-// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
+// 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.
//
// option. This file may not be copied, modified, or distributed
// except according to those terms.
-use core::prelude::*;
+#![allow(non_camel_case_types)]
+#![allow(unsigned_negation)]
-use metadata::csearch;
-use middle::astencode;
-use middle::ty;
-use middle;
+use self::ConstVal::*;
-use core::float;
-use core::vec;
-use syntax::{ast, ast_map, ast_util, visit};
-use syntax::ast::*;
+use self::ErrKind::*;
-use core::hashmap::linear::{LinearMap, LinearSet};
+use ast_map;
+use ast_map::blocks::FnLikeNode;
+use metadata::csearch;
+use middle::{astencode, def, infer, subst, traits};
+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;
-//
-// This pass classifies expressions by their constant-ness.
-//
-// Constant-ness comes in 3 flavours:
-//
-// - Integer-constants: can be evaluated by the frontend all the way down
-// to their actual value. They are used in a few places (enum
-// discriminants, switch arms) and are a subset of
-// general-constants. They cover all the integer and integer-ish
-// literals (nil, bool, int, uint, char, iNN, uNN) and all integer
-// operators and copies applied to them.
-//
-// - General-constants: can be evaluated by LLVM but not necessarily by
-// the frontend; usually due to reliance on target-specific stuff such
-// as "where in memory the value goes" or "what floating point mode the
-// target uses". This _includes_ integer-constants, plus the following
-// constructors:
-//
-// fixed-size vectors and strings: [] and ""/_
-// vector and string slices: &[] and &""
-// tuples: (,)
-// records: {...}
-// enums: foo(...)
-// floating point literals and operators
-// & and * pointers
-// copies of general constants
-//
-// (in theory, probably not at first: if/match on integer-const
-// conditions / descriminants)
-//
-// - Non-constants: everything else.
-//
+use syntax::ast::{self, Expr};
+use syntax::ast_util;
+use syntax::codemap::Span;
+use syntax::feature_gate;
+use syntax::parse::token::InternedString;
+use syntax::ptr::P;
+use syntax::{codemap, visit};
+
+use std::borrow::{Cow, IntoCow};
+use std::num::wrapping::OverflowingOps;
+use std::cmp::Ordering;
+use std::collections::hash_map::Entry::Vacant;
+use std::{i8, i16, i32, i64, u8, u16, u32, u64};
+use std::rc::Rc;
-pub enum constness {
- integral_const,
- general_const,
- non_const
+fn lookup_const<'a>(tcx: &'a ty::ctxt, e: &Expr) -> Option<&'a Expr> {
+ let opt_def = tcx.def_map.borrow().get(&e.id).map(|d| d.full_def());
+ match opt_def {
+ Some(def::DefConst(def_id)) |
+ Some(def::DefAssociatedConst(def_id, _)) => {
+ lookup_const_by_id(tcx, def_id, Some(e.id))
+ }
+ Some(def::DefVariant(enum_def, variant_def, _)) => {
+ lookup_variant_by_id(tcx, enum_def, variant_def)
+ }
+ _ => None
+ }
}
-pub fn join(a: constness, b: constness) -> constness {
- match (a, b) {
- (integral_const, integral_const) => integral_const,
- (integral_const, general_const)
- | (general_const, integral_const)
- | (general_const, general_const) => general_const,
- _ => non_const
+fn lookup_variant_by_id<'a>(tcx: &'a ty::ctxt,
+ enum_def: ast::DefId,
+ variant_def: ast::DefId)
+ -> Option<&'a Expr> {
+ fn variant_expr<'a>(variants: &'a [P<ast::Variant>], id: ast::NodeId)
+ -> Option<&'a Expr> {
+ for variant in variants {
+ if variant.node.id == id {
+ return variant.node.disr_expr.as_ref().map(|e| &**e);
+ }
+ }
+ None
+ }
+
+ if ast_util::is_local(enum_def) {
+ match tcx.map.find(enum_def.node) {
+ None => None,
+ Some(ast_map::NodeItem(it)) => match it.node {
+ ast::ItemEnum(ast::EnumDef { ref variants }, _) => {
+ variant_expr(&variants[..], variant_def.node)
+ }
+ _ => None
+ },
+ Some(_) => None
+ }
+ } else {
+ match tcx.extern_const_variants.borrow().get(&variant_def) {
+ Some(&ast::DUMMY_NODE_ID) => return None,
+ Some(&expr_id) => {
+ return Some(tcx.map.expect_expr(expr_id));
+ }
+ None => {}
+ }
+ let expr_id = match csearch::maybe_get_item_ast(tcx, enum_def,
+ Box::new(|a, b, c, d| astencode::decode_inlined_item(a, b, c, d))) {
+ csearch::FoundAst::Found(&ast::IIItem(ref item)) => match item.node {
+ ast::ItemEnum(ast::EnumDef { ref variants }, _) => {
+ // NOTE this doesn't do the right thing, it compares inlined
+ // NodeId's to the original variant_def's NodeId, but they
+ // come from different crates, so they will likely never match.
+ variant_expr(&variants[..], variant_def.node).map(|e| e.id)
+ }
+ _ => None
+ },
+ _ => None
+ };
+ tcx.extern_const_variants.borrow_mut().insert(variant_def,
+ expr_id.unwrap_or(ast::DUMMY_NODE_ID));
+ expr_id.map(|id| tcx.map.expect_expr(id))
}
}
-pub fn join_all(cs: &[constness]) -> constness {
- vec::foldl(integral_const, cs, |a, b| join(a, *b))
-}
-
-pub fn classify(e: @expr,
- tcx: ty::ctxt)
- -> constness {
- let did = ast_util::local_def(e.id);
- match tcx.ccache.find(&did) {
- Some(&x) => x,
- None => {
- let cn =
- match e.node {
- ast::expr_lit(lit) => {
- match lit.node {
- ast::lit_str(*) |
- ast::lit_float(*) => general_const,
- _ => integral_const
+pub fn lookup_const_by_id<'a, 'tcx: 'a>(tcx: &'a ty::ctxt<'tcx>,
+ def_id: ast::DefId,
+ maybe_ref_id: Option<ast::NodeId>)
+ -> Option<&'tcx Expr> {
+ if ast_util::is_local(def_id) {
+ match tcx.map.find(def_id.node) {
+ None => None,
+ Some(ast_map::NodeItem(it)) => match it.node {
+ ast::ItemConst(_, ref const_expr) => {
+ Some(&*const_expr)
}
- }
+ _ => None
+ },
+ Some(ast_map::NodeTraitItem(ti)) => match ti.node {
+ ast::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 = ty::trait_of_item(tcx, def_id)
+ .unwrap();
+ let substs = ty::node_id_item_substs(tcx, ref_id)
+ .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 {
+ ast::ConstImplItem(_, 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 csearch::maybe_get_item_ast(tcx, def_id,
+ Box::new(|a, b, c, d| astencode::decode_inlined_item(a, b, c, d))) {
+ csearch::FoundAst::Found(&ast::IIItem(ref item)) => match item.node {
+ ast::ItemConst(_, ref const_expr) => Some(const_expr.id),
+ _ => None
+ },
+ csearch::FoundAst::Found(&ast::IITraitItem(trait_id, ref ti)) => match ti.node {
+ ast::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 substs = ty::node_id_item_substs(tcx, ref_id)
+ .substs;
+ resolve_trait_associated_const(tcx, ti, trait_id,
+ substs).map(|e| e.id)
+ }
+ None => None
+ }
+ }
+ _ => None
+ },
+ csearch::FoundAst::Found(&ast::IIImplItem(_, ref ii)) => match ii.node {
+ ast::ConstImplItem(_, 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))
+ }
+}
- ast::expr_copy(inner) |
- ast::expr_unary(_, inner) |
- ast::expr_paren(inner) => {
- classify(inner, tcx)
- }
+fn inline_const_fn_from_external_crate(tcx: &ty::ctxt, def_id: ast::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 => {}
+ }
- ast::expr_binary(_, a, b) => {
- join(classify(a, tcx),
- classify(b, tcx))
- }
+ if !csearch::is_const_fn(&tcx.sess.cstore, def_id) {
+ tcx.extern_const_fns.borrow_mut().insert(def_id, ast::DUMMY_NODE_ID);
+ return None;
+ }
- ast::expr_tup(ref es) |
- ast::expr_vec(ref es, ast::m_imm) => {
- join_all(vec::map(*es, |e| classify(*e, tcx)))
- }
+ let fn_id = match csearch::maybe_get_item_ast(tcx, def_id,
+ box |a, b, c, d| astencode::decode_inlined_item(a, b, c, d)) {
+ csearch::FoundAst::Found(&ast::IIItem(ref item)) => Some(item.id),
+ csearch::FoundAst::Found(&ast::IIImplItem(_, 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
+}
- ast::expr_vstore(e, vstore) => {
- match vstore {
- ast::expr_vstore_slice => classify(e, tcx),
- ast::expr_vstore_uniq |
- ast::expr_vstore_box |
- ast::expr_vstore_mut_box |
- ast::expr_vstore_mut_slice => non_const
- }
- }
+pub fn lookup_const_fn_by_id<'tcx>(tcx: &ty::ctxt<'tcx>, def_id: ast::DefId)
+ -> Option<FnLikeNode<'tcx>>
+{
+ let fn_id = if !ast_util::is_local(def_id) {
+ if let Some(fn_id) = inline_const_fn_from_external_crate(tcx, def_id) {
+ fn_id
+ } else {
+ return None;
+ }
+ } else {
+ def_id.node
+ };
- ast::expr_struct(_, ref fs, None) => {
- let cs = do vec::map((*fs)) |f| {
- if f.node.mutbl == ast::m_imm {
- classify(f.node.expr, tcx)
- } else {
- non_const
- }
- };
- join_all(cs)
- }
+ let fn_like = match FnLikeNode::from_node(tcx.map.get(fn_id)) {
+ Some(fn_like) => fn_like,
+ None => return None
+ };
- ast::expr_cast(base, _) => {
- let ty = ty::expr_ty(tcx, e);
- let base = classify(base, tcx);
- if ty::type_is_integral(ty) {
- join(integral_const, base)
- } else if ty::type_is_fp(ty) {
- join(general_const, base)
- } else {
- non_const
- }
- }
+ match fn_like.kind() {
+ visit::FkItemFn(_, _, _, ast::Constness::Const, _, _) => {
+ Some(fn_like)
+ }
+ visit::FkMethod(_, m, _) => {
+ if m.constness == ast::Constness::Const {
+ Some(fn_like)
+ } else {
+ None
+ }
+ }
+ _ => None
+ }
+}
- ast::expr_field(base, _, _) => {
- classify(base, tcx)
- }
+#[derive(Clone, PartialEq)]
+pub enum ConstVal {
+ Float(f64),
+ Int(i64),
+ Uint(u64),
+ Str(InternedString),
+ Binary(Rc<Vec<u8>>),
+ Bool(bool),
+ Struct(ast::NodeId),
+ Tuple(ast::NodeId),
+}
- ast::expr_index(base, idx) => {
- join(classify(base, tcx),
- classify(idx, tcx))
- }
+pub fn const_expr_to_pat(tcx: &ty::ctxt, expr: &Expr, span: Span) -> P<ast::Pat> {
+ let pat = match expr.node {
+ ast::ExprTup(ref exprs) =>
+ ast::PatTup(exprs.iter().map(|expr| const_expr_to_pat(tcx, &**expr, span)).collect()),
- ast::expr_addr_of(ast::m_imm, base) => {
- classify(base, tcx)
- }
+ ast::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::DefStruct(def_id) => def_to_path(tcx, def_id),
+ def::DefVariant(_, variant_did, _) => def_to_path(tcx, variant_did),
+ _ => unreachable!()
+ };
+ let pats = args.iter().map(|expr| const_expr_to_pat(tcx, &**expr, span)).collect();
+ ast::PatEnum(path, Some(pats))
+ }
- // FIXME: (#3728) we can probably do something CCI-ish
- // surrounding nonlocal constants. But we don't yet.
- ast::expr_path(_) => {
- lookup_constness(tcx, e)
- }
+ ast::ExprStruct(ref path, ref fields, None) => {
+ let field_pats = fields.iter().map(|field| codemap::Spanned {
+ span: codemap::DUMMY_SP,
+ node: ast::FieldPat {
+ ident: field.ident.node,
+ pat: const_expr_to_pat(tcx, &*field.expr, span),
+ is_shorthand: false,
+ },
+ }).collect();
+ ast::PatStruct(path.clone(), field_pats, false)
+ }
- _ => non_const
- };
- tcx.ccache.insert(did, cn);
- cn
- }
+ ast::ExprVec(ref exprs) => {
+ let pats = exprs.iter().map(|expr| const_expr_to_pat(tcx, &**expr, span)).collect();
+ ast::PatVec(pats, None, vec![])
+ }
+
+ ast::ExprPath(_, ref path) => {
+ let opt_def = tcx.def_map.borrow().get(&expr.id).map(|d| d.full_def());
+ match opt_def {
+ Some(def::DefStruct(..)) =>
+ ast::PatStruct(path.clone(), vec![], false),
+ Some(def::DefVariant(..)) =>
+ ast::PatEnum(path.clone(), None),
+ _ => {
+ match lookup_const(tcx, expr) {
+ Some(actual) => return const_expr_to_pat(tcx, actual, span),
+ _ => unreachable!()
+ }
+ }
+ }
+ }
+
+ _ => ast::PatLit(P(expr.clone()))
+ };
+ P(ast::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, None) {
+ Ok(r) => r,
+ Err(s) => tcx.sess.span_fatal(s.span, &s.description())
}
}
-pub fn lookup_const(tcx: ty::ctxt, e: @expr) -> Option<@expr> {
- match tcx.def_map.find(&e.id) {
- Some(&ast::def_const(def_id)) => lookup_const_by_id(tcx, def_id),
- _ => None
+
+#[derive(Clone)]
+pub struct ConstEvalErr {
+ pub span: Span,
+ pub kind: ErrKind,
+}
+
+#[derive(Clone)]
+pub enum ErrKind {
+ CannotCast,
+ CannotCastTo(&'static str),
+ InvalidOpForBools(ast::BinOp_),
+ InvalidOpForFloats(ast::BinOp_),
+ InvalidOpForIntUint(ast::BinOp_),
+ InvalidOpForUintInt(ast::BinOp_),
+ NegateOnString,
+ NegateOnBoolean,
+ NegateOnBinary,
+ NegateOnStruct,
+ NegateOnTuple,
+ NotOnFloat,
+ NotOnString,
+ NotOnBinary,
+ NotOnStruct,
+ NotOnTuple,
+
+ 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,
+ ExpectedConstTuple,
+ ExpectedConstStruct,
+ TupleIndexOutOfBounds,
+
+ MiscBinaryOp,
+ MiscCatchAll,
+}
+
+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(),
+ 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(),
+ NegateOnString => "negate on string".into_cow(),
+ NegateOnBoolean => "negate on boolean".into_cow(),
+ NegateOnBinary => "negate on binary literal".into_cow(),
+ NegateOnStruct => "negate on struct".into_cow(),
+ NegateOnTuple => "negate on tuple".into_cow(),
+ NotOnFloat => "not on float or string".into_cow(),
+ NotOnString => "not on float or string".into_cow(),
+ NotOnBinary => "not on binary literal".into_cow(),
+ NotOnStruct => "not on struct".into_cow(),
+ NotOnTuple => "not on tuple".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 expr".into_cow(),
+ ExpectedConstTuple => "expected constant tuple".into_cow(),
+ ExpectedConstStruct => "expected constant struct".into_cow(),
+ TupleIndexOutOfBounds => "tuple index out of bounds".into_cow(),
+
+ MiscBinaryOp => "bad operands for binary".into_cow(),
+ MiscCatchAll => "unsupported constant expr".into_cow(),
+ }
}
}
-pub fn lookup_const_by_id(tcx: ty::ctxt,
- def_id: ast::def_id)
- -> Option<@expr> {
- if ast_util::is_local(def_id) {
- match tcx.items.find(&def_id.node) {
- None => None,
- Some(&ast_map::node_item(it, _)) => match it.node {
- item_const(_, const_expr) => Some(const_expr),
- _ => None
- },
- Some(_) => None
+pub type EvalResult = Result<ConstVal, ConstEvalErr>;
+pub type CastResult = Result<ConstVal, ErrKind>;
+
+#[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::TyIs = t {
+ tcx.sess.target.int_type
+ } else {
+ t
+ };
+ match t {
+ ast::TyIs => unreachable!(),
+ ast::TyI8 => IntTy::I8,
+ ast::TyI16 => IntTy::I16,
+ ast::TyI32 => IntTy::I32,
+ ast::TyI64 => IntTy::I64,
}
- } else {
- let maps = astencode::Maps {
- mutbl_map: @mut LinearSet::new(),
- root_map: @mut LinearMap::new(),
- last_use_map: @mut LinearMap::new(),
- method_map: @mut LinearMap::new(),
- vtable_map: @mut LinearMap::new(),
- write_guard_map: @mut LinearSet::new(),
- moves_map: @mut LinearSet::new(),
- capture_map: @mut LinearMap::new()
+ }
+}
+
+impl UintTy {
+ pub fn from(tcx: &ty::ctxt, t: ast::UintTy) -> UintTy {
+ let t = if let ast::TyUs = t {
+ tcx.sess.target.uint_type
+ } else {
+ t
};
- match csearch::maybe_get_item_ast(tcx, def_id,
- |a, b, c, d| astencode::decode_inlined_item(a, b, maps, /*bar*/ copy c, d)) {
- csearch::found(ast::ii_item(item)) => match item.node {
- item_const(_, const_expr) => Some(const_expr),
- _ => None
- },
- _ => None
+ match t {
+ ast::TyUs => unreachable!(),
+ ast::TyU8 => UintTy::U8,
+ ast::TyU16 => UintTy::U16,
+ ast::TyU32 => UintTy::U32,
+ ast::TyU64 => UintTy::U64,
}
}
}
-pub fn lookup_constness(tcx: ty::ctxt, e: @expr) -> constness {
- match lookup_const(tcx, e) {
- Some(rhs) => {
- let ty = ty::expr_ty(tcx, rhs);
- if ty::type_is_integral(ty) {
- integral_const
- } else {
- general_const
+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.$overflowing_op(b),
+ None => (0, true),
}
}
- None => non_const
+ } }
+}
+
+macro_rules! int_arith_body {
+ ($a:ident, $b:ident, $ety:ident, $overflowing_op:ident) => {
+ overflow_checking_body!(
+ $a, $b, $ety, $overflowing_op,
+ lhs: to_i8 to_i16 to_i32,
+ rhs: to_i8 to_i16 to_i32 to_i64, IntTy I8 I16 I32 I64, i64)
}
}
-pub fn process_crate(crate: @ast::crate,
- tcx: ty::ctxt) {
- let v = visit::mk_simple_visitor(@visit::SimpleVisitor {
- visit_expr_post: |e| { classify(e, tcx); },
- .. *visit::default_simple_visitor()
- });
- visit::visit_crate(*crate, (), v);
- tcx.sess.abort_if_errors();
+macro_rules! uint_arith_body {
+ ($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, $overflowing_op,
+ lhs: to_i8 to_i16 to_i32,
+ rhs: to_u32 to_u32 to_u32 to_u32, IntTy I8 I16 I32 I64, i64)
+ }
+}
-// FIXME (#33): this doesn't handle big integer/float literals correctly
-// (nor does the rest of our literal handling).
-#[deriving(Eq)]
-pub enum const_val {
- const_float(f64),
- const_int(i64),
- const_uint(u64),
- const_str(~str),
- const_bool(bool)
+macro_rules! uint_shift_body {
+ ($a:ident, $b:ident, $ety:ident, $overflowing_op:ident) => {
+ overflow_checking_body!(
+ $a, $b, $ety, $overflowing_op,
+ lhs: to_u8 to_u16 to_u32,
+ rhs: to_u32 to_u32 to_u32 to_u32, UintTy U8 U16 U32 U64, u64)
+ }
}
-pub fn eval_const_expr(tcx: middle::ty::ctxt, e: @expr) -> const_val {
- match eval_const_expr_partial(tcx, e) {
- Ok(ref r) => (/*bad*/copy *r),
- Err(ref s) => fail!(/*bad*/copy *s)
+macro_rules! pub_fn_checked_op {
+ {$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 eval_const_expr_partial(tcx: middle::ty::ctxt, e: @expr)
- -> Result<const_val, ~str> {
- use middle::ty;
- fn fromb(b: bool) -> Result<const_val, ~str> { Ok(const_int(b as i64)) }
- match e.node {
- expr_unary(neg, inner) => {
- match eval_const_expr_partial(tcx, inner) {
- Ok(const_float(f)) => Ok(const_float(-f)),
- Ok(const_int(i)) => Ok(const_int(-i)),
- Ok(const_uint(i)) => Ok(const_uint(-i)),
- Ok(const_str(_)) => Err(~"Negate on string"),
- Ok(const_bool(_)) => Err(~"Negate on boolean"),
- ref err => (/*bad*/copy *err)
+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
+}}
+
+// After type checking, `eval_const_expr_partial` should always suffice. The
+// reason for providing `eval_const_expr_with_substs` is to allow
+// trait-associated consts to be evaluated *during* type checking, when the
+// substs for each expression have not been written into `tcx` yet.
+pub fn eval_const_expr_partial<'tcx>(tcx: &ty::ctxt<'tcx>,
+ e: &Expr,
+ ty_hint: Option<Ty<'tcx>>) -> EvalResult {
+ eval_const_expr_with_substs(tcx, e, ty_hint, |id| {
+ ty::node_id_item_substs(tcx, id).substs
+ })
+}
+
+pub fn eval_const_expr_with_substs<'tcx, S>(tcx: &ty::ctxt<'tcx>,
+ e: &Expr,
+ ty_hint: Option<Ty<'tcx>>,
+ get_substs: S) -> EvalResult
+ where S: Fn(ast::NodeId) -> subst::Substs<'tcx> {
+ fn fromb(b: bool) -> ConstVal { Int(b as i64) }
+
+ let ety = ty_hint.or_else(|| ty::expr_ty_opt(tcx, 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 {
+ ast::ExprUnary(ast::UnNeg, ref inner) => {
+ match try!(eval_const_expr_partial(tcx, &**inner, ety)) {
+ Float(f) => Float(-f),
+ Int(n) => try!(const_int_checked_neg(n, e, expr_int_type)),
+ Uint(i) => {
+ if !tcx.sess.features.borrow().negate_unsigned {
+ feature_gate::emit_feature_err(
+ &tcx.sess.parse_sess.span_diagnostic,
+ "negate_unsigned",
+ e.span,
+ "unary negation of unsigned integers may be removed in the future");
+ }
+ try!(const_uint_checked_neg(i, e, expr_uint_type))
+ }
+ Str(_) => signal!(e, NegateOnString),
+ Bool(_) => signal!(e, NegateOnBoolean),
+ Binary(_) => signal!(e, NegateOnBinary),
+ Tuple(_) => signal!(e, NegateOnTuple),
+ Struct(..) => signal!(e, NegateOnStruct),
}
}
- expr_unary(not, inner) => {
- match eval_const_expr_partial(tcx, inner) {
- Ok(const_int(i)) => Ok(const_int(!i)),
- Ok(const_uint(i)) => Ok(const_uint(!i)),
- Ok(const_bool(b)) => Ok(const_bool(!b)),
- _ => Err(~"Not on float or string")
+ ast::ExprUnary(ast::UnNot, ref inner) => {
+ match try!(eval_const_expr_partial(tcx, &**inner, ety)) {
+ Int(i) => Int(!i),
+ Uint(i) => const_uint_not(i, expr_uint_type),
+ Bool(b) => Bool(!b),
+ Str(_) => signal!(e, NotOnString),
+ Float(_) => signal!(e, NotOnFloat),
+ Binary(_) => signal!(e, NotOnBinary),
+ Tuple(_) => signal!(e, NotOnTuple),
+ Struct(..) => signal!(e, NotOnStruct),
}
}
- expr_binary(op, a, b) => {
- match (eval_const_expr_partial(tcx, a),
- eval_const_expr_partial(tcx, b)) {
- (Ok(const_float(a)), Ok(const_float(b))) => {
- match op {
- add => Ok(const_float(a + b)),
- subtract => Ok(const_float(a - b)),
- mul => Ok(const_float(a * b)),
- div => Ok(const_float(a / b)),
- rem => Ok(const_float(a % b)),
- eq => fromb(a == b),
- lt => fromb(a < b),
- le => fromb(a <= b),
- ne => fromb(a != b),
- ge => fromb(a >= b),
- gt => fromb(a > b),
- _ => Err(~"Can't do this op on floats")
+ ast::ExprBinary(op, ref a, ref b) => {
+ let b_ty = match op.node {
+ ast::BiShl | ast::BiShr => Some(tcx.types.usize),
+ _ => ety
+ };
+ match (try!(eval_const_expr_partial(tcx, &**a, ety)),
+ try!(eval_const_expr_partial(tcx, &**b, b_ty))) {
+ (Float(a), Float(b)) => {
+ match op.node {
+ ast::BiAdd => Float(a + b),
+ ast::BiSub => Float(a - b),
+ ast::BiMul => Float(a * b),
+ ast::BiDiv => Float(a / b),
+ ast::BiRem => Float(a % b),
+ ast::BiEq => fromb(a == b),
+ ast::BiLt => fromb(a < b),
+ ast::BiLe => fromb(a <= b),
+ ast::BiNe => fromb(a != b),
+ ast::BiGe => fromb(a >= b),
+ ast::BiGt => fromb(a > b),
+ _ => signal!(e, InvalidOpForFloats(op.node))
}
}
- (Ok(const_int(a)), Ok(const_int(b))) => {
- match op {
- add => Ok(const_int(a + b)),
- subtract => Ok(const_int(a - b)),
- mul => Ok(const_int(a * b)),
- div if b == 0 => Err(~"divide by zero"),
- div => Ok(const_int(a / b)),
- rem if b == 0 => Err(~"modulo zero"),
- rem => Ok(const_int(a % b)),
- and | bitand => Ok(const_int(a & b)),
- or | bitor => Ok(const_int(a | b)),
- bitxor => Ok(const_int(a ^ b)),
- shl => Ok(const_int(a << b)),
- shr => Ok(const_int(a >> b)),
- eq => fromb(a == b),
- lt => fromb(a < b),
- le => fromb(a <= b),
- ne => fromb(a != b),
- ge => fromb(a >= b),
- gt => fromb(a > b)
+ (Int(a), Int(b)) => {
+ match op.node {
+ ast::BiAdd => try!(const_int_checked_add(a,b,e,expr_int_type)),
+ ast::BiSub => try!(const_int_checked_sub(a,b,e,expr_int_type)),
+ ast::BiMul => try!(const_int_checked_mul(a,b,e,expr_int_type)),
+ ast::BiDiv => try!(const_int_checked_div(a,b,e,expr_int_type)),
+ ast::BiRem => try!(const_int_checked_rem(a,b,e,expr_int_type)),
+ ast::BiAnd | ast::BiBitAnd => Int(a & b),
+ ast::BiOr | ast::BiBitOr => Int(a | b),
+ ast::BiBitXor => Int(a ^ b),
+ ast::BiShl => try!(const_int_checked_shl(a,b,e,expr_int_type)),
+ ast::BiShr => try!(const_int_checked_shr(a,b,e,expr_int_type)),
+ ast::BiEq => fromb(a == b),
+ ast::BiLt => fromb(a < b),
+ ast::BiLe => fromb(a <= b),
+ ast::BiNe => fromb(a != b),
+ ast::BiGe => fromb(a >= b),
+ ast::BiGt => fromb(a > b)
}
}
- (Ok(const_uint(a)), Ok(const_uint(b))) => {
- match op {
- add => Ok(const_uint(a + b)),
- subtract => Ok(const_uint(a - b)),
- mul => Ok(const_uint(a * b)),
- div if b == 0 => Err(~"divide by zero"),
- div => Ok(const_uint(a / b)),
- rem if b == 0 => Err(~"modulo zero"),
- rem => Ok(const_uint(a % b)),
- and | bitand => Ok(const_uint(a & b)),
- or | bitor => Ok(const_uint(a | b)),
- bitxor => Ok(const_uint(a ^ b)),
- shl => Ok(const_uint(a << b)),
- shr => Ok(const_uint(a >> b)),
- eq => fromb(a == b),
- lt => fromb(a < b),
- le => fromb(a <= b),
- ne => fromb(a != b),
- ge => fromb(a >= b),
- gt => fromb(a > b),
+ (Uint(a), Uint(b)) => {
+ match op.node {
+ ast::BiAdd => try!(const_uint_checked_add(a,b,e,expr_uint_type)),
+ ast::BiSub => try!(const_uint_checked_sub(a,b,e,expr_uint_type)),
+ ast::BiMul => try!(const_uint_checked_mul(a,b,e,expr_uint_type)),
+ ast::BiDiv => try!(const_uint_checked_div(a,b,e,expr_uint_type)),
+ ast::BiRem => try!(const_uint_checked_rem(a,b,e,expr_uint_type)),
+ ast::BiAnd | ast::BiBitAnd => Uint(a & b),
+ ast::BiOr | ast::BiBitOr => Uint(a | b),
+ ast::BiBitXor => Uint(a ^ b),
+ ast::BiShl => try!(const_uint_checked_shl(a,b,e,expr_uint_type)),
+ ast::BiShr => try!(const_uint_checked_shr(a,b,e,expr_uint_type)),
+ ast::BiEq => fromb(a == b),
+ ast::BiLt => fromb(a < b),
+ ast::BiLe => fromb(a <= b),
+ ast::BiNe => fromb(a != b),
+ ast::BiGe => fromb(a >= b),
+ ast::BiGt => fromb(a > b),
}
}
// shifts can have any integral type as their rhs
- (Ok(const_int(a)), Ok(const_uint(b))) => {
- match op {
- shl => Ok(const_int(a << b)),
- shr => Ok(const_int(a >> b)),
- _ => Err(~"Can't do this op on an int and uint")
+ (Int(a), Uint(b)) => {
+ match op.node {
+ ast::BiShl => try!(const_int_checked_shl_via_uint(a,b,e,expr_int_type)),
+ ast::BiShr => try!(const_int_checked_shr_via_uint(a,b,e,expr_int_type)),
+ _ => signal!(e, InvalidOpForIntUint(op.node)),
}
}
- (Ok(const_uint(a)), Ok(const_int(b))) => {
- match op {
- shl => Ok(const_uint(a << b)),
- shr => Ok(const_uint(a >> b)),
- _ => Err(~"Can't do this op on a uint and int")
+ (Uint(a), Int(b)) => {
+ match op.node {
+ ast::BiShl => try!(const_uint_checked_shl_via_int(a,b,e,expr_uint_type)),
+ ast::BiShr => try!(const_uint_checked_shr_via_int(a,b,e,expr_uint_type)),
+ _ => signal!(e, InvalidOpForUintInt(op.node)),
}
}
- (Ok(const_bool(a)), Ok(const_bool(b))) => {
- Ok(const_bool(match op {
- and => a && b,
- or => a || b,
- bitxor => a ^ b,
- bitand => a & b,
- bitor => a | b,
- eq => a == b,
- ne => a != b,
- _ => return Err(~"Can't do this op on bools")
- }))
+ (Bool(a), Bool(b)) => {
+ Bool(match op.node {
+ ast::BiAnd => a && b,
+ ast::BiOr => a || b,
+ ast::BiBitXor => a ^ b,
+ ast::BiBitAnd => a & b,
+ ast::BiBitOr => a | b,
+ ast::BiEq => a == b,
+ ast::BiNe => a != b,
+ _ => signal!(e, InvalidOpForBools(op.node)),
+ })
}
- _ => Err(~"Bad operands for binary")
+
+ _ => signal!(e, MiscBinaryOp),
}
}
- expr_cast(base, _) => {
- let ety = ty::expr_ty(tcx, e);
- let base = eval_const_expr_partial(tcx, base);
- match ty::get(ety).sty {
- ty::ty_float(_) => {
- match base {
- Ok(const_uint(u)) => Ok(const_float(u as f64)),
- Ok(const_int(i)) => Ok(const_float(i as f64)),
- Ok(const_float(_)) => base,
- _ => Err(~"Can't cast float to str")
- }
- }
- ty::ty_uint(_) => {
- match base {
- Ok(const_uint(_)) => base,
- Ok(const_int(i)) => Ok(const_uint(i as u64)),
- Ok(const_float(f)) => Ok(const_uint(f as u64)),
- _ => Err(~"Can't cast str to uint")
- }
- }
- ty::ty_int(_) | ty::ty_bool => {
- match base {
- Ok(const_uint(u)) => Ok(const_int(u as i64)),
- Ok(const_int(_)) => base,
- Ok(const_float(f)) => Ok(const_int(f as i64)),
- _ => Err(~"Can't cast str to int")
+ ast::ExprCast(ref base, ref target_ty) => {
+ // This tends to get called w/o the type actually having been
+ // populated in the ctxt, which was causing things to blow up
+ // (#5900). Fall back to doing a limited lookup to get past it.
+ 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")
+ });
+
+ // Prefer known type to noop, but always have a type hint.
+ //
+ // 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.
+ let base_hint = ty::expr_ty_opt(tcx, &**base).unwrap_or(ety);
+ let val = try!(eval_const_expr_partial(tcx, &**base, Some(base_hint)));
+ match cast_const(tcx, val, ety) {
+ Ok(val) => val,
+ Err(kind) => return Err(ConstEvalErr { span: e.span, kind: kind }),
+ }
+ }
+ ast::ExprPath(..) => {
+ let opt_def = tcx.def_map.borrow().get(&e.id).map(|d| d.full_def());
+ let (const_expr, const_ty) = match opt_def {
+ Some(def::DefConst(def_id)) => {
+ if ast_util::is_local(def_id) {
+ match tcx.map.find(def_id.node) {
+ Some(ast_map::NodeItem(it)) => match it.node {
+ ast::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)
+ }
+ }
+ Some(def::DefAssociatedConst(def_id, provenance)) => {
+ if ast_util::is_local(def_id) {
+ match provenance {
+ def::FromTrait(trait_id) => match tcx.map.find(def_id.node) {
+ Some(ast_map::NodeTraitItem(ti)) => match ti.node {
+ ast::ConstTraitItem(ref ty, _) => {
+ let substs = get_substs(e.id);
+ (resolve_trait_associated_const(tcx,
+ ti,
+ trait_id,
+ substs),
+ Some(&**ty))
+ }
+ _ => (None, None)
+ },
+ _ => (None, None)
+ },
+ def::FromImpl(_) => match tcx.map.find(def_id.node) {
+ Some(ast_map::NodeImplItem(ii)) => match ii.node {
+ ast::ConstImplItem(ref ty, ref expr) => {
+ (Some(&**expr), Some(&**ty))
+ }
+ _ => (None, None)
+ },
+ _ => (None, None)
+ },
+ }
+ } else {
+ (lookup_const_by_id(tcx, def_id, Some(e.id)), None)
+ }
+ }
+ Some(def::DefVariant(enum_def, variant_def, _)) => {
+ (lookup_variant_by_id(tcx, enum_def, variant_def), None)
+ }
+ _ => (None, None)
+ };
+ let const_expr = match const_expr {
+ Some(actual_e) => actual_e,
+ None => signal!(e, NonConstPath)
+ };
+ let ety = ety.or_else(|| const_ty.and_then(|ty| ast_ty_to_prim_ty(tcx, ty)));
+ try!(eval_const_expr_partial(tcx, const_expr, ety))
+ }
+ ast::ExprLit(ref lit) => {
+ lit_to_const(&**lit, ety)
+ }
+ ast::ExprParen(ref e) => try!(eval_const_expr_partial(tcx, &**e, ety)),
+ ast::ExprBlock(ref block) => {
+ match block.expr {
+ Some(ref expr) => try!(eval_const_expr_partial(tcx, &**expr, ety)),
+ None => Int(0)
+ }
+ }
+ ast::ExprTup(_) => Tuple(e.id),
+ ast::ExprStruct(..) => Struct(e.id),
+ ast::ExprTupField(ref base, index) => {
+ if let Ok(c) = eval_const_expr_partial(tcx, base, None) {
+ if let Tuple(tup_id) = c {
+ if let ast::ExprTup(ref fields) = tcx.map.expect_expr(tup_id).node {
+ if index.node < fields.len() {
+ return eval_const_expr_partial(tcx, &fields[index.node], None)
+ } else {
+ signal!(e, TupleIndexOutOfBounds);
+ }
+ } else {
+ unreachable!()
+ }
+ } else {
+ signal!(base, ExpectedConstTuple);
}
- }
- _ => Err(~"Can't cast this type")
+ } else {
+ signal!(base, NonConstPath)
}
}
- expr_path(_) => {
- match lookup_const(tcx, e) {
- Some(actual_e) => eval_const_expr_partial(tcx, actual_e),
- None => Err(~"Non-constant path in constant expr")
- }
+ ast::ExprField(ref base, field_name) => {
+ // Get the base expression if it is a struct and it is constant
+ if let Ok(c) = eval_const_expr_partial(tcx, base, None) {
+ if let Struct(struct_id) = c {
+ if let ast::ExprStruct(_, ref fields, _) = tcx.map.expect_expr(struct_id).node {
+ // Check that the given field exists and evaluate it
+ if let Some(f) = fields.iter().find(|f| f.ident.node.as_str()
+ == field_name.node.as_str()) {
+ return eval_const_expr_partial(tcx, &*f.expr, None)
+ } else {
+ signal!(e, MissingStructField);
+ }
+ } else {
+ unreachable!()
+ }
+ } else {
+ signal!(base, ExpectedConstStruct);
+ }
+ } else {
+ signal!(base, NonConstPath);
+ }
}
- expr_lit(lit) => Ok(lit_to_const(lit)),
- // If we have a vstore, just keep going; it has to be a string
- expr_vstore(e, _) => eval_const_expr_partial(tcx, e),
- expr_paren(e) => eval_const_expr_partial(tcx, e),
- _ => Err(~"Unsupported constant expr")
- }
-}
+ _ => signal!(e, MiscCatchAll)
+ };
-pub fn lit_to_const(lit: @lit) -> const_val {
- match lit.node {
- lit_str(s) => const_str(/*bad*/copy *s),
- lit_int(n, _) => const_int(n),
- lit_uint(n, _) => const_uint(n),
- lit_int_unsuffixed(n) => const_int(n),
- lit_float(n, _) => const_float(float::from_str(*n).get() as f64),
- lit_float_unsuffixed(n) =>
- const_float(float::from_str(*n).get() as f64),
- lit_nil => const_int(0i64),
- lit_bool(b) => const_bool(b)
- }
+ Ok(result)
}
-pub fn compare_const_vals(a: const_val, b: const_val) -> int {
- match (&a, &b) {
- (&const_int(a), &const_int(b)) => {
- if a == b {
- 0
- } else if a < b {
- -1
- } else {
- 1
+fn resolve_trait_associated_const<'a, 'tcx: 'a>(tcx: &'a ty::ctxt<'tcx>,
+ ti: &'tcx ast::TraitItem,
+ trait_id: ast::DefId,
+ rcvr_substs: subst::Substs<'tcx>)
+ -> Option<&'tcx Expr>
+{
+ let subst::SeparateVecsPerParamSpace {
+ types: rcvr_type,
+ selfs: rcvr_self,
+ fns: _,
+ } = rcvr_substs.types.split();
+ let trait_substs =
+ subst::Substs::erased(subst::VecPerParamSpace::new(rcvr_type,
+ rcvr_self,
+ Vec::new()));
+ let trait_substs = tcx.mk_substs(trait_substs);
+ debug!("resolve_trait_associated_const: trait_substs={:?}",
+ trait_substs);
+ let trait_ref = ty::Binder(ty::TraitRef { def_id: trait_id,
+ substs: trait_substs });
+
+ ty::populate_implementations_for_trait_if_necessary(tcx, trait_ref.def_id());
+ let infcx = infer::new_infer_ctxt(tcx);
+
+ let param_env = ty::empty_parameter_environment(tcx);
+ let mut selcx = traits::SelectionContext::new(&infcx, ¶m_env);
+ 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
}
- }
- (&const_uint(a), &const_uint(b)) => {
- if a == b {
- 0
- } else if a < b {
- -1
- } else {
- 1
+ Err(e) => {
+ tcx.sess.span_bug(ti.span,
+ &format!("Encountered error `{:?}` when trying \
+ to select an implementation for \
+ constant trait item reference.",
+ e))
}
- }
- (&const_float(a), &const_float(b)) => {
- if a == b {
- 0
- } else if a < b {
- -1
- } else {
- 1
+ };
+
+ match selection {
+ traits::VtableImpl(ref impl_data) => {
+ match ty::associated_consts(tcx, impl_data.impl_def_id)
+ .iter().find(|ic| ic.name == ti.ident.name) {
+ Some(ic) => lookup_const_by_id(tcx, ic.def_id, None),
+ None => match ti.node {
+ ast::ConstTraitItem(_, Some(ref expr)) => Some(&*expr),
+ _ => None,
+ },
+ }
}
- }
- (&const_str(ref a), &const_str(ref b)) => {
- if (*a) == (*b) {
- 0
- } else if (*a) < (*b) {
- -1
- } else {
- 1
+ _ => {
+ tcx.sess.span_bug(
+ ti.span,
+ &format!("resolve_trait_associated_const: unexpected vtable type"))
}
}
- (&const_bool(a), &const_bool(b)) => {
- if a == b {
- 0
- } else if a < b {
- -1
- } else {
- 1
+}
+
+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))),
+ }
}
}
- _ => fail!(~"compare_const_vals: ill-typed comparison")
- }
-}
-pub fn compare_lit_exprs(tcx: middle::ty::ctxt, a: @expr, b: @expr) -> int {
- compare_const_vals(eval_const_expr(tcx, a), eval_const_expr(tcx, b))
-}
+ // 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::TyIs), ast::TyI32, _) => return convert_val!(i32, Int, i64),
+ (&ty::TyInt(ast::TyIs), ast::TyI64, _) => return convert_val!(i64, Int, i64),
+ (&ty::TyInt(ast::TyIs), _, _) => panic!("unexpected target.int_type"),
+
+ (&ty::TyUint(ast::TyUs), _, ast::TyU32) => return convert_val!(u32, Uint, u64),
+ (&ty::TyUint(ast::TyUs), _, ast::TyU64) => return convert_val!(u64, Uint, u64),
+ (&ty::TyUint(ast::TyUs), _, _) => panic!("unexpected target.uint_type"),
+
+ _ => {}
+ }
-pub fn lit_expr_eq(tcx: middle::ty::ctxt, a: @expr, b: @expr) -> bool {
- compare_lit_exprs(tcx, a, b) == 0
+ match ty.sty {
+ ty::TyInt(ast::TyIs) => unreachable!(),
+ ty::TyUint(ast::TyUs) => unreachable!(),
+
+ ty::TyInt(ast::TyI8) => convert_val!(i8, Int, i64),
+ ty::TyInt(ast::TyI16) => convert_val!(i16, Int, i64),
+ ty::TyInt(ast::TyI32) => convert_val!(i32, Int, i64),
+ ty::TyInt(ast::TyI64) => convert_val!(i64, Int, i64),
+
+ ty::TyUint(ast::TyU8) => convert_val!(u8, Uint, u64),
+ ty::TyUint(ast::TyU16) => convert_val!(u16, Uint, u64),
+ ty::TyUint(ast::TyU32) => convert_val!(u32, Uint, u64),
+ ty::TyUint(ast::TyU64) => convert_val!(u64, Uint, u64),
+
+ ty::TyFloat(ast::TyF32) => convert_val!(f32, Float, f64),
+ ty::TyFloat(ast::TyF64) => convert_val!(f64, Float, f64),
+ _ => Err(ErrKind::CannotCast),
+ }
}
-pub fn lit_eq(a: @lit, b: @lit) -> bool {
- compare_const_vals(lit_to_const(a), lit_to_const(b)) == 0
+fn lit_to_const(lit: &ast::Lit, ty_hint: Option<Ty>) -> ConstVal {
+ match lit.node {
+ ast::LitStr(ref s, _) => Str((*s).clone()),
+ ast::LitBinary(ref data) => {
+ Binary(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) => {
+ Float(n.parse::<f64>().unwrap() as f64)
+ }
+ 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),
+ (&Binary(ref a), &Binary(ref b)) => a.cmp(b),
+ _ => return None
+ })
+}
-// Local Variables:
-// mode: rust
-// fill-column: 78;
-// indent-tabs-mode: nil
-// c-basic-offset: 4
-// buffer-file-coding-system: utf-8-unix
-// End:
+pub fn compare_lit_exprs<'tcx, S>(tcx: &ty::ctxt<'tcx>,
+ a: &Expr,
+ b: &Expr,
+ ty_hint: Option<Ty<'tcx>>,
+ get_substs: S) -> Option<Ordering>
+ where S: Fn(ast::NodeId) -> subst::Substs<'tcx> {
+ let a = match eval_const_expr_with_substs(tcx, a, ty_hint,
+ |id| {get_substs(id)}) {
+ Ok(a) => a,
+ Err(e) => {
+ tcx.sess.span_err(a.span, &e.description());
+ return None;
+ }
+ };
+ let b = match eval_const_expr_with_substs(tcx, b, ty_hint, get_substs) {
+ Ok(b) => b,
+ Err(e) => {
+ tcx.sess.span_err(b.span, &e.description());
+ return None;
+ }
+ };
+ compare_const_vals(&a, &b)
+}
projects / rustc.git / blobdiff