1 use crate::{ImplTraitContext, ImplTraitPosition, LoweringContext};
2 use rustc_ast::{Block, BlockCheckMode, Local, LocalKind, Stmt, StmtKind};
4 use rustc_session::parse::feature_err;
7 use smallvec::SmallVec;
9 impl<'a, 'hir> LoweringContext<'a, 'hir> {
10 pub(super) fn lower_block(
13 targeted_by_break: bool,
14 ) -> &'hir hir::Block<'hir> {
15 self.arena.alloc(self.lower_block_noalloc(b, targeted_by_break))
18 pub(super) fn lower_block_noalloc(
21 targeted_by_break: bool,
22 ) -> hir::Block<'hir> {
23 let (stmts, expr) = self.lower_stmts(&b.stmts);
24 let rules = self.lower_block_check_mode(&b.rules);
25 let hir_id = self.lower_node_id(b.id);
26 hir::Block { hir_id, stmts, expr, rules, span: self.lower_span(b.span), targeted_by_break }
31 mut ast_stmts: &[Stmt],
32 ) -> (&'hir [hir::Stmt<'hir>], Option<&'hir hir::Expr<'hir>>) {
33 let mut stmts = SmallVec::<[hir::Stmt<'hir>; 8]>::new();
35 while let [s, tail @ ..] = ast_stmts {
37 StmtKind::Local(ref local) => {
38 let hir_id = self.lower_node_id(s.id);
39 let els = if let LocalKind::InitElse(_, els) = &local.kind {
40 if !self.tcx.features().let_else {
42 &self.tcx.sess.parse_sess,
45 "`let...else` statements are unstable",
49 Some(self.lower_block(els, false))
53 let local = self.lower_local(local);
54 self.alias_attrs(hir_id, local.hir_id);
55 let kind = hir::StmtKind::Local(local, els);
56 let span = self.lower_span(s.span);
57 stmts.push(hir::Stmt { hir_id, kind, span });
59 StmtKind::Item(ref it) => {
60 stmts.extend(self.lower_item_ref(it).into_iter().enumerate().map(
62 let hir_id = match i {
63 0 => self.lower_node_id(s.id),
66 let kind = hir::StmtKind::Item(item_id);
67 let span = self.lower_span(s.span);
68 hir::Stmt { hir_id, kind, span }
72 StmtKind::Expr(ref e) => {
73 let e = self.lower_expr(e);
77 let hir_id = self.lower_node_id(s.id);
78 self.alias_attrs(hir_id, e.hir_id);
79 let kind = hir::StmtKind::Expr(e);
80 let span = self.lower_span(s.span);
81 stmts.push(hir::Stmt { hir_id, kind, span });
84 StmtKind::Semi(ref e) => {
85 let e = self.lower_expr(e);
86 let hir_id = self.lower_node_id(s.id);
87 self.alias_attrs(hir_id, e.hir_id);
88 let kind = hir::StmtKind::Semi(e);
89 let span = self.lower_span(s.span);
90 stmts.push(hir::Stmt { hir_id, kind, span });
93 StmtKind::MacCall(..) => panic!("shouldn't exist here"),
95 ast_stmts = &ast_stmts[1..];
97 (self.arena.alloc_from_iter(stmts), expr)
100 fn lower_local(&mut self, l: &Local) -> &'hir hir::Local<'hir> {
104 .map(|t| self.lower_ty(t, ImplTraitContext::Disallowed(ImplTraitPosition::Variable)));
105 let init = l.kind.init().map(|init| self.lower_expr(init));
106 let hir_id = self.lower_node_id(l.id);
107 let pat = self.lower_pat(&l.pat);
108 let span = self.lower_span(l.span);
109 let source = hir::LocalSource::Normal;
110 self.lower_attrs(hir_id, &l.attrs);
111 self.arena.alloc(hir::Local { hir_id, ty, pat, init, span, source })
114 fn lower_block_check_mode(&mut self, b: &BlockCheckMode) -> hir::BlockCheckMode {
116 BlockCheckMode::Default => hir::BlockCheckMode::DefaultBlock,
117 BlockCheckMode::Unsafe(u) => {
118 hir::BlockCheckMode::UnsafeBlock(self.lower_unsafe_source(u))