bjoernager/rust
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let-else: add hir::Let and type check it like a hir::Local

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unify typeck of hir::Local and hir::Let
remove extraneous pub(crate/super)
This commit is contained in:
Cormac Relf 2021-10-13 16:39:06 +11:00
parent a0a4c7d1e4
commit af2f0e6b7c
13 changed files with 160 additions and 92 deletions
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31
compiler/rustc_ast_lowering/src/block.rs
View file

@ -2,7 +2,6 @@ use crate::{ImplTraitContext, ImplTraitPosition, LoweringContext};
use rustc_ast::{AttrVec, Block, BlockCheckMode, Expr, Local, LocalKind, Stmt, StmtKind};
use rustc_hir as hir;
use rustc_session::parse::feature_err;
use rustc_span::symbol::Ident;
use rustc_span::{sym, DesugaringKind};
use smallvec::SmallVec;
@ -39,8 +38,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
let hir_id = self.lower_node_id(s.id);
match &local.kind {
LocalKind::InitElse(init, els) => {
let (s, e) = self.lower_let_else(hir_id, local, init, els, tail);
stmts.push(s);
let e = self.lower_let_else(hir_id, local, init, els, tail);
expr = Some(e);
// remaining statements are in let-else expression
break;
@ -125,36 +123,25 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
init: &Expr,
els: &Block,
tail: &[Stmt],
) -> (hir::Stmt<'hir>, &'hir hir::Expr<'hir>) {
) -> &'hir hir::Expr<'hir> {
let ty = local
.ty
.as_ref()
.map(|t| self.lower_ty(t, ImplTraitContext::Disallowed(ImplTraitPosition::Binding)));
let span = self.lower_span(local.span);
let span = self.mark_span_with_reason(DesugaringKind::LetElse, span, None);
let init = Some(self.lower_expr(init));
let val = Ident::with_dummy_span(sym::val);
let (pat, val_id) =
self.pat_ident_binding_mode(span, val, hir::BindingAnnotation::Unannotated);
let init = self.lower_expr(init);
let local_hir_id = self.lower_node_id(local.id);
self.lower_attrs(local_hir_id, &local.attrs);
// first statement which basically exists for the type annotation
let stmt = {
let local = self.arena.alloc(hir::Local {
let let_expr = {
let lex = self.arena.alloc(hir::Let {
hir_id: local_hir_id,
pat: self.lower_pat(&local.pat),
ty,
pat,
init,
span,
source: hir::LocalSource::Normal,
});
let kind = hir::StmtKind::Local(local);
hir::Stmt { hir_id: stmt_hir_id, kind, span }
};
let let_expr = {
let scrutinee = self.expr_ident(span, val, val_id);
let let_kind = hir::ExprKind::Let(self.lower_pat(&local.pat), scrutinee, span);
self.arena.alloc(self.expr(span, let_kind, AttrVec::new()))
self.arena.alloc(self.expr(span, hir::ExprKind::Let(lex), AttrVec::new()))
};
let then_expr = {
let (stmts, expr) = self.lower_stmts(tail);
@ -167,7 +154,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
};
self.alias_attrs(else_expr.hir_id, local_hir_id);
let if_expr = self.arena.alloc(hir::Expr {
hir_id: self.next_id(),
hir_id: stmt_hir_id,
span,
kind: hir::ExprKind::If(let_expr, then_expr, Some(else_expr)),
});
@ -180,6 +167,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
)
.emit();
}
(stmt, if_expr)
if_expr
}
}

14
compiler/rustc_ast_lowering/src/expr.rs
View file

@ -92,11 +92,15 @@ impl<'hir> LoweringContext<'_, 'hir> {
let ohs = self.lower_expr(ohs);
hir::ExprKind::AddrOf(k, m, ohs)
}
ExprKind::Let(ref pat, ref scrutinee, span) => hir::ExprKind::Let(
self.lower_pat(pat),
self.lower_expr(scrutinee),
self.lower_span(span),
),
ExprKind::Let(ref pat, ref scrutinee, span) => {
hir::ExprKind::Let(self.arena.alloc(hir::Let {
hir_id: self.next_id(),
span: self.lower_span(span),
pat: self.lower_pat(pat),
ty: None,
init: self.lower_expr(scrutinee),
}))
}
ExprKind::If(ref cond, ref then, ref else_opt) => {
self.lower_expr_if(cond, then, else_opt.as_deref())
}