849 lines
34 KiB
Rust
849 lines
34 KiB
Rust
// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use arena::TypedArena;
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use back::abi;
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use back::link;
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use llvm::{self, ValueRef, get_param};
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use metadata::csearch;
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use middle::subst::{Subst, Substs};
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use middle::subst::VecPerParamSpace;
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use middle::subst;
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use middle::traits;
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use trans::base::*;
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use trans::build::*;
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use trans::callee::*;
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use trans::callee;
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use trans::cleanup;
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use trans::common::*;
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use trans::datum::*;
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use trans::expr::{SaveIn, Ignore};
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use trans::expr;
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use trans::glue;
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use trans::machine;
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use trans::type_::Type;
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use trans::type_of::*;
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use middle::ty::{self, Ty};
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use middle::ty::MethodCall;
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use util::ppaux::Repr;
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use std::c_str::ToCStr;
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use std::rc::Rc;
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use syntax::abi::{Rust, RustCall};
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use syntax::parse::token;
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use syntax::{ast, ast_map, attr, visit};
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use syntax::ast_util::PostExpansionMethod;
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use syntax::codemap::DUMMY_SP;
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// drop_glue pointer, size, align.
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static VTABLE_OFFSET: uint = 3;
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/// The main "translation" pass for methods. Generates code
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/// for non-monomorphized methods only. Other methods will
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/// be generated once they are invoked with specific type parameters,
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/// see `trans::base::lval_static_fn()` or `trans::base::monomorphic_fn()`.
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pub fn trans_impl(ccx: &CrateContext,
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name: ast::Ident,
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impl_items: &[ast::ImplItem],
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generics: &ast::Generics,
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id: ast::NodeId) {
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let _icx = push_ctxt("meth::trans_impl");
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let tcx = ccx.tcx();
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debug!("trans_impl(name={}, id={})", name.repr(tcx), id);
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// Both here and below with generic methods, be sure to recurse and look for
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// items that we need to translate.
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if !generics.ty_params.is_empty() {
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let mut v = TransItemVisitor{ ccx: ccx };
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for impl_item in impl_items.iter() {
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match *impl_item {
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ast::MethodImplItem(ref method) => {
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visit::walk_method_helper(&mut v, &**method);
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}
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ast::TypeImplItem(_) => {}
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}
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}
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return;
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}
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for impl_item in impl_items.iter() {
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match *impl_item {
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ast::MethodImplItem(ref method) => {
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if method.pe_generics().ty_params.len() == 0u {
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let trans_everywhere = attr::requests_inline(method.attrs[]);
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for (ref ccx, is_origin) in ccx.maybe_iter(trans_everywhere) {
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let llfn = get_item_val(ccx, method.id);
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trans_fn(ccx,
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method.pe_fn_decl(),
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method.pe_body(),
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llfn,
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&Substs::trans_empty(),
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method.id,
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&[]);
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update_linkage(ccx,
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llfn,
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Some(method.id),
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if is_origin { OriginalTranslation } else { InlinedCopy });
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}
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}
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let mut v = TransItemVisitor {
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ccx: ccx,
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};
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visit::walk_method_helper(&mut v, &**method);
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}
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ast::TypeImplItem(_) => {}
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}
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}
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}
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pub fn trans_method_callee<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
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method_call: MethodCall,
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self_expr: Option<&ast::Expr>,
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arg_cleanup_scope: cleanup::ScopeId)
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-> Callee<'blk, 'tcx> {
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let _icx = push_ctxt("meth::trans_method_callee");
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let (origin, method_ty) =
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bcx.tcx().method_map
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.borrow()
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.get(&method_call)
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.map(|method| (method.origin.clone(), method.ty))
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.unwrap();
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match origin {
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ty::MethodStatic(did) |
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ty::MethodStaticUnboxedClosure(did) => {
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Callee {
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bcx: bcx,
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data: Fn(callee::trans_fn_ref(bcx.ccx(),
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did,
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MethodCallKey(method_call),
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bcx.fcx.param_substs).val),
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}
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}
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ty::MethodTypeParam(ty::MethodParam {
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ref trait_ref,
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method_num
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}) => {
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let trait_ref = ty::Binder(bcx.monomorphize(trait_ref));
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let span = bcx.tcx().map.span(method_call.expr_id);
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debug!("method_call={} trait_ref={}",
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method_call,
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trait_ref.repr(bcx.tcx()));
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let origin = fulfill_obligation(bcx.ccx(),
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span,
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trait_ref.clone());
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debug!("origin = {}", origin.repr(bcx.tcx()));
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trans_monomorphized_callee(bcx,
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method_call,
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trait_ref.def_id(),
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method_num,
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origin)
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}
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ty::MethodTraitObject(ref mt) => {
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let self_expr = match self_expr {
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Some(self_expr) => self_expr,
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None => {
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bcx.sess().span_bug(bcx.tcx().map.span(method_call.expr_id),
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"self expr wasn't provided for trait object \
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callee (trying to call overloaded op?)")
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}
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};
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trans_trait_callee(bcx,
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monomorphize_type(bcx, method_ty),
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mt.real_index,
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self_expr,
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arg_cleanup_scope)
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}
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}
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}
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pub fn trans_static_method_callee<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
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method_id: ast::DefId,
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trait_id: ast::DefId,
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expr_id: ast::NodeId,
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param_substs: &subst::Substs<'tcx>)
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-> Datum<'tcx, Rvalue>
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{
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let _icx = push_ctxt("meth::trans_static_method_callee");
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let tcx = ccx.tcx();
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debug!("trans_static_method_callee(method_id={}, trait_id={}, \
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expr_id={})",
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method_id,
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ty::item_path_str(tcx, trait_id),
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expr_id);
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let mname = if method_id.krate == ast::LOCAL_CRATE {
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match tcx.map.get(method_id.node) {
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ast_map::NodeTraitItem(method) => {
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let ident = match *method {
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ast::RequiredMethod(ref m) => m.ident,
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ast::ProvidedMethod(ref m) => m.pe_ident(),
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ast::TypeTraitItem(_) => {
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tcx.sess.bug("trans_static_method_callee() on \
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an associated type?!")
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}
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};
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ident.name
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}
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_ => panic!("callee is not a trait method")
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}
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} else {
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csearch::get_item_path(tcx, method_id).last().unwrap().name()
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};
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debug!("trans_static_method_callee: method_id={}, expr_id={}, \
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name={}", method_id, expr_id, token::get_name(mname));
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// Find the substitutions for the fn itself. This includes
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// type parameters that belong to the trait but also some that
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// belong to the method:
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let rcvr_substs = node_id_substs(ccx, ExprId(expr_id), param_substs);
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let subst::SeparateVecsPerParamSpace {
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types: rcvr_type,
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selfs: rcvr_self,
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fns: rcvr_method
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} = rcvr_substs.types.split();
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// Lookup the precise impl being called. To do that, we need to
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// create a trait reference identifying the self type and other
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// input type parameters. To create that trait reference, we have
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// to pick apart the type parameters to identify just those that
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// pertain to the trait. This is easiest to explain by example:
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//
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// trait Convert {
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// fn from<U:Foo>(n: U) -> Option<Self>;
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// }
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// ...
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// let f = <Vec<int> as Convert>::from::<String>(...)
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//
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// Here, in this call, which I've written with explicit UFCS
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// notation, the set of type parameters will be:
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//
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// rcvr_type: [] <-- nothing declared on the trait itself
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// rcvr_self: [Vec<int>] <-- the self type
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// rcvr_method: [String] <-- method type parameter
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//
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// So we create a trait reference using the first two,
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// basically corresponding to `<Vec<int> as Convert>`.
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// The remaining type parameters (`rcvr_method`) will be used below.
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let trait_substs =
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Substs::erased(VecPerParamSpace::new(rcvr_type,
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rcvr_self,
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Vec::new()));
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let trait_substs = tcx.mk_substs(trait_substs);
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debug!("trait_substs={}", trait_substs.repr(tcx));
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let trait_ref = ty::Binder(Rc::new(ty::TraitRef { def_id: trait_id,
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substs: trait_substs }));
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let vtbl = fulfill_obligation(ccx,
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DUMMY_SP,
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trait_ref);
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// Now that we know which impl is being used, we can dispatch to
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// the actual function:
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match vtbl {
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traits::VtableImpl(traits::VtableImplData {
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impl_def_id: impl_did,
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substs: impl_substs,
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nested: _ }) =>
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{
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assert!(impl_substs.types.all(|t| !ty::type_needs_infer(*t)));
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// Create the substitutions that are in scope. This combines
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// the type parameters from the impl with those declared earlier.
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// To see what I mean, consider a possible impl:
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//
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// impl<T> Convert for Vec<T> {
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// fn from<U:Foo>(n: U) { ... }
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// }
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//
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// Recall that we matched `<Vec<int> as Convert>`. Trait
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// resolution will have given us a substitution
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// containing `impl_substs=[[T=int],[],[]]` (the type
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// parameters defined on the impl). We combine
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// that with the `rcvr_method` from before, which tells us
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// the type parameters from the *method*, to yield
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// `callee_substs=[[T=int],[],[U=String]]`.
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let subst::SeparateVecsPerParamSpace {
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types: impl_type,
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selfs: impl_self,
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fns: _
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} = impl_substs.types.split();
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let callee_substs =
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Substs::erased(VecPerParamSpace::new(impl_type,
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impl_self,
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rcvr_method));
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let mth_id = method_with_name(ccx, impl_did, mname);
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trans_fn_ref_with_substs(ccx, mth_id, ExprId(expr_id),
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param_substs,
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callee_substs)
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}
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_ => {
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tcx.sess.bug(format!("static call to invalid vtable: {}",
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vtbl.repr(tcx))[]);
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}
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}
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}
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fn method_with_name(ccx: &CrateContext, impl_id: ast::DefId, name: ast::Name)
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-> ast::DefId {
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match ccx.impl_method_cache().borrow().get(&(impl_id, name)).cloned() {
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Some(m) => return m,
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None => {}
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}
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let impl_items = ccx.tcx().impl_items.borrow();
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let impl_items =
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impl_items.get(&impl_id)
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.expect("could not find impl while translating");
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let meth_did = impl_items.iter()
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.find(|&did| {
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ty::impl_or_trait_item(ccx.tcx(), did.def_id()).name() == name
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}).expect("could not find method while \
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translating");
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ccx.impl_method_cache().borrow_mut().insert((impl_id, name),
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meth_did.def_id());
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meth_did.def_id()
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}
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fn trans_monomorphized_callee<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
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method_call: MethodCall,
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trait_id: ast::DefId,
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n_method: uint,
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vtable: traits::Vtable<'tcx, ()>)
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-> Callee<'blk, 'tcx> {
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let _icx = push_ctxt("meth::trans_monomorphized_callee");
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match vtable {
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traits::VtableImpl(vtable_impl) => {
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let ccx = bcx.ccx();
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let impl_did = vtable_impl.impl_def_id;
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let mname = match ty::trait_item(ccx.tcx(), trait_id, n_method) {
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ty::MethodTraitItem(method) => method.name,
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ty::TypeTraitItem(_) => {
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bcx.tcx().sess.bug("can't monomorphize an associated \
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type")
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}
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};
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let mth_id = method_with_name(bcx.ccx(), impl_did, mname);
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// create a concatenated set of substitutions which includes
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// those from the impl and those from the method:
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let callee_substs =
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combine_impl_and_methods_tps(
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bcx, MethodCallKey(method_call), vtable_impl.substs);
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// translate the function
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let llfn = trans_fn_ref_with_substs(bcx.ccx(),
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mth_id,
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MethodCallKey(method_call),
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bcx.fcx.param_substs,
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callee_substs).val;
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Callee { bcx: bcx, data: Fn(llfn) }
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}
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traits::VtableUnboxedClosure(closure_def_id, substs) => {
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// The substitutions should have no type parameters remaining
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// after passing through fulfill_obligation
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let llfn = trans_fn_ref_with_substs(bcx.ccx(),
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closure_def_id,
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MethodCallKey(method_call),
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bcx.fcx.param_substs,
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substs).val;
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Callee {
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bcx: bcx,
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data: Fn(llfn),
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}
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}
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traits::VtableFnPointer(fn_ty) => {
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let llfn = trans_fn_pointer_shim(bcx.ccx(), fn_ty);
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Callee { bcx: bcx, data: Fn(llfn) }
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}
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traits::VtableObject(ref data) => {
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let llfn = trans_object_shim(bcx.ccx(), data.object_ty, trait_id, n_method);
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Callee { bcx: bcx, data: Fn(llfn) }
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}
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traits::VtableBuiltin(..) |
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traits::VtableParam(..) => {
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bcx.sess().bug(
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format!("resolved vtable bad vtable {} in trans",
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vtable.repr(bcx.tcx()))[]);
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}
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}
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}
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/// Creates a concatenated set of substitutions which includes those from the impl and those from
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/// the method. This are some subtle complications here. Statically, we have a list of type
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/// parameters like `[T0, T1, T2, M1, M2, M3]` where `Tn` are type parameters that appear on the
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/// receiver. For example, if the receiver is a method parameter `A` with a bound like
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/// `trait<B,C,D>` then `Tn` would be `[B,C,D]`.
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///
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/// The weird part is that the type `A` might now be bound to any other type, such as `foo<X>`.
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/// In that case, the vector we want is: `[X, M1, M2, M3]`. Therefore, what we do now is to slice
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/// off the method type parameters and append them to the type parameters from the type that the
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/// receiver is mapped to.
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fn combine_impl_and_methods_tps<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
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node: ExprOrMethodCall,
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rcvr_substs: subst::Substs<'tcx>)
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-> subst::Substs<'tcx>
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{
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let ccx = bcx.ccx();
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let node_substs = node_id_substs(ccx, node, bcx.fcx.param_substs);
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debug!("rcvr_substs={}", rcvr_substs.repr(ccx.tcx()));
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debug!("node_substs={}", node_substs.repr(ccx.tcx()));
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// Break apart the type parameters from the node and type
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// parameters from the receiver.
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let node_method = node_substs.types.split().fns;
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let subst::SeparateVecsPerParamSpace {
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types: rcvr_type,
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selfs: rcvr_self,
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fns: rcvr_method
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} = rcvr_substs.types.clone().split();
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assert!(rcvr_method.is_empty());
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subst::Substs {
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regions: subst::ErasedRegions,
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types: subst::VecPerParamSpace::new(rcvr_type, rcvr_self, node_method)
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}
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}
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/// Create a method callee where the method is coming from a trait object (e.g., Box<Trait> type).
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/// In this case, we must pull the fn pointer out of the vtable that is packaged up with the
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/// object. Objects are represented as a pair, so we first evaluate the self expression and then
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/// extract the self data and vtable out of the pair.
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fn trans_trait_callee<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
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method_ty: Ty<'tcx>,
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n_method: uint,
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self_expr: &ast::Expr,
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arg_cleanup_scope: cleanup::ScopeId)
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-> Callee<'blk, 'tcx> {
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let _icx = push_ctxt("meth::trans_trait_callee");
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let mut bcx = bcx;
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// Translate self_datum and take ownership of the value by
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// converting to an rvalue.
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let self_datum = unpack_datum!(
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bcx, expr::trans(bcx, self_expr));
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let llval = if type_needs_drop(bcx.tcx(), self_datum.ty) {
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let self_datum = unpack_datum!(
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bcx, self_datum.to_rvalue_datum(bcx, "trait_callee"));
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// Convert to by-ref since `trans_trait_callee_from_llval` wants it
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// that way.
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let self_datum = unpack_datum!(
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bcx, self_datum.to_ref_datum(bcx));
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// Arrange cleanup in case something should go wrong before the
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// actual call occurs.
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self_datum.add_clean(bcx.fcx, arg_cleanup_scope)
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} else {
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// We don't have to do anything about cleanups for &Trait and &mut Trait.
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assert!(self_datum.kind.is_by_ref());
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self_datum.val
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};
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trans_trait_callee_from_llval(bcx, method_ty, n_method, llval)
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}
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|
|
/// Same as `trans_trait_callee()` above, except that it is given a by-ref pointer to the object
|
|
/// pair.
|
|
pub fn trans_trait_callee_from_llval<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
|
|
callee_ty: Ty<'tcx>,
|
|
n_method: uint,
|
|
llpair: ValueRef)
|
|
-> Callee<'blk, 'tcx> {
|
|
let _icx = push_ctxt("meth::trans_trait_callee");
|
|
let ccx = bcx.ccx();
|
|
|
|
// Load the data pointer from the object.
|
|
debug!("(translating trait callee) loading second index from pair");
|
|
let llboxptr = GEPi(bcx, llpair, &[0u, abi::FAT_PTR_ADDR]);
|
|
let llbox = Load(bcx, llboxptr);
|
|
let llself = PointerCast(bcx, llbox, Type::i8p(ccx));
|
|
|
|
// Load the function from the vtable and cast it to the expected type.
|
|
debug!("(translating trait callee) loading method");
|
|
// Replace the self type (&Self or Box<Self>) with an opaque pointer.
|
|
let llcallee_ty = match callee_ty.sty {
|
|
ty::ty_bare_fn(_, ref f) if f.abi == Rust || f.abi == RustCall => {
|
|
type_of_rust_fn(ccx,
|
|
Some(Type::i8p(ccx)),
|
|
f.sig.0.inputs.slice_from(1),
|
|
f.sig.0.output,
|
|
f.abi)
|
|
}
|
|
_ => {
|
|
ccx.sess().bug("meth::trans_trait_callee given non-bare-rust-fn");
|
|
}
|
|
};
|
|
let llvtable = Load(bcx,
|
|
PointerCast(bcx,
|
|
GEPi(bcx, llpair,
|
|
&[0u, abi::FAT_PTR_EXTRA]),
|
|
Type::vtable(ccx).ptr_to().ptr_to()));
|
|
let mptr = Load(bcx, GEPi(bcx, llvtable, &[0u, n_method + VTABLE_OFFSET]));
|
|
let mptr = PointerCast(bcx, mptr, llcallee_ty.ptr_to());
|
|
|
|
return Callee {
|
|
bcx: bcx,
|
|
data: TraitItem(MethodData {
|
|
llfn: mptr,
|
|
llself: llself,
|
|
})
|
|
};
|
|
}
|
|
|
|
/// Generate a shim function that allows an object type like `SomeTrait` to
|
|
/// implement the type `SomeTrait`. Imagine a trait definition:
|
|
///
|
|
/// trait SomeTrait { fn get(&self) -> int; ... }
|
|
///
|
|
/// And a generic bit of code:
|
|
///
|
|
/// fn foo<T:SomeTrait>(t: &T) {
|
|
/// let x = SomeTrait::get;
|
|
/// x(t)
|
|
/// }
|
|
///
|
|
/// What is the value of `x` when `foo` is invoked with `T=SomeTrait`?
|
|
/// The answer is that it it is a shim function generate by this
|
|
/// routine:
|
|
///
|
|
/// fn shim(t: &SomeTrait) -> int {
|
|
/// // ... call t.get() virtually ...
|
|
/// }
|
|
///
|
|
/// In fact, all virtual calls can be thought of as normal trait calls
|
|
/// that go through this shim function.
|
|
pub fn trans_object_shim<'a, 'tcx>(
|
|
ccx: &'a CrateContext<'a, 'tcx>,
|
|
object_ty: Ty<'tcx>,
|
|
trait_id: ast::DefId,
|
|
method_offset_in_trait: uint)
|
|
-> ValueRef
|
|
{
|
|
let _icx = push_ctxt("trans_object_shim");
|
|
let tcx = ccx.tcx();
|
|
|
|
debug!("trans_object_shim(object_ty={}, trait_id={}, n_method={})",
|
|
object_ty.repr(tcx),
|
|
trait_id.repr(tcx),
|
|
method_offset_in_trait);
|
|
|
|
let object_trait_ref =
|
|
match object_ty.sty {
|
|
ty::ty_trait(ref data) => {
|
|
data.principal_trait_ref_with_self_ty(tcx, object_ty)
|
|
}
|
|
_ => {
|
|
tcx.sess.bug(format!("trans_object_shim() called on non-object: {}",
|
|
object_ty.repr(tcx)).as_slice());
|
|
}
|
|
};
|
|
|
|
// Upcast to the trait in question and extract out the substitutions.
|
|
let upcast_trait_ref = traits::upcast(ccx.tcx(), object_trait_ref.clone(), trait_id).unwrap();
|
|
let object_substs = upcast_trait_ref.substs().clone().erase_regions();
|
|
debug!("trans_object_shim: object_substs={}", object_substs.repr(tcx));
|
|
|
|
// Lookup the type of this method as deeclared in the trait and apply substitutions.
|
|
let method_ty = match ty::trait_item(tcx, trait_id, method_offset_in_trait) {
|
|
ty::MethodTraitItem(method) => method,
|
|
ty::TypeTraitItem(_) => {
|
|
tcx.sess.bug("can't create a method shim for an associated type")
|
|
}
|
|
};
|
|
let fty = method_ty.fty.subst(tcx, &object_substs);
|
|
let fty = tcx.mk_bare_fn(fty);
|
|
debug!("trans_object_shim: fty={}", fty.repr(tcx));
|
|
|
|
//
|
|
let method_bare_fn_ty =
|
|
ty::mk_bare_fn(tcx, None, fty);
|
|
let function_name =
|
|
link::mangle_internal_name_by_type_and_seq(ccx, method_bare_fn_ty, "object_shim");
|
|
let llfn =
|
|
decl_internal_rust_fn(ccx, method_bare_fn_ty, function_name.as_slice());
|
|
|
|
//
|
|
let block_arena = TypedArena::new();
|
|
let empty_substs = Substs::trans_empty();
|
|
let fcx = new_fn_ctxt(ccx,
|
|
llfn,
|
|
ast::DUMMY_NODE_ID,
|
|
false,
|
|
fty.sig.0.output,
|
|
&empty_substs,
|
|
None,
|
|
&block_arena);
|
|
let mut bcx = init_function(&fcx, false, fty.sig.0.output);
|
|
|
|
// the first argument (`self`) will be a trait object
|
|
let llobject = get_param(fcx.llfn, fcx.arg_pos(0) as u32);
|
|
|
|
debug!("trans_object_shim: llobject={}",
|
|
bcx.val_to_string(llobject));
|
|
|
|
// the remaining arguments will be, well, whatever they are
|
|
let llargs: Vec<_> =
|
|
fty.sig.0.inputs[1..].iter()
|
|
.enumerate()
|
|
.map(|(i, _)| {
|
|
let llarg = get_param(fcx.llfn, fcx.arg_pos(i+1) as u32);
|
|
debug!("trans_object_shim: input #{} == {}",
|
|
i, bcx.val_to_string(llarg));
|
|
llarg
|
|
})
|
|
.collect();
|
|
assert!(!fcx.needs_ret_allocas);
|
|
|
|
let dest =
|
|
fcx.llretslotptr.get().map(
|
|
|_| expr::SaveIn(fcx.get_ret_slot(bcx, fty.sig.0.output, "ret_slot")));
|
|
|
|
let method_offset_in_vtable =
|
|
traits::get_vtable_index_of_object_method(bcx.tcx(),
|
|
object_trait_ref.clone(),
|
|
trait_id,
|
|
method_offset_in_trait);
|
|
debug!("trans_object_shim: method_offset_in_vtable={}",
|
|
method_offset_in_vtable);
|
|
|
|
bcx = trans_call_inner(bcx,
|
|
None,
|
|
method_bare_fn_ty,
|
|
|bcx, _| trans_trait_callee_from_llval(bcx,
|
|
method_bare_fn_ty,
|
|
method_offset_in_vtable,
|
|
llobject),
|
|
ArgVals(llargs.as_slice()),
|
|
dest).bcx;
|
|
|
|
finish_fn(&fcx, bcx, fty.sig.0.output);
|
|
|
|
llfn
|
|
}
|
|
|
|
/// Creates a returns a dynamic vtable for the given type and vtable origin.
|
|
/// This is used only for objects.
|
|
///
|
|
/// The `trait_ref` encodes the erased self type. Hence if we are
|
|
/// making an object `Foo<Trait>` from a value of type `Foo<T>`, then
|
|
/// `trait_ref` would map `T:Trait`, but `box_ty` would be
|
|
/// `Foo<T>`. This `box_ty` is primarily used to encode the destructor.
|
|
/// This will hopefully change now that DST is underway.
|
|
pub fn get_vtable<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
|
|
box_ty: Ty<'tcx>,
|
|
trait_ref: ty::PolyTraitRef<'tcx>)
|
|
-> ValueRef
|
|
{
|
|
debug!("get_vtable(box_ty={}, trait_ref={})",
|
|
box_ty.repr(bcx.tcx()),
|
|
trait_ref.repr(bcx.tcx()));
|
|
|
|
let tcx = bcx.tcx();
|
|
let ccx = bcx.ccx();
|
|
let _icx = push_ctxt("meth::get_vtable");
|
|
|
|
// Check the cache.
|
|
let cache_key = (box_ty, trait_ref.clone());
|
|
match ccx.vtables().borrow().get(&cache_key) {
|
|
Some(&val) => { return val }
|
|
None => { }
|
|
}
|
|
|
|
// Not in the cache. Build it.
|
|
let methods = traits::supertraits(tcx, trait_ref.clone()).flat_map(|trait_ref| {
|
|
let vtable = fulfill_obligation(bcx.ccx(),
|
|
DUMMY_SP,
|
|
trait_ref.clone());
|
|
match vtable {
|
|
traits::VtableBuiltin(_) => {
|
|
Vec::new().into_iter()
|
|
}
|
|
traits::VtableImpl(
|
|
traits::VtableImplData {
|
|
impl_def_id: id,
|
|
substs,
|
|
nested: _ }) => {
|
|
emit_vtable_methods(bcx, id, substs).into_iter()
|
|
}
|
|
traits::VtableUnboxedClosure(closure_def_id, substs) => {
|
|
let llfn = trans_fn_ref_with_substs(
|
|
bcx.ccx(),
|
|
closure_def_id,
|
|
ExprId(0),
|
|
bcx.fcx.param_substs,
|
|
substs.clone()).val;
|
|
|
|
(vec!(llfn)).into_iter()
|
|
}
|
|
traits::VtableFnPointer(bare_fn_ty) => {
|
|
let llfn = vec![trans_fn_pointer_shim(bcx.ccx(), bare_fn_ty)];
|
|
llfn.into_iter()
|
|
}
|
|
traits::VtableObject(ref data) => {
|
|
// this would imply that the Self type being erased is
|
|
// an object type; this cannot happen because we
|
|
// cannot cast an unsized type into a trait object
|
|
bcx.sess().bug(
|
|
format!("cannot get vtable for an object type: {}",
|
|
data.repr(bcx.tcx())).as_slice());
|
|
}
|
|
traits::VtableParam => {
|
|
bcx.sess().bug(
|
|
format!("resolved vtable for {} to bad vtable {} in trans",
|
|
trait_ref.repr(bcx.tcx()),
|
|
vtable.repr(bcx.tcx()))[]);
|
|
}
|
|
}
|
|
});
|
|
|
|
let size_ty = sizing_type_of(ccx, trait_ref.self_ty());
|
|
let size = machine::llsize_of_alloc(ccx, size_ty);
|
|
let ll_size = C_uint(ccx, size);
|
|
let align = align_of(ccx, trait_ref.self_ty());
|
|
let ll_align = C_uint(ccx, align);
|
|
|
|
// Generate a destructor for the vtable.
|
|
let drop_glue = glue::get_drop_glue(ccx, box_ty);
|
|
let vtable = make_vtable(ccx, drop_glue, ll_size, ll_align, methods);
|
|
|
|
ccx.vtables().borrow_mut().insert(cache_key, vtable);
|
|
vtable
|
|
}
|
|
|
|
/// Helper function to declare and initialize the vtable.
|
|
pub fn make_vtable<I: Iterator<Item=ValueRef>>(ccx: &CrateContext,
|
|
drop_glue: ValueRef,
|
|
size: ValueRef,
|
|
align: ValueRef,
|
|
ptrs: I)
|
|
-> ValueRef {
|
|
let _icx = push_ctxt("meth::make_vtable");
|
|
|
|
let head = vec![drop_glue, size, align];
|
|
let components: Vec<_> = head.into_iter().chain(ptrs).collect();
|
|
|
|
unsafe {
|
|
let tbl = C_struct(ccx, components[], false);
|
|
let sym = token::gensym("vtable");
|
|
let vt_gvar = format!("vtable{}", sym.uint()).with_c_str(|buf| {
|
|
llvm::LLVMAddGlobal(ccx.llmod(), val_ty(tbl).to_ref(), buf)
|
|
});
|
|
llvm::LLVMSetInitializer(vt_gvar, tbl);
|
|
llvm::LLVMSetGlobalConstant(vt_gvar, llvm::True);
|
|
llvm::SetLinkage(vt_gvar, llvm::InternalLinkage);
|
|
vt_gvar
|
|
}
|
|
}
|
|
|
|
fn emit_vtable_methods<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
|
|
impl_id: ast::DefId,
|
|
substs: subst::Substs<'tcx>)
|
|
-> Vec<ValueRef> {
|
|
let ccx = bcx.ccx();
|
|
let tcx = ccx.tcx();
|
|
|
|
let trt_id = match ty::impl_trait_ref(tcx, impl_id) {
|
|
Some(t_id) => t_id.def_id,
|
|
None => ccx.sess().bug("make_impl_vtable: don't know how to \
|
|
make a vtable for a type impl!")
|
|
};
|
|
|
|
ty::populate_implementations_for_trait_if_necessary(bcx.tcx(), trt_id);
|
|
|
|
let trait_item_def_ids = ty::trait_item_def_ids(tcx, trt_id);
|
|
trait_item_def_ids.iter().flat_map(|method_def_id| {
|
|
let method_def_id = method_def_id.def_id();
|
|
let name = ty::impl_or_trait_item(tcx, method_def_id).name();
|
|
// The substitutions we have are on the impl, so we grab
|
|
// the method type from the impl to substitute into.
|
|
let m_id = method_with_name(ccx, impl_id, name);
|
|
let ti = ty::impl_or_trait_item(tcx, m_id);
|
|
match ti {
|
|
ty::MethodTraitItem(m) => {
|
|
debug!("(making impl vtable) emitting method {} at subst {}",
|
|
m.repr(tcx),
|
|
substs.repr(tcx));
|
|
if m.generics.has_type_params(subst::FnSpace) ||
|
|
ty::type_has_self(ty::mk_bare_fn(tcx, None, tcx.mk_bare_fn(m.fty.clone())))
|
|
{
|
|
debug!("(making impl vtable) method has self or type \
|
|
params: {}",
|
|
token::get_name(name));
|
|
Some(C_null(Type::nil(ccx).ptr_to())).into_iter()
|
|
} else {
|
|
let fn_ref = trans_fn_ref_with_substs(
|
|
ccx,
|
|
m_id,
|
|
ExprId(0),
|
|
bcx.fcx.param_substs,
|
|
substs.clone()).val;
|
|
|
|
// currently, at least, by-value self is not object safe
|
|
assert!(m.explicit_self != ty::ByValueExplicitSelfCategory);
|
|
|
|
Some(fn_ref).into_iter()
|
|
}
|
|
}
|
|
ty::TypeTraitItem(_) => {
|
|
None.into_iter()
|
|
}
|
|
}
|
|
}).collect()
|
|
}
|
|
|
|
/// Generates the code to convert from a pointer (`Box<T>`, `&T`, etc) into an object
|
|
/// (`Box<Trait>`, `&Trait`, etc). This means creating a pair where the first word is the vtable
|
|
/// and the second word is the pointer.
|
|
pub fn trans_trait_cast<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
|
|
datum: Datum<'tcx, Expr>,
|
|
id: ast::NodeId,
|
|
trait_ref: ty::PolyTraitRef<'tcx>,
|
|
dest: expr::Dest)
|
|
-> Block<'blk, 'tcx> {
|
|
let mut bcx = bcx;
|
|
let _icx = push_ctxt("meth::trans_trait_cast");
|
|
|
|
let lldest = match dest {
|
|
Ignore => {
|
|
return datum.clean(bcx, "trait_trait_cast", id);
|
|
}
|
|
SaveIn(dest) => dest
|
|
};
|
|
|
|
debug!("trans_trait_cast: trait_ref={}",
|
|
trait_ref.repr(bcx.tcx()));
|
|
|
|
let datum_ty = datum.ty;
|
|
let llbox_ty = type_of(bcx.ccx(), datum_ty);
|
|
|
|
// Store the pointer into the first half of pair.
|
|
let llboxdest = GEPi(bcx, lldest, &[0u, abi::FAT_PTR_ADDR]);
|
|
let llboxdest = PointerCast(bcx, llboxdest, llbox_ty.ptr_to());
|
|
bcx = datum.store_to(bcx, llboxdest);
|
|
|
|
// Store the vtable into the second half of pair.
|
|
let vtable = get_vtable(bcx, datum_ty, trait_ref);
|
|
let llvtabledest = GEPi(bcx, lldest, &[0u, abi::FAT_PTR_EXTRA]);
|
|
let llvtabledest = PointerCast(bcx, llvtabledest, val_ty(vtable).ptr_to());
|
|
Store(bcx, vtable, llvtabledest);
|
|
|
|
bcx
|
|
}
|