| use super::{ImplTraitContext, LoweringContext, ParamMode, ParenthesizedGenericArgs}; |
| |
| use rustc_ast::ast::*; |
| use rustc_ast::attr; |
| use rustc_ast::ptr::P as AstP; |
| use rustc_data_structures::fx::FxHashMap; |
| use rustc_data_structures::stack::ensure_sufficient_stack; |
| use rustc_data_structures::thin_vec::ThinVec; |
| use rustc_errors::struct_span_err; |
| use rustc_hir as hir; |
| use rustc_hir::def::Res; |
| use rustc_span::source_map::{respan, DesugaringKind, ForLoopLoc, Span, Spanned}; |
| use rustc_span::symbol::{sym, Ident, Symbol}; |
| use rustc_target::asm; |
| use std::collections::hash_map::Entry; |
| use std::fmt::Write; |
| |
| impl<'hir> LoweringContext<'_, 'hir> { |
| fn lower_exprs(&mut self, exprs: &[AstP<Expr>]) -> &'hir [hir::Expr<'hir>] { |
| self.arena.alloc_from_iter(exprs.iter().map(|x| self.lower_expr_mut(x))) |
| } |
| |
| pub(super) fn lower_expr(&mut self, e: &Expr) -> &'hir hir::Expr<'hir> { |
| self.arena.alloc(self.lower_expr_mut(e)) |
| } |
| |
| pub(super) fn lower_expr_mut(&mut self, e: &Expr) -> hir::Expr<'hir> { |
| ensure_sufficient_stack(|| { |
| let kind = match e.kind { |
| ExprKind::Box(ref inner) => hir::ExprKind::Box(self.lower_expr(inner)), |
| ExprKind::Array(ref exprs) => hir::ExprKind::Array(self.lower_exprs(exprs)), |
| ExprKind::Repeat(ref expr, ref count) => { |
| let expr = self.lower_expr(expr); |
| let count = self.lower_anon_const(count); |
| hir::ExprKind::Repeat(expr, count) |
| } |
| ExprKind::Tup(ref elts) => hir::ExprKind::Tup(self.lower_exprs(elts)), |
| ExprKind::Call(ref f, ref args) => { |
| let f = self.lower_expr(f); |
| hir::ExprKind::Call(f, self.lower_exprs(args)) |
| } |
| ExprKind::MethodCall(ref seg, ref args, span) => { |
| let hir_seg = self.arena.alloc(self.lower_path_segment( |
| e.span, |
| seg, |
| ParamMode::Optional, |
| 0, |
| ParenthesizedGenericArgs::Err, |
| ImplTraitContext::disallowed(), |
| None, |
| )); |
| let args = self.lower_exprs(args); |
| hir::ExprKind::MethodCall(hir_seg, seg.ident.span, args, span) |
| } |
| ExprKind::Binary(binop, ref lhs, ref rhs) => { |
| let binop = self.lower_binop(binop); |
| let lhs = self.lower_expr(lhs); |
| let rhs = self.lower_expr(rhs); |
| hir::ExprKind::Binary(binop, lhs, rhs) |
| } |
| ExprKind::Unary(op, ref ohs) => { |
| let op = self.lower_unop(op); |
| let ohs = self.lower_expr(ohs); |
| hir::ExprKind::Unary(op, ohs) |
| } |
| ExprKind::Lit(ref l) => hir::ExprKind::Lit(respan(l.span, l.kind.clone())), |
| ExprKind::Cast(ref expr, ref ty) => { |
| let expr = self.lower_expr(expr); |
| let ty = self.lower_ty(ty, ImplTraitContext::disallowed()); |
| hir::ExprKind::Cast(expr, ty) |
| } |
| ExprKind::Type(ref expr, ref ty) => { |
| let expr = self.lower_expr(expr); |
| let ty = self.lower_ty(ty, ImplTraitContext::disallowed()); |
| hir::ExprKind::Type(expr, ty) |
| } |
| ExprKind::AddrOf(k, m, ref ohs) => { |
| let ohs = self.lower_expr(ohs); |
| hir::ExprKind::AddrOf(k, m, ohs) |
| } |
| ExprKind::Let(ref pat, ref scrutinee) => { |
| self.lower_expr_let(e.span, pat, scrutinee) |
| } |
| ExprKind::If(ref cond, ref then, ref else_opt) => { |
| self.lower_expr_if(e.span, cond, then, else_opt.as_deref()) |
| } |
| ExprKind::While(ref cond, ref body, opt_label) => self |
| .with_loop_scope(e.id, |this| { |
| this.lower_expr_while_in_loop_scope(e.span, cond, body, opt_label) |
| }), |
| ExprKind::Loop(ref body, opt_label) => self.with_loop_scope(e.id, |this| { |
| hir::ExprKind::Loop( |
| this.lower_block(body, false), |
| opt_label, |
| hir::LoopSource::Loop, |
| ) |
| }), |
| ExprKind::TryBlock(ref body) => self.lower_expr_try_block(body), |
| ExprKind::Match(ref expr, ref arms) => hir::ExprKind::Match( |
| self.lower_expr(expr), |
| self.arena.alloc_from_iter(arms.iter().map(|x| self.lower_arm(x))), |
| hir::MatchSource::Normal, |
| ), |
| ExprKind::Async(capture_clause, closure_node_id, ref block) => self |
| .make_async_expr( |
| capture_clause, |
| closure_node_id, |
| None, |
| block.span, |
| hir::AsyncGeneratorKind::Block, |
| |this| this.with_new_scopes(|this| this.lower_block_expr(block)), |
| ), |
| ExprKind::Await(ref expr) => self.lower_expr_await(e.span, expr), |
| ExprKind::Closure( |
| capture_clause, |
| asyncness, |
| movability, |
| ref decl, |
| ref body, |
| fn_decl_span, |
| ) => { |
| if let Async::Yes { closure_id, .. } = asyncness { |
| self.lower_expr_async_closure( |
| capture_clause, |
| closure_id, |
| decl, |
| body, |
| fn_decl_span, |
| ) |
| } else { |
| self.lower_expr_closure( |
| capture_clause, |
| movability, |
| decl, |
| body, |
| fn_decl_span, |
| ) |
| } |
| } |
| ExprKind::Block(ref blk, opt_label) => { |
| hir::ExprKind::Block(self.lower_block(blk, opt_label.is_some()), opt_label) |
| } |
| ExprKind::Assign(ref el, ref er, span) => { |
| hir::ExprKind::Assign(self.lower_expr(el), self.lower_expr(er), span) |
| } |
| ExprKind::AssignOp(op, ref el, ref er) => hir::ExprKind::AssignOp( |
| self.lower_binop(op), |
| self.lower_expr(el), |
| self.lower_expr(er), |
| ), |
| ExprKind::Field(ref el, ident) => hir::ExprKind::Field(self.lower_expr(el), ident), |
| ExprKind::Index(ref el, ref er) => { |
| hir::ExprKind::Index(self.lower_expr(el), self.lower_expr(er)) |
| } |
| ExprKind::Range(Some(ref e1), Some(ref e2), RangeLimits::Closed) => { |
| self.lower_expr_range_closed(e.span, e1, e2) |
| } |
| ExprKind::Range(ref e1, ref e2, lims) => { |
| self.lower_expr_range(e.span, e1.as_deref(), e2.as_deref(), lims) |
| } |
| ExprKind::Path(ref qself, ref path) => { |
| let qpath = self.lower_qpath( |
| e.id, |
| qself, |
| path, |
| ParamMode::Optional, |
| ImplTraitContext::disallowed(), |
| ); |
| hir::ExprKind::Path(qpath) |
| } |
| ExprKind::Break(opt_label, ref opt_expr) => { |
| let opt_expr = opt_expr.as_ref().map(|x| self.lower_expr(x)); |
| hir::ExprKind::Break(self.lower_jump_destination(e.id, opt_label), opt_expr) |
| } |
| ExprKind::Continue(opt_label) => { |
| hir::ExprKind::Continue(self.lower_jump_destination(e.id, opt_label)) |
| } |
| ExprKind::Ret(ref e) => { |
| let e = e.as_ref().map(|x| self.lower_expr(x)); |
| hir::ExprKind::Ret(e) |
| } |
| ExprKind::InlineAsm(ref asm) => self.lower_expr_asm(e.span, asm), |
| ExprKind::LlvmInlineAsm(ref asm) => self.lower_expr_llvm_asm(asm), |
| ExprKind::Struct(ref path, ref fields, ref maybe_expr) => { |
| let maybe_expr = maybe_expr.as_ref().map(|x| self.lower_expr(x)); |
| hir::ExprKind::Struct( |
| self.arena.alloc(self.lower_qpath( |
| e.id, |
| &None, |
| path, |
| ParamMode::Optional, |
| ImplTraitContext::disallowed(), |
| )), |
| self.arena.alloc_from_iter(fields.iter().map(|x| self.lower_field(x))), |
| maybe_expr, |
| ) |
| } |
| ExprKind::Yield(ref opt_expr) => self.lower_expr_yield(e.span, opt_expr.as_deref()), |
| ExprKind::Err => hir::ExprKind::Err, |
| ExprKind::Try(ref sub_expr) => self.lower_expr_try(e.span, sub_expr), |
| ExprKind::Paren(ref ex) => { |
| let mut ex = self.lower_expr_mut(ex); |
| // Include parens in span, but only if it is a super-span. |
| if e.span.contains(ex.span) { |
| ex.span = e.span; |
| } |
| // Merge attributes into the inner expression. |
| let mut attrs = e.attrs.clone(); |
| attrs.extend::<Vec<_>>(ex.attrs.into()); |
| ex.attrs = attrs; |
| return ex; |
| } |
| |
| // Desugar `ExprForLoop` |
| // from: `[opt_ident]: for <pat> in <head> <body>` |
| ExprKind::ForLoop(ref pat, ref head, ref body, opt_label) => { |
| return self.lower_expr_for(e, pat, head, body, opt_label); |
| } |
| ExprKind::MacCall(_) => panic!("{:?} shouldn't exist here", e.span), |
| }; |
| |
| hir::Expr { |
| hir_id: self.lower_node_id(e.id), |
| kind, |
| span: e.span, |
| attrs: e.attrs.iter().map(|a| self.lower_attr(a)).collect::<Vec<_>>().into(), |
| } |
| }) |
| } |
| |
| fn lower_unop(&mut self, u: UnOp) -> hir::UnOp { |
| match u { |
| UnOp::Deref => hir::UnOp::UnDeref, |
| UnOp::Not => hir::UnOp::UnNot, |
| UnOp::Neg => hir::UnOp::UnNeg, |
| } |
| } |
| |
| fn lower_binop(&mut self, b: BinOp) -> hir::BinOp { |
| Spanned { |
| node: match b.node { |
| BinOpKind::Add => hir::BinOpKind::Add, |
| BinOpKind::Sub => hir::BinOpKind::Sub, |
| BinOpKind::Mul => hir::BinOpKind::Mul, |
| BinOpKind::Div => hir::BinOpKind::Div, |
| BinOpKind::Rem => hir::BinOpKind::Rem, |
| BinOpKind::And => hir::BinOpKind::And, |
| BinOpKind::Or => hir::BinOpKind::Or, |
| BinOpKind::BitXor => hir::BinOpKind::BitXor, |
| BinOpKind::BitAnd => hir::BinOpKind::BitAnd, |
| BinOpKind::BitOr => hir::BinOpKind::BitOr, |
| BinOpKind::Shl => hir::BinOpKind::Shl, |
| BinOpKind::Shr => hir::BinOpKind::Shr, |
| BinOpKind::Eq => hir::BinOpKind::Eq, |
| BinOpKind::Lt => hir::BinOpKind::Lt, |
| BinOpKind::Le => hir::BinOpKind::Le, |
| BinOpKind::Ne => hir::BinOpKind::Ne, |
| BinOpKind::Ge => hir::BinOpKind::Ge, |
| BinOpKind::Gt => hir::BinOpKind::Gt, |
| }, |
| span: b.span, |
| } |
| } |
| |
| /// Emit an error and lower `ast::ExprKind::Let(pat, scrutinee)` into: |
| /// ```rust |
| /// match scrutinee { pats => true, _ => false } |
| /// ``` |
| fn lower_expr_let(&mut self, span: Span, pat: &Pat, scrutinee: &Expr) -> hir::ExprKind<'hir> { |
| // If we got here, the `let` expression is not allowed. |
| |
| if self.sess.opts.unstable_features.is_nightly_build() { |
| self.sess |
| .struct_span_err(span, "`let` expressions are not supported here") |
| .note("only supported directly in conditions of `if`- and `while`-expressions") |
| .note("as well as when nested within `&&` and parenthesis in those conditions") |
| .emit(); |
| } else { |
| self.sess |
| .struct_span_err(span, "expected expression, found statement (`let`)") |
| .note("variable declaration using `let` is a statement") |
| .emit(); |
| } |
| |
| // For better recovery, we emit: |
| // ``` |
| // match scrutinee { pat => true, _ => false } |
| // ``` |
| // While this doesn't fully match the user's intent, it has key advantages: |
| // 1. We can avoid using `abort_if_errors`. |
| // 2. We can typeck both `pat` and `scrutinee`. |
| // 3. `pat` is allowed to be refutable. |
| // 4. The return type of the block is `bool` which seems like what the user wanted. |
| let scrutinee = self.lower_expr(scrutinee); |
| let then_arm = { |
| let pat = self.lower_pat(pat); |
| let expr = self.expr_bool(span, true); |
| self.arm(pat, expr) |
| }; |
| let else_arm = { |
| let pat = self.pat_wild(span); |
| let expr = self.expr_bool(span, false); |
| self.arm(pat, expr) |
| }; |
| hir::ExprKind::Match( |
| scrutinee, |
| arena_vec![self; then_arm, else_arm], |
| hir::MatchSource::Normal, |
| ) |
| } |
| |
| fn lower_expr_if( |
| &mut self, |
| span: Span, |
| cond: &Expr, |
| then: &Block, |
| else_opt: Option<&Expr>, |
| ) -> hir::ExprKind<'hir> { |
| // FIXME(#53667): handle lowering of && and parens. |
| |
| // `_ => else_block` where `else_block` is `{}` if there's `None`: |
| let else_pat = self.pat_wild(span); |
| let (else_expr, contains_else_clause) = match else_opt { |
| None => (self.expr_block_empty(span), false), |
| Some(els) => (self.lower_expr(els), true), |
| }; |
| let else_arm = self.arm(else_pat, else_expr); |
| |
| // Handle then + scrutinee: |
| let then_expr = self.lower_block_expr(then); |
| let (then_pat, scrutinee, desugar) = match cond.kind { |
| // `<pat> => <then>`: |
| ExprKind::Let(ref pat, ref scrutinee) => { |
| let scrutinee = self.lower_expr(scrutinee); |
| let pat = self.lower_pat(pat); |
| (pat, scrutinee, hir::MatchSource::IfLetDesugar { contains_else_clause }) |
| } |
| // `true => <then>`: |
| _ => { |
| // Lower condition: |
| let cond = self.lower_expr(cond); |
| let span_block = |
| self.mark_span_with_reason(DesugaringKind::CondTemporary, cond.span, None); |
| // Wrap in a construct equivalent to `{ let _t = $cond; _t }` |
| // to preserve drop semantics since `if cond { ... }` does not |
| // let temporaries live outside of `cond`. |
| let cond = self.expr_drop_temps(span_block, cond, ThinVec::new()); |
| let pat = self.pat_bool(span, true); |
| (pat, cond, hir::MatchSource::IfDesugar { contains_else_clause }) |
| } |
| }; |
| let then_arm = self.arm(then_pat, self.arena.alloc(then_expr)); |
| |
| hir::ExprKind::Match(scrutinee, arena_vec![self; then_arm, else_arm], desugar) |
| } |
| |
| fn lower_expr_while_in_loop_scope( |
| &mut self, |
| span: Span, |
| cond: &Expr, |
| body: &Block, |
| opt_label: Option<Label>, |
| ) -> hir::ExprKind<'hir> { |
| // FIXME(#53667): handle lowering of && and parens. |
| |
| // Note that the block AND the condition are evaluated in the loop scope. |
| // This is done to allow `break` from inside the condition of the loop. |
| |
| // `_ => break`: |
| let else_arm = { |
| let else_pat = self.pat_wild(span); |
| let else_expr = self.expr_break(span, ThinVec::new()); |
| self.arm(else_pat, else_expr) |
| }; |
| |
| // Handle then + scrutinee: |
| let then_expr = self.lower_block_expr(body); |
| let (then_pat, scrutinee, desugar, source) = match cond.kind { |
| ExprKind::Let(ref pat, ref scrutinee) => { |
| // to: |
| // |
| // [opt_ident]: loop { |
| // match <sub_expr> { |
| // <pat> => <body>, |
| // _ => break |
| // } |
| // } |
| let scrutinee = self.with_loop_condition_scope(|t| t.lower_expr(scrutinee)); |
| let pat = self.lower_pat(pat); |
| (pat, scrutinee, hir::MatchSource::WhileLetDesugar, hir::LoopSource::WhileLet) |
| } |
| _ => { |
| // We desugar: `'label: while $cond $body` into: |
| // |
| // ``` |
| // 'label: loop { |
| // match drop-temps { $cond } { |
| // true => $body, |
| // _ => break, |
| // } |
| // } |
| // ``` |
| |
| // Lower condition: |
| let cond = self.with_loop_condition_scope(|this| this.lower_expr(cond)); |
| let span_block = |
| self.mark_span_with_reason(DesugaringKind::CondTemporary, cond.span, None); |
| // Wrap in a construct equivalent to `{ let _t = $cond; _t }` |
| // to preserve drop semantics since `while cond { ... }` does not |
| // let temporaries live outside of `cond`. |
| let cond = self.expr_drop_temps(span_block, cond, ThinVec::new()); |
| // `true => <then>`: |
| let pat = self.pat_bool(span, true); |
| (pat, cond, hir::MatchSource::WhileDesugar, hir::LoopSource::While) |
| } |
| }; |
| let then_arm = self.arm(then_pat, self.arena.alloc(then_expr)); |
| |
| // `match <scrutinee> { ... }` |
| let match_expr = |
| self.expr_match(span, scrutinee, arena_vec![self; then_arm, else_arm], desugar); |
| |
| // `[opt_ident]: loop { ... }` |
| hir::ExprKind::Loop(self.block_expr(self.arena.alloc(match_expr)), opt_label, source) |
| } |
| |
| /// Desugar `try { <stmts>; <expr> }` into `{ <stmts>; ::std::ops::Try::from_ok(<expr>) }`, |
| /// `try { <stmts>; }` into `{ <stmts>; ::std::ops::Try::from_ok(()) }` |
| /// and save the block id to use it as a break target for desugaring of the `?` operator. |
| fn lower_expr_try_block(&mut self, body: &Block) -> hir::ExprKind<'hir> { |
| self.with_catch_scope(body.id, |this| { |
| let mut block = this.lower_block_noalloc(body, true); |
| |
| let try_span = this.mark_span_with_reason( |
| DesugaringKind::TryBlock, |
| body.span, |
| this.allow_try_trait.clone(), |
| ); |
| |
| // Final expression of the block (if present) or `()` with span at the end of block |
| let tail_expr = block |
| .expr |
| .take() |
| .unwrap_or_else(|| this.expr_unit(this.sess.source_map().end_point(try_span))); |
| |
| let ok_wrapped_span = |
| this.mark_span_with_reason(DesugaringKind::TryBlock, tail_expr.span, None); |
| |
| // `::std::ops::Try::from_ok($tail_expr)` |
| block.expr = Some(this.wrap_in_try_constructor( |
| sym::from_ok, |
| try_span, |
| tail_expr, |
| ok_wrapped_span, |
| )); |
| |
| hir::ExprKind::Block(this.arena.alloc(block), None) |
| }) |
| } |
| |
| fn wrap_in_try_constructor( |
| &mut self, |
| method: Symbol, |
| method_span: Span, |
| expr: &'hir hir::Expr<'hir>, |
| overall_span: Span, |
| ) -> &'hir hir::Expr<'hir> { |
| let path = &[sym::ops, sym::Try, method]; |
| let constructor = |
| self.arena.alloc(self.expr_std_path(method_span, path, None, ThinVec::new())); |
| self.expr_call(overall_span, constructor, std::slice::from_ref(expr)) |
| } |
| |
| fn lower_arm(&mut self, arm: &Arm) -> hir::Arm<'hir> { |
| hir::Arm { |
| hir_id: self.next_id(), |
| attrs: self.lower_attrs(&arm.attrs), |
| pat: self.lower_pat(&arm.pat), |
| guard: match arm.guard { |
| Some(ref x) => Some(hir::Guard::If(self.lower_expr(x))), |
| _ => None, |
| }, |
| body: self.lower_expr(&arm.body), |
| span: arm.span, |
| } |
| } |
| |
| /// Lower an `async` construct to a generator that is then wrapped so it implements `Future`. |
| /// |
| /// This results in: |
| /// |
| /// ```text |
| /// std::future::from_generator(static move? |_task_context| -> <ret_ty> { |
| /// <body> |
| /// }) |
| /// ``` |
| pub(super) fn make_async_expr( |
| &mut self, |
| capture_clause: CaptureBy, |
| closure_node_id: NodeId, |
| ret_ty: Option<AstP<Ty>>, |
| span: Span, |
| async_gen_kind: hir::AsyncGeneratorKind, |
| body: impl FnOnce(&mut Self) -> hir::Expr<'hir>, |
| ) -> hir::ExprKind<'hir> { |
| let output = match ret_ty { |
| Some(ty) => hir::FnRetTy::Return(self.lower_ty(&ty, ImplTraitContext::disallowed())), |
| None => hir::FnRetTy::DefaultReturn(span), |
| }; |
| |
| // Resume argument type. We let the compiler infer this to simplify the lowering. It is |
| // fully constrained by `future::from_generator`. |
| let input_ty = hir::Ty { hir_id: self.next_id(), kind: hir::TyKind::Infer, span }; |
| |
| // The closure/generator `FnDecl` takes a single (resume) argument of type `input_ty`. |
| let decl = self.arena.alloc(hir::FnDecl { |
| inputs: arena_vec![self; input_ty], |
| output, |
| c_variadic: false, |
| implicit_self: hir::ImplicitSelfKind::None, |
| }); |
| |
| // Lower the argument pattern/ident. The ident is used again in the `.await` lowering. |
| let (pat, task_context_hid) = self.pat_ident_binding_mode( |
| span, |
| Ident::with_dummy_span(sym::_task_context), |
| hir::BindingAnnotation::Mutable, |
| ); |
| let param = hir::Param { attrs: &[], hir_id: self.next_id(), pat, span }; |
| let params = arena_vec![self; param]; |
| |
| let body_id = self.lower_body(move |this| { |
| this.generator_kind = Some(hir::GeneratorKind::Async(async_gen_kind)); |
| |
| let old_ctx = this.task_context; |
| this.task_context = Some(task_context_hid); |
| let res = body(this); |
| this.task_context = old_ctx; |
| (params, res) |
| }); |
| |
| // `static |_task_context| -> <ret_ty> { body }`: |
| let generator_kind = hir::ExprKind::Closure( |
| capture_clause, |
| decl, |
| body_id, |
| span, |
| Some(hir::Movability::Static), |
| ); |
| let generator = hir::Expr { |
| hir_id: self.lower_node_id(closure_node_id), |
| kind: generator_kind, |
| span, |
| attrs: ThinVec::new(), |
| }; |
| |
| // `future::from_generator`: |
| let unstable_span = |
| self.mark_span_with_reason(DesugaringKind::Async, span, self.allow_gen_future.clone()); |
| let gen_future = self.expr_std_path( |
| unstable_span, |
| &[sym::future, sym::from_generator], |
| None, |
| ThinVec::new(), |
| ); |
| |
| // `future::from_generator(generator)`: |
| hir::ExprKind::Call(self.arena.alloc(gen_future), arena_vec![self; generator]) |
| } |
| |
| /// Desugar `<expr>.await` into: |
| /// ```rust |
| /// match <expr> { |
| /// mut pinned => loop { |
| /// match unsafe { ::std::future::Future::poll( |
| /// <::std::pin::Pin>::new_unchecked(&mut pinned), |
| /// ::std::future::get_context(task_context), |
| /// ) } { |
| /// ::std::task::Poll::Ready(result) => break result, |
| /// ::std::task::Poll::Pending => {} |
| /// } |
| /// task_context = yield (); |
| /// } |
| /// } |
| /// ``` |
| fn lower_expr_await(&mut self, await_span: Span, expr: &Expr) -> hir::ExprKind<'hir> { |
| match self.generator_kind { |
| Some(hir::GeneratorKind::Async(_)) => {} |
| Some(hir::GeneratorKind::Gen) | None => { |
| let mut err = struct_span_err!( |
| self.sess, |
| await_span, |
| E0728, |
| "`await` is only allowed inside `async` functions and blocks" |
| ); |
| err.span_label(await_span, "only allowed inside `async` functions and blocks"); |
| if let Some(item_sp) = self.current_item { |
| err.span_label(item_sp, "this is not `async`"); |
| } |
| err.emit(); |
| } |
| } |
| let span = self.mark_span_with_reason(DesugaringKind::Await, await_span, None); |
| let gen_future_span = self.mark_span_with_reason( |
| DesugaringKind::Await, |
| await_span, |
| self.allow_gen_future.clone(), |
| ); |
| let expr = self.lower_expr(expr); |
| |
| let pinned_ident = Ident::with_dummy_span(sym::pinned); |
| let (pinned_pat, pinned_pat_hid) = |
| self.pat_ident_binding_mode(span, pinned_ident, hir::BindingAnnotation::Mutable); |
| |
| let task_context_ident = Ident::with_dummy_span(sym::_task_context); |
| |
| // unsafe { |
| // ::std::future::Future::poll( |
| // ::std::pin::Pin::new_unchecked(&mut pinned), |
| // ::std::future::get_context(task_context), |
| // ) |
| // } |
| let poll_expr = { |
| let pinned = self.expr_ident(span, pinned_ident, pinned_pat_hid); |
| let ref_mut_pinned = self.expr_mut_addr_of(span, pinned); |
| let task_context = if let Some(task_context_hid) = self.task_context { |
| self.expr_ident_mut(span, task_context_ident, task_context_hid) |
| } else { |
| // Use of `await` outside of an async context, we cannot use `task_context` here. |
| self.expr_err(span) |
| }; |
| let pin_ty_id = self.next_id(); |
| let new_unchecked_expr_kind = self.expr_call_std_assoc_fn( |
| pin_ty_id, |
| span, |
| &[sym::pin, sym::Pin], |
| "new_unchecked", |
| arena_vec![self; ref_mut_pinned], |
| ); |
| let new_unchecked = self.expr(span, new_unchecked_expr_kind, ThinVec::new()); |
| let get_context = self.expr_call_std_path_mut( |
| gen_future_span, |
| &[sym::future, sym::get_context], |
| arena_vec![self; task_context], |
| ); |
| let call = self.expr_call_std_path( |
| span, |
| &[sym::future, sym::Future, sym::poll], |
| arena_vec![self; new_unchecked, get_context], |
| ); |
| self.arena.alloc(self.expr_unsafe(call)) |
| }; |
| |
| // `::std::task::Poll::Ready(result) => break result` |
| let loop_node_id = self.resolver.next_node_id(); |
| let loop_hir_id = self.lower_node_id(loop_node_id); |
| let ready_arm = { |
| let x_ident = Ident::with_dummy_span(sym::result); |
| let (x_pat, x_pat_hid) = self.pat_ident(span, x_ident); |
| let x_expr = self.expr_ident(span, x_ident, x_pat_hid); |
| let ready_pat = self.pat_std_enum( |
| span, |
| &[sym::task, sym::Poll, sym::Ready], |
| arena_vec![self; x_pat], |
| ); |
| let break_x = self.with_loop_scope(loop_node_id, move |this| { |
| let expr_break = |
| hir::ExprKind::Break(this.lower_loop_destination(None), Some(x_expr)); |
| this.arena.alloc(this.expr(await_span, expr_break, ThinVec::new())) |
| }); |
| self.arm(ready_pat, break_x) |
| }; |
| |
| // `::std::task::Poll::Pending => {}` |
| let pending_arm = { |
| let pending_pat = self.pat_std_enum(span, &[sym::task, sym::Poll, sym::Pending], &[]); |
| let empty_block = self.expr_block_empty(span); |
| self.arm(pending_pat, empty_block) |
| }; |
| |
| let inner_match_stmt = { |
| let match_expr = self.expr_match( |
| span, |
| poll_expr, |
| arena_vec![self; ready_arm, pending_arm], |
| hir::MatchSource::AwaitDesugar, |
| ); |
| self.stmt_expr(span, match_expr) |
| }; |
| |
| // task_context = yield (); |
| let yield_stmt = { |
| let unit = self.expr_unit(span); |
| let yield_expr = self.expr( |
| span, |
| hir::ExprKind::Yield(unit, hir::YieldSource::Await { expr: Some(expr.hir_id) }), |
| ThinVec::new(), |
| ); |
| let yield_expr = self.arena.alloc(yield_expr); |
| |
| if let Some(task_context_hid) = self.task_context { |
| let lhs = self.expr_ident(span, task_context_ident, task_context_hid); |
| let assign = |
| self.expr(span, hir::ExprKind::Assign(lhs, yield_expr, span), AttrVec::new()); |
| self.stmt_expr(span, assign) |
| } else { |
| // Use of `await` outside of an async context. Return `yield_expr` so that we can |
| // proceed with type checking. |
| self.stmt(span, hir::StmtKind::Semi(yield_expr)) |
| } |
| }; |
| |
| let loop_block = self.block_all(span, arena_vec![self; inner_match_stmt, yield_stmt], None); |
| |
| // loop { .. } |
| let loop_expr = self.arena.alloc(hir::Expr { |
| hir_id: loop_hir_id, |
| kind: hir::ExprKind::Loop(loop_block, None, hir::LoopSource::Loop), |
| span, |
| attrs: ThinVec::new(), |
| }); |
| |
| // mut pinned => loop { ... } |
| let pinned_arm = self.arm(pinned_pat, loop_expr); |
| |
| // match <expr> { |
| // mut pinned => loop { .. } |
| // } |
| hir::ExprKind::Match(expr, arena_vec![self; pinned_arm], hir::MatchSource::AwaitDesugar) |
| } |
| |
| fn lower_expr_closure( |
| &mut self, |
| capture_clause: CaptureBy, |
| movability: Movability, |
| decl: &FnDecl, |
| body: &Expr, |
| fn_decl_span: Span, |
| ) -> hir::ExprKind<'hir> { |
| // Lower outside new scope to preserve `is_in_loop_condition`. |
| let fn_decl = self.lower_fn_decl(decl, None, false, None); |
| |
| self.with_new_scopes(move |this| { |
| let prev = this.current_item; |
| this.current_item = Some(fn_decl_span); |
| let mut generator_kind = None; |
| let body_id = this.lower_fn_body(decl, |this| { |
| let e = this.lower_expr_mut(body); |
| generator_kind = this.generator_kind; |
| e |
| }); |
| let generator_option = |
| this.generator_movability_for_fn(&decl, fn_decl_span, generator_kind, movability); |
| this.current_item = prev; |
| hir::ExprKind::Closure(capture_clause, fn_decl, body_id, fn_decl_span, generator_option) |
| }) |
| } |
| |
| fn generator_movability_for_fn( |
| &mut self, |
| decl: &FnDecl, |
| fn_decl_span: Span, |
| generator_kind: Option<hir::GeneratorKind>, |
| movability: Movability, |
| ) -> Option<hir::Movability> { |
| match generator_kind { |
| Some(hir::GeneratorKind::Gen) => { |
| if decl.inputs.len() > 1 { |
| struct_span_err!( |
| self.sess, |
| fn_decl_span, |
| E0628, |
| "too many parameters for a generator (expected 0 or 1 parameters)" |
| ) |
| .emit(); |
| } |
| Some(movability) |
| } |
| Some(hir::GeneratorKind::Async(_)) => { |
| panic!("non-`async` closure body turned `async` during lowering"); |
| } |
| None => { |
| if movability == Movability::Static { |
| struct_span_err!(self.sess, fn_decl_span, E0697, "closures cannot be static") |
| .emit(); |
| } |
| None |
| } |
| } |
| } |
| |
| fn lower_expr_async_closure( |
| &mut self, |
| capture_clause: CaptureBy, |
| closure_id: NodeId, |
| decl: &FnDecl, |
| body: &Expr, |
| fn_decl_span: Span, |
| ) -> hir::ExprKind<'hir> { |
| let outer_decl = |
| FnDecl { inputs: decl.inputs.clone(), output: FnRetTy::Default(fn_decl_span) }; |
| // 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(move |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 parameters 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 FnRetTy::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, |
| hir::AsyncGeneratorKind::Closure, |
| |this| this.with_new_scopes(|this| this.lower_expr_mut(body)), |
| ); |
| this.expr(fn_decl_span, async_body, ThinVec::new()) |
| }); |
| hir::ExprKind::Closure(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<'hir> { |
| let id = self.next_id(); |
| let e1 = self.lower_expr_mut(e1); |
| let e2 = self.lower_expr_mut(e2); |
| self.expr_call_std_assoc_fn( |
| id, |
| span, |
| &[sym::ops, sym::RangeInclusive], |
| "new", |
| arena_vec![self; e1, e2], |
| ) |
| } |
| |
| fn lower_expr_range( |
| &mut self, |
| span: Span, |
| e1: Option<&Expr>, |
| e2: Option<&Expr>, |
| lims: RangeLimits, |
| ) -> hir::ExprKind<'hir> { |
| use rustc_ast::ast::RangeLimits::*; |
| |
| let path = match (e1, e2, lims) { |
| (None, None, HalfOpen) => sym::RangeFull, |
| (Some(..), None, HalfOpen) => sym::RangeFrom, |
| (None, Some(..), HalfOpen) => sym::RangeTo, |
| (Some(..), Some(..), HalfOpen) => sym::Range, |
| (None, Some(..), Closed) => sym::RangeToInclusive, |
| (Some(..), Some(..), Closed) => unreachable!(), |
| (_, None, Closed) => { |
| self.diagnostic().span_fatal(span, "inclusive range with no end").raise() |
| } |
| }; |
| |
| let fields = self.arena.alloc_from_iter( |
| e1.iter().map(|e| ("start", e)).chain(e2.iter().map(|e| ("end", e))).map(|(s, e)| { |
| let expr = self.lower_expr(&e); |
| let ident = Ident::new(Symbol::intern(s), e.span); |
| self.field(ident, expr, e.span) |
| }), |
| ); |
| |
| let is_unit = fields.is_empty(); |
| let struct_path = [sym::ops, path]; |
| let struct_path = self.std_path(span, &struct_path, None, is_unit); |
| let struct_path = hir::QPath::Resolved(None, struct_path); |
| |
| if is_unit { |
| hir::ExprKind::Path(struct_path) |
| } else { |
| hir::ExprKind::Struct(self.arena.alloc(struct_path), fields, None) |
| } |
| } |
| |
| fn lower_loop_destination(&mut self, destination: Option<(NodeId, Label)>) -> hir::Destination { |
| let target_id = match destination { |
| Some((id, _)) => { |
| if let Some(loop_id) = self.resolver.get_label_res(id) { |
| Ok(self.lower_node_id(loop_id)) |
| } else { |
| Err(hir::LoopIdError::UnresolvedLabel) |
| } |
| } |
| None => self |
| .loop_scopes |
| .last() |
| .cloned() |
| .map(|id| Ok(self.lower_node_id(id))) |
| .unwrap_or(Err(hir::LoopIdError::OutsideLoopScope)), |
| }; |
| hir::Destination { label: destination.map(|(_, label)| label), target_id } |
| } |
| |
| fn lower_jump_destination(&mut self, id: NodeId, opt_label: Option<Label>) -> hir::Destination { |
| if self.is_in_loop_condition && opt_label.is_none() { |
| hir::Destination { |
| label: None, |
| target_id: Err(hir::LoopIdError::UnlabeledCfInWhileCondition), |
| } |
| } else { |
| self.lower_loop_destination(opt_label.map(|label| (id, label))) |
| } |
| } |
| |
| fn with_catch_scope<T>(&mut self, catch_id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T { |
| let len = self.catch_scopes.len(); |
| self.catch_scopes.push(catch_id); |
| |
| let result = f(self); |
| assert_eq!( |
| len + 1, |
| self.catch_scopes.len(), |
| "catch scopes should be added and removed in stack order" |
| ); |
| |
| self.catch_scopes.pop().unwrap(); |
| |
| result |
| } |
| |
| fn with_loop_scope<T>(&mut self, loop_id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T { |
| // We're no longer in the base loop's condition; we're in another loop. |
| let was_in_loop_condition = self.is_in_loop_condition; |
| self.is_in_loop_condition = false; |
| |
| let len = self.loop_scopes.len(); |
| self.loop_scopes.push(loop_id); |
| |
| let result = f(self); |
| assert_eq!( |
| len + 1, |
| self.loop_scopes.len(), |
| "loop scopes should be added and removed in stack order" |
| ); |
| |
| self.loop_scopes.pop().unwrap(); |
| |
| self.is_in_loop_condition = was_in_loop_condition; |
| |
| result |
| } |
| |
| fn with_loop_condition_scope<T>(&mut self, f: impl FnOnce(&mut Self) -> T) -> T { |
| let was_in_loop_condition = self.is_in_loop_condition; |
| self.is_in_loop_condition = true; |
| |
| let result = f(self); |
| |
| self.is_in_loop_condition = was_in_loop_condition; |
| |
| result |
| } |
| |
| fn lower_expr_asm(&mut self, sp: Span, asm: &InlineAsm) -> hir::ExprKind<'hir> { |
| if self.sess.asm_arch.is_none() { |
| struct_span_err!(self.sess, sp, E0472, "asm! is unsupported on this target").emit(); |
| } |
| if asm.options.contains(InlineAsmOptions::ATT_SYNTAX) |
| && !matches!( |
| self.sess.asm_arch, |
| Some(asm::InlineAsmArch::X86 | asm::InlineAsmArch::X86_64) |
| ) |
| { |
| self.sess |
| .struct_span_err(sp, "the `att_syntax` option is only supported on x86") |
| .emit(); |
| } |
| |
| // Lower operands to HIR, filter_map skips any operands with invalid |
| // register classes. |
| let sess = self.sess; |
| let operands: Vec<_> = asm |
| .operands |
| .iter() |
| .filter_map(|(op, op_sp)| { |
| let lower_reg = |reg| { |
| Some(match reg { |
| InlineAsmRegOrRegClass::Reg(s) => asm::InlineAsmRegOrRegClass::Reg( |
| asm::InlineAsmReg::parse( |
| sess.asm_arch?, |
| |feature| sess.target_features.contains(&Symbol::intern(feature)), |
| &sess.target.target, |
| s, |
| ) |
| .map_err(|e| { |
| let msg = format!("invalid register `{}`: {}", s.as_str(), e); |
| sess.struct_span_err(*op_sp, &msg).emit(); |
| }) |
| .ok()?, |
| ), |
| InlineAsmRegOrRegClass::RegClass(s) => { |
| asm::InlineAsmRegOrRegClass::RegClass( |
| asm::InlineAsmRegClass::parse(sess.asm_arch?, s) |
| .map_err(|e| { |
| let msg = format!( |
| "invalid register class `{}`: {}", |
| s.as_str(), |
| e |
| ); |
| sess.struct_span_err(*op_sp, &msg).emit(); |
| }) |
| .ok()?, |
| ) |
| } |
| }) |
| }; |
| |
| // lower_reg is executed last because we need to lower all |
| // sub-expressions even if we throw them away later. |
| let op = match *op { |
| InlineAsmOperand::In { reg, ref expr } => hir::InlineAsmOperand::In { |
| expr: self.lower_expr_mut(expr), |
| reg: lower_reg(reg)?, |
| }, |
| InlineAsmOperand::Out { reg, late, ref expr } => hir::InlineAsmOperand::Out { |
| late, |
| expr: expr.as_ref().map(|expr| self.lower_expr_mut(expr)), |
| reg: lower_reg(reg)?, |
| }, |
| InlineAsmOperand::InOut { reg, late, ref expr } => { |
| hir::InlineAsmOperand::InOut { |
| late, |
| expr: self.lower_expr_mut(expr), |
| reg: lower_reg(reg)?, |
| } |
| } |
| InlineAsmOperand::SplitInOut { reg, late, ref in_expr, ref out_expr } => { |
| hir::InlineAsmOperand::SplitInOut { |
| late, |
| in_expr: self.lower_expr_mut(in_expr), |
| out_expr: out_expr.as_ref().map(|expr| self.lower_expr_mut(expr)), |
| reg: lower_reg(reg)?, |
| } |
| } |
| InlineAsmOperand::Const { ref expr } => { |
| hir::InlineAsmOperand::Const { expr: self.lower_expr_mut(expr) } |
| } |
| InlineAsmOperand::Sym { ref expr } => { |
| hir::InlineAsmOperand::Sym { expr: self.lower_expr_mut(expr) } |
| } |
| }; |
| Some(op) |
| }) |
| .collect(); |
| |
| // Stop if there were any errors when lowering the register classes |
| if operands.len() != asm.operands.len() { |
| return hir::ExprKind::Err; |
| } |
| |
| // Validate template modifiers against the register classes for the operands |
| let asm_arch = sess.asm_arch.unwrap(); |
| for p in &asm.template { |
| if let InlineAsmTemplatePiece::Placeholder { |
| operand_idx, |
| modifier: Some(modifier), |
| span: placeholder_span, |
| } = *p |
| { |
| let op_sp = asm.operands[operand_idx].1; |
| match &operands[operand_idx] { |
| hir::InlineAsmOperand::In { reg, .. } |
| | hir::InlineAsmOperand::Out { reg, .. } |
| | hir::InlineAsmOperand::InOut { reg, .. } |
| | hir::InlineAsmOperand::SplitInOut { reg, .. } => { |
| let class = reg.reg_class(); |
| let valid_modifiers = class.valid_modifiers(asm_arch); |
| if !valid_modifiers.contains(&modifier) { |
| let mut err = sess.struct_span_err( |
| placeholder_span, |
| "invalid asm template modifier for this register class", |
| ); |
| err.span_label(placeholder_span, "template modifier"); |
| err.span_label(op_sp, "argument"); |
| if !valid_modifiers.is_empty() { |
| let mut mods = format!("`{}`", valid_modifiers[0]); |
| for m in &valid_modifiers[1..] { |
| let _ = write!(mods, ", `{}`", m); |
| } |
| err.note(&format!( |
| "the `{}` register class supports \ |
| the following template modifiers: {}", |
| class.name(), |
| mods |
| )); |
| } else { |
| err.note(&format!( |
| "the `{}` register class does not support template modifiers", |
| class.name() |
| )); |
| } |
| err.emit(); |
| } |
| } |
| hir::InlineAsmOperand::Const { .. } => { |
| let mut err = sess.struct_span_err( |
| placeholder_span, |
| "asm template modifiers are not allowed for `const` arguments", |
| ); |
| err.span_label(placeholder_span, "template modifier"); |
| err.span_label(op_sp, "argument"); |
| err.emit(); |
| } |
| hir::InlineAsmOperand::Sym { .. } => { |
| let mut err = sess.struct_span_err( |
| placeholder_span, |
| "asm template modifiers are not allowed for `sym` arguments", |
| ); |
| err.span_label(placeholder_span, "template modifier"); |
| err.span_label(op_sp, "argument"); |
| err.emit(); |
| } |
| } |
| } |
| } |
| |
| let mut used_input_regs = FxHashMap::default(); |
| let mut used_output_regs = FxHashMap::default(); |
| for (idx, op) in operands.iter().enumerate() { |
| let op_sp = asm.operands[idx].1; |
| if let Some(reg) = op.reg() { |
| // Validate register classes against currently enabled target |
| // features. We check that at least one type is available for |
| // the current target. |
| let reg_class = reg.reg_class(); |
| let mut required_features = vec![]; |
| for &(_, feature) in reg_class.supported_types(asm_arch) { |
| if let Some(feature) = feature { |
| if self.sess.target_features.contains(&Symbol::intern(feature)) { |
| required_features.clear(); |
| break; |
| } else { |
| required_features.push(feature); |
| } |
| } else { |
| required_features.clear(); |
| break; |
| } |
| } |
| required_features.sort(); |
| required_features.dedup(); |
| match &required_features[..] { |
| [] => {} |
| [feature] => { |
| let msg = format!( |
| "register class `{}` requires the `{}` target feature", |
| reg_class.name(), |
| feature |
| ); |
| sess.struct_span_err(op_sp, &msg).emit(); |
| } |
| features => { |
| let msg = format!( |
| "register class `{}` requires at least one target feature: {}", |
| reg_class.name(), |
| features.join(", ") |
| ); |
| sess.struct_span_err(op_sp, &msg).emit(); |
| } |
| } |
| |
| // Check for conflicts between explicit register operands. |
| if let asm::InlineAsmRegOrRegClass::Reg(reg) = reg { |
| let (input, output) = match op { |
| hir::InlineAsmOperand::In { .. } => (true, false), |
| // Late output do not conflict with inputs, but normal outputs do |
| hir::InlineAsmOperand::Out { late, .. } => (!late, true), |
| hir::InlineAsmOperand::InOut { .. } |
| | hir::InlineAsmOperand::SplitInOut { .. } => (true, true), |
| hir::InlineAsmOperand::Const { .. } | hir::InlineAsmOperand::Sym { .. } => { |
| unreachable!() |
| } |
| }; |
| |
| // Flag to output the error only once per operand |
| let mut skip = false; |
| reg.overlapping_regs(|r| { |
| let mut check = |used_regs: &mut FxHashMap<asm::InlineAsmReg, usize>, |
| input| { |
| match used_regs.entry(r) { |
| Entry::Occupied(o) => { |
| if !skip { |
| skip = true; |
| |
| let idx2 = *o.get(); |
| let op2 = &operands[idx2]; |
| let op_sp2 = asm.operands[idx2].1; |
| let reg2 = match op2.reg() { |
| Some(asm::InlineAsmRegOrRegClass::Reg(r)) => r, |
| _ => unreachable!(), |
| }; |
| |
| let msg = format!( |
| "register `{}` conflicts with register `{}`", |
| reg.name(), |
| reg2.name() |
| ); |
| let mut err = sess.struct_span_err(op_sp, &msg); |
| err.span_label( |
| op_sp, |
| &format!("register `{}`", reg.name()), |
| ); |
| err.span_label( |
| op_sp2, |
| &format!("register `{}`", reg2.name()), |
| ); |
| |
| match (op, op2) { |
| ( |
| hir::InlineAsmOperand::In { .. }, |
| hir::InlineAsmOperand::Out { late, .. }, |
| ) |
| | ( |
| hir::InlineAsmOperand::Out { late, .. }, |
| hir::InlineAsmOperand::In { .. }, |
| ) => { |
| assert!(!*late); |
| let out_op_sp = if input { op_sp2 } else { op_sp }; |
| let msg = "use `lateout` instead of \ |
| `out` to avoid conflict"; |
| err.span_help(out_op_sp, msg); |
| } |
| _ => {} |
| } |
| |
| err.emit(); |
| } |
| } |
| Entry::Vacant(v) => { |
| v.insert(idx); |
| } |
| } |
| }; |
| if input { |
| check(&mut used_input_regs, true); |
| } |
| if output { |
| check(&mut used_output_regs, false); |
| } |
| }); |
| } |
| } |
| } |
| |
| let operands = self.arena.alloc_from_iter(operands); |
| let template = self.arena.alloc_from_iter(asm.template.iter().cloned()); |
| let line_spans = self.arena.alloc_slice(&asm.line_spans[..]); |
| let hir_asm = hir::InlineAsm { template, operands, options: asm.options, line_spans }; |
| hir::ExprKind::InlineAsm(self.arena.alloc(hir_asm)) |
| } |
| |
| fn lower_expr_llvm_asm(&mut self, asm: &LlvmInlineAsm) -> hir::ExprKind<'hir> { |
| let inner = hir::LlvmInlineAsmInner { |
| inputs: asm.inputs.iter().map(|&(c, _)| c).collect(), |
| outputs: asm |
| .outputs |
| .iter() |
| .map(|out| hir::LlvmInlineAsmOutput { |
| constraint: out.constraint, |
| is_rw: out.is_rw, |
| is_indirect: out.is_indirect, |
| span: out.expr.span, |
| }) |
| .collect(), |
| asm: asm.asm, |
| asm_str_style: asm.asm_str_style, |
| clobbers: asm.clobbers.clone(), |
| volatile: asm.volatile, |
| alignstack: asm.alignstack, |
| dialect: asm.dialect, |
| }; |
| let hir_asm = hir::LlvmInlineAsm { |
| inner, |
| inputs_exprs: self.arena.alloc_from_iter( |
| asm.inputs.iter().map(|&(_, ref input)| self.lower_expr_mut(input)), |
| ), |
| outputs_exprs: self |
| .arena |
| .alloc_from_iter(asm.outputs.iter().map(|out| self.lower_expr_mut(&out.expr))), |
| }; |
| hir::ExprKind::LlvmInlineAsm(self.arena.alloc(hir_asm)) |
| } |
| |
| fn lower_field(&mut self, f: &Field) -> hir::Field<'hir> { |
| hir::Field { |
| hir_id: self.next_id(), |
| ident: f.ident, |
| expr: self.lower_expr(&f.expr), |
| span: f.span, |
| is_shorthand: f.is_shorthand, |
| } |
| } |
| |
| fn lower_expr_yield(&mut self, span: Span, opt_expr: Option<&Expr>) -> hir::ExprKind<'hir> { |
| match self.generator_kind { |
| Some(hir::GeneratorKind::Gen) => {} |
| Some(hir::GeneratorKind::Async(_)) => { |
| struct_span_err!( |
| self.sess, |
| span, |
| E0727, |
| "`async` generators are not yet supported" |
| ) |
| .emit(); |
| } |
| None => self.generator_kind = Some(hir::GeneratorKind::Gen), |
| } |
| |
| let expr = |
| opt_expr.as_ref().map(|x| self.lower_expr(x)).unwrap_or_else(|| self.expr_unit(span)); |
| |
| hir::ExprKind::Yield(expr, hir::YieldSource::Yield) |
| } |
| |
| /// Desugar `ExprForLoop` from: `[opt_ident]: for <pat> in <head> <body>` into: |
| /// ```rust |
| /// { |
| /// let result = match ::std::iter::IntoIterator::into_iter(<head>) { |
| /// mut iter => { |
| /// [opt_ident]: loop { |
| /// let mut __next; |
| /// match ::std::iter::Iterator::next(&mut iter) { |
| /// ::std::option::Option::Some(val) => __next = val, |
| /// ::std::option::Option::None => break |
| /// }; |
| /// let <pat> = __next; |
| /// StmtKind::Expr(<body>); |
| /// } |
| /// } |
| /// }; |
| /// result |
| /// } |
| /// ``` |
| fn lower_expr_for( |
| &mut self, |
| e: &Expr, |
| pat: &Pat, |
| head: &Expr, |
| body: &Block, |
| opt_label: Option<Label>, |
| ) -> hir::Expr<'hir> { |
| let orig_head_span = head.span; |
| // expand <head> |
| let mut head = self.lower_expr_mut(head); |
| let desugared_span = self.mark_span_with_reason( |
| DesugaringKind::ForLoop(ForLoopLoc::Head), |
| orig_head_span, |
| None, |
| ); |
| head.span = desugared_span; |
| |
| let iter = Ident::with_dummy_span(sym::iter); |
| |
| let next_ident = Ident::with_dummy_span(sym::__next); |
| let (next_pat, next_pat_hid) = self.pat_ident_binding_mode( |
| desugared_span, |
| next_ident, |
| hir::BindingAnnotation::Mutable, |
| ); |
| |
| // `::std::option::Option::Some(val) => __next = val` |
| let pat_arm = { |
| let val_ident = Ident::with_dummy_span(sym::val); |
| let (val_pat, val_pat_hid) = self.pat_ident(pat.span, val_ident); |
| let val_expr = self.expr_ident(pat.span, val_ident, val_pat_hid); |
| let next_expr = self.expr_ident(pat.span, next_ident, next_pat_hid); |
| let assign = self.arena.alloc(self.expr( |
| pat.span, |
| hir::ExprKind::Assign(next_expr, val_expr, pat.span), |
| ThinVec::new(), |
| )); |
| let some_pat = self.pat_some(pat.span, val_pat); |
| self.arm(some_pat, assign) |
| }; |
| |
| // `::std::option::Option::None => break` |
| let break_arm = { |
| let break_expr = |
| self.with_loop_scope(e.id, |this| this.expr_break(e.span, ThinVec::new())); |
| let pat = self.pat_none(e.span); |
| self.arm(pat, break_expr) |
| }; |
| |
| // `mut iter` |
| let (iter_pat, iter_pat_nid) = |
| self.pat_ident_binding_mode(desugared_span, iter, hir::BindingAnnotation::Mutable); |
| |
| // `match ::std::iter::Iterator::next(&mut iter) { ... }` |
| let match_expr = { |
| let iter = self.expr_ident(desugared_span, iter, iter_pat_nid); |
| let ref_mut_iter = self.expr_mut_addr_of(desugared_span, iter); |
| let next_path = &[sym::iter, sym::Iterator, sym::next]; |
| let next_expr = |
| self.expr_call_std_path(desugared_span, next_path, arena_vec![self; ref_mut_iter]); |
| let arms = arena_vec![self; pat_arm, break_arm]; |
| |
| self.expr_match(desugared_span, next_expr, arms, hir::MatchSource::ForLoopDesugar) |
| }; |
| let match_stmt = self.stmt_expr(desugared_span, match_expr); |
| |
| let next_expr = self.expr_ident(desugared_span, next_ident, next_pat_hid); |
| |
| // `let mut __next` |
| let next_let = self.stmt_let_pat( |
| ThinVec::new(), |
| desugared_span, |
| None, |
| next_pat, |
| hir::LocalSource::ForLoopDesugar, |
| ); |
| |
| // `let <pat> = __next` |
| let pat = self.lower_pat(pat); |
| let pat_let = self.stmt_let_pat( |
| ThinVec::new(), |
| desugared_span, |
| Some(next_expr), |
| pat, |
| hir::LocalSource::ForLoopDesugar, |
| ); |
| |
| let body_block = self.with_loop_scope(e.id, |this| this.lower_block(body, false)); |
| let body_expr = self.expr_block(body_block, ThinVec::new()); |
| let body_stmt = self.stmt_expr(body.span, body_expr); |
| |
| let loop_block = self.block_all( |
| e.span, |
| arena_vec![self; next_let, match_stmt, pat_let, body_stmt], |
| None, |
| ); |
| |
| // `[opt_ident]: loop { ... }` |
| let kind = hir::ExprKind::Loop(loop_block, opt_label, hir::LoopSource::ForLoop); |
| let loop_expr = self.arena.alloc(hir::Expr { |
| hir_id: self.lower_node_id(e.id), |
| kind, |
| span: e.span, |
| attrs: ThinVec::new(), |
| }); |
| |
| // `mut iter => { ... }` |
| let iter_arm = self.arm(iter_pat, loop_expr); |
| |
| let into_iter_span = self.mark_span_with_reason( |
| DesugaringKind::ForLoop(ForLoopLoc::IntoIter), |
| orig_head_span, |
| None, |
| ); |
| |
| // `match ::std::iter::IntoIterator::into_iter(<head>) { ... }` |
| let into_iter_expr = { |
| let into_iter_path = &[sym::iter, sym::IntoIterator, sym::into_iter]; |
| self.expr_call_std_path(into_iter_span, into_iter_path, arena_vec![self; head]) |
| }; |
| |
| let match_expr = self.arena.alloc(self.expr_match( |
| desugared_span, |
| into_iter_expr, |
| arena_vec![self; iter_arm], |
| hir::MatchSource::ForLoopDesugar, |
| )); |
| |
| // This is effectively `{ let _result = ...; _result }`. |
| // The construct was introduced in #21984 and is necessary to make sure that |
| // temporaries in the `head` expression are dropped and do not leak to the |
| // surrounding scope of the `match` since the `match` is not a terminating scope. |
| // |
| // Also, add the attributes to the outer returned expr node. |
| self.expr_drop_temps_mut(desugared_span, match_expr, e.attrs.clone()) |
| } |
| |
| /// Desugar `ExprKind::Try` from: `<expr>?` into: |
| /// ```rust |
| /// match Try::into_result(<expr>) { |
| /// Ok(val) => #[allow(unreachable_code)] val, |
| /// Err(err) => #[allow(unreachable_code)] |
| /// // If there is an enclosing `try {...}`: |
| /// break 'catch_target Try::from_error(From::from(err)), |
| /// // Otherwise: |
| /// return Try::from_error(From::from(err)), |
| /// } |
| /// ``` |
| fn lower_expr_try(&mut self, span: Span, sub_expr: &Expr) -> hir::ExprKind<'hir> { |
| let unstable_span = self.mark_span_with_reason( |
| DesugaringKind::QuestionMark, |
| span, |
| self.allow_try_trait.clone(), |
| ); |
| let try_span = self.sess.source_map().end_point(span); |
| let try_span = self.mark_span_with_reason( |
| DesugaringKind::QuestionMark, |
| try_span, |
| self.allow_try_trait.clone(), |
| ); |
| |
| // `Try::into_result(<expr>)` |
| let scrutinee = { |
| // expand <expr> |
| let sub_expr = self.lower_expr_mut(sub_expr); |
| |
| let path = &[sym::ops, sym::Try, sym::into_result]; |
| self.expr_call_std_path(unstable_span, path, arena_vec![self; sub_expr]) |
| }; |
| |
| // `#[allow(unreachable_code)]` |
| let attr = { |
| // `allow(unreachable_code)` |
| let allow = { |
| let allow_ident = Ident::new(sym::allow, span); |
| let uc_ident = Ident::new(sym::unreachable_code, span); |
| let uc_nested = attr::mk_nested_word_item(uc_ident); |
| attr::mk_list_item(allow_ident, vec![uc_nested]) |
| }; |
| attr::mk_attr_outer(allow) |
| }; |
| let attrs = vec![attr]; |
| |
| // `Ok(val) => #[allow(unreachable_code)] val,` |
| let ok_arm = { |
| let val_ident = Ident::with_dummy_span(sym::val); |
| let (val_pat, val_pat_nid) = self.pat_ident(span, val_ident); |
| let val_expr = self.arena.alloc(self.expr_ident_with_attrs( |
| span, |
| val_ident, |
| val_pat_nid, |
| ThinVec::from(attrs.clone()), |
| )); |
| let ok_pat = self.pat_ok(span, val_pat); |
| self.arm(ok_pat, val_expr) |
| }; |
| |
| // `Err(err) => #[allow(unreachable_code)] |
| // return Try::from_error(From::from(err)),` |
| let err_arm = { |
| let err_ident = Ident::with_dummy_span(sym::err); |
| let (err_local, err_local_nid) = self.pat_ident(try_span, err_ident); |
| let from_expr = { |
| let from_path = &[sym::convert, sym::From, sym::from]; |
| let err_expr = self.expr_ident_mut(try_span, err_ident, err_local_nid); |
| self.expr_call_std_path(try_span, from_path, arena_vec![self; err_expr]) |
| }; |
| let from_err_expr = |
| self.wrap_in_try_constructor(sym::from_error, unstable_span, from_expr, try_span); |
| let thin_attrs = ThinVec::from(attrs); |
| let catch_scope = self.catch_scopes.last().copied(); |
| let ret_expr = if let Some(catch_node) = catch_scope { |
| let target_id = Ok(self.lower_node_id(catch_node)); |
| self.arena.alloc(self.expr( |
| try_span, |
| hir::ExprKind::Break( |
| hir::Destination { label: None, target_id }, |
| Some(from_err_expr), |
| ), |
| thin_attrs, |
| )) |
| } else { |
| self.arena.alloc(self.expr( |
| try_span, |
| hir::ExprKind::Ret(Some(from_err_expr)), |
| thin_attrs, |
| )) |
| }; |
| |
| let err_pat = self.pat_err(try_span, err_local); |
| self.arm(err_pat, ret_expr) |
| }; |
| |
| hir::ExprKind::Match( |
| scrutinee, |
| arena_vec![self; err_arm, ok_arm], |
| hir::MatchSource::TryDesugar, |
| ) |
| } |
| |
| // ========================================================================= |
| // Helper methods for building HIR. |
| // ========================================================================= |
| |
| /// Constructs a `true` or `false` literal expression. |
| pub(super) fn expr_bool(&mut self, span: Span, val: bool) -> &'hir hir::Expr<'hir> { |
| let lit = Spanned { span, node: LitKind::Bool(val) }; |
| self.arena.alloc(self.expr(span, hir::ExprKind::Lit(lit), ThinVec::new())) |
| } |
| |
| /// Wrap the given `expr` in a terminating scope using `hir::ExprKind::DropTemps`. |
| /// |
| /// In terms of drop order, it has the same effect as wrapping `expr` in |
| /// `{ let _t = $expr; _t }` but should provide better compile-time performance. |
| /// |
| /// The drop order can be important in e.g. `if expr { .. }`. |
| pub(super) fn expr_drop_temps( |
| &mut self, |
| span: Span, |
| expr: &'hir hir::Expr<'hir>, |
| attrs: AttrVec, |
| ) -> &'hir hir::Expr<'hir> { |
| self.arena.alloc(self.expr_drop_temps_mut(span, expr, attrs)) |
| } |
| |
| pub(super) fn expr_drop_temps_mut( |
| &mut self, |
| span: Span, |
| expr: &'hir hir::Expr<'hir>, |
| attrs: AttrVec, |
| ) -> hir::Expr<'hir> { |
| self.expr(span, hir::ExprKind::DropTemps(expr), attrs) |
| } |
| |
| fn expr_match( |
| &mut self, |
| span: Span, |
| arg: &'hir hir::Expr<'hir>, |
| arms: &'hir [hir::Arm<'hir>], |
| source: hir::MatchSource, |
| ) -> hir::Expr<'hir> { |
| self.expr(span, hir::ExprKind::Match(arg, arms, source), ThinVec::new()) |
| } |
| |
| fn expr_break(&mut self, span: Span, attrs: AttrVec) -> &'hir hir::Expr<'hir> { |
| let expr_break = hir::ExprKind::Break(self.lower_loop_destination(None), None); |
| self.arena.alloc(self.expr(span, expr_break, attrs)) |
| } |
| |
| fn expr_mut_addr_of(&mut self, span: Span, e: &'hir hir::Expr<'hir>) -> hir::Expr<'hir> { |
| self.expr( |
| span, |
| hir::ExprKind::AddrOf(hir::BorrowKind::Ref, hir::Mutability::Mut, e), |
| ThinVec::new(), |
| ) |
| } |
| |
| fn expr_unit(&mut self, sp: Span) -> &'hir hir::Expr<'hir> { |
| self.arena.alloc(self.expr(sp, hir::ExprKind::Tup(&[]), ThinVec::new())) |
| } |
| |
| fn expr_call_mut( |
| &mut self, |
| span: Span, |
| e: &'hir hir::Expr<'hir>, |
| args: &'hir [hir::Expr<'hir>], |
| ) -> hir::Expr<'hir> { |
| self.expr(span, hir::ExprKind::Call(e, args), ThinVec::new()) |
| } |
| |
| fn expr_call( |
| &mut self, |
| span: Span, |
| e: &'hir hir::Expr<'hir>, |
| args: &'hir [hir::Expr<'hir>], |
| ) -> &'hir hir::Expr<'hir> { |
| self.arena.alloc(self.expr_call_mut(span, e, args)) |
| } |
| |
| // Note: associated functions must use `expr_call_std_path`. |
| fn expr_call_std_path_mut( |
| &mut self, |
| span: Span, |
| path_components: &[Symbol], |
| args: &'hir [hir::Expr<'hir>], |
| ) -> hir::Expr<'hir> { |
| let path = |
| self.arena.alloc(self.expr_std_path(span, path_components, None, ThinVec::new())); |
| self.expr_call_mut(span, path, args) |
| } |
| |
| fn expr_call_std_path( |
| &mut self, |
| span: Span, |
| path_components: &[Symbol], |
| args: &'hir [hir::Expr<'hir>], |
| ) -> &'hir hir::Expr<'hir> { |
| self.arena.alloc(self.expr_call_std_path_mut(span, path_components, args)) |
| } |
| |
| // Create an expression calling an associated function of an std type. |
| // |
| // Associated functions cannot be resolved through the normal `std_path` function, |
| // as they are resolved differently and so cannot use `expr_call_std_path`. |
| // |
| // This function accepts the path component (`ty_path_components`) separately from |
| // the name of the associated function (`assoc_fn_name`) in order to facilitate |
| // separate resolution of the type and creation of a path referring to its associated |
| // function. |
| fn expr_call_std_assoc_fn( |
| &mut self, |
| ty_path_id: hir::HirId, |
| span: Span, |
| ty_path_components: &[Symbol], |
| assoc_fn_name: &str, |
| args: &'hir [hir::Expr<'hir>], |
| ) -> hir::ExprKind<'hir> { |
| let ty_path = self.std_path(span, ty_path_components, None, false); |
| let ty = |
| self.arena.alloc(self.ty_path(ty_path_id, span, hir::QPath::Resolved(None, ty_path))); |
| let fn_seg = self.arena.alloc(hir::PathSegment::from_ident(Ident::from_str(assoc_fn_name))); |
| let fn_path = hir::QPath::TypeRelative(ty, fn_seg); |
| let fn_expr = |
| self.arena.alloc(self.expr(span, hir::ExprKind::Path(fn_path), ThinVec::new())); |
| hir::ExprKind::Call(fn_expr, args) |
| } |
| |
| fn expr_std_path( |
| &mut self, |
| span: Span, |
| components: &[Symbol], |
| params: Option<&'hir hir::GenericArgs<'hir>>, |
| attrs: AttrVec, |
| ) -> hir::Expr<'hir> { |
| let path = self.std_path(span, components, params, true); |
| self.expr(span, hir::ExprKind::Path(hir::QPath::Resolved(None, path)), attrs) |
| } |
| |
| pub(super) fn expr_ident( |
| &mut self, |
| sp: Span, |
| ident: Ident, |
| binding: hir::HirId, |
| ) -> &'hir hir::Expr<'hir> { |
| self.arena.alloc(self.expr_ident_mut(sp, ident, binding)) |
| } |
| |
| pub(super) fn expr_ident_mut( |
| &mut self, |
| sp: Span, |
| ident: Ident, |
| binding: hir::HirId, |
| ) -> hir::Expr<'hir> { |
| self.expr_ident_with_attrs(sp, ident, binding, ThinVec::new()) |
| } |
| |
| fn expr_ident_with_attrs( |
| &mut self, |
| span: Span, |
| ident: Ident, |
| binding: hir::HirId, |
| attrs: AttrVec, |
| ) -> hir::Expr<'hir> { |
| let expr_path = hir::ExprKind::Path(hir::QPath::Resolved( |
| None, |
| self.arena.alloc(hir::Path { |
| span, |
| res: Res::Local(binding), |
| segments: arena_vec![self; hir::PathSegment::from_ident(ident)], |
| }), |
| )); |
| |
| self.expr(span, expr_path, attrs) |
| } |
| |
| fn expr_unsafe(&mut self, expr: &'hir hir::Expr<'hir>) -> hir::Expr<'hir> { |
| let hir_id = self.next_id(); |
| let span = expr.span; |
| self.expr( |
| span, |
| hir::ExprKind::Block( |
| self.arena.alloc(hir::Block { |
| stmts: &[], |
| expr: Some(expr), |
| hir_id, |
| rules: hir::BlockCheckMode::UnsafeBlock(hir::UnsafeSource::CompilerGenerated), |
| span, |
| targeted_by_break: false, |
| }), |
| None, |
| ), |
| ThinVec::new(), |
| ) |
| } |
| |
| fn expr_block_empty(&mut self, span: Span) -> &'hir hir::Expr<'hir> { |
| let blk = self.block_all(span, &[], None); |
| let expr = self.expr_block(blk, ThinVec::new()); |
| self.arena.alloc(expr) |
| } |
| |
| pub(super) fn expr_block( |
| &mut self, |
| b: &'hir hir::Block<'hir>, |
| attrs: AttrVec, |
| ) -> hir::Expr<'hir> { |
| self.expr(b.span, hir::ExprKind::Block(b, None), attrs) |
| } |
| |
| pub(super) fn expr( |
| &mut self, |
| span: Span, |
| kind: hir::ExprKind<'hir>, |
| attrs: AttrVec, |
| ) -> hir::Expr<'hir> { |
| hir::Expr { hir_id: self.next_id(), kind, span, attrs } |
| } |
| |
| fn field(&mut self, ident: Ident, expr: &'hir hir::Expr<'hir>, span: Span) -> hir::Field<'hir> { |
| hir::Field { hir_id: self.next_id(), ident, span, expr, is_shorthand: false } |
| } |
| |
| fn arm(&mut self, pat: &'hir hir::Pat<'hir>, expr: &'hir hir::Expr<'hir>) -> hir::Arm<'hir> { |
| hir::Arm { |
| hir_id: self.next_id(), |
| attrs: &[], |
| pat, |
| guard: None, |
| span: expr.span, |
| body: expr, |
| } |
| } |
| } |
