gccrs: Replace AST::Method with existing AST::Function

gccrs: Replace AST::Method with existing AST::Function

gcc/rust/ChangeLog:

	* ast/rust-item.h
	(class Method): Remove.
	(Function::self_param): New.
	(Function::has_self_param): New.
	(Function::Function): Initialize self_param.
	(Function::operator=): Likewise.
	(Function::get_self_param): New.
	* ast/rust-ast.cc
	(Method::as_string): Remove.
	(Method::accept_vis): Remove.

	* ast/rust-ast-collector.cc
	(TokenCollector::visit):
	Remove AST::Method visitor, handle self_param in AST::Function visitor.
	* ast/rust-ast-collector.h
	(TokenCollector::visit): Remove AST::Method visitor.
	* ast/rust-ast-full-decls.h (class Method): Remove.

	* ast/rust-ast-visitor.h
	(ASTVisitor::visit): Remove AST::Method visitor.
	(DefaultASTVisitor::visit): Likewise.
	* ast/rust-ast-visitor.cc
	(DefaultASTVisitor::visit):
	Remove AST::Method visitor, handle self_param in AST::Function visitor.

	* checks/errors/rust-feature-gate.cc
	(FeatureGate::visit): Remove AST::Method visitor.
	* checks/errors/rust-feature-gate.h
	(FeatureGate::visit): Likewise..

	* expand/rust-cfg-strip.cc
	(CfgStrip::visit):
	Remove AST::Method visitor, handle self_param in AST::Function visitor.
	* expand/rust-cfg-strip.h
	(CfgStrip::visit): Remove AST::Method visitor.

	* expand/rust-derive-clone.cc
	(DeriveClone::clone_fn): Return AST::Function instead of AST::Method.
	* expand/rust-derive.h (DeriveVisitor::visit): Remove AST::Method visitor.

	* expand/rust-expand-visitor.cc
	(ExpandVisitor::visit):
	Remove AST::Method visitor, handle self_param in AST::Function visitor.
	* expand/rust-expand-visitor.h:
	(ExpandVisitor::visit): Remove AST::Method visitor.

	* hir/rust-ast-lower-base.cc (ASTLoweringBase::visit): Likewise.
	* hir/rust-ast-lower-base.h (ASTLoweringBase::visit): Likewise.

	* hir/rust-ast-lower-implitem.h
	(ASTLowerImplItem::visit):
	Remove AST::Method visitor, handle self_param in AST::Function visitor.

	* parse/rust-parse-impl.h: Include optional.h.
	(Parser::parse_function): Adjust AST::Function construction.
	(Parser::parse_inherent_impl_function_or_method):
	Construct AST::Function instead of AST::Method,
	adjust AST::Function construction.
	(Parser::parse_trait_impl_function_or_method): Likewise.
	(Parser::parse_method):
	Return std::unique_ptr<AST::Function> instead of AST::Method.

	* parse/rust-parse.h
	(Parser::parse_method): Likewise.

	* resolve/rust-ast-resolve-base.cc
	(ResolverBase::visit): Remove AST::Method visitor.
	* resolve/rust-ast-resolve-base.h
	(ResolverBase::visit): Likewise.

	* resolve/rust-ast-resolve-implitem.h
	(ResolveToplevelImplItem::visit): Likewise.

	* resolve/rust-ast-resolve-item.cc
	(ResolveItem::visit): Remove AST::Method visitor,
	handle self_param in AST::Function visitor.
	* resolve/rust-ast-resolve-item.h
	(ResolveItem::visit): Remove AST::Method visitor.

	* resolve/rust-default-resolver.cc
	(DefaultResolver::visit): Remove AST::Method visitor.
	* resolve/rust-default-resolver.h
	(DefaultResolver::visit): Likewise.

	* resolve/rust-early-name-resolver.cc
	(EarlyNameResolver::visit): Remove AST::Method visitor,
	handle self_param in AST::Function visitor.
	* resolve/rust-early-name-resolver.h
	(EarlyNameResolver::visit): Remove AST::Method visitor.

	* resolve/rust-toplevel-name-resolver-2.0.cc
	(TopLevel::visit): Likewise.
	* resolve/rust-toplevel-name-resolver-2.0.h
	(TopLevel::visit): Likewise.

	* util/rust-attributes.cc
	(AttributeChecker::visit): Likewise.
	* util/rust-attributes.h
	(AttributeChecker::visit): Likewise.

Signed-off-by: Owen Avery <powerboat9.gamer@gmail.com>