| // Copyright 2012-2015 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 self::ConstVal::*; |
| use self::ErrKind::*; |
| use self::EvalHint::*; |
| |
| use front::map as ast_map; |
| use front::map::blocks::FnLikeNode; |
| use middle::cstore::{self, CrateStore, InlinedItem}; |
| use middle::{infer, subst, traits}; |
| use middle::def::Def; |
| use middle::subst::Subst; |
| use middle::def_id::DefId; |
| use middle::pat_util::def_to_path; |
| use middle::ty::{self, Ty}; |
| use middle::astconv_util::ast_ty_to_prim_ty; |
| use util::num::ToPrimitive; |
| use util::nodemap::NodeMap; |
| use session::Session; |
| |
| use graphviz::IntoCow; |
| use syntax::ast; |
| use rustc_front::hir::Expr; |
| use rustc_front::hir; |
| use rustc_front::intravisit::FnKind; |
| use syntax::codemap::Span; |
| use syntax::parse::token::InternedString; |
| use syntax::ptr::P; |
| use syntax::codemap; |
| |
| use std::borrow::Cow; |
| use std::cmp::Ordering; |
| use std::collections::hash_map::Entry::Vacant; |
| use std::hash; |
| use std::mem::transmute; |
| use std::{i8, i16, i32, i64, u8, u16, u32, u64}; |
| use std::rc::Rc; |
| |
| fn lookup_variant_by_id<'a>(tcx: &'a ty::ctxt, |
| enum_def: DefId, |
| variant_def: DefId) |
| -> Option<&'a 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(enum_node_id) = tcx.map.as_local_node_id(enum_def) { |
| let variant_node_id = tcx.map.as_local_node_id(variant_def).unwrap(); |
| 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. |
| /// * `maybe_ref_id` is the id of the expr referencing the constant. |
| /// * `param_substs` is the monomorphization substitution for the expression. |
| /// |
| /// `maybe_ref_id` and `param_substs` are optional and are used for |
| /// finding substitutions in associated constants. This generally |
| /// happens in late/trans const evaluation. |
| pub fn lookup_const_by_id<'a, 'tcx: 'a>(tcx: &'a ty::ctxt<'tcx>, |
| def_id: DefId, |
| maybe_ref_id: Option<ast::NodeId>, |
| param_substs: Option<&'tcx subst::Substs<'tcx>>) |
| -> Option<&'tcx Expr> { |
| 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 const_expr) => { |
| Some(&*const_expr) |
| } |
| _ => None |
| }, |
| Some(ast_map::NodeTraitItem(ti)) => match ti.node { |
| hir::ConstTraitItem(_, _) => { |
| match maybe_ref_id { |
| // If we have a trait item, and we know the expression |
| // that's the source of the obligation to resolve it, |
| // `resolve_trait_associated_const` will select an impl |
| // or the default. |
| Some(ref_id) => { |
| let trait_id = tcx.trait_of_item(def_id) |
| .unwrap(); |
| let mut substs = tcx.node_id_item_substs(ref_id) |
| .substs; |
| if let Some(param_substs) = param_substs { |
| substs = substs.subst(tcx, param_substs); |
| } |
| resolve_trait_associated_const(tcx, ti, trait_id, |
| substs) |
| } |
| // 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 |
| } |
| } |
| _ => None |
| }, |
| Some(ast_map::NodeImplItem(ii)) => match ii.node { |
| hir::ImplItemKind::Const(_, ref expr) => { |
| Some(&*expr) |
| } |
| _ => None |
| }, |
| Some(_) => None |
| } |
| } else { |
| match tcx.extern_const_statics.borrow().get(&def_id) { |
| Some(&ast::DUMMY_NODE_ID) => return None, |
| Some(&expr_id) => { |
| return Some(tcx.map.expect_expr(expr_id)); |
| } |
| None => {} |
| } |
| let mut used_ref_id = false; |
| let expr_id = match tcx.sess.cstore.maybe_get_item_ast(tcx, def_id) { |
| cstore::FoundAst::Found(&InlinedItem::Item(ref item)) => match item.node { |
| hir::ItemConst(_, ref const_expr) => Some(const_expr.id), |
| _ => None |
| }, |
| cstore::FoundAst::Found(&InlinedItem::TraitItem(trait_id, ref ti)) => match ti.node { |
| hir::ConstTraitItem(_, _) => { |
| used_ref_id = true; |
| match maybe_ref_id { |
| // 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 expression that refers to it. |
| Some(ref_id) => { |
| let mut substs = tcx.node_id_item_substs(ref_id) |
| .substs; |
| if let Some(param_substs) = param_substs { |
| substs = substs.subst(tcx, param_substs); |
| } |
| resolve_trait_associated_const(tcx, ti, trait_id, |
| substs).map(|e| e.id) |
| } |
| None => None |
| } |
| } |
| _ => None |
| }, |
| cstore::FoundAst::Found(&InlinedItem::ImplItem(_, ref ii)) => match ii.node { |
| hir::ImplItemKind::Const(_, ref expr) => Some(expr.id), |
| _ => None |
| }, |
| _ => None |
| }; |
| // If we used the reference expression, 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_ref_id { |
| tcx.extern_const_statics |
| .borrow_mut().insert(def_id, |
| expr_id.unwrap_or(ast::DUMMY_NODE_ID)); |
| } |
| expr_id.map(|id| tcx.map.expect_expr(id)) |
| } |
| } |
| |
| fn inline_const_fn_from_external_crate(tcx: &ty::ctxt, 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) { |
| cstore::FoundAst::Found(&InlinedItem::Item(ref item)) => Some(item.id), |
| cstore::FoundAst::Found(&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<'tcx>(tcx: &ty::ctxt<'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 |
| } |
| } |
| |
| #[derive(Clone, Debug, RustcEncodable, RustcDecodable)] |
| pub enum ConstVal { |
| Float(f64), |
| Int(i64), |
| Uint(u64), |
| Str(InternedString), |
| ByteStr(Rc<Vec<u8>>), |
| Bool(bool), |
| Struct(ast::NodeId), |
| Tuple(ast::NodeId), |
| Function(DefId), |
| Array(ast::NodeId, u64), |
| Repeat(ast::NodeId, u64), |
| } |
| |
| impl hash::Hash for ConstVal { |
| fn hash<H: hash::Hasher>(&self, state: &mut H) { |
| match *self { |
| Float(a) => unsafe { transmute::<_,u64>(a) }.hash(state), |
| Int(a) => a.hash(state), |
| Uint(a) => a.hash(state), |
| Str(ref a) => a.hash(state), |
| ByteStr(ref a) => a.hash(state), |
| Bool(a) => a.hash(state), |
| Struct(a) => a.hash(state), |
| Tuple(a) => a.hash(state), |
| Function(a) => a.hash(state), |
| Array(a, n) => { a.hash(state); n.hash(state) }, |
| Repeat(a, n) => { a.hash(state); n.hash(state) }, |
| } |
| } |
| } |
| |
| /// Note that equality for `ConstVal` means that the it is the same |
| /// constant, not that the rust values are equal. In particular, `NaN |
| /// == NaN` (at least if it's the same NaN; distinct encodings for NaN |
| /// are considering unequal). |
| impl PartialEq for ConstVal { |
| fn eq(&self, other: &ConstVal) -> bool { |
| match (self, other) { |
| (&Float(a), &Float(b)) => unsafe{transmute::<_,u64>(a) == transmute::<_,u64>(b)}, |
| (&Int(a), &Int(b)) => a == b, |
| (&Uint(a), &Uint(b)) => a == b, |
| (&Str(ref a), &Str(ref b)) => a == b, |
| (&ByteStr(ref a), &ByteStr(ref b)) => a == b, |
| (&Bool(a), &Bool(b)) => a == b, |
| (&Struct(a), &Struct(b)) => a == b, |
| (&Tuple(a), &Tuple(b)) => a == b, |
| (&Function(a), &Function(b)) => a == b, |
| (&Array(a, an), &Array(b, bn)) => (a == b) && (an == bn), |
| (&Repeat(a, an), &Repeat(b, bn)) => (a == b) && (an == bn), |
| _ => false, |
| } |
| } |
| } |
| |
| impl Eq for ConstVal { } |
| |
| impl ConstVal { |
| pub fn description(&self) -> &'static str { |
| match *self { |
| Float(_) => "float", |
| Int(i) if i < 0 => "negative integer", |
| Int(_) => "positive integer", |
| Uint(_) => "unsigned integer", |
| Str(_) => "string literal", |
| ByteStr(_) => "byte string literal", |
| Bool(_) => "boolean", |
| Struct(_) => "struct", |
| Tuple(_) => "tuple", |
| Function(_) => "function definition", |
| Array(..) => "array", |
| Repeat(..) => "repeat", |
| } |
| } |
| } |
| |
| pub fn const_expr_to_pat(tcx: &ty::ctxt, expr: &Expr, span: Span) -> P<hir::Pat> { |
| let pat = match expr.node { |
| hir::ExprTup(ref exprs) => |
| hir::PatTup(exprs.iter().map(|expr| const_expr_to_pat(tcx, &**expr, span)).collect()), |
| |
| hir::ExprCall(ref callee, ref args) => { |
| let def = *tcx.def_map.borrow().get(&callee.id).unwrap(); |
| if let Vacant(entry) = tcx.def_map.borrow_mut().entry(expr.id) { |
| entry.insert(def); |
| } |
| let path = match def.full_def() { |
| Def::Struct(def_id) => def_to_path(tcx, def_id), |
| Def::Variant(_, variant_did) => def_to_path(tcx, variant_did), |
| Def::Fn(..) => return P(hir::Pat { |
| id: expr.id, |
| node: hir::PatLit(P(expr.clone())), |
| span: span, |
| }), |
| _ => unreachable!() |
| }; |
| let pats = args.iter().map(|expr| const_expr_to_pat(tcx, &**expr, span)).collect(); |
| hir::PatEnum(path, Some(pats)) |
| } |
| |
| hir::ExprStruct(ref path, ref fields, None) => { |
| let field_pats = fields.iter().map(|field| codemap::Spanned { |
| span: codemap::DUMMY_SP, |
| node: hir::FieldPat { |
| name: field.name.node, |
| pat: const_expr_to_pat(tcx, &*field.expr, span), |
| is_shorthand: false, |
| }, |
| }).collect(); |
| hir::PatStruct(path.clone(), field_pats, false) |
| } |
| |
| hir::ExprVec(ref exprs) => { |
| let pats = exprs.iter().map(|expr| const_expr_to_pat(tcx, &**expr, span)).collect(); |
| hir::PatVec(pats, None, hir::HirVec::new()) |
| } |
| |
| hir::ExprPath(_, ref path) => { |
| let opt_def = tcx.def_map.borrow().get(&expr.id).map(|d| d.full_def()); |
| match opt_def { |
| Some(Def::Struct(..)) => |
| hir::PatStruct(path.clone(), hir::HirVec::new(), false), |
| Some(Def::Variant(..)) => |
| hir::PatEnum(path.clone(), None), |
| Some(Def::Const(def_id)) | |
| Some(Def::AssociatedConst(def_id)) => { |
| let expr = lookup_const_by_id(tcx, def_id, Some(expr.id), None).unwrap(); |
| return const_expr_to_pat(tcx, expr, span); |
| }, |
| _ => unreachable!(), |
| } |
| } |
| |
| _ => hir::PatLit(P(expr.clone())) |
| }; |
| P(hir::Pat { id: expr.id, node: pat, span: span }) |
| } |
| |
| pub fn eval_const_expr(tcx: &ty::ctxt, e: &Expr) -> ConstVal { |
| match eval_const_expr_partial(tcx, e, ExprTypeChecked, None) { |
| Ok(r) => r, |
| Err(s) => tcx.sess.span_fatal(s.span, &s.description()) |
| } |
| } |
| |
| pub type FnArgMap<'a> = Option<&'a NodeMap<ConstVal>>; |
| |
| #[derive(Clone)] |
| pub struct ConstEvalErr { |
| pub span: Span, |
| pub kind: ErrKind, |
| } |
| |
| #[derive(Clone)] |
| pub enum ErrKind { |
| CannotCast, |
| CannotCastTo(&'static str), |
| InvalidOpForInts(hir::BinOp_), |
| InvalidOpForUInts(hir::BinOp_), |
| InvalidOpForBools(hir::BinOp_), |
| InvalidOpForFloats(hir::BinOp_), |
| InvalidOpForIntUint(hir::BinOp_), |
| InvalidOpForUintInt(hir::BinOp_), |
| NegateOn(ConstVal), |
| NotOn(ConstVal), |
| CallOn(ConstVal), |
| |
| NegateWithOverflow(i64), |
| AddiWithOverflow(i64, i64), |
| SubiWithOverflow(i64, i64), |
| MuliWithOverflow(i64, i64), |
| AdduWithOverflow(u64, u64), |
| SubuWithOverflow(u64, u64), |
| MuluWithOverflow(u64, u64), |
| DivideByZero, |
| DivideWithOverflow, |
| ModuloByZero, |
| ModuloWithOverflow, |
| ShiftLeftWithOverflow, |
| ShiftRightWithOverflow, |
| MissingStructField, |
| NonConstPath, |
| UnimplementedConstVal(&'static str), |
| UnresolvedPath, |
| ExpectedConstTuple, |
| ExpectedConstStruct, |
| TupleIndexOutOfBounds, |
| IndexedNonVec, |
| IndexNegative, |
| IndexNotInt, |
| IndexOutOfBounds, |
| RepeatCountNotNatural, |
| RepeatCountNotInt, |
| |
| MiscBinaryOp, |
| MiscCatchAll, |
| |
| IndexOpFeatureGated, |
| } |
| |
| impl ConstEvalErr { |
| pub fn description(&self) -> Cow<str> { |
| use self::ErrKind::*; |
| |
| match self.kind { |
| CannotCast => "can't cast this type".into_cow(), |
| CannotCastTo(s) => format!("can't cast this type to {}", s).into_cow(), |
| InvalidOpForInts(_) => "can't do this op on signed integrals".into_cow(), |
| InvalidOpForUInts(_) => "can't do this op on unsigned integrals".into_cow(), |
| InvalidOpForBools(_) => "can't do this op on bools".into_cow(), |
| InvalidOpForFloats(_) => "can't do this op on floats".into_cow(), |
| InvalidOpForIntUint(..) => "can't do this op on an isize and usize".into_cow(), |
| InvalidOpForUintInt(..) => "can't do this op on a usize and isize".into_cow(), |
| NegateOn(ref const_val) => format!("negate on {}", const_val.description()).into_cow(), |
| NotOn(ref const_val) => format!("not on {}", const_val.description()).into_cow(), |
| CallOn(ref const_val) => format!("call on {}", const_val.description()).into_cow(), |
| |
| NegateWithOverflow(..) => "attempted to negate with overflow".into_cow(), |
| AddiWithOverflow(..) => "attempted to add with overflow".into_cow(), |
| SubiWithOverflow(..) => "attempted to sub with overflow".into_cow(), |
| MuliWithOverflow(..) => "attempted to mul with overflow".into_cow(), |
| AdduWithOverflow(..) => "attempted to add with overflow".into_cow(), |
| SubuWithOverflow(..) => "attempted to sub with overflow".into_cow(), |
| MuluWithOverflow(..) => "attempted to mul with overflow".into_cow(), |
| DivideByZero => "attempted to divide by zero".into_cow(), |
| DivideWithOverflow => "attempted to divide with overflow".into_cow(), |
| ModuloByZero => "attempted remainder with a divisor of zero".into_cow(), |
| ModuloWithOverflow => "attempted remainder with overflow".into_cow(), |
| ShiftLeftWithOverflow => "attempted left shift with overflow".into_cow(), |
| ShiftRightWithOverflow => "attempted right shift with overflow".into_cow(), |
| MissingStructField => "nonexistent struct field".into_cow(), |
| NonConstPath => "non-constant path in constant expression".into_cow(), |
| UnimplementedConstVal(what) => |
| format!("unimplemented constant expression: {}", what).into_cow(), |
| UnresolvedPath => "unresolved path in constant expression".into_cow(), |
| ExpectedConstTuple => "expected constant tuple".into_cow(), |
| ExpectedConstStruct => "expected constant struct".into_cow(), |
| TupleIndexOutOfBounds => "tuple index out of bounds".into_cow(), |
| IndexedNonVec => "indexing is only supported for arrays".into_cow(), |
| IndexNegative => "indices must be non-negative integers".into_cow(), |
| IndexNotInt => "indices must be integers".into_cow(), |
| IndexOutOfBounds => "array index out of bounds".into_cow(), |
| RepeatCountNotNatural => "repeat count must be a natural number".into_cow(), |
| RepeatCountNotInt => "repeat count must be integers".into_cow(), |
| |
| MiscBinaryOp => "bad operands for binary".into_cow(), |
| MiscCatchAll => "unsupported constant expr".into_cow(), |
| IndexOpFeatureGated => "the index operation on const values is unstable".into_cow(), |
| } |
| } |
| } |
| |
| 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), |
| } |
| } |
| } |
| |
| #[derive(Copy, Clone, PartialEq, Debug)] |
| pub enum IntTy { I8, I16, I32, I64 } |
| #[derive(Copy, Clone, PartialEq, Debug)] |
| pub enum UintTy { U8, U16, U32, U64 } |
| |
| impl IntTy { |
| pub fn from(tcx: &ty::ctxt, t: ast::IntTy) -> IntTy { |
| let t = if let ast::IntTy::Is = t { |
| tcx.sess.target.int_type |
| } else { |
| t |
| }; |
| match t { |
| ast::IntTy::Is => unreachable!(), |
| ast::IntTy::I8 => IntTy::I8, |
| ast::IntTy::I16 => IntTy::I16, |
| ast::IntTy::I32 => IntTy::I32, |
| ast::IntTy::I64 => IntTy::I64, |
| } |
| } |
| } |
| |
| impl UintTy { |
| pub fn from(tcx: &ty::ctxt, t: ast::UintTy) -> UintTy { |
| let t = if let ast::UintTy::Us = t { |
| tcx.sess.target.uint_type |
| } else { |
| t |
| }; |
| match t { |
| ast::UintTy::Us => unreachable!(), |
| ast::UintTy::U8 => UintTy::U8, |
| ast::UintTy::U16 => UintTy::U16, |
| ast::UintTy::U32 => UintTy::U32, |
| ast::UintTy::U64 => UintTy::U64, |
| } |
| } |
| } |
| |
| macro_rules! signal { |
| ($e:expr, $exn:expr) => { |
| return Err(ConstEvalErr { span: $e.span, kind: $exn }) |
| } |
| } |
| |
| // The const_{int,uint}_checked_{neg,add,sub,mul,div,shl,shr} family |
| // of functions catch and signal overflow errors during constant |
| // evaluation. |
| // |
| // They all take the operator's arguments (`a` and `b` if binary), the |
| // overall expression (`e`) and, if available, whole expression's |
| // concrete type (`opt_ety`). |
| // |
| // If the whole expression's concrete type is None, then this is a |
| // constant evaluation happening before type check (e.g. in the check |
| // to confirm that a pattern range's left-side is not greater than its |
| // right-side). We do not do arithmetic modulo the type's bitwidth in |
| // such a case; we just do 64-bit arithmetic and assume that later |
| // passes will do it again with the type information, and thus do the |
| // overflow checks then. |
| |
| pub fn const_int_checked_neg<'a>( |
| a: i64, e: &'a Expr, opt_ety: Option<IntTy>) -> EvalResult { |
| |
| let (min,max) = match opt_ety { |
| // (-i8::MIN is itself not an i8, etc, but this is an easy way |
| // to allow literals to pass the check. Of course that does |
| // not work for i64::MIN.) |
| Some(IntTy::I8) => (-(i8::MAX as i64), -(i8::MIN as i64)), |
| Some(IntTy::I16) => (-(i16::MAX as i64), -(i16::MIN as i64)), |
| Some(IntTy::I32) => (-(i32::MAX as i64), -(i32::MIN as i64)), |
| None | Some(IntTy::I64) => (-i64::MAX, -(i64::MIN+1)), |
| }; |
| |
| let oflo = a < min || a > max; |
| if oflo { |
| signal!(e, NegateWithOverflow(a)); |
| } else { |
| Ok(Int(-a)) |
| } |
| } |
| |
| pub fn const_uint_checked_neg<'a>( |
| a: u64, _e: &'a Expr, _opt_ety: Option<UintTy>) -> EvalResult { |
| // This always succeeds, and by definition, returns `(!a)+1`. |
| Ok(Uint((!a).wrapping_add(1))) |
| } |
| |
| fn const_uint_not(a: u64, opt_ety: Option<UintTy>) -> ConstVal { |
| let mask = match opt_ety { |
| Some(UintTy::U8) => u8::MAX as u64, |
| Some(UintTy::U16) => u16::MAX as u64, |
| Some(UintTy::U32) => u32::MAX as u64, |
| None | Some(UintTy::U64) => u64::MAX, |
| }; |
| Uint(!a & mask) |
| } |
| |
| macro_rules! overflow_checking_body { |
| ($a:ident, $b:ident, $ety:ident, $overflowing_op:ident, |
| lhs: $to_8_lhs:ident $to_16_lhs:ident $to_32_lhs:ident, |
| rhs: $to_8_rhs:ident $to_16_rhs:ident $to_32_rhs:ident $to_64_rhs:ident, |
| $EnumTy:ident $T8: ident $T16: ident $T32: ident $T64: ident, |
| $result_type: ident) => { { |
| let (a,b,opt_ety) = ($a,$b,$ety); |
| match opt_ety { |
| Some($EnumTy::$T8) => match (a.$to_8_lhs(), b.$to_8_rhs()) { |
| (Some(a), Some(b)) => { |
| let (a, oflo) = a.$overflowing_op(b); |
| (a as $result_type, oflo) |
| } |
| (None, _) | (_, None) => (0, true) |
| }, |
| Some($EnumTy::$T16) => match (a.$to_16_lhs(), b.$to_16_rhs()) { |
| (Some(a), Some(b)) => { |
| let (a, oflo) = a.$overflowing_op(b); |
| (a as $result_type, oflo) |
| } |
| (None, _) | (_, None) => (0, true) |
| }, |
| Some($EnumTy::$T32) => match (a.$to_32_lhs(), b.$to_32_rhs()) { |
| (Some(a), Some(b)) => { |
| let (a, oflo) = a.$overflowing_op(b); |
| (a as $result_type, oflo) |
| } |
| (None, _) | (_, None) => (0, true) |
| }, |
| None | Some($EnumTy::$T64) => match b.$to_64_rhs() { |
| Some(b) => a.$overflowing_op(b), |
| None => (0, true), |
| } |
| } |
| } } |
| } |
| |
| macro_rules! int_arith_body { |
| ($a:ident, $b:ident, $ety:ident, $overflowing_op:ident) => { |
| overflow_checking_body!( |
| $a, $b, $ety, $overflowing_op, |
| lhs: to_i8 to_i16 to_i32, |
| rhs: to_i8 to_i16 to_i32 to_i64, IntTy I8 I16 I32 I64, i64) |
| } |
| } |
| |
| macro_rules! uint_arith_body { |
| ($a:ident, $b:ident, $ety:ident, $overflowing_op:ident) => { |
| overflow_checking_body!( |
| $a, $b, $ety, $overflowing_op, |
| lhs: to_u8 to_u16 to_u32, |
| rhs: to_u8 to_u16 to_u32 to_u64, UintTy U8 U16 U32 U64, u64) |
| } |
| } |
| |
| macro_rules! int_shift_body { |
| ($a:ident, $b:ident, $ety:ident, $overflowing_op:ident) => { |
| overflow_checking_body!( |
| $a, $b, $ety, $overflowing_op, |
| lhs: to_i8 to_i16 to_i32, |
| rhs: to_u32 to_u32 to_u32 to_u32, IntTy I8 I16 I32 I64, i64) |
| } |
| } |
| |
| macro_rules! uint_shift_body { |
| ($a:ident, $b:ident, $ety:ident, $overflowing_op:ident) => { |
| overflow_checking_body!( |
| $a, $b, $ety, $overflowing_op, |
| lhs: to_u8 to_u16 to_u32, |
| rhs: to_u32 to_u32 to_u32 to_u32, UintTy U8 U16 U32 U64, u64) |
| } |
| } |
| |
| macro_rules! pub_fn_checked_op { |
| {$fn_name:ident ($a:ident : $a_ty:ty, $b:ident : $b_ty:ty,.. $WhichTy:ident) { |
| $ret_oflo_body:ident $overflowing_op:ident |
| $const_ty:ident $signal_exn:expr |
| }} => { |
| pub fn $fn_name<'a>($a: $a_ty, |
| $b: $b_ty, |
| e: &'a Expr, |
| opt_ety: Option<$WhichTy>) -> EvalResult { |
| let (ret, oflo) = $ret_oflo_body!($a, $b, opt_ety, $overflowing_op); |
| if !oflo { Ok($const_ty(ret)) } else { signal!(e, $signal_exn) } |
| } |
| } |
| } |
| |
| pub_fn_checked_op!{ const_int_checked_add(a: i64, b: i64,.. IntTy) { |
| int_arith_body overflowing_add Int AddiWithOverflow(a, b) |
| }} |
| |
| pub_fn_checked_op!{ const_int_checked_sub(a: i64, b: i64,.. IntTy) { |
| int_arith_body overflowing_sub Int SubiWithOverflow(a, b) |
| }} |
| |
| pub_fn_checked_op!{ const_int_checked_mul(a: i64, b: i64,.. IntTy) { |
| int_arith_body overflowing_mul Int MuliWithOverflow(a, b) |
| }} |
| |
| pub fn const_int_checked_div<'a>( |
| a: i64, b: i64, e: &'a Expr, opt_ety: Option<IntTy>) -> EvalResult { |
| if b == 0 { signal!(e, DivideByZero); } |
| let (ret, oflo) = int_arith_body!(a, b, opt_ety, overflowing_div); |
| if !oflo { Ok(Int(ret)) } else { signal!(e, DivideWithOverflow) } |
| } |
| |
| pub fn const_int_checked_rem<'a>( |
| a: i64, b: i64, e: &'a Expr, opt_ety: Option<IntTy>) -> EvalResult { |
| if b == 0 { signal!(e, ModuloByZero); } |
| let (ret, oflo) = int_arith_body!(a, b, opt_ety, overflowing_rem); |
| if !oflo { Ok(Int(ret)) } else { signal!(e, ModuloWithOverflow) } |
| } |
| |
| pub_fn_checked_op!{ const_int_checked_shl(a: i64, b: i64,.. IntTy) { |
| int_shift_body overflowing_shl Int ShiftLeftWithOverflow |
| }} |
| |
| pub_fn_checked_op!{ const_int_checked_shl_via_uint(a: i64, b: u64,.. IntTy) { |
| int_shift_body overflowing_shl Int ShiftLeftWithOverflow |
| }} |
| |
| pub_fn_checked_op!{ const_int_checked_shr(a: i64, b: i64,.. IntTy) { |
| int_shift_body overflowing_shr Int ShiftRightWithOverflow |
| }} |
| |
| pub_fn_checked_op!{ const_int_checked_shr_via_uint(a: i64, b: u64,.. IntTy) { |
| int_shift_body overflowing_shr Int ShiftRightWithOverflow |
| }} |
| |
| pub_fn_checked_op!{ const_uint_checked_add(a: u64, b: u64,.. UintTy) { |
| uint_arith_body overflowing_add Uint AdduWithOverflow(a, b) |
| }} |
| |
| pub_fn_checked_op!{ const_uint_checked_sub(a: u64, b: u64,.. UintTy) { |
| uint_arith_body overflowing_sub Uint SubuWithOverflow(a, b) |
| }} |
| |
| pub_fn_checked_op!{ const_uint_checked_mul(a: u64, b: u64,.. UintTy) { |
| uint_arith_body overflowing_mul Uint MuluWithOverflow(a, b) |
| }} |
| |
| pub fn const_uint_checked_div<'a>( |
| a: u64, b: u64, e: &'a Expr, opt_ety: Option<UintTy>) -> EvalResult { |
| if b == 0 { signal!(e, DivideByZero); } |
| let (ret, oflo) = uint_arith_body!(a, b, opt_ety, overflowing_div); |
| if !oflo { Ok(Uint(ret)) } else { signal!(e, DivideWithOverflow) } |
| } |
| |
| pub fn const_uint_checked_rem<'a>( |
| a: u64, b: u64, e: &'a Expr, opt_ety: Option<UintTy>) -> EvalResult { |
| if b == 0 { signal!(e, ModuloByZero); } |
| let (ret, oflo) = uint_arith_body!(a, b, opt_ety, overflowing_rem); |
| if !oflo { Ok(Uint(ret)) } else { signal!(e, ModuloWithOverflow) } |
| } |
| |
| pub_fn_checked_op!{ const_uint_checked_shl(a: u64, b: u64,.. UintTy) { |
| uint_shift_body overflowing_shl Uint ShiftLeftWithOverflow |
| }} |
| |
| pub_fn_checked_op!{ const_uint_checked_shl_via_int(a: u64, b: i64,.. UintTy) { |
| uint_shift_body overflowing_shl Uint ShiftLeftWithOverflow |
| }} |
| |
| pub_fn_checked_op!{ const_uint_checked_shr(a: u64, b: u64,.. UintTy) { |
| uint_shift_body overflowing_shr Uint ShiftRightWithOverflow |
| }} |
| |
| pub_fn_checked_op!{ const_uint_checked_shr_via_int(a: u64, b: i64,.. UintTy) { |
| uint_shift_body overflowing_shr Uint ShiftRightWithOverflow |
| }} |
| |
| /// 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<'tcx>(tcx: &ty::ctxt<'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.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.expr_ty_opt(e) |
| } |
| }; |
| |
| // If type of expression itself is int or uint, normalize in these |
| // bindings so that isize/usize is mapped to a type with an |
| // inherently known bitwidth. |
| let expr_int_type = ety.and_then(|ty| { |
| if let ty::TyInt(t) = ty.sty { |
| Some(IntTy::from(tcx, t)) } else { None } |
| }); |
| let expr_uint_type = ety.and_then(|ty| { |
| if let ty::TyUint(t) = ty.sty { |
| Some(UintTy::from(tcx, t)) } else { None } |
| }); |
| |
| let result = match e.node { |
| hir::ExprUnary(hir::UnNeg, ref inner) => { |
| match try!(eval_const_expr_partial(tcx, &**inner, ty_hint, fn_args)) { |
| Float(f) => Float(-f), |
| Int(n) => try!(const_int_checked_neg(n, e, expr_int_type)), |
| Uint(i) => { |
| try!(const_uint_checked_neg(i, e, expr_uint_type)) |
| } |
| const_val => signal!(e, NegateOn(const_val)), |
| } |
| } |
| hir::ExprUnary(hir::UnNot, ref inner) => { |
| match try!(eval_const_expr_partial(tcx, &**inner, ty_hint, fn_args)) { |
| Int(i) => Int(!i), |
| Uint(i) => const_uint_not(i, expr_uint_type), |
| Bool(b) => Bool(!b), |
| const_val => signal!(e, NotOn(const_val)), |
| } |
| } |
| hir::ExprBinary(op, ref a, ref b) => { |
| let b_ty = match op.node { |
| hir::BiShl | hir::BiShr => ty_hint.checked_or(tcx.types.usize), |
| _ => ty_hint |
| }; |
| match (try!(eval_const_expr_partial(tcx, &**a, ty_hint, fn_args)), |
| try!(eval_const_expr_partial(tcx, &**b, b_ty, fn_args))) { |
| (Float(a), Float(b)) => { |
| match op.node { |
| hir::BiAdd => Float(a + b), |
| hir::BiSub => Float(a - b), |
| hir::BiMul => Float(a * b), |
| hir::BiDiv => Float(a / b), |
| hir::BiRem => Float(a % b), |
| hir::BiEq => Bool(a == b), |
| hir::BiLt => Bool(a < b), |
| hir::BiLe => Bool(a <= b), |
| hir::BiNe => Bool(a != b), |
| hir::BiGe => Bool(a >= b), |
| hir::BiGt => Bool(a > b), |
| _ => signal!(e, InvalidOpForFloats(op.node)), |
| } |
| } |
| (Int(a), Int(b)) => { |
| match op.node { |
| hir::BiAdd => try!(const_int_checked_add(a,b,e,expr_int_type)), |
| hir::BiSub => try!(const_int_checked_sub(a,b,e,expr_int_type)), |
| hir::BiMul => try!(const_int_checked_mul(a,b,e,expr_int_type)), |
| hir::BiDiv => try!(const_int_checked_div(a,b,e,expr_int_type)), |
| hir::BiRem => try!(const_int_checked_rem(a,b,e,expr_int_type)), |
| hir::BiBitAnd => Int(a & b), |
| hir::BiBitOr => Int(a | b), |
| hir::BiBitXor => Int(a ^ b), |
| hir::BiShl => try!(const_int_checked_shl(a,b,e,expr_int_type)), |
| hir::BiShr => try!(const_int_checked_shr(a,b,e,expr_int_type)), |
| hir::BiEq => Bool(a == b), |
| hir::BiLt => Bool(a < b), |
| hir::BiLe => Bool(a <= b), |
| hir::BiNe => Bool(a != b), |
| hir::BiGe => Bool(a >= b), |
| hir::BiGt => Bool(a > b), |
| _ => signal!(e, InvalidOpForInts(op.node)), |
| } |
| } |
| (Uint(a), Uint(b)) => { |
| match op.node { |
| hir::BiAdd => try!(const_uint_checked_add(a,b,e,expr_uint_type)), |
| hir::BiSub => try!(const_uint_checked_sub(a,b,e,expr_uint_type)), |
| hir::BiMul => try!(const_uint_checked_mul(a,b,e,expr_uint_type)), |
| hir::BiDiv => try!(const_uint_checked_div(a,b,e,expr_uint_type)), |
| hir::BiRem => try!(const_uint_checked_rem(a,b,e,expr_uint_type)), |
| hir::BiBitAnd => Uint(a & b), |
| hir::BiBitOr => Uint(a | b), |
| hir::BiBitXor => Uint(a ^ b), |
| hir::BiShl => try!(const_uint_checked_shl(a,b,e,expr_uint_type)), |
| hir::BiShr => try!(const_uint_checked_shr(a,b,e,expr_uint_type)), |
| hir::BiEq => Bool(a == b), |
| hir::BiLt => Bool(a < b), |
| hir::BiLe => Bool(a <= b), |
| hir::BiNe => Bool(a != b), |
| hir::BiGe => Bool(a >= b), |
| hir::BiGt => Bool(a > b), |
| _ => signal!(e, InvalidOpForUInts(op.node)), |
| } |
| } |
| // shifts can have any integral type as their rhs |
| (Int(a), Uint(b)) => { |
| match op.node { |
| hir::BiShl => try!(const_int_checked_shl_via_uint(a,b,e,expr_int_type)), |
| hir::BiShr => try!(const_int_checked_shr_via_uint(a,b,e,expr_int_type)), |
| _ => signal!(e, InvalidOpForIntUint(op.node)), |
| } |
| } |
| (Uint(a), Int(b)) => { |
| match op.node { |
| hir::BiShl => try!(const_uint_checked_shl_via_int(a,b,e,expr_uint_type)), |
| hir::BiShr => try!(const_uint_checked_shr_via_int(a,b,e,expr_uint_type)), |
| _ => signal!(e, InvalidOpForUintInt(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, |
| _ => signal!(e, InvalidOpForBools(op.node)), |
| }) |
| } |
| |
| _ => signal!(e, MiscBinaryOp), |
| } |
| } |
| hir::ExprCast(ref base, ref target_ty) => { |
| let ety = ety.or_else(|| ast_ty_to_prim_ty(tcx, &**target_ty)) |
| .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 { |
| // FIXME (#23833): the type-hint can cause problems, |
| // e.g. `(i8::MAX + 1_i8) as u32` feeds in `u32` as result |
| // type to the sum, and thus no overflow is signaled. |
| match tcx.expr_ty_opt(&base) { |
| Some(t) => UncheckedExprHint(t), |
| None => ty_hint |
| } |
| }; |
| |
| let val = try!(eval_const_expr_partial(tcx, &**base, base_hint, fn_args)); |
| match cast_const(tcx, val, ety) { |
| Ok(val) => val, |
| Err(kind) => return Err(ConstEvalErr { span: e.span, kind: kind }), |
| } |
| } |
| hir::ExprPath(..) => { |
| let opt_def = if let Some(def) = tcx.def_map.borrow().get(&e.id) { |
| // After type-checking, def_map contains definition of the |
| // item referred to by the path. During type-checking, it |
| // can contain the raw output of path resolution, which |
| // might be a partially resolved path. |
| // FIXME: There's probably a better way to make sure we don't |
| // panic here. |
| if def.depth != 0 { |
| signal!(e, UnresolvedPath); |
| } |
| Some(def.full_def()) |
| } else { |
| None |
| }; |
| let (const_expr, const_ty) = match opt_def { |
| Some(Def::Const(def_id)) => { |
| if let Some(node_id) = tcx.map.as_local_node_id(def_id) { |
| match tcx.map.find(node_id) { |
| Some(ast_map::NodeItem(it)) => match it.node { |
| hir::ItemConst(ref ty, ref expr) => { |
| (Some(&**expr), Some(&**ty)) |
| } |
| _ => (None, None) |
| }, |
| _ => (None, None) |
| } |
| } else { |
| (lookup_const_by_id(tcx, def_id, Some(e.id), None), None) |
| } |
| } |
| Some(Def::AssociatedConst(def_id)) => { |
| if let Some(node_id) = tcx.map.as_local_node_id(def_id) { |
| match tcx.impl_or_trait_item(def_id).container() { |
| ty::TraitContainer(trait_id) => match tcx.map.find(node_id) { |
| Some(ast_map::NodeTraitItem(ti)) => match ti.node { |
| hir::ConstTraitItem(ref ty, _) => { |
| if let ExprTypeChecked = ty_hint { |
| let substs = tcx.node_id_item_substs(e.id).substs; |
| (resolve_trait_associated_const(tcx, |
| ti, |
| trait_id, |
| substs), |
| Some(&**ty)) |
| } else { |
| (None, None) |
| } |
| } |
| _ => (None, None) |
| }, |
| _ => (None, None) |
| }, |
| ty::ImplContainer(_) => match tcx.map.find(node_id) { |
| Some(ast_map::NodeImplItem(ii)) => match ii.node { |
| hir::ImplItemKind::Const(ref ty, ref expr) => { |
| (Some(&**expr), Some(&**ty)) |
| } |
| _ => (None, None) |
| }, |
| _ => (None, None) |
| }, |
| } |
| } else { |
| (lookup_const_by_id(tcx, def_id, Some(e.id), None), None) |
| } |
| } |
| Some(Def::Variant(enum_def, variant_def)) => { |
| (lookup_variant_by_id(tcx, enum_def, variant_def), None) |
| } |
| Some(Def::Struct(..)) => { |
| return Ok(ConstVal::Struct(e.id)) |
| } |
| Some(Def::Local(_, id)) => { |
| debug!("Def::Local({:?}): {:?}", id, fn_args); |
| if let Some(val) = fn_args.and_then(|args| args.get(&id)) { |
| return Ok(val.clone()); |
| } else { |
| (None, None) |
| } |
| }, |
| Some(Def::Method(id)) | Some(Def::Fn(id)) => return Ok(Function(id)), |
| _ => (None, None) |
| }; |
| let const_expr = match const_expr { |
| Some(actual_e) => actual_e, |
| None => signal!(e, NonConstPath) |
| }; |
| let item_hint = if let UncheckedExprNoHint = ty_hint { |
| match const_ty { |
| Some(ty) => match ast_ty_to_prim_ty(tcx, ty) { |
| Some(ty) => UncheckedExprHint(ty), |
| None => UncheckedExprNoHint |
| }, |
| None => UncheckedExprNoHint |
| } |
| } else { |
| ty_hint |
| }; |
| try!(eval_const_expr_partial(tcx, const_expr, item_hint, fn_args)) |
| } |
| hir::ExprCall(ref callee, ref args) => { |
| let sub_ty_hint = ty_hint.erase_hint(); |
| let callee_val = try!(eval_const_expr_partial(tcx, callee, sub_ty_hint, fn_args)); |
| let did = match callee_val { |
| Function(did) => did, |
| 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().expr) |
| } else { |
| signal!(e, NonConstPath) |
| }; |
| let result = result.as_ref().expect("const fn has no result expression"); |
| assert_eq!(decl.inputs.len(), args.len()); |
| |
| let mut call_args = NodeMap(); |
| for (arg, arg_expr) in decl.inputs.iter().zip(args.iter()) { |
| let arg_val = try!(eval_const_expr_partial( |
| tcx, |
| arg_expr, |
| sub_ty_hint, |
| fn_args |
| )); |
| debug!("const call arg: {:?}", arg); |
| let old = call_args.insert(arg.pat.id, arg_val); |
| assert!(old.is_none()); |
| } |
| debug!("const call({:?})", call_args); |
| try!(eval_const_expr_partial(tcx, &**result, ty_hint, Some(&call_args))) |
| }, |
| hir::ExprLit(ref lit) => lit_to_const(tcx.sess, e.span, &**lit, ety), |
| hir::ExprBlock(ref block) => { |
| match block.expr { |
| Some(ref expr) => try!(eval_const_expr_partial(tcx, &**expr, ty_hint, fn_args)), |
| None => unreachable!(), |
| } |
| } |
| hir::ExprType(ref e, _) => try!(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 = try!(eval_const_expr_partial(tcx, arr, arr_hint, fn_args)); |
| let idx_hint = ty_hint.checked_or(tcx.types.usize); |
| let idx = match try!(eval_const_expr_partial(tcx, idx, idx_hint, fn_args)) { |
| Int(i) if i >= 0 => i as u64, |
| Int(_) => signal!(idx, IndexNegative), |
| Uint(i) => i, |
| _ => signal!(idx, IndexNotInt), |
| }; |
| match arr { |
| Array(_, n) if idx >= n => signal!(e, IndexOutOfBounds), |
| Array(v, _) => if let hir::ExprVec(ref v) = tcx.map.expect_expr(v).node { |
| try!(eval_const_expr_partial(tcx, &*v[idx as usize], ty_hint, fn_args)) |
| } else { |
| unreachable!() |
| }, |
| |
| Repeat(_, n) if idx >= n => signal!(e, IndexOutOfBounds), |
| Repeat(elem, _) => try!(eval_const_expr_partial( |
| tcx, |
| &*tcx.map.expect_expr(elem), |
| ty_hint, |
| fn_args, |
| )), |
| |
| ByteStr(ref data) if idx as usize >= data.len() |
| => signal!(e, IndexOutOfBounds), |
| ByteStr(data) => Uint(data[idx as usize] as u64), |
| |
| Str(ref s) if idx as usize >= s.len() |
| => signal!(e, IndexOutOfBounds), |
| Str(_) => unimplemented!(), // there's no const_char type |
| _ => signal!(e, IndexedNonVec), |
| } |
| } |
| hir::ExprVec(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 try!(eval_const_expr_partial(tcx, &**n, len_hint, fn_args)) { |
| Int(i) if i >= 0 => i as u64, |
| Int(_) => signal!(e, RepeatCountNotNatural), |
| Uint(i) => i, |
| _ => signal!(e, RepeatCountNotInt), |
| }, |
| ) |
| }, |
| hir::ExprTupField(ref base, index) => { |
| let base_hint = ty_hint.erase_hint(); |
| let c = try!(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() { |
| return eval_const_expr_partial(tcx, &fields[index.node], base_hint, fn_args) |
| } else { |
| signal!(e, TupleIndexOutOfBounds); |
| } |
| } else { |
| unreachable!() |
| } |
| } 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 = try!(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) { |
| return eval_const_expr_partial(tcx, &*f.expr, base_hint, fn_args) |
| } else { |
| signal!(e, MissingStructField); |
| } |
| } else { |
| unreachable!() |
| } |
| } else { |
| signal!(base, ExpectedConstStruct); |
| } |
| } |
| _ => signal!(e, MiscCatchAll) |
| }; |
| |
| Ok(result) |
| } |
| |
| fn resolve_trait_associated_const<'a, 'tcx: 'a>(tcx: &'a ty::ctxt<'tcx>, |
| ti: &'tcx hir::TraitItem, |
| trait_id: DefId, |
| rcvr_substs: subst::Substs<'tcx>) |
| -> Option<&'tcx Expr> |
| { |
| let trait_ref = ty::Binder( |
| rcvr_substs.erase_regions().to_trait_ref(tcx, trait_id) |
| ); |
| debug!("resolve_trait_associated_const: trait_ref={:?}", |
| trait_ref); |
| |
| tcx.populate_implementations_for_trait_if_necessary(trait_ref.def_id()); |
| let infcx = infer::new_infer_ctxt(tcx, &tcx.tables, None); |
| |
| 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 |
| } |
| }; |
| |
| match selection { |
| traits::VtableImpl(ref impl_data) => { |
| match tcx.associated_consts(impl_data.impl_def_id) |
| .iter().find(|ic| ic.name == ti.name) { |
| Some(ic) => lookup_const_by_id(tcx, ic.def_id, None, None), |
| None => match ti.node { |
| hir::ConstTraitItem(_, Some(ref expr)) => Some(&*expr), |
| _ => None, |
| }, |
| } |
| } |
| _ => { |
| tcx.sess.span_bug( |
| ti.span, |
| "resolve_trait_associated_const: unexpected vtable type") |
| } |
| } |
| } |
| |
| fn cast_const<'tcx>(tcx: &ty::ctxt<'tcx>, val: ConstVal, ty: Ty) -> CastResult { |
| macro_rules! convert_val { |
| ($intermediate_ty:ty, $const_type:ident, $target_ty:ty) => { |
| match val { |
| Bool(b) => Ok($const_type(b as u64 as $intermediate_ty as $target_ty)), |
| Uint(u) => Ok($const_type(u as $intermediate_ty as $target_ty)), |
| Int(i) => Ok($const_type(i as $intermediate_ty as $target_ty)), |
| Float(f) => Ok($const_type(f as $intermediate_ty as $target_ty)), |
| _ => Err(ErrKind::CannotCastTo(stringify!($const_type))), |
| } |
| } |
| } |
| |
| // Issue #23890: If isize/usize, then dispatch to appropriate target representation type |
| match (&ty.sty, tcx.sess.target.int_type, tcx.sess.target.uint_type) { |
| (&ty::TyInt(ast::IntTy::Is), ast::IntTy::I32, _) => return convert_val!(i32, Int, i64), |
| (&ty::TyInt(ast::IntTy::Is), ast::IntTy::I64, _) => return convert_val!(i64, Int, i64), |
| (&ty::TyInt(ast::IntTy::Is), _, _) => panic!("unexpected target.int_type"), |
| |
| (&ty::TyUint(ast::UintTy::Us), _, ast::UintTy::U32) => return convert_val!(u32, Uint, u64), |
| (&ty::TyUint(ast::UintTy::Us), _, ast::UintTy::U64) => return convert_val!(u64, Uint, u64), |
| (&ty::TyUint(ast::UintTy::Us), _, _) => panic!("unexpected target.uint_type"), |
| |
| _ => {} |
| } |
| |
| match ty.sty { |
| ty::TyInt(ast::IntTy::Is) => unreachable!(), |
| ty::TyUint(ast::UintTy::Us) => unreachable!(), |
| |
| ty::TyInt(ast::IntTy::I8) => convert_val!(i8, Int, i64), |
| ty::TyInt(ast::IntTy::I16) => convert_val!(i16, Int, i64), |
| ty::TyInt(ast::IntTy::I32) => convert_val!(i32, Int, i64), |
| ty::TyInt(ast::IntTy::I64) => convert_val!(i64, Int, i64), |
| |
| ty::TyUint(ast::UintTy::U8) => convert_val!(u8, Uint, u64), |
| ty::TyUint(ast::UintTy::U16) => convert_val!(u16, Uint, u64), |
| ty::TyUint(ast::UintTy::U32) => convert_val!(u32, Uint, u64), |
| ty::TyUint(ast::UintTy::U64) => convert_val!(u64, Uint, u64), |
| |
| ty::TyFloat(ast::FloatTy::F32) => convert_val!(f32, Float, f64), |
| ty::TyFloat(ast::FloatTy::F64) => convert_val!(f64, Float, f64), |
| _ => Err(ErrKind::CannotCast), |
| } |
| } |
| |
| fn lit_to_const(sess: &Session, span: Span, lit: &ast::Lit, ty_hint: Option<Ty>) -> ConstVal { |
| match lit.node { |
| ast::LitStr(ref s, _) => Str((*s).clone()), |
| ast::LitByteStr(ref data) => { |
| ByteStr(data.clone()) |
| } |
| ast::LitByte(n) => Uint(n as u64), |
| ast::LitChar(n) => Uint(n as u64), |
| ast::LitInt(n, ast::SignedIntLit(_, ast::Plus)) => Int(n as i64), |
| ast::LitInt(n, ast::UnsuffixedIntLit(ast::Plus)) => { |
| match ty_hint.map(|ty| &ty.sty) { |
| Some(&ty::TyUint(_)) => Uint(n), |
| _ => Int(n as i64) |
| } |
| } |
| ast::LitInt(n, ast::SignedIntLit(_, ast::Minus)) | |
| ast::LitInt(n, ast::UnsuffixedIntLit(ast::Minus)) => Int(-(n as i64)), |
| ast::LitInt(n, ast::UnsignedIntLit(_)) => Uint(n), |
| ast::LitFloat(ref n, _) | |
| ast::LitFloatUnsuffixed(ref n) => { |
| if let Ok(x) = n.parse::<f64>() { |
| Float(x) |
| } else { |
| // FIXME(#31407) this is only necessary because float parsing is buggy |
| sess.span_bug(span, "could not evaluate float literal (see issue #31407)"); |
| } |
| } |
| ast::LitBool(b) => Bool(b) |
| } |
| } |
| |
| pub fn compare_const_vals(a: &ConstVal, b: &ConstVal) -> Option<Ordering> { |
| Some(match (a, b) { |
| (&Int(a), &Int(b)) => a.cmp(&b), |
| (&Uint(a), &Uint(b)) => a.cmp(&b), |
| (&Float(a), &Float(b)) => { |
| // This is pretty bad but it is the existing behavior. |
| if a == b { |
| Ordering::Equal |
| } else if a < b { |
| Ordering::Less |
| } else { |
| Ordering::Greater |
| } |
| } |
| (&Str(ref a), &Str(ref b)) => a.cmp(b), |
| (&Bool(a), &Bool(b)) => a.cmp(&b), |
| (&ByteStr(ref a), &ByteStr(ref b)) => a.cmp(b), |
| _ => return None |
| }) |
| } |
| |
| pub fn compare_lit_exprs<'tcx>(tcx: &ty::ctxt<'tcx>, |
| a: &Expr, |
| b: &Expr) -> Option<Ordering> { |
| let a = match eval_const_expr_partial(tcx, a, ExprTypeChecked, None) { |
| Ok(a) => a, |
| Err(e) => { |
| tcx.sess.span_err(a.span, &e.description()); |
| return None; |
| } |
| }; |
| let b = match eval_const_expr_partial(tcx, b, ExprTypeChecked, None) { |
| Ok(b) => b, |
| Err(e) => { |
| tcx.sess.span_err(b.span, &e.description()); |
| return None; |
| } |
| }; |
| compare_const_vals(&a, &b) |
| } |
