diff --git a/compiler/rustc_ast_lowering/src/pat.rs b/compiler/rustc_ast_lowering/src/pat.rs index cb7b7c0eb6116..a1cbcde1f4291 100644 --- a/compiler/rustc_ast_lowering/src/pat.rs +++ b/compiler/rustc_ast_lowering/src/pat.rs @@ -10,82 +10,90 @@ use rustc_span::symbol::Ident; use rustc_span::{source_map::Spanned, Span}; impl<'a, 'hir> LoweringContext<'a, 'hir> { - crate fn lower_pat(&mut self, p: &Pat) -> &'hir hir::Pat<'hir> { + crate fn lower_pat(&mut self, mut pattern: &Pat) -> &'hir hir::Pat<'hir> { ensure_sufficient_stack(|| { - let node = match p.kind { - PatKind::Wild => hir::PatKind::Wild, - PatKind::Ident(ref binding_mode, ident, ref sub) => { - let lower_sub = |this: &mut Self| sub.as_ref().map(|s| this.lower_pat(&*s)); - let node = self.lower_pat_ident(p, binding_mode, ident, lower_sub); - node - } - PatKind::Lit(ref e) => hir::PatKind::Lit(self.lower_expr(e)), - PatKind::TupleStruct(ref path, ref pats) => { - let qpath = self.lower_qpath( - p.id, - &None, - path, - ParamMode::Optional, - ImplTraitContext::disallowed(), - ); - let (pats, ddpos) = self.lower_pat_tuple(pats, "tuple struct"); - hir::PatKind::TupleStruct(qpath, pats, ddpos) - } - PatKind::Or(ref pats) => hir::PatKind::Or( - self.arena.alloc_from_iter(pats.iter().map(|x| self.lower_pat(x))), - ), - PatKind::Path(ref qself, ref path) => { - let qpath = self.lower_qpath( - p.id, - qself, - path, - ParamMode::Optional, - ImplTraitContext::disallowed(), - ); - hir::PatKind::Path(qpath) - } - PatKind::Struct(ref path, ref fields, etc) => { - let qpath = self.lower_qpath( - p.id, - &None, - path, - ParamMode::Optional, - ImplTraitContext::disallowed(), - ); + // loop here to avoid recursion + let node = loop { + match pattern.kind { + PatKind::Wild => break hir::PatKind::Wild, + PatKind::Ident(ref binding_mode, ident, ref sub) => { + let lower_sub = |this: &mut Self| sub.as_ref().map(|s| this.lower_pat(&*s)); + break self.lower_pat_ident(pattern, binding_mode, ident, lower_sub); + } + PatKind::Lit(ref e) => break hir::PatKind::Lit(self.lower_expr(e)), + PatKind::TupleStruct(ref path, ref pats) => { + let qpath = self.lower_qpath( + pattern.id, + &None, + path, + ParamMode::Optional, + ImplTraitContext::disallowed(), + ); + let (pats, ddpos) = self.lower_pat_tuple(pats, "tuple struct"); + break hir::PatKind::TupleStruct(qpath, pats, ddpos); + } + PatKind::Or(ref pats) => { + break hir::PatKind::Or( + self.arena.alloc_from_iter(pats.iter().map(|x| self.lower_pat(x))), + ); + } + PatKind::Path(ref qself, ref path) => { + let qpath = self.lower_qpath( + pattern.id, + qself, + path, + ParamMode::Optional, + ImplTraitContext::disallowed(), + ); + break hir::PatKind::Path(qpath); + } + PatKind::Struct(ref path, ref fields, etc) => { + let qpath = self.lower_qpath( + pattern.id, + &None, + path, + ParamMode::Optional, + ImplTraitContext::disallowed(), + ); - let fs = self.arena.alloc_from_iter(fields.iter().map(|f| hir::FieldPat { - hir_id: self.next_id(), - ident: f.ident, - pat: self.lower_pat(&f.pat), - is_shorthand: f.is_shorthand, - span: f.span, - })); - hir::PatKind::Struct(qpath, fs, etc) - } - PatKind::Tuple(ref pats) => { - let (pats, ddpos) = self.lower_pat_tuple(pats, "tuple"); - hir::PatKind::Tuple(pats, ddpos) - } - PatKind::Box(ref inner) => hir::PatKind::Box(self.lower_pat(inner)), - PatKind::Ref(ref inner, mutbl) => hir::PatKind::Ref(self.lower_pat(inner), mutbl), - PatKind::Range(ref e1, ref e2, Spanned { node: ref end, .. }) => { - hir::PatKind::Range( - e1.as_deref().map(|e| self.lower_expr(e)), - e2.as_deref().map(|e| self.lower_expr(e)), - self.lower_range_end(end, e2.is_some()), - ) - } - PatKind::Slice(ref pats) => self.lower_pat_slice(pats), - PatKind::Rest => { - // If we reach here the `..` pattern is not semantically allowed. - self.ban_illegal_rest_pat(p.span) + let fs = self.arena.alloc_from_iter(fields.iter().map(|f| hir::FieldPat { + hir_id: self.next_id(), + ident: f.ident, + pat: self.lower_pat(&f.pat), + is_shorthand: f.is_shorthand, + span: f.span, + })); + break hir::PatKind::Struct(qpath, fs, etc); + } + PatKind::Tuple(ref pats) => { + let (pats, ddpos) = self.lower_pat_tuple(pats, "tuple"); + break hir::PatKind::Tuple(pats, ddpos); + } + PatKind::Box(ref inner) => { + break hir::PatKind::Box(self.lower_pat(inner)); + } + PatKind::Ref(ref inner, mutbl) => { + break hir::PatKind::Ref(self.lower_pat(inner), mutbl); + } + PatKind::Range(ref e1, ref e2, Spanned { node: ref end, .. }) => { + break hir::PatKind::Range( + e1.as_deref().map(|e| self.lower_expr(e)), + e2.as_deref().map(|e| self.lower_expr(e)), + self.lower_range_end(end, e2.is_some()), + ); + } + PatKind::Slice(ref pats) => break self.lower_pat_slice(pats), + PatKind::Rest => { + // If we reach here the `..` pattern is not semantically allowed. + break self.ban_illegal_rest_pat(pattern.span); + } + // return inner to be processed in next loop + PatKind::Paren(ref inner) => pattern = inner, + PatKind::MacCall(_) => panic!("{:?} shouldn't exist here", pattern.span), } - // FIXME: consider not using recursion to lower this. - PatKind::Paren(ref inner) => return self.lower_pat(inner), - PatKind::MacCall(_) => panic!("{:?} shouldn't exist here", p.span), }; - self.pat_with_node_id_of(p, node) + self.pat_with_node_id_of(pattern, node) }) }