diff options
| -rw-r--r-- | src/librustc/hir/lowering/expr.rs | 116 |
1 files changed, 67 insertions, 49 deletions
diff --git a/src/librustc/hir/lowering/expr.rs b/src/librustc/hir/lowering/expr.rs index 6ae39d192c3..01eca00a913 100644 --- a/src/librustc/hir/lowering/expr.rs +++ b/src/librustc/hir/lowering/expr.rs @@ -268,55 +268,13 @@ impl LoweringContext<'_> { capture_clause, asyncness, movability, ref decl, ref body, fn_decl_span ) => { if let IsAsync::Async { closure_id, .. } = asyncness { - let outer_decl = FnDecl { - inputs: decl.inputs.clone(), - output: FunctionRetTy::Default(fn_decl_span), - c_variadic: false, - }; - // We need to lower the declaration outside the new scope, because we - // have to conserve the state of being inside a loop condition for the - // closure argument types. - let fn_decl = self.lower_fn_decl(&outer_decl, None, false, None); - - self.with_new_scopes(|this| { - // FIXME(cramertj): allow `async` non-`move` closures with arguments. - if capture_clause == CaptureBy::Ref && - !decl.inputs.is_empty() - { - struct_span_err!( - this.sess, - fn_decl_span, - E0708, - "`async` non-`move` closures with arguments \ - are not currently supported", - ) - .help("consider using `let` statements to manually capture \ - variables by reference before entering an \ - `async move` closure") - .emit(); - } - - // Transform `async |x: u8| -> X { ... }` into - // `|x: u8| future_from_generator(|| -> X { ... })`. - let body_id = this.lower_fn_body(&outer_decl, |this| { - let async_ret_ty = if let FunctionRetTy::Ty(ty) = &decl.output { - Some(ty.clone()) - } else { None }; - let async_body = this.make_async_expr( - capture_clause, closure_id, async_ret_ty, body.span, - |this| { - this.with_new_scopes(|this| this.lower_expr(body)) - }); - this.expr(fn_decl_span, async_body, ThinVec::new()) - }); - hir::ExprKind::Closure( - this.lower_capture_clause(capture_clause), - fn_decl, - body_id, - fn_decl_span, - None, - ) - }) + self.lower_expr_async_closure( + capture_clause, + closure_id, + decl, + body, + fn_decl_span, + ) } else { // Lower outside new scope to preserve `is_in_loop_condition`. let fn_decl = self.lower_fn_decl(decl, None, false, None); @@ -449,6 +407,66 @@ impl LoweringContext<'_> { } } + fn lower_expr_async_closure( + &mut self, + capture_clause: CaptureBy, + closure_id: NodeId, + decl: &FnDecl, + body: &Expr, + fn_decl_span: Span, + ) -> hir::ExprKind { + let outer_decl = FnDecl { + inputs: decl.inputs.clone(), + output: FunctionRetTy::Default(fn_decl_span), + c_variadic: false, + }; + // We need to lower the declaration outside the new scope, because we + // have to conserve the state of being inside a loop condition for the + // closure argument types. + let fn_decl = self.lower_fn_decl(&outer_decl, None, false, None); + + self.with_new_scopes(|this| { + // FIXME(cramertj): allow `async` non-`move` closures with arguments. + if capture_clause == CaptureBy::Ref && !decl.inputs.is_empty() { + struct_span_err!( + this.sess, + fn_decl_span, + E0708, + "`async` non-`move` closures with arguments are not currently supported", + ) + .help( + "consider using `let` statements to manually capture \ + variables by reference before entering an `async move` closure" + ) + .emit(); + } + + // Transform `async |x: u8| -> X { ... }` into + // `|x: u8| future_from_generator(|| -> X { ... })`. + let body_id = this.lower_fn_body(&outer_decl, |this| { + let async_ret_ty = if let FunctionRetTy::Ty(ty) = &decl.output { + Some(ty.clone()) + } else { + None + }; + let async_body = this.make_async_expr( + capture_clause, closure_id, async_ret_ty, body.span, + |this| { + this.with_new_scopes(|this| this.lower_expr(body)) + } + ); + this.expr(fn_decl_span, async_body, ThinVec::new()) + }); + hir::ExprKind::Closure( + this.lower_capture_clause(capture_clause), + fn_decl, + body_id, + fn_decl_span, + None, + ) + }) + } + /// Desugar `<start>..=<end>` into `std::ops::RangeInclusive::new(<start>, <end>)`. fn lower_expr_range_closed(&mut self, span: Span, e1: &Expr, e2: &Expr) -> hir::ExprKind { let id = self.next_id(); |