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use rustc::hir::def_id::DefId;
use rustc::hir::intravisit::{self, Visitor, NestedVisitorMap};
use rustc::hir::{self, Pat, PatKind, Expr};
use rustc::middle::region;
use rustc::ty::{self, Ty};
use rustc_data_structures::sync::Lrc;
use syntax_pos::Span;
use super::FnCtxt;
use util::nodemap::FxHashMap;
struct InteriorVisitor<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
fcx: &'a FnCtxt<'a, 'gcx, 'tcx>,
types: FxHashMap<Ty<'tcx>, usize>,
region_scope_tree: Lrc<region::ScopeTree>,
expr_count: usize,
}
impl<'a, 'gcx, 'tcx> InteriorVisitor<'a, 'gcx, 'tcx> {
fn record(&mut self,
ty: Ty<'tcx>,
scope: Option<region::Scope>,
expr: Option<&'tcx Expr>,
source_span: Span) {
use syntax_pos::DUMMY_SP;
let live_across_yield = scope.map_or(Some(DUMMY_SP), |s| {
self.region_scope_tree.yield_in_scope(s).and_then(|(yield_span, expr_count)| {
debug!("comparing counts yield: {} self: {}, source_span = {:?}",
expr_count, self.expr_count, source_span);
if expr_count >= self.expr_count {
Some(yield_span)
} else {
None
}
})
});
if let Some(yield_span) = live_across_yield {
let ty = self.fcx.resolve_type_vars_if_possible(&ty);
debug!("type in expr = {:?}, scope = {:?}, type = {:?}, count = {}, yield_span = {:?}",
expr, scope, ty, self.expr_count, yield_span);
if self.fcx.any_unresolved_type_vars(&ty) {
let mut err = struct_span_err!(self.fcx.tcx.sess, source_span, E0698,
"type inside generator must be known in this context");
err.span_note(yield_span,
"the type is part of the generator because of this `yield`");
err.emit();
} else {
let entries = self.types.len();
self.types.entry(&ty).or_insert(entries);
}
} else {
debug!("no type in expr = {:?}, count = {:?}, span = {:?}",
expr, self.expr_count, expr.map(|e| e.span));
}
}
}
pub fn resolve_interior<'a, 'gcx, 'tcx>(fcx: &'a FnCtxt<'a, 'gcx, 'tcx>,
def_id: DefId,
body_id: hir::BodyId,
interior: Ty<'tcx>) {
let body = fcx.tcx.hir.body(body_id);
let mut visitor = InteriorVisitor {
fcx,
types: FxHashMap(),
region_scope_tree: fcx.tcx.region_scope_tree(def_id),
expr_count: 0,
};
intravisit::walk_body(&mut visitor, body);
let region_expr_count = visitor.region_scope_tree.body_expr_count(body_id).unwrap();
assert_eq!(region_expr_count, visitor.expr_count);
let mut types: Vec<_> = visitor.types.drain().collect();
types.sort_by_key(|t| t.1);
let type_list = fcx.tcx.mk_type_list(types.into_iter().map(|t| t.0));
debug!("Types in generator {:?}, span = {:?}", type_list, body.value.span);
let mut counter = 0;
let type_list = fcx.tcx.fold_regions(&type_list, &mut false, |_, current_depth| {
counter += 1;
fcx.tcx.mk_region(ty::ReLateBound(current_depth, ty::BrAnon(counter)))
});
let witness = fcx.tcx.mk_generator_witness(ty::Binder::bind(type_list));
debug!("Types in generator after region replacement {:?}, span = {:?}",
witness, body.value.span);
match fcx.at(&fcx.misc(body.value.span), fcx.param_env).eq(interior, witness) {
Ok(ok) => fcx.register_infer_ok_obligations(ok),
_ => bug!(),
}
}
impl<'a, 'gcx, 'tcx> Visitor<'tcx> for InteriorVisitor<'a, 'gcx, 'tcx> {
fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
NestedVisitorMap::None
}
fn visit_pat(&mut self, pat: &'tcx Pat) {
intravisit::walk_pat(self, pat);
self.expr_count += 1;
if let PatKind::Binding(..) = pat.node {
let scope = self.region_scope_tree.var_scope(pat.hir_id.local_id);
let ty = self.fcx.tables.borrow().pat_ty(pat);
self.record(ty, Some(scope), None, pat.span);
}
}
fn visit_expr(&mut self, expr: &'tcx Expr) {
intravisit::walk_expr(self, expr);
self.expr_count += 1;
let scope = self.region_scope_tree.temporary_scope(expr.hir_id.local_id);
let ty = self.fcx.tables.borrow().expr_ty(expr);
self.record(ty, scope, Some(expr), expr.span);
for adjustment in self.fcx.tables.borrow().expr_adjustments(expr) {
self.record(adjustment.target, scope, Some(expr), expr.span);
}
}
}