123 lines
4.7 KiB
Rust
123 lines
4.7 KiB
Rust
use crate::{ImplTraitContext, ImplTraitPosition, LoweringContext};
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use rustc_ast::{Block, BlockCheckMode, Local, LocalKind, Stmt, StmtKind};
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use rustc_hir as hir;
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use rustc_session::parse::feature_err;
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use rustc_span::sym;
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use smallvec::SmallVec;
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impl<'a, 'hir> LoweringContext<'a, 'hir> {
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pub(super) fn lower_block(
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&mut self,
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b: &Block,
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targeted_by_break: bool,
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) -> &'hir hir::Block<'hir> {
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self.arena.alloc(self.lower_block_noalloc(b, targeted_by_break))
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}
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pub(super) fn lower_block_noalloc(
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&mut self,
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b: &Block,
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targeted_by_break: bool,
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) -> hir::Block<'hir> {
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let (stmts, expr) = self.lower_stmts(&b.stmts);
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let rules = self.lower_block_check_mode(&b.rules);
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let hir_id = self.lower_node_id(b.id);
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hir::Block { hir_id, stmts, expr, rules, span: self.lower_span(b.span), targeted_by_break }
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}
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fn lower_stmts(
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&mut self,
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mut ast_stmts: &[Stmt],
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) -> (&'hir [hir::Stmt<'hir>], Option<&'hir hir::Expr<'hir>>) {
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let mut stmts = SmallVec::<[hir::Stmt<'hir>; 8]>::new();
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let mut expr = None;
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while let [s, tail @ ..] = ast_stmts {
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match s.kind {
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StmtKind::Local(ref local) => {
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let hir_id = self.lower_node_id(s.id);
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let local = self.lower_local(local);
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self.alias_attrs(hir_id, local.hir_id);
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let kind = hir::StmtKind::Local(local);
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let span = self.lower_span(s.span);
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stmts.push(hir::Stmt { hir_id, kind, span });
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}
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StmtKind::Item(ref it) => {
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stmts.extend(self.lower_item_ref(it).into_iter().enumerate().map(
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|(i, item_id)| {
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let hir_id = match i {
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0 => self.lower_node_id(s.id),
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_ => self.next_id(),
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};
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let kind = hir::StmtKind::Item(item_id);
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let span = self.lower_span(s.span);
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hir::Stmt { hir_id, kind, span }
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},
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));
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}
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StmtKind::Expr(ref e) => {
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let e = self.lower_expr(e);
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if tail.is_empty() {
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expr = Some(e);
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} else {
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let hir_id = self.lower_node_id(s.id);
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self.alias_attrs(hir_id, e.hir_id);
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let kind = hir::StmtKind::Expr(e);
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let span = self.lower_span(s.span);
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stmts.push(hir::Stmt { hir_id, kind, span });
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}
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}
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StmtKind::Semi(ref e) => {
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let e = self.lower_expr(e);
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let hir_id = self.lower_node_id(s.id);
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self.alias_attrs(hir_id, e.hir_id);
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let kind = hir::StmtKind::Semi(e);
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let span = self.lower_span(s.span);
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stmts.push(hir::Stmt { hir_id, kind, span });
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}
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StmtKind::Empty => {}
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StmtKind::MacCall(..) => panic!("shouldn't exist here"),
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}
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ast_stmts = &ast_stmts[1..];
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}
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(self.arena.alloc_from_iter(stmts), expr)
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}
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fn lower_local(&mut self, l: &Local) -> &'hir hir::Local<'hir> {
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let ty = l
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.ty
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.as_ref()
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.map(|t| self.lower_ty(t, ImplTraitContext::Disallowed(ImplTraitPosition::Variable)));
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let init = l.kind.init().map(|init| self.lower_expr(init));
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let hir_id = self.lower_node_id(l.id);
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let pat = self.lower_pat(&l.pat);
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let els = if let LocalKind::InitElse(_, els) = &l.kind {
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if !self.tcx.features().let_else {
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feature_err(
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&self.tcx.sess.parse_sess,
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sym::let_else,
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l.span,
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"`let...else` statements are unstable",
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)
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.emit();
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}
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Some(self.lower_block(els, false))
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} else {
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None
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};
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let span = self.lower_span(l.span);
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let source = hir::LocalSource::Normal;
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self.lower_attrs(hir_id, &l.attrs);
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self.arena.alloc(hir::Local { hir_id, ty, pat, init, els, span, source })
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}
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fn lower_block_check_mode(&mut self, b: &BlockCheckMode) -> hir::BlockCheckMode {
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match *b {
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BlockCheckMode::Default => hir::BlockCheckMode::DefaultBlock,
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BlockCheckMode::Unsafe(u) => {
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hir::BlockCheckMode::UnsafeBlock(self.lower_unsafe_source(u))
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}
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}
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}
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}
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