Auto merge of #6756 - smoelius:clippy_utils, r=flip1995,obi-obk

Factor out `clippy_utils` crate

As discussed in https://github.com/rust-lang/rust-clippy/pull/6746, this PR factors out `clippy_lints::utils` as its own crate, `clippy_utils` .

This change will allow `clippy_utils` to be used in lints outside of Clippy.

There is no plan to publish this crate on `crates.io` (see https://github.com/rust-lang/rust-clippy/pull/6746#issuecomment-780747522). Dependent crates should obtain it from GitHub.

changelog: Factor out `clippy_utils` so it can be used by external tools (not published)

.gitignore

@@ -18,6 +18,7 @@ out
 *Cargo.lock
 /target
 /clippy_lints/target
+/clippy_utils/target
 /clippy_workspace_tests/target
 /clippy_dev/target
 /rustc_tools_util/target

clippy_lints/Cargo.toml

@@ -18,6 +18,7 @@ edition = "2018"
 
 [dependencies]
 cargo_metadata = "0.12"
+clippy_utils = { path = "../clippy_utils" }
 if_chain = "1.0.0"
 itertools = "0.9"
 pulldown-cmark = { version = "0.8", default-features = false }
@@ -38,4 +39,4 @@ syn = { version = "1", features = ["full"] }
 [features]
 deny-warnings = []
 # build clippy with internal lints enabled, off by default
-internal-lints = []
+internal-lints = ["clippy_utils/internal-lints"]

clippy_lints/src/consts.rs

@@ -1,574 +1 @@
-#![allow(clippy::float_cmp)]
+pub use clippy_utils::consts::*;
-
-use crate::utils::{clip, sext, unsext};
-use if_chain::if_chain;
-use rustc_ast::ast::{self, LitFloatType, LitKind};
-use rustc_data_structures::sync::Lrc;
-use rustc_hir::def::{DefKind, Res};
-use rustc_hir::{BinOp, BinOpKind, Block, Expr, ExprKind, HirId, QPath, UnOp};
-use rustc_lint::LateContext;
-use rustc_middle::mir::interpret::Scalar;
-use rustc_middle::ty::subst::{Subst, SubstsRef};
-use rustc_middle::ty::{self, FloatTy, ScalarInt, Ty, TyCtxt};
-use rustc_middle::{bug, span_bug};
-use rustc_span::symbol::Symbol;
-use std::cmp::Ordering::{self, Equal};
-use std::convert::TryInto;
-use std::hash::{Hash, Hasher};
-
-/// 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<[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 reference
-    Ref(Box<Constant>),
-    /// 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,
-            (&Self::Ref(ref lb), &Self::Ref(ref rb)) => *lb == *rb,
-            // 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::Ref(ref r) => {
-                r.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,
-                }
-            },
-            (&Self::Ref(ref lb), &Self::Ref(ref rb)) => Self::partial_cmp(tcx, cmp_type, lb, rb),
-            // 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 {
-    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 {
-            ast::FloatTy::F32 => Constant::F32(is.as_str().parse().unwrap()),
-            ast::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<'tcx>(
-    lcx: &LateContext<'tcx>,
-    typeck_results: &ty::TypeckResults<'tcx>,
-    e: &Expr<'_>,
-) -> Option<(Constant, bool)> {
-    let mut cx = ConstEvalLateContext {
-        lcx,
-        typeck_results,
-        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<'tcx>(
-    lcx: &LateContext<'tcx>,
-    typeck_results: &ty::TypeckResults<'tcx>,
-    e: &Expr<'_>,
-) -> Option<Constant> {
-    constant(lcx, typeck_results, e).and_then(|(cst, res)| if res { None } else { Some(cst) })
-}
-
-/// Creates a `ConstEvalLateContext` from the given `LateContext` and `TypeckResults`.
-pub fn constant_context<'a, 'tcx>(
-    lcx: &'a LateContext<'tcx>,
-    typeck_results: &'a ty::TypeckResults<'tcx>,
-) -> ConstEvalLateContext<'a, 'tcx> {
-    ConstEvalLateContext {
-        lcx,
-        typeck_results,
-        param_env: lcx.param_env,
-        needed_resolution: false,
-        substs: lcx.tcx.intern_substs(&[]),
-    }
-}
-
-pub struct ConstEvalLateContext<'a, 'tcx> {
-    lcx: &'a LateContext<'tcx>,
-    typeck_results: &'a ty::TypeckResults<'tcx>,
-    param_env: ty::ParamEnv<'tcx>,
-    needed_resolution: bool,
-    substs: SubstsRef<'tcx>,
-}
-
-impl<'a, 'tcx> ConstEvalLateContext<'a, 'tcx> {
-    /// Simple constant folding: Insert an expression, get a constant or none.
-    pub fn expr(&mut self, e: &Expr<'_>) -> Option<Constant> {
-        match e.kind {
-            ExprKind::Path(ref qpath) => self.fetch_path(qpath, e.hir_id, self.typeck_results.expr_ty(e)),
-            ExprKind::Block(ref block, _) => self.block(block),
-            ExprKind::Lit(ref lit) => Some(lit_to_constant(&lit.node, self.typeck_results.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.typeck_results.expr_ty(e).kind() {
-                    ty::Array(_, n) => n.try_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 {
-                UnOp::Not => self.constant_not(&o, self.typeck_results.expr_ty(e)),
-                UnOp::Neg => self.constant_negate(&o, self.typeck_results.expr_ty(e)),
-                UnOp::Deref => Some(if let Constant::Ref(r) = o { *r } else { o }),
-            }),
-            ExprKind::If(ref cond, ref then, ref otherwise) => self.ifthenelse(cond, then, *otherwise),
-            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.typeck_results.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 as u128,
-                           "<impl i16>" => i16::MAX as u128,
-                           "<impl i32>" => i32::MAX as u128,
-                           "<impl i64>" => i64::MAX as u128,
-                           "<impl i128>" => i128::MAX as u128,
-                           _ => return None,
-                       };
-                       Some(Constant::Int(value))
-                    }
-                    else {
-                        None
-                    }
-                }
-            },
-            ExprKind::Index(ref arr, ref index) => self.index(arr, index),
-            ExprKind::AddrOf(_, _, ref inner) => self.expr(inner).map(|r| Constant::Ref(Box::new(r))),
-            // TODO: add other expressions.
-            _ => None,
-        }
-    }
-
-    #[allow(clippy::cast_possible_wrap)]
-    fn constant_not(&self, o: &Constant, ty: Ty<'_>) -> Option<Constant> {
-        use self::Constant::{Bool, Int};
-        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::{Int, F32, F64};
-        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, ty: Ty<'tcx>) -> Option<Constant> {
-        let res = self.typeck_results.qpath_res(qpath, id);
-        match res {
-            Res::Def(DefKind::Const | DefKind::AssocConst, def_id) => {
-                let substs = self.typeck_results.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,
-                        ty::WithOptConstParam::unknown(def_id),
-                        substs,
-                        None,
-                        None,
-                    )
-                    .ok()
-                    .map(|val| rustc_middle::ty::Const::from_value(self.lcx.tcx, val, ty))?;
-                let result = miri_to_const(&result);
-                if result.is_some() {
-                    self.needed_resolution = true;
-                }
-                result
-            },
-            // FIXME: cover all usable cases.
-            _ => None,
-        }
-    }
-
-    fn index(&mut self, lhs: &'_ Expr<'_>, index: &'_ Expr<'_>) -> Option<Constant> {
-        let lhs = self.expr(lhs);
-        let index = self.expr(index);
-
-        match (lhs, index) {
-            (Some(Constant::Vec(vec)), Some(Constant::Int(index))) => match vec.get(index as usize) {
-                Some(Constant::F32(x)) => Some(Constant::F32(*x)),
-                Some(Constant::F64(x)) => Some(Constant::F64(*x)),
-                _ => None,
-            },
-            (Some(Constant::Vec(vec)), _) => {
-                if !vec.is_empty() && vec.iter().all(|x| *x == vec[0]) {
-                    match vec.get(0) {
-                        Some(Constant::F32(x)) => Some(Constant::F32(*x)),
-                        Some(Constant::F64(x)) => Some(Constant::F64(*x)),
-                        _ => None,
-                    }
-                } else {
-                    None
-                }
-            },
-            _ => 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.typeck_results.expr_ty_opt(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_middle::mir::interpret::ConstValue;
-    match result.val {
-        ty::ConstKind::Value(ConstValue::Scalar(Scalar::Int(int))) => {
-            match result.ty.kind() {
-                ty::Bool => Some(Constant::Bool(int == ScalarInt::TRUE)),
-                ty::Uint(_) | ty::Int(_) => Some(Constant::Int(int.assert_bits(int.size()))),
-                ty::Float(FloatTy::F32) => Some(Constant::F32(f32::from_bits(
-                    int.try_into().expect("invalid f32 bit representation"),
-                ))),
-                ty::Float(FloatTy::F64) => Some(Constant::F64(f64::from_bits(
-                    int.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(int.assert_bits(int.size())));
-                    }
-                    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_uninit_and_ptr_outside_interpreter(start..end)
-                        .to_owned(),
-                )
-                .ok()
-                .map(Constant::Str),
-                _ => None,
-            },
-            _ => None,
-        },
-        ty::ConstKind::Value(ConstValue::ByRef { alloc, offset: _ }) => match result.ty.kind() {
-            ty::Array(sub_type, len) => match sub_type.kind() {
-                ty::Float(FloatTy::F32) => match miri_to_const(len) {
-                    Some(Constant::Int(len)) => alloc
-                        .inspect_with_uninit_and_ptr_outside_interpreter(0..(4 * len as usize))
-                        .to_owned()
-                        .chunks(4)
-                        .map(|chunk| {
-                            Some(Constant::F32(f32::from_le_bytes(
-                                chunk.try_into().expect("this shouldn't happen"),
-                            )))
-                        })
-                        .collect::<Option<Vec<Constant>>>()
-                        .map(Constant::Vec),
-                    _ => None,
-                },
-                ty::Float(FloatTy::F64) => match miri_to_const(len) {
-                    Some(Constant::Int(len)) => alloc
-                        .inspect_with_uninit_and_ptr_outside_interpreter(0..(8 * len as usize))
-                        .to_owned()
-                        .chunks(8)
-                        .map(|chunk| {
-                            Some(Constant::F64(f64::from_le_bytes(
-                                chunk.try_into().expect("this shouldn't happen"),
-                            )))
-                        })
-                        .collect::<Option<Vec<Constant>>>()
-                        .map(Constant::Vec),
-                    _ => None,
-                },
-                // FIXME: implement other array type conversions.
-                _ => None,
-            },
-            _ => None,
-        },
-        // FIXME: implement other conversions.
-        _ => None,
-    }
-}

clippy_lints/src/lib.rs

@@ -1,13 +1,9 @@
 // error-pattern:cargo-clippy
 
-#![feature(bindings_after_at)]
 #![feature(box_patterns)]
 #![feature(box_syntax)]
-#![feature(concat_idents)]
-#![feature(crate_visibility_modifier)]
 #![feature(drain_filter)]
 #![feature(in_band_lifetimes)]
-#![feature(once_cell)]
 #![feature(or_patterns)]
 #![feature(rustc_private)]
 #![feature(stmt_expr_attributes)]
@@ -149,6 +145,20 @@ macro_rules! declare_clippy_lint {
     };
 }
 
+#[macro_export]
+macro_rules! sym {
+    ( $($x:tt)* ) => { clippy_utils::sym!($($x)*) }
+}
+
+#[macro_export]
+macro_rules! unwrap_cargo_metadata {
+    ( $($x:tt)* ) => { clippy_utils::unwrap_cargo_metadata!($($x)*) }
+}
+
+macro_rules! extract_msrv_attr {
+    ( $($x:tt)* ) => { clippy_utils::extract_msrv_attr!($($x)*); }
+}
+
 mod consts;
 #[macro_use]
 mod utils;

clippy_utils/Cargo.toml

@@ -0,0 +1,19 @@
+[package]
+name = "clippy_utils"
+version = "0.1.52"
+authors = ["The Rust Clippy Developers"]
+edition = "2018"
+publish = false
+
+[dependencies]
+if_chain = "1.0.0"
+itertools = "0.9"
+regex-syntax = "0.6"
+serde = { version = "1.0", features = ["derive"] }
+smallvec = { version = "1", features = ["union"] }
+toml = "0.5.3"
+unicode-normalization = "0.1"
+rustc-semver="1.1.0"
+
+[features]
+internal-lints = []

clippy_utils/src/ast_utils.rs

@@ -4,7 +4,7 @@
 
 #![allow(clippy::similar_names, clippy::wildcard_imports, clippy::enum_glob_use)]
 
-use crate::utils::{both, over};
+use crate::{both, over};
 use rustc_ast::ptr::P;
 use rustc_ast::{self as ast, *};
 use rustc_span::symbol::Ident;

clippy_utils/src/consts.rs

@@ -0,0 +1,574 @@
+#![allow(clippy::float_cmp)]
+
+use crate::{clip, sext, unsext};
+use if_chain::if_chain;
+use rustc_ast::ast::{self, LitFloatType, LitKind};
+use rustc_data_structures::sync::Lrc;
+use rustc_hir::def::{DefKind, Res};
+use rustc_hir::{BinOp, BinOpKind, Block, Expr, ExprKind, HirId, QPath, UnOp};
+use rustc_lint::LateContext;
+use rustc_middle::mir::interpret::Scalar;
+use rustc_middle::ty::subst::{Subst, SubstsRef};
+use rustc_middle::ty::{self, FloatTy, ScalarInt, Ty, TyCtxt};
+use rustc_middle::{bug, span_bug};
+use rustc_span::symbol::Symbol;
+use std::cmp::Ordering::{self, Equal};
+use std::convert::TryInto;
+use std::hash::{Hash, Hasher};
+
+/// 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<[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 reference
+    Ref(Box<Constant>),
+    /// 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,
+            (&Self::Ref(ref lb), &Self::Ref(ref rb)) => *lb == *rb,
+            // 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::Ref(ref r) => {
+                r.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,
+                }
+            },
+            (&Self::Ref(ref lb), &Self::Ref(ref rb)) => Self::partial_cmp(tcx, cmp_type, lb, rb),
+            // 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 {
+    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 {
+            ast::FloatTy::F32 => Constant::F32(is.as_str().parse().unwrap()),
+            ast::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<'tcx>(
+    lcx: &LateContext<'tcx>,
+    typeck_results: &ty::TypeckResults<'tcx>,
+    e: &Expr<'_>,
+) -> Option<(Constant, bool)> {
+    let mut cx = ConstEvalLateContext {
+        lcx,
+        typeck_results,
+        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<'tcx>(
+    lcx: &LateContext<'tcx>,
+    typeck_results: &ty::TypeckResults<'tcx>,
+    e: &Expr<'_>,
+) -> Option<Constant> {
+    constant(lcx, typeck_results, e).and_then(|(cst, res)| if res { None } else { Some(cst) })
+}
+
+/// Creates a `ConstEvalLateContext` from the given `LateContext` and `TypeckResults`.
+pub fn constant_context<'a, 'tcx>(
+    lcx: &'a LateContext<'tcx>,
+    typeck_results: &'a ty::TypeckResults<'tcx>,
+) -> ConstEvalLateContext<'a, 'tcx> {
+    ConstEvalLateContext {
+        lcx,
+        typeck_results,
+        param_env: lcx.param_env,
+        needed_resolution: false,
+        substs: lcx.tcx.intern_substs(&[]),
+    }
+}
+
+pub struct ConstEvalLateContext<'a, 'tcx> {
+    lcx: &'a LateContext<'tcx>,
+    typeck_results: &'a ty::TypeckResults<'tcx>,
+    param_env: ty::ParamEnv<'tcx>,
+    needed_resolution: bool,
+    substs: SubstsRef<'tcx>,
+}
+
+impl<'a, 'tcx> ConstEvalLateContext<'a, 'tcx> {
+    /// Simple constant folding: Insert an expression, get a constant or none.
+    pub fn expr(&mut self, e: &Expr<'_>) -> Option<Constant> {
+        match e.kind {
+            ExprKind::Path(ref qpath) => self.fetch_path(qpath, e.hir_id, self.typeck_results.expr_ty(e)),
+            ExprKind::Block(ref block, _) => self.block(block),
+            ExprKind::Lit(ref lit) => Some(lit_to_constant(&lit.node, self.typeck_results.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.typeck_results.expr_ty(e).kind() {
+                    ty::Array(_, n) => n.try_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 {
+                UnOp::Not => self.constant_not(&o, self.typeck_results.expr_ty(e)),
+                UnOp::Neg => self.constant_negate(&o, self.typeck_results.expr_ty(e)),
+                UnOp::Deref => Some(if let Constant::Ref(r) = o { *r } else { o }),
+            }),
+            ExprKind::If(ref cond, ref then, ref otherwise) => self.ifthenelse(cond, then, *otherwise),
+            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.typeck_results.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 as u128,
+                           "<impl i16>" => i16::MAX as u128,
+                           "<impl i32>" => i32::MAX as u128,
+                           "<impl i64>" => i64::MAX as u128,
+                           "<impl i128>" => i128::MAX as u128,
+                           _ => return None,
+                       };
+                       Some(Constant::Int(value))
+                    }
+                    else {
+                        None
+                    }
+                }
+            },
+            ExprKind::Index(ref arr, ref index) => self.index(arr, index),
+            ExprKind::AddrOf(_, _, ref inner) => self.expr(inner).map(|r| Constant::Ref(Box::new(r))),
+            // TODO: add other expressions.
+            _ => None,
+        }
+    }
+
+    #[allow(clippy::cast_possible_wrap)]
+    fn constant_not(&self, o: &Constant, ty: Ty<'_>) -> Option<Constant> {
+        use self::Constant::{Bool, Int};
+        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::{Int, F32, F64};
+        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, ty: Ty<'tcx>) -> Option<Constant> {
+        let res = self.typeck_results.qpath_res(qpath, id);
+        match res {
+            Res::Def(DefKind::Const | DefKind::AssocConst, def_id) => {
+                let substs = self.typeck_results.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,
+                        ty::WithOptConstParam::unknown(def_id),
+                        substs,
+                        None,
+                        None,
+                    )
+                    .ok()
+                    .map(|val| rustc_middle::ty::Const::from_value(self.lcx.tcx, val, ty))?;
+                let result = miri_to_const(&result);
+                if result.is_some() {
+                    self.needed_resolution = true;
+                }
+                result
+            },
+            // FIXME: cover all usable cases.
+            _ => None,
+        }
+    }
+
+    fn index(&mut self, lhs: &'_ Expr<'_>, index: &'_ Expr<'_>) -> Option<Constant> {
+        let lhs = self.expr(lhs);
+        let index = self.expr(index);
+
+        match (lhs, index) {
+            (Some(Constant::Vec(vec)), Some(Constant::Int(index))) => match vec.get(index as usize) {
+                Some(Constant::F32(x)) => Some(Constant::F32(*x)),
+                Some(Constant::F64(x)) => Some(Constant::F64(*x)),
+                _ => None,
+            },
+            (Some(Constant::Vec(vec)), _) => {
+                if !vec.is_empty() && vec.iter().all(|x| *x == vec[0]) {
+                    match vec.get(0) {
+                        Some(Constant::F32(x)) => Some(Constant::F32(*x)),
+                        Some(Constant::F64(x)) => Some(Constant::F64(*x)),
+                        _ => None,
+                    }
+                } else {
+                    None
+                }
+            },
+            _ => 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.typeck_results.expr_ty_opt(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_middle::mir::interpret::ConstValue;
+    match result.val {
+        ty::ConstKind::Value(ConstValue::Scalar(Scalar::Int(int))) => {
+            match result.ty.kind() {
+                ty::Bool => Some(Constant::Bool(int == ScalarInt::TRUE)),
+                ty::Uint(_) | ty::Int(_) => Some(Constant::Int(int.assert_bits(int.size()))),
+                ty::Float(FloatTy::F32) => Some(Constant::F32(f32::from_bits(
+                    int.try_into().expect("invalid f32 bit representation"),
+                ))),
+                ty::Float(FloatTy::F64) => Some(Constant::F64(f64::from_bits(
+                    int.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(int.assert_bits(int.size())));
+                    }
+                    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_uninit_and_ptr_outside_interpreter(start..end)
+                        .to_owned(),
+                )
+                .ok()
+                .map(Constant::Str),
+                _ => None,
+            },
+            _ => None,
+        },
+        ty::ConstKind::Value(ConstValue::ByRef { alloc, offset: _ }) => match result.ty.kind() {
+            ty::Array(sub_type, len) => match sub_type.kind() {
+                ty::Float(FloatTy::F32) => match miri_to_const(len) {
+                    Some(Constant::Int(len)) => alloc
+                        .inspect_with_uninit_and_ptr_outside_interpreter(0..(4 * len as usize))
+                        .to_owned()
+                        .chunks(4)
+                        .map(|chunk| {
+                            Some(Constant::F32(f32::from_le_bytes(
+                                chunk.try_into().expect("this shouldn't happen"),
+                            )))
+                        })
+                        .collect::<Option<Vec<Constant>>>()
+                        .map(Constant::Vec),
+                    _ => None,
+                },
+                ty::Float(FloatTy::F64) => match miri_to_const(len) {
+                    Some(Constant::Int(len)) => alloc
+                        .inspect_with_uninit_and_ptr_outside_interpreter(0..(8 * len as usize))
+                        .to_owned()
+                        .chunks(8)
+                        .map(|chunk| {
+                            Some(Constant::F64(f64::from_le_bytes(
+                                chunk.try_into().expect("this shouldn't happen"),
+                            )))
+                        })
+                        .collect::<Option<Vec<Constant>>>()
+                        .map(Constant::Vec),
+                    _ => None,
+                },
+                // FIXME: implement other array type conversions.
+                _ => None,
+            },
+            _ => None,
+        },
+        // FIXME: implement other conversions.
+        _ => None,
+    }
+}

clippy_utils/src/eager_or_lazy.rs

@@ -9,7 +9,7 @@
 //!  - or-fun-call
 //!  - option-if-let-else
 
-use crate::utils::{is_ctor_or_promotable_const_function, is_type_diagnostic_item, match_type, paths};
+use crate::{is_ctor_or_promotable_const_function, is_type_diagnostic_item, match_type, paths};
 use rustc_hir::def::{DefKind, Res};
 
 use rustc_hir::intravisit;

clippy_utils/src/higher.rs

@@ -3,7 +3,7 @@
 
 #![deny(clippy::missing_docs_in_private_items)]
 
-use crate::utils::{is_expn_of, match_def_path, paths};
+use crate::{is_expn_of, match_def_path, paths};
 use if_chain::if_chain;
 use rustc_ast::ast;
 use rustc_hir as hir;

clippy_utils/src/hir_utils.rs

@@ -1,5 +1,5 @@
 use crate::consts::{constant_context, constant_simple};
-use crate::utils::differing_macro_contexts;
+use crate::differing_macro_contexts;
 use rustc_ast::ast::InlineAsmTemplatePiece;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};

clippy_utils/src/ptr.rs

@@ -1,4 +1,4 @@
-use crate::utils::{get_pat_name, match_var, snippet};
+use crate::{get_pat_name, match_var, snippet};
 use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
 use rustc_hir::{Body, BodyId, Expr, ExprKind, Param};
 use rustc_lint::LateContext;

clippy_utils/src/sugg.rs

@@ -1,7 +1,7 @@
 //! Contains utility functions to generate suggestions.
 #![deny(clippy::missing_docs_in_private_items)]
 
-use crate::utils::{higher, snippet, snippet_opt, snippet_with_macro_callsite};
+use crate::{higher, snippet, snippet_opt, snippet_with_macro_callsite};
 use rustc_ast::util::parser::AssocOp;
 use rustc_ast::{ast, token};
 use rustc_ast_pretty::pprust::token_kind_to_string;

clippy_utils/src/usage.rs

@@ -1,4 +1,4 @@
-use crate::utils;
+use crate as utils;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_hir as hir;
 use rustc_hir::def::Res;

clippy_utils/src/visitors.rs

@@ -1,4 +1,4 @@
-use crate::utils::path_to_local_id;
+use crate::path_to_local_id;
 use rustc_hir as hir;
 use rustc_hir::intravisit::{self, walk_expr, NestedVisitorMap, Visitor};
 use rustc_hir::{Arm, Body, Expr, HirId, Stmt};

doc/adding_lints.md

@@ -292,7 +292,7 @@ the next section. Let's worry about the details later and emit our lint for
 
 Depending on how complex we want our lint message to be, we can choose from a
 variety of lint emission functions. They can all be found in
-[`clippy_lints/src/utils/diagnostics.rs`][diagnostics].
+[`clippy_utils/src/diagnostics.rs`][diagnostics].
 
 `span_lint_and_help` seems most appropriate in this case. It allows us to
 provide an extra help message and we can't really suggest a better name
@@ -321,7 +321,7 @@ When code or an identifier must appear in a message or label, it should be
 surrounded with single grave accents \`.
 
 [check_fn]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_lint/trait.EarlyLintPass.html#method.check_fn
-[diagnostics]: https://github.com/rust-lang/rust-clippy/blob/master/clippy_lints/src/utils/diagnostics.rs
+[diagnostics]: https://github.com/rust-lang/rust-clippy/blob/master/clippy_utils/src/diagnostics.rs
 [the rustc-dev-guide]: https://rustc-dev-guide.rust-lang.org/diagnostics.html
 
 ## Adding the lint logic
@@ -537,7 +537,7 @@ directory. Adding a configuration to a lint can be useful for thresholds or to c
 behavior that can be seen as a false positive for some users. Adding a configuration is done 
 in the following steps:
 
-1. Adding a new configuration entry to [clippy_lints::utils::conf](/clippy_lints/src/utils/conf.rs)
+1. Adding a new configuration entry to [clippy_utils::conf](/clippy_utils/src/conf.rs)
     like this:
     ```rust
     /// Lint: LINT_NAME. <The configuration field doc comment>
@@ -636,7 +636,7 @@ documentation currently. This is unfortunate, but in most cases you can probably
 get away with copying things from existing similar lints. If you are stuck,
 don't hesitate to ask on [Zulip] or in the issue/PR.
 
-[utils]: https://github.com/rust-lang/rust-clippy/blob/master/clippy_lints/src/utils/mod.rs
+[utils]: https://github.com/rust-lang/rust-clippy/blob/master/clippy_utils/src/lib.rs
 [if_chain]: https://docs.rs/if_chain/*/if_chain/
 [from_expansion]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_span/struct.Span.html#method.from_expansion
 [in_external_macro]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/lint/fn.in_external_macro.html

doc/common_tools_writing_lints.md

@@ -78,7 +78,7 @@ impl LateLintPass<'_> for MyStructLint {
 There are two ways to do this, depending if the target trait is part of lang items.
 
 ```rust
-use crate::utils::{implements_trait, match_trait_method, paths};
+use clippy_utils::{implements_trait, match_trait_method, paths};
 
 impl LateLintPass<'_> for MyStructLint {
     fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
@@ -112,7 +112,7 @@ We access lang items through the type context `tcx`. `tcx` is of type [`TyCtxt`]
 To check if our type defines a method called `some_method`:
 
 ```rust
-use crate::utils::{is_type_diagnostic_item, return_ty};
+use clippy_utils::{is_type_diagnostic_item, return_ty};
 
 impl<'tcx> LateLintPass<'tcx> for MyTypeImpl {
     fn check_impl_item(&mut self, cx: &LateContext<'tcx>, impl_item: &'tcx ImplItem<'_>) {
@@ -135,7 +135,7 @@ impl<'tcx> LateLintPass<'tcx> for MyTypeImpl {
 
 # Dealing with macros
 
-There are several helpers in Clippy's utils to deal with macros:
+There are several helpers in [`clippy_utils`][utils] to deal with macros:
 
 - `in_macro()`: detect if the given span is expanded by a macro
 
@@ -199,4 +199,5 @@ assert_eq!(differing_macro_contexts(x_is_some_span, x_unwrap_span), true);
 [LateContext]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_lint/struct.LateContext.html
 [TyCtxt]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/context/struct.TyCtxt.html
 [pat_ty]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/context/struct.TypeckResults.html#method.pat_ty
-[paths]: ../clippy_lints/src/utils/paths.rs
+[paths]: ../clippy_utils/src/paths.rs
+[utils]: https://github.com/rust-lang/rust-clippy/blob/master/clippy_utils/src/lib.rs

tests/versioncheck.rs

@@ -2,21 +2,24 @@
 use rustc_tools_util::VersionInfo;
 
 #[test]
-fn check_that_clippy_lints_has_the_same_version_as_clippy() {
+fn check_that_clippy_lints_and_clippy_utils_have_the_same_version_as_clippy() {
     let clippy_meta = cargo_metadata::MetadataCommand::new()
         .no_deps()
         .exec()
         .expect("could not obtain cargo metadata");
-    std::env::set_current_dir(std::env::current_dir().unwrap().join("clippy_lints")).unwrap();
+
-    let clippy_lints_meta = cargo_metadata::MetadataCommand::new()
+    for krate in &["clippy_lints", "clippy_utils"] {
-        .no_deps()
+        let krate_meta = clippy_meta
-        .exec()
+            .packages
-        .expect("could not obtain cargo metadata");
+            .iter()
-    assert_eq!(clippy_lints_meta.packages[0].version, clippy_meta.packages[0].version);
+            .find(|package| package.name == *krate)
-    for package in &clippy_meta.packages[0].dependencies {
+            .expect("could not obtain cargo metadata");
-        if package.name == "clippy_lints" {
+        assert_eq!(krate_meta.version, clippy_meta.packages[0].version);
-            assert!(package.req.matches(&clippy_lints_meta.packages[0].version));
+        for package in &clippy_meta.packages[0].dependencies {
-            return;
+            if package.name == *krate {
+                assert!(package.req.matches(&krate_meta.version));
+                break;
+            }
         }
     }
 }