| // Copyright 2012-2016 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| //#![allow(non_camel_case_types)] |
| |
| use rustc::middle::const_val::ConstVal::*; |
| use rustc::middle::const_val::ConstVal; |
| use self::ErrKind::*; |
| use self::EvalHint::*; |
| |
| use rustc::hir::map as ast_map; |
| use rustc::hir::map::blocks::FnLikeNode; |
| use rustc::middle::cstore::InlinedItem; |
| use rustc::traits; |
| use rustc::hir::def::{Def, CtorKind, PathResolution}; |
| use rustc::hir::def_id::DefId; |
| use rustc::hir::pat_util::def_to_path; |
| use rustc::ty::{self, Ty, TyCtxt}; |
| use rustc::ty::util::IntTypeExt; |
| use rustc::ty::subst::Substs; |
| use rustc::traits::Reveal; |
| use rustc::util::common::ErrorReported; |
| use rustc::util::nodemap::DefIdMap; |
| use rustc::lint; |
| |
| use graphviz::IntoCow; |
| use syntax::ast; |
| use rustc::hir::{Expr, PatKind}; |
| use rustc::hir; |
| use rustc::hir::intravisit::FnKind; |
| use syntax::ptr::P; |
| use syntax::codemap; |
| use syntax::attr::IntType; |
| use syntax_pos::{self, Span}; |
| |
| use std::borrow::Cow; |
| use std::cmp::Ordering; |
| use std::collections::hash_map::Entry::Vacant; |
| |
| use rustc_const_math::*; |
| use rustc_errors::DiagnosticBuilder; |
| |
| macro_rules! math { |
| ($e:expr, $op:expr) => { |
| match $op { |
| Ok(val) => val, |
| Err(e) => signal!($e, Math(e)), |
| } |
| } |
| } |
| |
| fn lookup_variant_by_id<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| variant_def: DefId) |
| -> Option<&'tcx Expr> { |
| fn variant_expr<'a>(variants: &'a [hir::Variant], id: ast::NodeId) |
| -> Option<&'a Expr> { |
| for variant in variants { |
| if variant.node.data.id() == id { |
| return variant.node.disr_expr.as_ref().map(|e| &**e); |
| } |
| } |
| None |
| } |
| |
| if let Some(variant_node_id) = tcx.map.as_local_node_id(variant_def) { |
| let enum_node_id = tcx.map.get_parent(variant_node_id); |
| match tcx.map.find(enum_node_id) { |
| None => None, |
| Some(ast_map::NodeItem(it)) => match it.node { |
| hir::ItemEnum(hir::EnumDef { ref variants }, _) => { |
| variant_expr(variants, variant_node_id) |
| } |
| _ => None |
| }, |
| Some(_) => None |
| } |
| } else { |
| None |
| } |
| } |
| |
| /// * `def_id` is the id of the constant. |
| /// * `substs` is the monomorphized substitutions for the expression. |
| /// |
| /// `substs` is optional and is used for associated constants. |
| /// This generally happens in late/trans const evaluation. |
| pub fn lookup_const_by_id<'a, 'tcx: 'a>(tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| def_id: DefId, |
| substs: Option<&'tcx Substs<'tcx>>) |
| -> Option<(&'tcx Expr, Option<ty::Ty<'tcx>>)> { |
| if let Some(node_id) = tcx.map.as_local_node_id(def_id) { |
| match tcx.map.find(node_id) { |
| None => None, |
| Some(ast_map::NodeItem(it)) => match it.node { |
| hir::ItemConst(ref ty, ref const_expr) => { |
| Some((&const_expr, tcx.ast_ty_to_prim_ty(ty))) |
| } |
| _ => None |
| }, |
| Some(ast_map::NodeTraitItem(ti)) => match ti.node { |
| hir::ConstTraitItem(..) => { |
| if let Some(substs) = substs { |
| // If we have a trait item and the substitutions for it, |
| // `resolve_trait_associated_const` will select an impl |
| // or the default. |
| let trait_id = tcx.map.get_parent(node_id); |
| let trait_id = tcx.map.local_def_id(trait_id); |
| resolve_trait_associated_const(tcx, ti, trait_id, substs) |
| } else { |
| // Technically, without knowing anything about the |
| // expression that generates the obligation, we could |
| // still return the default if there is one. However, |
| // it's safer to return `None` than to return some value |
| // that may differ from what you would get from |
| // correctly selecting an impl. |
| None |
| } |
| } |
| _ => None |
| }, |
| Some(ast_map::NodeImplItem(ii)) => match ii.node { |
| hir::ImplItemKind::Const(ref ty, ref expr) => { |
| Some((&expr, tcx.ast_ty_to_prim_ty(ty))) |
| } |
| _ => None |
| }, |
| Some(_) => None |
| } |
| } else { |
| match tcx.extern_const_statics.borrow().get(&def_id) { |
| Some(&None) => return None, |
| Some(&Some((expr_id, ty))) => { |
| return Some((tcx.map.expect_expr(expr_id), ty)); |
| } |
| None => {} |
| } |
| let mut used_substs = false; |
| let expr_ty = match tcx.sess.cstore.maybe_get_item_ast(tcx, def_id) { |
| Some((&InlinedItem::Item(_, ref item), _)) => match item.node { |
| hir::ItemConst(ref ty, ref const_expr) => { |
| Some((&**const_expr, tcx.ast_ty_to_prim_ty(ty))) |
| }, |
| _ => None |
| }, |
| Some((&InlinedItem::TraitItem(trait_id, ref ti), _)) => match ti.node { |
| hir::ConstTraitItem(..) => { |
| used_substs = true; |
| if let Some(substs) = substs { |
| // As mentioned in the comments above for in-crate |
| // constants, we only try to find the expression for |
| // a trait-associated const if the caller gives us |
| // the substitutions for the reference to it. |
| resolve_trait_associated_const(tcx, ti, trait_id, substs) |
| } else { |
| None |
| } |
| } |
| _ => None |
| }, |
| Some((&InlinedItem::ImplItem(_, ref ii), _)) => match ii.node { |
| hir::ImplItemKind::Const(ref ty, ref expr) => { |
| Some((&**expr, tcx.ast_ty_to_prim_ty(ty))) |
| }, |
| _ => None |
| }, |
| _ => None |
| }; |
| // If we used the substitutions, particularly to choose an impl |
| // of a trait-associated const, don't cache that, because the next |
| // lookup with the same def_id may yield a different result. |
| if !used_substs { |
| tcx.extern_const_statics |
| .borrow_mut() |
| .insert(def_id, expr_ty.map(|(e, t)| (e.id, t))); |
| } |
| expr_ty |
| } |
| } |
| |
| fn inline_const_fn_from_external_crate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| def_id: DefId) |
| -> Option<ast::NodeId> { |
| match tcx.extern_const_fns.borrow().get(&def_id) { |
| Some(&ast::DUMMY_NODE_ID) => return None, |
| Some(&fn_id) => return Some(fn_id), |
| None => {} |
| } |
| |
| if !tcx.sess.cstore.is_const_fn(def_id) { |
| tcx.extern_const_fns.borrow_mut().insert(def_id, ast::DUMMY_NODE_ID); |
| return None; |
| } |
| |
| let fn_id = match tcx.sess.cstore.maybe_get_item_ast(tcx, def_id) { |
| Some((&InlinedItem::Item(_, ref item), _)) => Some(item.id), |
| Some((&InlinedItem::ImplItem(_, ref item), _)) => Some(item.id), |
| _ => None |
| }; |
| tcx.extern_const_fns.borrow_mut().insert(def_id, |
| fn_id.unwrap_or(ast::DUMMY_NODE_ID)); |
| fn_id |
| } |
| |
| pub fn lookup_const_fn_by_id<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) |
| -> Option<FnLikeNode<'tcx>> |
| { |
| let fn_id = if let Some(node_id) = tcx.map.as_local_node_id(def_id) { |
| node_id |
| } else { |
| if let Some(fn_id) = inline_const_fn_from_external_crate(tcx, def_id) { |
| fn_id |
| } else { |
| return None; |
| } |
| }; |
| |
| let fn_like = match FnLikeNode::from_node(tcx.map.get(fn_id)) { |
| Some(fn_like) => fn_like, |
| None => return None |
| }; |
| |
| match fn_like.kind() { |
| FnKind::ItemFn(_, _, _, hir::Constness::Const, ..) => { |
| Some(fn_like) |
| } |
| FnKind::Method(_, m, ..) => { |
| if m.constness == hir::Constness::Const { |
| Some(fn_like) |
| } else { |
| None |
| } |
| } |
| _ => None |
| } |
| } |
| |
| pub fn const_expr_to_pat<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| expr: &Expr, |
| pat_id: ast::NodeId, |
| span: Span) |
| -> Result<P<hir::Pat>, DefId> { |
| let pat_ty = tcx.tables().expr_ty(expr); |
| debug!("expr={:?} pat_ty={:?} pat_id={}", expr, pat_ty, pat_id); |
| match pat_ty.sty { |
| ty::TyFloat(_) => { |
| tcx.sess.add_lint( |
| lint::builtin::ILLEGAL_FLOATING_POINT_CONSTANT_PATTERN, |
| pat_id, |
| span, |
| format!("floating point constants cannot be used in patterns")); |
| } |
| ty::TyAdt(adt_def, _) if adt_def.is_union() => { |
| // Matching on union fields is unsafe, we can't hide it in constants |
| tcx.sess.span_err(span, "cannot use unions in constant patterns"); |
| } |
| ty::TyAdt(adt_def, _) => { |
| if !tcx.has_attr(adt_def.did, "structural_match") { |
| tcx.sess.add_lint( |
| lint::builtin::ILLEGAL_STRUCT_OR_ENUM_CONSTANT_PATTERN, |
| pat_id, |
| span, |
| format!("to use a constant of type `{}` \ |
| in a pattern, \ |
| `{}` must be annotated with `#[derive(PartialEq, Eq)]`", |
| tcx.item_path_str(adt_def.did), |
| tcx.item_path_str(adt_def.did))); |
| } |
| } |
| _ => { } |
| } |
| let pat = match expr.node { |
| hir::ExprTup(ref exprs) => |
| PatKind::Tuple(exprs.iter() |
| .map(|expr| const_expr_to_pat(tcx, &expr, pat_id, span)) |
| .collect::<Result<_, _>>()?, None), |
| |
| hir::ExprCall(ref callee, ref args) => { |
| let def = tcx.expect_def(callee.id); |
| if let Vacant(entry) = tcx.def_map.borrow_mut().entry(expr.id) { |
| entry.insert(PathResolution::new(def)); |
| } |
| let path = match def { |
| Def::StructCtor(def_id, CtorKind::Fn) | |
| Def::VariantCtor(def_id, CtorKind::Fn) => def_to_path(tcx, def_id), |
| Def::Fn(..) | Def::Method(..) => return Ok(P(hir::Pat { |
| id: expr.id, |
| node: PatKind::Lit(P(expr.clone())), |
| span: span, |
| })), |
| _ => bug!() |
| }; |
| let pats = args.iter() |
| .map(|expr| const_expr_to_pat(tcx, &**expr, pat_id, span)) |
| .collect::<Result<_, _>>()?; |
| PatKind::TupleStruct(path, pats, None) |
| } |
| |
| hir::ExprStruct(ref path, ref fields, None) => { |
| let field_pats = |
| fields.iter() |
| .map(|field| Ok(codemap::Spanned { |
| span: syntax_pos::DUMMY_SP, |
| node: hir::FieldPat { |
| name: field.name.node, |
| pat: const_expr_to_pat(tcx, &field.expr, pat_id, span)?, |
| is_shorthand: false, |
| }, |
| })) |
| .collect::<Result<_, _>>()?; |
| PatKind::Struct((**path).clone(), field_pats, false) |
| } |
| |
| hir::ExprArray(ref exprs) => { |
| let pats = exprs.iter() |
| .map(|expr| const_expr_to_pat(tcx, &expr, pat_id, span)) |
| .collect::<Result<_, _>>()?; |
| PatKind::Slice(pats, None, hir::HirVec::new()) |
| } |
| |
| hir::ExprPath(_, ref path) => { |
| match tcx.expect_def(expr.id) { |
| Def::StructCtor(_, CtorKind::Const) | |
| Def::VariantCtor(_, CtorKind::Const) => PatKind::Path(None, path.clone()), |
| Def::Const(def_id) | Def::AssociatedConst(def_id) => { |
| let substs = Some(tcx.tables().node_id_item_substs(expr.id) |
| .unwrap_or_else(|| tcx.intern_substs(&[]))); |
| let (expr, _ty) = lookup_const_by_id(tcx, def_id, substs).unwrap(); |
| return const_expr_to_pat(tcx, expr, pat_id, span); |
| }, |
| _ => bug!(), |
| } |
| } |
| |
| _ => PatKind::Lit(P(expr.clone())) |
| }; |
| Ok(P(hir::Pat { id: expr.id, node: pat, span: span })) |
| } |
| |
| pub fn report_const_eval_err<'a, 'tcx>( |
| tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| err: &ConstEvalErr, |
| primary_span: Span, |
| primary_kind: &str) |
| -> DiagnosticBuilder<'tcx> |
| { |
| let mut err = err; |
| while let &ConstEvalErr { kind: ErroneousReferencedConstant(box ref i_err), .. } = err { |
| err = i_err; |
| } |
| |
| let mut diag = struct_span_err!(tcx.sess, err.span, E0080, "constant evaluation error"); |
| note_const_eval_err(tcx, err, primary_span, primary_kind, &mut diag); |
| diag |
| } |
| |
| pub fn fatal_const_eval_err<'a, 'tcx>( |
| tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| err: &ConstEvalErr, |
| primary_span: Span, |
| primary_kind: &str) |
| -> ! |
| { |
| report_const_eval_err(tcx, err, primary_span, primary_kind).emit(); |
| tcx.sess.abort_if_errors(); |
| unreachable!() |
| } |
| |
| pub fn note_const_eval_err<'a, 'tcx>( |
| _tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| err: &ConstEvalErr, |
| primary_span: Span, |
| primary_kind: &str, |
| diag: &mut DiagnosticBuilder) |
| { |
| match err.description() { |
| ConstEvalErrDescription::Simple(message) => { |
| diag.span_label(err.span, &message); |
| } |
| } |
| |
| if !primary_span.contains(err.span) { |
| diag.span_note(primary_span, |
| &format!("for {} here", primary_kind)); |
| } |
| } |
| |
| pub fn eval_const_expr<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| e: &Expr) -> ConstVal { |
| match eval_const_expr_checked(tcx, e) { |
| Ok(r) => r, |
| // non-const path still needs to be a fatal error, because enums are funky |
| Err(s) => { |
| report_const_eval_err(tcx, &s, e.span, "expression").emit(); |
| match s.kind { |
| NonConstPath | |
| UnimplementedConstVal(_) => tcx.sess.abort_if_errors(), |
| _ => {} |
| } |
| Dummy |
| }, |
| } |
| } |
| |
| pub fn eval_const_expr_checked<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| e: &Expr) -> EvalResult |
| { |
| eval_const_expr_partial(tcx, e, ExprTypeChecked, None) |
| } |
| |
| pub type FnArgMap<'a> = Option<&'a DefIdMap<ConstVal>>; |
| |
| #[derive(Clone, Debug)] |
| pub struct ConstEvalErr { |
| pub span: Span, |
| pub kind: ErrKind, |
| } |
| |
| #[derive(Clone, Debug)] |
| pub enum ErrKind { |
| CannotCast, |
| CannotCastTo(&'static str), |
| InvalidOpForInts(hir::BinOp_), |
| InvalidOpForBools(hir::BinOp_), |
| InvalidOpForFloats(hir::BinOp_), |
| InvalidOpForIntUint(hir::BinOp_), |
| InvalidOpForUintInt(hir::BinOp_), |
| NegateOn(ConstVal), |
| NotOn(ConstVal), |
| CallOn(ConstVal), |
| |
| MissingStructField, |
| NonConstPath, |
| UnimplementedConstVal(&'static str), |
| UnresolvedPath, |
| ExpectedConstTuple, |
| ExpectedConstStruct, |
| TupleIndexOutOfBounds, |
| IndexedNonVec, |
| IndexNegative, |
| IndexNotInt, |
| IndexOutOfBounds { len: u64, index: u64 }, |
| RepeatCountNotNatural, |
| RepeatCountNotInt, |
| |
| MiscBinaryOp, |
| MiscCatchAll, |
| |
| IndexOpFeatureGated, |
| Math(ConstMathErr), |
| |
| IntermediateUnsignedNegative, |
| /// Expected, Got |
| TypeMismatch(String, ConstInt), |
| |
| BadType(ConstVal), |
| ErroneousReferencedConstant(Box<ConstEvalErr>), |
| CharCast(ConstInt), |
| } |
| |
| impl From<ConstMathErr> for ErrKind { |
| fn from(err: ConstMathErr) -> ErrKind { |
| Math(err) |
| } |
| } |
| |
| #[derive(Clone, Debug)] |
| pub enum ConstEvalErrDescription<'a> { |
| Simple(Cow<'a, str>), |
| } |
| |
| impl<'a> ConstEvalErrDescription<'a> { |
| /// Return a one-line description of the error, for lints and such |
| pub fn into_oneline(self) -> Cow<'a, str> { |
| match self { |
| ConstEvalErrDescription::Simple(simple) => simple, |
| } |
| } |
| } |
| |
| impl ConstEvalErr { |
| pub fn description(&self) -> ConstEvalErrDescription { |
| use self::ErrKind::*; |
| use self::ConstEvalErrDescription::*; |
| |
| macro_rules! simple { |
| ($msg:expr) => ({ Simple($msg.into_cow()) }); |
| ($fmt:expr, $($arg:tt)+) => ({ |
| Simple(format!($fmt, $($arg)+).into_cow()) |
| }) |
| } |
| |
| match self.kind { |
| CannotCast => simple!("can't cast this type"), |
| CannotCastTo(s) => simple!("can't cast this type to {}", s), |
| InvalidOpForInts(_) => simple!("can't do this op on integrals"), |
| InvalidOpForBools(_) => simple!("can't do this op on bools"), |
| InvalidOpForFloats(_) => simple!("can't do this op on floats"), |
| InvalidOpForIntUint(..) => simple!("can't do this op on an isize and usize"), |
| InvalidOpForUintInt(..) => simple!("can't do this op on a usize and isize"), |
| NegateOn(ref const_val) => simple!("negate on {}", const_val.description()), |
| NotOn(ref const_val) => simple!("not on {}", const_val.description()), |
| CallOn(ref const_val) => simple!("call on {}", const_val.description()), |
| |
| MissingStructField => simple!("nonexistent struct field"), |
| NonConstPath => simple!("non-constant path in constant expression"), |
| UnimplementedConstVal(what) => |
| simple!("unimplemented constant expression: {}", what), |
| UnresolvedPath => simple!("unresolved path in constant expression"), |
| ExpectedConstTuple => simple!("expected constant tuple"), |
| ExpectedConstStruct => simple!("expected constant struct"), |
| TupleIndexOutOfBounds => simple!("tuple index out of bounds"), |
| IndexedNonVec => simple!("indexing is only supported for arrays"), |
| IndexNegative => simple!("indices must be non-negative integers"), |
| IndexNotInt => simple!("indices must be integers"), |
| IndexOutOfBounds { len, index } => { |
| simple!("index out of bounds: the len is {} but the index is {}", |
| len, index) |
| } |
| RepeatCountNotNatural => simple!("repeat count must be a natural number"), |
| RepeatCountNotInt => simple!("repeat count must be integers"), |
| |
| MiscBinaryOp => simple!("bad operands for binary"), |
| MiscCatchAll => simple!("unsupported constant expr"), |
| IndexOpFeatureGated => simple!("the index operation on const values is unstable"), |
| Math(ref err) => Simple(err.description().into_cow()), |
| |
| IntermediateUnsignedNegative => simple!( |
| "during the computation of an unsigned a negative \ |
| number was encountered. This is most likely a bug in\ |
| the constant evaluator"), |
| |
| TypeMismatch(ref expected, ref got) => { |
| simple!("expected {}, found {}", expected, got.description()) |
| }, |
| BadType(ref i) => simple!("value of wrong type: {:?}", i), |
| ErroneousReferencedConstant(_) => simple!("could not evaluate referenced constant"), |
| CharCast(ref got) => { |
| simple!("only `u8` can be cast as `char`, not `{}`", got.description()) |
| }, |
| } |
| } |
| } |
| |
| pub type EvalResult = Result<ConstVal, ConstEvalErr>; |
| pub type CastResult = Result<ConstVal, ErrKind>; |
| |
| // FIXME: Long-term, this enum should go away: trying to evaluate |
| // an expression which hasn't been type-checked is a recipe for |
| // disaster. That said, it's not clear how to fix ast_ty_to_ty |
| // to avoid the ordering issue. |
| |
| /// Hint to determine how to evaluate constant expressions which |
| /// might not be type-checked. |
| #[derive(Copy, Clone, Debug)] |
| pub enum EvalHint<'tcx> { |
| /// We have a type-checked expression. |
| ExprTypeChecked, |
| /// We have an expression which hasn't been type-checked, but we have |
| /// an idea of what the type will be because of the context. For example, |
| /// the length of an array is always `usize`. (This is referred to as |
| /// a hint because it isn't guaranteed to be consistent with what |
| /// type-checking would compute.) |
| UncheckedExprHint(Ty<'tcx>), |
| /// We have an expression which has not yet been type-checked, and |
| /// and we have no clue what the type will be. |
| UncheckedExprNoHint, |
| } |
| |
| impl<'tcx> EvalHint<'tcx> { |
| fn erase_hint(&self) -> EvalHint<'tcx> { |
| match *self { |
| ExprTypeChecked => ExprTypeChecked, |
| UncheckedExprHint(_) | UncheckedExprNoHint => UncheckedExprNoHint, |
| } |
| } |
| fn checked_or(&self, ty: Ty<'tcx>) -> EvalHint<'tcx> { |
| match *self { |
| ExprTypeChecked => ExprTypeChecked, |
| _ => UncheckedExprHint(ty), |
| } |
| } |
| } |
| |
| macro_rules! signal { |
| ($e:expr, $exn:expr) => { |
| return Err(ConstEvalErr { span: $e.span, kind: $exn }) |
| } |
| } |
| |
| /// Evaluate a constant expression in a context where the expression isn't |
| /// guaranteed to be evaluatable. `ty_hint` is usually ExprTypeChecked, |
| /// but a few places need to evaluate constants during type-checking, like |
| /// computing the length of an array. (See also the FIXME above EvalHint.) |
| pub fn eval_const_expr_partial<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| e: &Expr, |
| ty_hint: EvalHint<'tcx>, |
| fn_args: FnArgMap) -> EvalResult { |
| // Try to compute the type of the expression based on the EvalHint. |
| // (See also the definition of EvalHint, and the FIXME above EvalHint.) |
| let ety = match ty_hint { |
| ExprTypeChecked => { |
| // After type-checking, expr_ty is guaranteed to succeed. |
| Some(tcx.tables().expr_ty(e)) |
| } |
| UncheckedExprHint(ty) => { |
| // Use the type hint; it's not guaranteed to be right, but it's |
| // usually good enough. |
| Some(ty) |
| } |
| UncheckedExprNoHint => { |
| // This expression might not be type-checked, and we have no hint. |
| // Try to query the context for a type anyway; we might get lucky |
| // (for example, if the expression was imported from another crate). |
| tcx.tables().expr_ty_opt(e) |
| } |
| }; |
| let result = match e.node { |
| hir::ExprUnary(hir::UnNeg, ref inner) => { |
| // unary neg literals already got their sign during creation |
| if let hir::ExprLit(ref lit) = inner.node { |
| use syntax::ast::*; |
| use syntax::ast::LitIntType::*; |
| const I8_OVERFLOW: u64 = ::std::i8::MAX as u64 + 1; |
| const I16_OVERFLOW: u64 = ::std::i16::MAX as u64 + 1; |
| const I32_OVERFLOW: u64 = ::std::i32::MAX as u64 + 1; |
| const I64_OVERFLOW: u64 = ::std::i64::MAX as u64 + 1; |
| match (&lit.node, ety.map(|t| &t.sty)) { |
| (&LitKind::Int(I8_OVERFLOW, Unsuffixed), Some(&ty::TyInt(IntTy::I8))) | |
| (&LitKind::Int(I8_OVERFLOW, Signed(IntTy::I8)), _) => { |
| return Ok(Integral(I8(::std::i8::MIN))) |
| }, |
| (&LitKind::Int(I16_OVERFLOW, Unsuffixed), Some(&ty::TyInt(IntTy::I16))) | |
| (&LitKind::Int(I16_OVERFLOW, Signed(IntTy::I16)), _) => { |
| return Ok(Integral(I16(::std::i16::MIN))) |
| }, |
| (&LitKind::Int(I32_OVERFLOW, Unsuffixed), Some(&ty::TyInt(IntTy::I32))) | |
| (&LitKind::Int(I32_OVERFLOW, Signed(IntTy::I32)), _) => { |
| return Ok(Integral(I32(::std::i32::MIN))) |
| }, |
| (&LitKind::Int(I64_OVERFLOW, Unsuffixed), Some(&ty::TyInt(IntTy::I64))) | |
| (&LitKind::Int(I64_OVERFLOW, Signed(IntTy::I64)), _) => { |
| return Ok(Integral(I64(::std::i64::MIN))) |
| }, |
| (&LitKind::Int(n, Unsuffixed), Some(&ty::TyInt(IntTy::Is))) | |
| (&LitKind::Int(n, Signed(IntTy::Is)), _) => { |
| match tcx.sess.target.int_type { |
| IntTy::I16 => if n == I16_OVERFLOW { |
| return Ok(Integral(Isize(Is16(::std::i16::MIN)))); |
| }, |
| IntTy::I32 => if n == I32_OVERFLOW { |
| return Ok(Integral(Isize(Is32(::std::i32::MIN)))); |
| }, |
| IntTy::I64 => if n == I64_OVERFLOW { |
| return Ok(Integral(Isize(Is64(::std::i64::MIN)))); |
| }, |
| _ => bug!(), |
| } |
| }, |
| _ => {}, |
| } |
| } |
| match eval_const_expr_partial(tcx, &inner, ty_hint, fn_args)? { |
| Float(f) => Float(-f), |
| Integral(i) => Integral(math!(e, -i)), |
| const_val => signal!(e, NegateOn(const_val)), |
| } |
| } |
| hir::ExprUnary(hir::UnNot, ref inner) => { |
| match eval_const_expr_partial(tcx, &inner, ty_hint, fn_args)? { |
| Integral(i) => Integral(math!(e, !i)), |
| Bool(b) => Bool(!b), |
| const_val => signal!(e, NotOn(const_val)), |
| } |
| } |
| hir::ExprUnary(hir::UnDeref, _) => signal!(e, UnimplementedConstVal("deref operation")), |
| hir::ExprBinary(op, ref a, ref b) => { |
| let b_ty = match op.node { |
| hir::BiShl | hir::BiShr => ty_hint.erase_hint(), |
| _ => ty_hint |
| }; |
| // technically, if we don't have type hints, but integral eval |
| // gives us a type through a type-suffix, cast or const def type |
| // we need to re-eval the other value of the BinOp if it was |
| // not inferred |
| match (eval_const_expr_partial(tcx, &a, ty_hint, fn_args)?, |
| eval_const_expr_partial(tcx, &b, b_ty, fn_args)?) { |
| (Float(a), Float(b)) => { |
| use std::cmp::Ordering::*; |
| match op.node { |
| hir::BiAdd => Float(math!(e, a + b)), |
| hir::BiSub => Float(math!(e, a - b)), |
| hir::BiMul => Float(math!(e, a * b)), |
| hir::BiDiv => Float(math!(e, a / b)), |
| hir::BiRem => Float(math!(e, a % b)), |
| hir::BiEq => Bool(math!(e, a.try_cmp(b)) == Equal), |
| hir::BiLt => Bool(math!(e, a.try_cmp(b)) == Less), |
| hir::BiLe => Bool(math!(e, a.try_cmp(b)) != Greater), |
| hir::BiNe => Bool(math!(e, a.try_cmp(b)) != Equal), |
| hir::BiGe => Bool(math!(e, a.try_cmp(b)) != Less), |
| hir::BiGt => Bool(math!(e, a.try_cmp(b)) == Greater), |
| _ => signal!(e, InvalidOpForFloats(op.node)), |
| } |
| } |
| (Integral(a), Integral(b)) => { |
| use std::cmp::Ordering::*; |
| match op.node { |
| hir::BiAdd => Integral(math!(e, a + b)), |
| hir::BiSub => Integral(math!(e, a - b)), |
| hir::BiMul => Integral(math!(e, a * b)), |
| hir::BiDiv => Integral(math!(e, a / b)), |
| hir::BiRem => Integral(math!(e, a % b)), |
| hir::BiBitAnd => Integral(math!(e, a & b)), |
| hir::BiBitOr => Integral(math!(e, a | b)), |
| hir::BiBitXor => Integral(math!(e, a ^ b)), |
| hir::BiShl => Integral(math!(e, a << b)), |
| hir::BiShr => Integral(math!(e, a >> b)), |
| hir::BiEq => Bool(math!(e, a.try_cmp(b)) == Equal), |
| hir::BiLt => Bool(math!(e, a.try_cmp(b)) == Less), |
| hir::BiLe => Bool(math!(e, a.try_cmp(b)) != Greater), |
| hir::BiNe => Bool(math!(e, a.try_cmp(b)) != Equal), |
| hir::BiGe => Bool(math!(e, a.try_cmp(b)) != Less), |
| hir::BiGt => Bool(math!(e, a.try_cmp(b)) == Greater), |
| _ => signal!(e, InvalidOpForInts(op.node)), |
| } |
| } |
| (Bool(a), Bool(b)) => { |
| Bool(match op.node { |
| hir::BiAnd => a && b, |
| hir::BiOr => a || b, |
| hir::BiBitXor => a ^ b, |
| hir::BiBitAnd => a & b, |
| hir::BiBitOr => a | b, |
| hir::BiEq => a == b, |
| hir::BiNe => a != b, |
| hir::BiLt => a < b, |
| hir::BiLe => a <= b, |
| hir::BiGe => a >= b, |
| hir::BiGt => a > b, |
| _ => signal!(e, InvalidOpForBools(op.node)), |
| }) |
| } |
| |
| _ => signal!(e, MiscBinaryOp), |
| } |
| } |
| hir::ExprCast(ref base, ref target_ty) => { |
| let ety = tcx.ast_ty_to_prim_ty(&target_ty).or(ety) |
| .unwrap_or_else(|| { |
| tcx.sess.span_fatal(target_ty.span, |
| "target type not found for const cast") |
| }); |
| |
| let base_hint = if let ExprTypeChecked = ty_hint { |
| ExprTypeChecked |
| } else { |
| match tcx.tables().expr_ty_opt(&base) { |
| Some(t) => UncheckedExprHint(t), |
| None => ty_hint |
| } |
| }; |
| |
| let val = match eval_const_expr_partial(tcx, &base, base_hint, fn_args) { |
| Ok(val) => val, |
| Err(ConstEvalErr { kind: ErroneousReferencedConstant( |
| box ConstEvalErr { kind: TypeMismatch(_, val), .. }), .. }) | |
| Err(ConstEvalErr { kind: TypeMismatch(_, val), .. }) => { |
| // Something like `5i8 as usize` doesn't need a type hint for the base |
| // instead take the type hint from the inner value |
| let hint = match val.int_type() { |
| Some(IntType::UnsignedInt(ty)) => ty_hint.checked_or(tcx.mk_mach_uint(ty)), |
| Some(IntType::SignedInt(ty)) => ty_hint.checked_or(tcx.mk_mach_int(ty)), |
| // we had a type hint, so we can't have an unknown type |
| None => bug!(), |
| }; |
| eval_const_expr_partial(tcx, &base, hint, fn_args)? |
| }, |
| Err(e) => return Err(e), |
| }; |
| match cast_const(tcx, val, ety) { |
| Ok(val) => val, |
| Err(kind) => return Err(ConstEvalErr { span: e.span, kind: kind }), |
| } |
| } |
| hir::ExprPath(..) => { |
| // This function can be used before type checking when not all paths are fully resolved. |
| // FIXME: There's probably a better way to make sure we don't panic here. |
| let resolution = tcx.expect_resolution(e.id); |
| if resolution.depth != 0 { |
| signal!(e, UnresolvedPath); |
| } |
| match resolution.base_def { |
| Def::Const(def_id) | |
| Def::AssociatedConst(def_id) => { |
| let substs = if let ExprTypeChecked = ty_hint { |
| Some(tcx.tables().node_id_item_substs(e.id) |
| .unwrap_or_else(|| tcx.intern_substs(&[]))) |
| } else { |
| None |
| }; |
| if let Some((expr, ty)) = lookup_const_by_id(tcx, def_id, substs) { |
| let item_hint = match ty { |
| Some(ty) => ty_hint.checked_or(ty), |
| None => ty_hint, |
| }; |
| match eval_const_expr_partial(tcx, expr, item_hint, None) { |
| Ok(val) => val, |
| Err(err) => { |
| debug!("bad reference: {:?}, {:?}", err.description(), err.span); |
| signal!(e, ErroneousReferencedConstant(box err)) |
| }, |
| } |
| } else { |
| signal!(e, NonConstPath); |
| } |
| }, |
| Def::VariantCtor(variant_def, ..) => { |
| if let Some(const_expr) = lookup_variant_by_id(tcx, variant_def) { |
| match eval_const_expr_partial(tcx, const_expr, ty_hint, None) { |
| Ok(val) => val, |
| Err(err) => { |
| debug!("bad reference: {:?}, {:?}", err.description(), err.span); |
| signal!(e, ErroneousReferencedConstant(box err)) |
| }, |
| } |
| } else { |
| signal!(e, UnimplementedConstVal("enum variants")); |
| } |
| } |
| Def::StructCtor(..) => { |
| ConstVal::Struct(e.id) |
| } |
| Def::Local(def_id) => { |
| debug!("Def::Local({:?}): {:?}", def_id, fn_args); |
| if let Some(val) = fn_args.and_then(|args| args.get(&def_id)) { |
| val.clone() |
| } else { |
| signal!(e, NonConstPath); |
| } |
| }, |
| Def::Method(id) | Def::Fn(id) => Function(id), |
| _ => signal!(e, NonConstPath), |
| } |
| } |
| hir::ExprCall(ref callee, ref args) => { |
| let sub_ty_hint = ty_hint.erase_hint(); |
| let callee_val = eval_const_expr_partial(tcx, callee, sub_ty_hint, fn_args)?; |
| let did = match callee_val { |
| Function(did) => did, |
| Struct(_) => signal!(e, UnimplementedConstVal("tuple struct constructors")), |
| callee => signal!(e, CallOn(callee)), |
| }; |
| let (decl, result) = if let Some(fn_like) = lookup_const_fn_by_id(tcx, did) { |
| (fn_like.decl(), fn_like.body()) |
| } else { |
| signal!(e, NonConstPath) |
| }; |
| assert_eq!(decl.inputs.len(), args.len()); |
| |
| let mut call_args = DefIdMap(); |
| for (arg, arg_expr) in decl.inputs.iter().zip(args.iter()) { |
| let arg_hint = ty_hint.erase_hint(); |
| let arg_val = eval_const_expr_partial( |
| tcx, |
| arg_expr, |
| arg_hint, |
| fn_args |
| )?; |
| debug!("const call arg: {:?}", arg); |
| let old = call_args.insert(tcx.expect_def(arg.pat.id).def_id(), arg_val); |
| assert!(old.is_none()); |
| } |
| debug!("const call({:?})", call_args); |
| eval_const_expr_partial(tcx, &result, ty_hint, Some(&call_args))? |
| }, |
| hir::ExprLit(ref lit) => match lit_to_const(&lit.node, tcx, ety) { |
| Ok(val) => val, |
| Err(err) => signal!(e, err), |
| }, |
| hir::ExprBlock(ref block) => { |
| match block.expr { |
| Some(ref expr) => eval_const_expr_partial(tcx, &expr, ty_hint, fn_args)?, |
| None => signal!(e, UnimplementedConstVal("empty block")), |
| } |
| } |
| hir::ExprType(ref e, _) => eval_const_expr_partial(tcx, &e, ty_hint, fn_args)?, |
| hir::ExprTup(_) => Tuple(e.id), |
| hir::ExprStruct(..) => Struct(e.id), |
| hir::ExprIndex(ref arr, ref idx) => { |
| if !tcx.sess.features.borrow().const_indexing { |
| signal!(e, IndexOpFeatureGated); |
| } |
| let arr_hint = ty_hint.erase_hint(); |
| let arr = eval_const_expr_partial(tcx, arr, arr_hint, fn_args)?; |
| let idx_hint = ty_hint.checked_or(tcx.types.usize); |
| let idx = match eval_const_expr_partial(tcx, idx, idx_hint, fn_args)? { |
| Integral(Usize(i)) => i.as_u64(tcx.sess.target.uint_type), |
| Integral(_) => bug!(), |
| _ => signal!(idx, IndexNotInt), |
| }; |
| assert_eq!(idx as usize as u64, idx); |
| match arr { |
| Array(_, n) if idx >= n => { |
| signal!(e, IndexOutOfBounds { len: n, index: idx }) |
| } |
| Array(v, n) => if let hir::ExprArray(ref v) = tcx.map.expect_expr(v).node { |
| assert_eq!(n as usize as u64, n); |
| eval_const_expr_partial(tcx, &v[idx as usize], ty_hint, fn_args)? |
| } else { |
| bug!() |
| }, |
| |
| Repeat(_, n) if idx >= n => { |
| signal!(e, IndexOutOfBounds { len: n, index: idx }) |
| } |
| Repeat(elem, _) => eval_const_expr_partial( |
| tcx, |
| &tcx.map.expect_expr(elem), |
| ty_hint, |
| fn_args, |
| )?, |
| |
| ByteStr(ref data) if idx >= data.len() as u64 => { |
| signal!(e, IndexOutOfBounds { len: data.len() as u64, index: idx }) |
| } |
| ByteStr(data) => { |
| Integral(U8(data[idx as usize])) |
| }, |
| |
| _ => signal!(e, IndexedNonVec), |
| } |
| } |
| hir::ExprArray(ref v) => Array(e.id, v.len() as u64), |
| hir::ExprRepeat(_, ref n) => { |
| let len_hint = ty_hint.checked_or(tcx.types.usize); |
| Repeat( |
| e.id, |
| match eval_const_expr_partial(tcx, &n, len_hint, fn_args)? { |
| Integral(Usize(i)) => i.as_u64(tcx.sess.target.uint_type), |
| Integral(_) => signal!(e, RepeatCountNotNatural), |
| _ => signal!(e, RepeatCountNotInt), |
| }, |
| ) |
| }, |
| hir::ExprTupField(ref base, index) => { |
| let base_hint = ty_hint.erase_hint(); |
| let c = eval_const_expr_partial(tcx, base, base_hint, fn_args)?; |
| if let Tuple(tup_id) = c { |
| if let hir::ExprTup(ref fields) = tcx.map.expect_expr(tup_id).node { |
| if index.node < fields.len() { |
| eval_const_expr_partial(tcx, &fields[index.node], ty_hint, fn_args)? |
| } else { |
| signal!(e, TupleIndexOutOfBounds); |
| } |
| } else { |
| bug!() |
| } |
| } else { |
| signal!(base, ExpectedConstTuple); |
| } |
| } |
| hir::ExprField(ref base, field_name) => { |
| let base_hint = ty_hint.erase_hint(); |
| // Get the base expression if it is a struct and it is constant |
| let c = eval_const_expr_partial(tcx, base, base_hint, fn_args)?; |
| if let Struct(struct_id) = c { |
| if let hir::ExprStruct(_, ref fields, _) = tcx.map.expect_expr(struct_id).node { |
| // Check that the given field exists and evaluate it |
| // if the idents are compared run-pass/issue-19244 fails |
| if let Some(f) = fields.iter().find(|f| f.name.node |
| == field_name.node) { |
| eval_const_expr_partial(tcx, &f.expr, ty_hint, fn_args)? |
| } else { |
| signal!(e, MissingStructField); |
| } |
| } else { |
| bug!() |
| } |
| } else { |
| signal!(base, ExpectedConstStruct); |
| } |
| } |
| hir::ExprAddrOf(..) => signal!(e, UnimplementedConstVal("address operator")), |
| _ => signal!(e, MiscCatchAll) |
| }; |
| |
| match (ety.map(|t| &t.sty), result) { |
| (Some(ref ty_hint), Integral(i)) => match infer(i, tcx, ty_hint) { |
| Ok(inferred) => Ok(Integral(inferred)), |
| Err(err) => signal!(e, err), |
| }, |
| (_, result) => Ok(result), |
| } |
| } |
| |
| fn infer<'a, 'tcx>(i: ConstInt, |
| tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| ty_hint: &ty::TypeVariants<'tcx>) |
| -> Result<ConstInt, ErrKind> { |
| use syntax::ast::*; |
| |
| match (ty_hint, i) { |
| (&ty::TyInt(IntTy::I8), result @ I8(_)) => Ok(result), |
| (&ty::TyInt(IntTy::I16), result @ I16(_)) => Ok(result), |
| (&ty::TyInt(IntTy::I32), result @ I32(_)) => Ok(result), |
| (&ty::TyInt(IntTy::I64), result @ I64(_)) => Ok(result), |
| (&ty::TyInt(IntTy::Is), result @ Isize(_)) => Ok(result), |
| |
| (&ty::TyUint(UintTy::U8), result @ U8(_)) => Ok(result), |
| (&ty::TyUint(UintTy::U16), result @ U16(_)) => Ok(result), |
| (&ty::TyUint(UintTy::U32), result @ U32(_)) => Ok(result), |
| (&ty::TyUint(UintTy::U64), result @ U64(_)) => Ok(result), |
| (&ty::TyUint(UintTy::Us), result @ Usize(_)) => Ok(result), |
| |
| (&ty::TyInt(IntTy::I8), Infer(i)) => Ok(I8(i as i64 as i8)), |
| (&ty::TyInt(IntTy::I16), Infer(i)) => Ok(I16(i as i64 as i16)), |
| (&ty::TyInt(IntTy::I32), Infer(i)) => Ok(I32(i as i64 as i32)), |
| (&ty::TyInt(IntTy::I64), Infer(i)) => Ok(I64(i as i64)), |
| (&ty::TyInt(IntTy::Is), Infer(i)) => { |
| Ok(Isize(ConstIsize::new_truncating(i as i64, tcx.sess.target.int_type))) |
| }, |
| |
| (&ty::TyInt(IntTy::I8), InferSigned(i)) => Ok(I8(i as i8)), |
| (&ty::TyInt(IntTy::I16), InferSigned(i)) => Ok(I16(i as i16)), |
| (&ty::TyInt(IntTy::I32), InferSigned(i)) => Ok(I32(i as i32)), |
| (&ty::TyInt(IntTy::I64), InferSigned(i)) => Ok(I64(i)), |
| (&ty::TyInt(IntTy::Is), InferSigned(i)) => { |
| Ok(Isize(ConstIsize::new_truncating(i, tcx.sess.target.int_type))) |
| }, |
| |
| (&ty::TyUint(UintTy::U8), Infer(i)) => Ok(U8(i as u8)), |
| (&ty::TyUint(UintTy::U16), Infer(i)) => Ok(U16(i as u16)), |
| (&ty::TyUint(UintTy::U32), Infer(i)) => Ok(U32(i as u32)), |
| (&ty::TyUint(UintTy::U64), Infer(i)) => Ok(U64(i)), |
| (&ty::TyUint(UintTy::Us), Infer(i)) => { |
| Ok(Usize(ConstUsize::new_truncating(i, tcx.sess.target.uint_type))) |
| }, |
| (&ty::TyUint(_), InferSigned(_)) => Err(IntermediateUnsignedNegative), |
| |
| (&ty::TyInt(ity), i) => Err(TypeMismatch(ity.to_string(), i)), |
| (&ty::TyUint(ity), i) => Err(TypeMismatch(ity.to_string(), i)), |
| |
| (&ty::TyAdt(adt, _), i) if adt.is_enum() => { |
| let hints = tcx.lookup_repr_hints(adt.did); |
| let int_ty = tcx.enum_repr_type(hints.iter().next()); |
| infer(i, tcx, &int_ty.to_ty(tcx).sty) |
| }, |
| (_, i) => Err(BadType(ConstVal::Integral(i))), |
| } |
| } |
| |
| fn resolve_trait_associated_const<'a, 'tcx: 'a>(tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| ti: &'tcx hir::TraitItem, |
| trait_id: DefId, |
| rcvr_substs: &'tcx Substs<'tcx>) |
| -> Option<(&'tcx Expr, Option<ty::Ty<'tcx>>)> |
| { |
| let trait_ref = ty::Binder(ty::TraitRef::new(trait_id, rcvr_substs)); |
| debug!("resolve_trait_associated_const: trait_ref={:?}", |
| trait_ref); |
| |
| tcx.populate_implementations_for_trait_if_necessary(trait_id); |
| tcx.infer_ctxt(None, None, Reveal::NotSpecializable).enter(|infcx| { |
| let mut selcx = traits::SelectionContext::new(&infcx); |
| let obligation = traits::Obligation::new(traits::ObligationCause::dummy(), |
| trait_ref.to_poly_trait_predicate()); |
| let selection = match selcx.select(&obligation) { |
| Ok(Some(vtable)) => vtable, |
| // Still ambiguous, so give up and let the caller decide whether this |
| // expression is really needed yet. Some associated constant values |
| // can't be evaluated until monomorphization is done in trans. |
| Ok(None) => { |
| return None |
| } |
| Err(_) => { |
| return None |
| } |
| }; |
| |
| // NOTE: this code does not currently account for specialization, but when |
| // it does so, it should hook into the Reveal to determine when the |
| // constant should resolve; this will also require plumbing through to this |
| // function whether we are in "trans mode" to pick the right Reveal |
| // when constructing the inference context above. |
| match selection { |
| traits::VtableImpl(ref impl_data) => { |
| let ac = tcx.associated_items(impl_data.impl_def_id) |
| .find(|item| item.kind == ty::AssociatedKind::Const && item.name == ti.name); |
| match ac { |
| Some(ic) => lookup_const_by_id(tcx, ic.def_id, None), |
| None => match ti.node { |
| hir::ConstTraitItem(ref ty, Some(ref expr)) => { |
| Some((&*expr, tcx.ast_ty_to_prim_ty(ty))) |
| }, |
| _ => None, |
| }, |
| } |
| } |
| _ => { |
| span_bug!(ti.span, |
| "resolve_trait_associated_const: unexpected vtable type") |
| } |
| } |
| }) |
| } |
| |
| fn cast_const_int<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, val: ConstInt, ty: ty::Ty) -> CastResult { |
| let v = val.to_u64_unchecked(); |
| match ty.sty { |
| ty::TyBool if v == 0 => Ok(Bool(false)), |
| ty::TyBool if v == 1 => Ok(Bool(true)), |
| ty::TyInt(ast::IntTy::I8) => Ok(Integral(I8(v as i64 as i8))), |
| ty::TyInt(ast::IntTy::I16) => Ok(Integral(I16(v as i64 as i16))), |
| ty::TyInt(ast::IntTy::I32) => Ok(Integral(I32(v as i64 as i32))), |
| ty::TyInt(ast::IntTy::I64) => Ok(Integral(I64(v as i64))), |
| ty::TyInt(ast::IntTy::Is) => { |
| Ok(Integral(Isize(ConstIsize::new_truncating(v as i64, tcx.sess.target.int_type)))) |
| }, |
| ty::TyUint(ast::UintTy::U8) => Ok(Integral(U8(v as u8))), |
| ty::TyUint(ast::UintTy::U16) => Ok(Integral(U16(v as u16))), |
| ty::TyUint(ast::UintTy::U32) => Ok(Integral(U32(v as u32))), |
| ty::TyUint(ast::UintTy::U64) => Ok(Integral(U64(v))), |
| ty::TyUint(ast::UintTy::Us) => { |
| Ok(Integral(Usize(ConstUsize::new_truncating(v, tcx.sess.target.uint_type)))) |
| }, |
| ty::TyFloat(ast::FloatTy::F64) => match val.erase_type() { |
| Infer(u) => Ok(Float(F64(u as f64))), |
| InferSigned(i) => Ok(Float(F64(i as f64))), |
| _ => bug!("ConstInt::erase_type returned something other than Infer/InferSigned"), |
| }, |
| ty::TyFloat(ast::FloatTy::F32) => match val.erase_type() { |
| Infer(u) => Ok(Float(F32(u as f32))), |
| InferSigned(i) => Ok(Float(F32(i as f32))), |
| _ => bug!("ConstInt::erase_type returned something other than Infer/InferSigned"), |
| }, |
| ty::TyRawPtr(_) => Err(ErrKind::UnimplementedConstVal("casting an address to a raw ptr")), |
| ty::TyChar => match infer(val, tcx, &ty::TyUint(ast::UintTy::U8)) { |
| Ok(U8(u)) => Ok(Char(u as char)), |
| // can only occur before typeck, typeck blocks `T as char` for `T` != `u8` |
| _ => Err(CharCast(val)), |
| }, |
| _ => Err(CannotCast), |
| } |
| } |
| |
| fn cast_const_float<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| val: ConstFloat, |
| ty: ty::Ty) -> CastResult { |
| match ty.sty { |
| ty::TyInt(_) | ty::TyUint(_) => { |
| let i = match val { |
| F32(f) if f >= 0.0 => Infer(f as u64), |
| FInfer { f64: f, .. } | |
| F64(f) if f >= 0.0 => Infer(f as u64), |
| |
| F32(f) => InferSigned(f as i64), |
| FInfer { f64: f, .. } | |
| F64(f) => InferSigned(f as i64) |
| }; |
| |
| if let (InferSigned(_), &ty::TyUint(_)) = (i, &ty.sty) { |
| return Err(CannotCast); |
| } |
| |
| cast_const_int(tcx, i, ty) |
| } |
| ty::TyFloat(ast::FloatTy::F64) => Ok(Float(F64(match val { |
| F32(f) => f as f64, |
| FInfer { f64: f, .. } | F64(f) => f |
| }))), |
| ty::TyFloat(ast::FloatTy::F32) => Ok(Float(F32(match val { |
| F64(f) => f as f32, |
| FInfer { f32: f, .. } | F32(f) => f |
| }))), |
| _ => Err(CannotCast), |
| } |
| } |
| |
| fn cast_const<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, val: ConstVal, ty: ty::Ty) -> CastResult { |
| match val { |
| Integral(i) => cast_const_int(tcx, i, ty), |
| Bool(b) => cast_const_int(tcx, Infer(b as u64), ty), |
| Float(f) => cast_const_float(tcx, f, ty), |
| Char(c) => cast_const_int(tcx, Infer(c as u64), ty), |
| Function(_) => Err(UnimplementedConstVal("casting fn pointers")), |
| ByteStr(b) => match ty.sty { |
| ty::TyRawPtr(_) => { |
| Err(ErrKind::UnimplementedConstVal("casting a bytestr to a raw ptr")) |
| }, |
| ty::TyRef(_, ty::TypeAndMut { ref ty, mutbl: hir::MutImmutable }) => match ty.sty { |
| ty::TyArray(ty, n) if ty == tcx.types.u8 && n == b.len() => Ok(ByteStr(b)), |
| ty::TySlice(_) => { |
| Err(ErrKind::UnimplementedConstVal("casting a bytestr to slice")) |
| }, |
| _ => Err(CannotCast), |
| }, |
| _ => Err(CannotCast), |
| }, |
| Str(s) => match ty.sty { |
| ty::TyRawPtr(_) => Err(ErrKind::UnimplementedConstVal("casting a str to a raw ptr")), |
| ty::TyRef(_, ty::TypeAndMut { ref ty, mutbl: hir::MutImmutable }) => match ty.sty { |
| ty::TyStr => Ok(Str(s)), |
| _ => Err(CannotCast), |
| }, |
| _ => Err(CannotCast), |
| }, |
| _ => Err(CannotCast), |
| } |
| } |
| |
| fn lit_to_const<'a, 'tcx>(lit: &ast::LitKind, |
| tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| ty_hint: Option<Ty<'tcx>>) |
| -> Result<ConstVal, ErrKind> { |
| use syntax::ast::*; |
| use syntax::ast::LitIntType::*; |
| match *lit { |
| LitKind::Str(ref s, _) => Ok(Str(s.as_str())), |
| LitKind::ByteStr(ref data) => Ok(ByteStr(data.clone())), |
| LitKind::Byte(n) => Ok(Integral(U8(n))), |
| LitKind::Int(n, Signed(ity)) => { |
| infer(InferSigned(n as i64), tcx, &ty::TyInt(ity)).map(Integral) |
| }, |
| |
| LitKind::Int(n, Unsuffixed) => { |
| match ty_hint.map(|t| &t.sty) { |
| Some(&ty::TyInt(ity)) => { |
| infer(InferSigned(n as i64), tcx, &ty::TyInt(ity)).map(Integral) |
| }, |
| Some(&ty::TyUint(uty)) => { |
| infer(Infer(n), tcx, &ty::TyUint(uty)).map(Integral) |
| }, |
| None => Ok(Integral(Infer(n))), |
| Some(&ty::TyAdt(adt, _)) => { |
| let hints = tcx.lookup_repr_hints(adt.did); |
| let int_ty = tcx.enum_repr_type(hints.iter().next()); |
| infer(Infer(n), tcx, &int_ty.to_ty(tcx).sty).map(Integral) |
| }, |
| Some(ty_hint) => bug!("bad ty_hint: {:?}, {:?}", ty_hint, lit), |
| } |
| }, |
| LitKind::Int(n, Unsigned(ity)) => { |
| infer(Infer(n), tcx, &ty::TyUint(ity)).map(Integral) |
| }, |
| |
| LitKind::Float(n, fty) => { |
| parse_float(&n.as_str(), Some(fty)).map(Float) |
| } |
| LitKind::FloatUnsuffixed(n) => { |
| let fty_hint = match ty_hint.map(|t| &t.sty) { |
| Some(&ty::TyFloat(fty)) => Some(fty), |
| _ => None |
| }; |
| parse_float(&n.as_str(), fty_hint).map(Float) |
| } |
| LitKind::Bool(b) => Ok(Bool(b)), |
| LitKind::Char(c) => Ok(Char(c)), |
| } |
| } |
| |
| fn parse_float(num: &str, fty_hint: Option<ast::FloatTy>) |
| -> Result<ConstFloat, ErrKind> { |
| let val = match fty_hint { |
| Some(ast::FloatTy::F32) => num.parse::<f32>().map(F32), |
| Some(ast::FloatTy::F64) => num.parse::<f64>().map(F64), |
| None => { |
| num.parse::<f32>().and_then(|f32| { |
| num.parse::<f64>().map(|f64| { |
| FInfer { f32: f32, f64: f64 } |
| }) |
| }) |
| } |
| }; |
| val.map_err(|_| { |
| // FIXME(#31407) this is only necessary because float parsing is buggy |
| UnimplementedConstVal("could not evaluate float literal (see issue #31407)") |
| }) |
| } |
| |
| pub fn compare_const_vals(tcx: TyCtxt, span: Span, a: &ConstVal, b: &ConstVal) |
| -> Result<Ordering, ErrorReported> |
| { |
| let result = match (a, b) { |
| (&Integral(a), &Integral(b)) => a.try_cmp(b).ok(), |
| (&Float(a), &Float(b)) => a.try_cmp(b).ok(), |
| (&Str(ref a), &Str(ref b)) => Some(a.cmp(b)), |
| (&Bool(a), &Bool(b)) => Some(a.cmp(&b)), |
| (&ByteStr(ref a), &ByteStr(ref b)) => Some(a.cmp(b)), |
| (&Char(a), &Char(ref b)) => Some(a.cmp(b)), |
| _ => None, |
| }; |
| |
| match result { |
| Some(result) => Ok(result), |
| None => { |
| // FIXME: can this ever be reached? |
| span_err!(tcx.sess, span, E0298, |
| "type mismatch comparing {} and {}", |
| a.description(), |
| b.description()); |
| Err(ErrorReported) |
| } |
| } |
| } |
| |
| pub fn compare_lit_exprs<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| span: Span, |
| a: &Expr, |
| b: &Expr) -> Result<Ordering, ErrorReported> { |
| let a = match eval_const_expr_partial(tcx, a, ExprTypeChecked, None) { |
| Ok(a) => a, |
| Err(e) => { |
| report_const_eval_err(tcx, &e, a.span, "expression").emit(); |
| return Err(ErrorReported); |
| } |
| }; |
| let b = match eval_const_expr_partial(tcx, b, ExprTypeChecked, None) { |
| Ok(b) => b, |
| Err(e) => { |
| report_const_eval_err(tcx, &e, b.span, "expression").emit(); |
| return Err(ErrorReported); |
| } |
| }; |
| compare_const_vals(tcx, span, &a, &b) |
| } |
| |
| |
| /// Returns the value of the length-valued expression |
| pub fn eval_length<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| count_expr: &hir::Expr, |
| reason: &str) |
| -> Result<usize, ErrorReported> |
| { |
| let hint = UncheckedExprHint(tcx.types.usize); |
| match eval_const_expr_partial(tcx, count_expr, hint, None) { |
| Ok(Integral(Usize(count))) => { |
| let val = count.as_u64(tcx.sess.target.uint_type); |
| assert_eq!(val as usize as u64, val); |
| Ok(val as usize) |
| }, |
| Ok(const_val) => { |
| struct_span_err!(tcx.sess, count_expr.span, E0306, |
| "expected `usize` for {}, found {}", |
| reason, |
| const_val.description()) |
| .span_label(count_expr.span, &format!("expected `usize`")) |
| .emit(); |
| |
| Err(ErrorReported) |
| } |
| Err(err) => { |
| let mut diag = report_const_eval_err( |
| tcx, &err, count_expr.span, reason); |
| |
| match count_expr.node { |
| hir::ExprPath(None, hir::Path { |
| global: false, |
| ref segments, |
| .. |
| }) if segments.len() == 1 => { |
| if let Some(Def::Local(..)) = tcx.expect_def_or_none(count_expr.id) { |
| diag.note(&format!("`{}` is a variable", segments[0].name)); |
| } |
| } |
| _ => {} |
| } |
| |
| diag.emit(); |
| Err(ErrorReported) |
| } |
| } |
| } |
