src/abg-reader.cc (read_context::push_decl_to_current_scope)
(read_context::push_and_key_type_decl): Add an overload that takes
a node and update_depth_info boolean.
(build_var_decl, build_type_decl, build_qualified_type_decl)
(build_pointer_type_def, build_reference_type_def)
(build_enum_type_decl, build_type_decl)
(build_template_type_parameter, build_template_non_type_parameter)
(build_template_template_parameter, build_template_parameter)
(build_type): Make these functions take an update_depth_info
parameter. Pass it do read_context::push_and_key_type_decl or
read_context::push_decl_to_current_scope rather than call
update_read_context.
(build_function_decl, build_class_decl)
(build_function_template_decl): Change the seen_by_reader
parameter into update_depth_info. Pass the update_depth_info bool
to read_context::push_decl_to_current_scope rather than call
update_depth_info here.
(handle_class, handle_function_template_decl): Adjust.
* tests/data/test-read-write/test12.xml: Add new test input.
* tests/test-read-write.cc (InOutSpec in_out_specs): Add it to the
list of input to de-serialize, serialize back and compare the two.
* tests/Makefile.am: Add the new test input to the distribution.
