-#![allow(clippy::float_cmp)]
-
-use crate::utils::{clip, higher, sext, unsext};
-use if_chain::if_chain;
-use rustc::hir::def::{DefKind, Res};
-use rustc::hir::*;
-use rustc::lint::LateContext;
-use rustc::ty::subst::{Subst, SubstsRef};
-use rustc::ty::{self, Ty, TyCtxt};
-use rustc::{bug, span_bug};
-use rustc_data_structures::sync::Lrc;
-use rustc_span::symbol::Symbol;
-use std::cmp::Ordering::{self, Equal};
-use std::cmp::PartialOrd;
-use std::convert::TryInto;
-use std::hash::{Hash, Hasher};
-use syntax::ast::{FloatTy, LitKind};
-
-/// A `LitKind`-like enum to fold constant `Expr`s into.
-#[derive(Debug, Clone)]
-pub enum Constant {
- /// A `String` (e.g., "abc").
- Str(String),
- /// A binary string (e.g., `b"abc"`).
- Binary(Lrc<Vec<u8>>),
- /// A single `char` (e.g., `'a'`).
- Char(char),
- /// An integer's bit representation.
- Int(u128),
- /// An `f32`.
- F32(f32),
- /// An `f64`.
- F64(f64),
- /// `true` or `false`.
- Bool(bool),
- /// An array of constants.
- Vec(Vec<Constant>),
- /// Also an array, but with only one constant, repeated N times.
- Repeat(Box<Constant>, u64),
- /// A tuple of constants.
- Tuple(Vec<Constant>),
- /// A raw pointer.
- RawPtr(u128),
- /// A literal with syntax error.
- Err(Symbol),
-}
-
-impl PartialEq for Constant {
- fn eq(&self, other: &Self) -> bool {
- match (self, other) {
- (&Self::Str(ref ls), &Self::Str(ref rs)) => ls == rs,
- (&Self::Binary(ref l), &Self::Binary(ref r)) => l == r,
- (&Self::Char(l), &Self::Char(r)) => l == r,
- (&Self::Int(l), &Self::Int(r)) => l == r,
- (&Self::F64(l), &Self::F64(r)) => {
- // We want `Fw32 == FwAny` and `FwAny == Fw64`, and by transitivity we must have
- // `Fw32 == Fw64`, so don’t compare them.
- // `to_bits` is required to catch non-matching 0.0, -0.0, and NaNs.
- l.to_bits() == r.to_bits()
- },
- (&Self::F32(l), &Self::F32(r)) => {
- // We want `Fw32 == FwAny` and `FwAny == Fw64`, and by transitivity we must have
- // `Fw32 == Fw64`, so don’t compare them.
- // `to_bits` is required to catch non-matching 0.0, -0.0, and NaNs.
- f64::from(l).to_bits() == f64::from(r).to_bits()
- },
- (&Self::Bool(l), &Self::Bool(r)) => l == r,
- (&Self::Vec(ref l), &Self::Vec(ref r)) | (&Self::Tuple(ref l), &Self::Tuple(ref r)) => l == r,
- (&Self::Repeat(ref lv, ref ls), &Self::Repeat(ref rv, ref rs)) => ls == rs && lv == rv,
- // TODO: are there inter-type equalities?
- _ => false,
- }
- }
-}
-
-impl Hash for Constant {
- fn hash<H>(&self, state: &mut H)
- where
- H: Hasher,
- {
- std::mem::discriminant(self).hash(state);
- match *self {
- Self::Str(ref s) => {
- s.hash(state);
- },
- Self::Binary(ref b) => {
- b.hash(state);
- },
- Self::Char(c) => {
- c.hash(state);
- },
- Self::Int(i) => {
- i.hash(state);
- },
- Self::F32(f) => {
- f64::from(f).to_bits().hash(state);
- },
- Self::F64(f) => {
- f.to_bits().hash(state);
- },
- Self::Bool(b) => {
- b.hash(state);
- },
- Self::Vec(ref v) | Self::Tuple(ref v) => {
- v.hash(state);
- },
- Self::Repeat(ref c, l) => {
- c.hash(state);
- l.hash(state);
- },
- Self::RawPtr(u) => {
- u.hash(state);
- },
- Self::Err(ref s) => {
- s.hash(state);
- },
- }
- }
-}
-
-impl Constant {
- pub fn partial_cmp(tcx: TyCtxt<'_>, cmp_type: Ty<'_>, left: &Self, right: &Self) -> Option<Ordering> {
- match (left, right) {
- (&Self::Str(ref ls), &Self::Str(ref rs)) => Some(ls.cmp(rs)),
- (&Self::Char(ref l), &Self::Char(ref r)) => Some(l.cmp(r)),
- (&Self::Int(l), &Self::Int(r)) => {
- if let ty::Int(int_ty) = cmp_type.kind {
- Some(sext(tcx, l, int_ty).cmp(&sext(tcx, r, int_ty)))
- } else {
- Some(l.cmp(&r))
- }
- },
- (&Self::F64(l), &Self::F64(r)) => l.partial_cmp(&r),
- (&Self::F32(l), &Self::F32(r)) => l.partial_cmp(&r),
- (&Self::Bool(ref l), &Self::Bool(ref r)) => Some(l.cmp(r)),
- (&Self::Tuple(ref l), &Self::Tuple(ref r)) | (&Self::Vec(ref l), &Self::Vec(ref r)) => l
- .iter()
- .zip(r.iter())
- .map(|(li, ri)| Self::partial_cmp(tcx, cmp_type, li, ri))
- .find(|r| r.map_or(true, |o| o != Ordering::Equal))
- .unwrap_or_else(|| Some(l.len().cmp(&r.len()))),
- (&Self::Repeat(ref lv, ref ls), &Self::Repeat(ref rv, ref rs)) => {
- match Self::partial_cmp(tcx, cmp_type, lv, rv) {
- Some(Equal) => Some(ls.cmp(rs)),
- x => x,
- }
- },
- // TODO: are there any useful inter-type orderings?
- _ => None,
- }
- }
-}
-
-/// Parses a `LitKind` to a `Constant`.
-pub fn lit_to_constant(lit: &LitKind, ty: Option<Ty<'_>>) -> Constant {
- use syntax::ast::*;
-
- match *lit {
- LitKind::Str(ref is, _) => Constant::Str(is.to_string()),
- LitKind::Byte(b) => Constant::Int(u128::from(b)),
- LitKind::ByteStr(ref s) => Constant::Binary(Lrc::clone(s)),
- LitKind::Char(c) => Constant::Char(c),
- LitKind::Int(n, _) => Constant::Int(n),
- LitKind::Float(ref is, LitFloatType::Suffixed(fty)) => match fty {
- FloatTy::F32 => Constant::F32(is.as_str().parse().unwrap()),
- FloatTy::F64 => Constant::F64(is.as_str().parse().unwrap()),
- },
- LitKind::Float(ref is, LitFloatType::Unsuffixed) => match ty.expect("type of float is known").kind {
- ty::Float(FloatTy::F32) => Constant::F32(is.as_str().parse().unwrap()),
- ty::Float(FloatTy::F64) => Constant::F64(is.as_str().parse().unwrap()),
- _ => bug!(),
- },
- LitKind::Bool(b) => Constant::Bool(b),
- LitKind::Err(s) => Constant::Err(s),
- }
-}
-
-pub fn constant<'c, 'cc>(
- lcx: &LateContext<'c, 'cc>,
- tables: &'c ty::TypeckTables<'cc>,
- e: &Expr<'_>,
-) -> Option<(Constant, bool)> {
- let mut cx = ConstEvalLateContext {
- lcx,
- tables,
- param_env: lcx.param_env,
- needed_resolution: false,
- substs: lcx.tcx.intern_substs(&[]),
- };
- cx.expr(e).map(|cst| (cst, cx.needed_resolution))
-}
-
-pub fn constant_simple<'c, 'cc>(
- lcx: &LateContext<'c, 'cc>,
- tables: &'c ty::TypeckTables<'cc>,
- e: &Expr<'_>,
-) -> Option<Constant> {
- constant(lcx, tables, e).and_then(|(cst, res)| if res { None } else { Some(cst) })
-}
-
-/// Creates a `ConstEvalLateContext` from the given `LateContext` and `TypeckTables`.
-pub fn constant_context<'c, 'cc>(
- lcx: &'c LateContext<'c, 'cc>,
- tables: &'c ty::TypeckTables<'cc>,
-) -> ConstEvalLateContext<'c, 'cc> {
- ConstEvalLateContext {
- lcx,
- tables,
- param_env: lcx.param_env,
- needed_resolution: false,
- substs: lcx.tcx.intern_substs(&[]),
- }
-}
-
-pub struct ConstEvalLateContext<'a, 'tcx> {
- lcx: &'a LateContext<'a, 'tcx>,
- tables: &'a ty::TypeckTables<'tcx>,
- param_env: ty::ParamEnv<'tcx>,
- needed_resolution: bool,
- substs: SubstsRef<'tcx>,
-}
-
-impl<'c, 'cc> ConstEvalLateContext<'c, 'cc> {
- /// Simple constant folding: Insert an expression, get a constant or none.
- pub fn expr(&mut self, e: &Expr<'_>) -> Option<Constant> {
- if let Some((ref cond, ref then, otherwise)) = higher::if_block(&e) {
- return self.ifthenelse(cond, then, otherwise);
- }
- match e.kind {
- ExprKind::Path(ref qpath) => self.fetch_path(qpath, e.hir_id),
- ExprKind::Block(ref block, _) => self.block(block),
- ExprKind::Lit(ref lit) => Some(lit_to_constant(&lit.node, self.tables.expr_ty_opt(e))),
- ExprKind::Array(ref vec) => self.multi(vec).map(Constant::Vec),
- ExprKind::Tup(ref tup) => self.multi(tup).map(Constant::Tuple),
- ExprKind::Repeat(ref value, _) => {
- let n = match self.tables.expr_ty(e).kind {
- ty::Array(_, n) => n.eval_usize(self.lcx.tcx, self.lcx.param_env),
- _ => span_bug!(e.span, "typeck error"),
- };
- self.expr(value).map(|v| Constant::Repeat(Box::new(v), n))
- },
- ExprKind::Unary(op, ref operand) => self.expr(operand).and_then(|o| match op {
- UnNot => self.constant_not(&o, self.tables.expr_ty(e)),
- UnNeg => self.constant_negate(&o, self.tables.expr_ty(e)),
- UnDeref => Some(o),
- }),
- ExprKind::Binary(op, ref left, ref right) => self.binop(op, left, right),
- ExprKind::Call(ref callee, ref args) => {
- // We only handle a few const functions for now.
- if_chain! {
- if args.is_empty();
- if let ExprKind::Path(qpath) = &callee.kind;
- let res = self.tables.qpath_res(qpath, callee.hir_id);
- if let Some(def_id) = res.opt_def_id();
- let def_path: Vec<_> = self.lcx.get_def_path(def_id).into_iter().map(Symbol::as_str).collect();
- let def_path: Vec<&str> = def_path.iter().take(4).map(|s| &**s).collect();
- if let ["core", "num", int_impl, "max_value"] = *def_path;
- then {
- let value = match int_impl {
- "<impl i8>" => i8::max_value() as u128,
- "<impl i16>" => i16::max_value() as u128,
- "<impl i32>" => i32::max_value() as u128,
- "<impl i64>" => i64::max_value() as u128,
- "<impl i128>" => i128::max_value() as u128,
- _ => return None,
- };
- Some(Constant::Int(value))
- }
- else {
- None
- }
- }
- },
- // TODO: add other expressions.
- _ => None,
- }
- }
-
- #[allow(clippy::cast_possible_wrap)]
- fn constant_not(&self, o: &Constant, ty: Ty<'_>) -> Option<Constant> {
- use self::Constant::*;
- match *o {
- Bool(b) => Some(Bool(!b)),
- Int(value) => {
- let value = !value;
- match ty.kind {
- ty::Int(ity) => Some(Int(unsext(self.lcx.tcx, value as i128, ity))),
- ty::Uint(ity) => Some(Int(clip(self.lcx.tcx, value, ity))),
- _ => None,
- }
- },
- _ => None,
- }
- }
-
- fn constant_negate(&self, o: &Constant, ty: Ty<'_>) -> Option<Constant> {
- use self::Constant::*;
- match *o {
- Int(value) => {
- let ity = match ty.kind {
- ty::Int(ity) => ity,
- _ => return None,
- };
- // sign extend
- let value = sext(self.lcx.tcx, value, ity);
- let value = value.checked_neg()?;
- // clear unused bits
- Some(Int(unsext(self.lcx.tcx, value, ity)))
- },
- F32(f) => Some(F32(-f)),
- F64(f) => Some(F64(-f)),
- _ => None,
- }
- }
-
- /// Create `Some(Vec![..])` of all constants, unless there is any
- /// non-constant part.
- fn multi(&mut self, vec: &[Expr<'_>]) -> Option<Vec<Constant>> {
- vec.iter().map(|elem| self.expr(elem)).collect::<Option<_>>()
- }
-
- /// Lookup a possibly constant expression from a `ExprKind::Path`.
- fn fetch_path(&mut self, qpath: &QPath<'_>, id: HirId) -> Option<Constant> {
- let res = self.tables.qpath_res(qpath, id);
- match res {
- Res::Def(DefKind::Const, def_id) | Res::Def(DefKind::AssocConst, def_id) => {
- let substs = self.tables.node_substs(id);
- let substs = if self.substs.is_empty() {
- substs
- } else {
- substs.subst(self.lcx.tcx, self.substs)
- };
-
- let result = self
- .lcx
- .tcx
- .const_eval_resolve(self.param_env, def_id, substs, None)
- .ok()?;
- let result = miri_to_const(&result);
- if result.is_some() {
- self.needed_resolution = true;
- }
- result
- },
- // FIXME: cover all usable cases.
- _ => None,
- }
- }
-
- /// A block can only yield a constant if it only has one constant expression.
- fn block(&mut self, block: &Block<'_>) -> Option<Constant> {
- if block.stmts.is_empty() {
- block.expr.as_ref().and_then(|b| self.expr(b))
- } else {
- None
- }
- }
-
- fn ifthenelse(&mut self, cond: &Expr<'_>, then: &Expr<'_>, otherwise: Option<&Expr<'_>>) -> Option<Constant> {
- if let Some(Constant::Bool(b)) = self.expr(cond) {
- if b {
- self.expr(&*then)
- } else {
- otherwise.as_ref().and_then(|expr| self.expr(expr))
- }
- } else {
- None
- }
- }
-
- fn binop(&mut self, op: BinOp, left: &Expr<'_>, right: &Expr<'_>) -> Option<Constant> {
- let l = self.expr(left)?;
- let r = self.expr(right);
- match (l, r) {
- (Constant::Int(l), Some(Constant::Int(r))) => match self.tables.expr_ty(left).kind {
- ty::Int(ity) => {
- let l = sext(self.lcx.tcx, l, ity);
- let r = sext(self.lcx.tcx, r, ity);
- let zext = |n: i128| Constant::Int(unsext(self.lcx.tcx, n, ity));
- match op.node {
- BinOpKind::Add => l.checked_add(r).map(zext),
- BinOpKind::Sub => l.checked_sub(r).map(zext),
- BinOpKind::Mul => l.checked_mul(r).map(zext),
- BinOpKind::Div if r != 0 => l.checked_div(r).map(zext),
- BinOpKind::Rem if r != 0 => l.checked_rem(r).map(zext),
- BinOpKind::Shr => l.checked_shr(r.try_into().expect("invalid shift")).map(zext),
- BinOpKind::Shl => l.checked_shl(r.try_into().expect("invalid shift")).map(zext),
- BinOpKind::BitXor => Some(zext(l ^ r)),
- BinOpKind::BitOr => Some(zext(l | r)),
- BinOpKind::BitAnd => Some(zext(l & r)),
- BinOpKind::Eq => Some(Constant::Bool(l == r)),
- BinOpKind::Ne => Some(Constant::Bool(l != r)),
- BinOpKind::Lt => Some(Constant::Bool(l < r)),
- BinOpKind::Le => Some(Constant::Bool(l <= r)),
- BinOpKind::Ge => Some(Constant::Bool(l >= r)),
- BinOpKind::Gt => Some(Constant::Bool(l > r)),
- _ => None,
- }
- },
- ty::Uint(_) => match op.node {
- BinOpKind::Add => l.checked_add(r).map(Constant::Int),
- BinOpKind::Sub => l.checked_sub(r).map(Constant::Int),
- BinOpKind::Mul => l.checked_mul(r).map(Constant::Int),
- BinOpKind::Div => l.checked_div(r).map(Constant::Int),
- BinOpKind::Rem => l.checked_rem(r).map(Constant::Int),
- BinOpKind::Shr => l.checked_shr(r.try_into().expect("shift too large")).map(Constant::Int),
- BinOpKind::Shl => l.checked_shl(r.try_into().expect("shift too large")).map(Constant::Int),
- BinOpKind::BitXor => Some(Constant::Int(l ^ r)),
- BinOpKind::BitOr => Some(Constant::Int(l | r)),
- BinOpKind::BitAnd => Some(Constant::Int(l & r)),
- BinOpKind::Eq => Some(Constant::Bool(l == r)),
- BinOpKind::Ne => Some(Constant::Bool(l != r)),
- BinOpKind::Lt => Some(Constant::Bool(l < r)),
- BinOpKind::Le => Some(Constant::Bool(l <= r)),
- BinOpKind::Ge => Some(Constant::Bool(l >= r)),
- BinOpKind::Gt => Some(Constant::Bool(l > r)),
- _ => None,
- },
- _ => None,
- },
- (Constant::F32(l), Some(Constant::F32(r))) => match op.node {
- BinOpKind::Add => Some(Constant::F32(l + r)),
- BinOpKind::Sub => Some(Constant::F32(l - r)),
- BinOpKind::Mul => Some(Constant::F32(l * r)),
- BinOpKind::Div => Some(Constant::F32(l / r)),
- BinOpKind::Rem => Some(Constant::F32(l % r)),
- BinOpKind::Eq => Some(Constant::Bool(l == r)),
- BinOpKind::Ne => Some(Constant::Bool(l != r)),
- BinOpKind::Lt => Some(Constant::Bool(l < r)),
- BinOpKind::Le => Some(Constant::Bool(l <= r)),
- BinOpKind::Ge => Some(Constant::Bool(l >= r)),
- BinOpKind::Gt => Some(Constant::Bool(l > r)),
- _ => None,
- },
- (Constant::F64(l), Some(Constant::F64(r))) => match op.node {
- BinOpKind::Add => Some(Constant::F64(l + r)),
- BinOpKind::Sub => Some(Constant::F64(l - r)),
- BinOpKind::Mul => Some(Constant::F64(l * r)),
- BinOpKind::Div => Some(Constant::F64(l / r)),
- BinOpKind::Rem => Some(Constant::F64(l % r)),
- BinOpKind::Eq => Some(Constant::Bool(l == r)),
- BinOpKind::Ne => Some(Constant::Bool(l != r)),
- BinOpKind::Lt => Some(Constant::Bool(l < r)),
- BinOpKind::Le => Some(Constant::Bool(l <= r)),
- BinOpKind::Ge => Some(Constant::Bool(l >= r)),
- BinOpKind::Gt => Some(Constant::Bool(l > r)),
- _ => None,
- },
- (l, r) => match (op.node, l, r) {
- (BinOpKind::And, Constant::Bool(false), _) => Some(Constant::Bool(false)),
- (BinOpKind::Or, Constant::Bool(true), _) => Some(Constant::Bool(true)),
- (BinOpKind::And, Constant::Bool(true), Some(r)) | (BinOpKind::Or, Constant::Bool(false), Some(r)) => {
- Some(r)
- },
- (BinOpKind::BitXor, Constant::Bool(l), Some(Constant::Bool(r))) => Some(Constant::Bool(l ^ r)),
- (BinOpKind::BitAnd, Constant::Bool(l), Some(Constant::Bool(r))) => Some(Constant::Bool(l & r)),
- (BinOpKind::BitOr, Constant::Bool(l), Some(Constant::Bool(r))) => Some(Constant::Bool(l | r)),
- _ => None,
- },
- }
- }
-}
-
-pub fn miri_to_const(result: &ty::Const<'_>) -> Option<Constant> {
- use rustc::mir::interpret::{ConstValue, Scalar};
- match result.val {
- ty::ConstKind::Value(ConstValue::Scalar(Scalar::Raw { data: d, .. })) => match result.ty.kind {
- ty::Bool => Some(Constant::Bool(d == 1)),
- ty::Uint(_) | ty::Int(_) => Some(Constant::Int(d)),
- ty::Float(FloatTy::F32) => Some(Constant::F32(f32::from_bits(
- d.try_into().expect("invalid f32 bit representation"),
- ))),
- ty::Float(FloatTy::F64) => Some(Constant::F64(f64::from_bits(
- d.try_into().expect("invalid f64 bit representation"),
- ))),
- ty::RawPtr(type_and_mut) => {
- if let ty::Uint(_) = type_and_mut.ty.kind {
- return Some(Constant::RawPtr(d));
- }
- None
- },
- // FIXME: implement other conversions.
- _ => None,
- },
- ty::ConstKind::Value(ConstValue::Slice { data, start, end }) => match result.ty.kind {
- ty::Ref(_, tam, _) => match tam.kind {
- ty::Str => String::from_utf8(
- data.inspect_with_undef_and_ptr_outside_interpreter(start..end)
- .to_owned(),
- )
- .ok()
- .map(Constant::Str),
- _ => None,
- },
- _ => None,
- },
- // FIXME: implement other conversions.
- _ => None,
- }
-}
+pub use clippy_utils::consts::*;
projects / rust.git / blobdiff