mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-12-24 03:53:20 +00:00
375 lines
14 KiB
Rust
375 lines
14 KiB
Rust
#![allow(cast_possible_truncation)]
|
||
|
||
use rustc::lint::LateContext;
|
||
use rustc::hir::def::Def;
|
||
use rustc_const_eval::lookup_const_by_id;
|
||
use rustc_const_math::ConstInt;
|
||
use rustc::hir::*;
|
||
use rustc::ty::{self, TyCtxt, Ty};
|
||
use rustc::ty::subst::{Substs, Subst};
|
||
use std::cmp::Ordering::{self, Equal};
|
||
use std::cmp::PartialOrd;
|
||
use std::hash::{Hash, Hasher};
|
||
use std::mem;
|
||
use std::rc::Rc;
|
||
use syntax::ast::{FloatTy, LitKind, StrStyle, NodeId};
|
||
use syntax::ptr::P;
|
||
|
||
#[derive(Debug, Copy, Clone)]
|
||
pub enum FloatWidth {
|
||
F32,
|
||
F64,
|
||
Any,
|
||
}
|
||
|
||
impl From<FloatTy> for FloatWidth {
|
||
fn from(ty: FloatTy) -> FloatWidth {
|
||
match ty {
|
||
FloatTy::F32 => FloatWidth::F32,
|
||
FloatTy::F64 => FloatWidth::F64,
|
||
}
|
||
}
|
||
}
|
||
|
||
/// A `LitKind`-like enum to fold constant `Expr`s into.
|
||
#[derive(Debug, Clone)]
|
||
pub enum Constant {
|
||
/// a String "abc"
|
||
Str(String, StrStyle),
|
||
/// a Binary String b"abc"
|
||
Binary(Rc<Vec<u8>>),
|
||
/// a single char 'a'
|
||
Char(char),
|
||
/// an integer, third argument is whether the value is negated
|
||
Int(ConstInt),
|
||
/// a float with given type
|
||
Float(String, FloatWidth),
|
||
/// 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>, usize),
|
||
/// a tuple of constants
|
||
Tuple(Vec<Constant>),
|
||
}
|
||
|
||
impl PartialEq for Constant {
|
||
fn eq(&self, other: &Constant) -> bool {
|
||
match (self, other) {
|
||
(&Constant::Str(ref ls, ref l_sty), &Constant::Str(ref rs, ref r_sty)) => ls == rs && l_sty == r_sty,
|
||
(&Constant::Binary(ref l), &Constant::Binary(ref r)) => l == r,
|
||
(&Constant::Char(l), &Constant::Char(r)) => l == r,
|
||
(&Constant::Int(l), &Constant::Int(r)) => {
|
||
l.is_negative() == r.is_negative() && l.to_u128_unchecked() == r.to_u128_unchecked()
|
||
},
|
||
(&Constant::Float(ref ls, _), &Constant::Float(ref rs, _)) => {
|
||
// we want `Fw32 == FwAny` and `FwAny == Fw64`, by transitivity we must have
|
||
// `Fw32 == Fw64` so don’t compare them
|
||
match (ls.parse::<f64>(), rs.parse::<f64>()) {
|
||
// mem::transmute is required to catch non-matching 0.0, -0.0, and NaNs
|
||
(Ok(l), Ok(r)) => unsafe { mem::transmute::<f64, u64>(l) == mem::transmute::<f64, u64>(r) },
|
||
_ => false,
|
||
}
|
||
},
|
||
(&Constant::Bool(l), &Constant::Bool(r)) => l == r,
|
||
(&Constant::Vec(ref l), &Constant::Vec(ref r)) => l == r,
|
||
(&Constant::Repeat(ref lv, ref ls), &Constant::Repeat(ref rv, ref rs)) => ls == rs && lv == rv,
|
||
(&Constant::Tuple(ref l), &Constant::Tuple(ref r)) => l == r,
|
||
_ => false, //TODO: Are there inter-type equalities?
|
||
}
|
||
}
|
||
}
|
||
|
||
impl Hash for Constant {
|
||
fn hash<H>(&self, state: &mut H)
|
||
where H: Hasher
|
||
{
|
||
match *self {
|
||
Constant::Str(ref s, ref k) => {
|
||
s.hash(state);
|
||
k.hash(state);
|
||
},
|
||
Constant::Binary(ref b) => {
|
||
b.hash(state);
|
||
},
|
||
Constant::Char(c) => {
|
||
c.hash(state);
|
||
},
|
||
Constant::Int(i) => {
|
||
i.to_u128_unchecked().hash(state);
|
||
i.is_negative().hash(state);
|
||
},
|
||
Constant::Float(ref f, _) => {
|
||
// don’t use the width here because of PartialEq implementation
|
||
if let Ok(f) = f.parse::<f64>() {
|
||
unsafe { mem::transmute::<f64, u64>(f) }.hash(state);
|
||
}
|
||
},
|
||
Constant::Bool(b) => {
|
||
b.hash(state);
|
||
},
|
||
Constant::Vec(ref v) |
|
||
Constant::Tuple(ref v) => {
|
||
v.hash(state);
|
||
},
|
||
Constant::Repeat(ref c, l) => {
|
||
c.hash(state);
|
||
l.hash(state);
|
||
},
|
||
}
|
||
}
|
||
}
|
||
|
||
impl PartialOrd for Constant {
|
||
fn partial_cmp(&self, other: &Constant) -> Option<Ordering> {
|
||
match (self, other) {
|
||
(&Constant::Str(ref ls, ref l_sty), &Constant::Str(ref rs, ref r_sty)) => {
|
||
if l_sty == r_sty {
|
||
Some(ls.cmp(rs))
|
||
} else {
|
||
None
|
||
}
|
||
},
|
||
(&Constant::Char(ref l), &Constant::Char(ref r)) => Some(l.cmp(r)),
|
||
(&Constant::Int(l), &Constant::Int(r)) => Some(l.cmp(&r)),
|
||
(&Constant::Float(ref ls, _), &Constant::Float(ref rs, _)) => {
|
||
match (ls.parse::<f64>(), rs.parse::<f64>()) {
|
||
(Ok(ref l), Ok(ref r)) => {
|
||
match (l.partial_cmp(r), l.is_sign_positive() == r.is_sign_positive()) {
|
||
// Check for comparison of -0.0 and 0.0
|
||
(Some(Ordering::Equal), false) => None,
|
||
(x, _) => x,
|
||
}
|
||
},
|
||
_ => None,
|
||
}
|
||
},
|
||
(&Constant::Bool(ref l), &Constant::Bool(ref r)) => Some(l.cmp(r)),
|
||
(&Constant::Tuple(ref l), &Constant::Tuple(ref r)) |
|
||
(&Constant::Vec(ref l), &Constant::Vec(ref r)) => l.partial_cmp(r),
|
||
(&Constant::Repeat(ref lv, ref ls), &Constant::Repeat(ref rv, ref rs)) => {
|
||
match lv.partial_cmp(rv) {
|
||
Some(Equal) => Some(ls.cmp(rs)),
|
||
x => x,
|
||
}
|
||
},
|
||
_ => None, //TODO: Are there any useful inter-type orderings?
|
||
}
|
||
}
|
||
}
|
||
|
||
/// parse a `LitKind` to a `Constant`
|
||
#[allow(cast_possible_wrap)]
|
||
pub fn lit_to_constant<'a, 'tcx>(lit: &LitKind, tcx: TyCtxt<'a, 'tcx, 'tcx>, mut ty: Ty<'tcx>) -> Constant {
|
||
use syntax::ast::*;
|
||
use syntax::ast::LitIntType::*;
|
||
use rustc::ty::util::IntTypeExt;
|
||
|
||
if let ty::TyAdt(adt, _) = ty.sty {
|
||
if adt.is_enum() {
|
||
ty = adt.repr.discr_type().to_ty(tcx)
|
||
}
|
||
}
|
||
match *lit {
|
||
LitKind::Str(ref is, style) => Constant::Str(is.to_string(), style),
|
||
LitKind::Byte(b) => Constant::Int(ConstInt::U8(b)),
|
||
LitKind::ByteStr(ref s) => Constant::Binary(s.clone()),
|
||
LitKind::Char(c) => Constant::Char(c),
|
||
LitKind::Int(n, hint) => {
|
||
match (&ty.sty, hint) {
|
||
(&ty::TyInt(ity), _) |
|
||
(_, Signed(ity)) => {
|
||
Constant::Int(ConstInt::new_signed_truncating(n as i128, ity, tcx.sess.target.int_type))
|
||
},
|
||
(&ty::TyUint(uty), _) |
|
||
(_, Unsigned(uty)) => {
|
||
Constant::Int(ConstInt::new_unsigned_truncating(n as u128, uty, tcx.sess.target.uint_type))
|
||
},
|
||
_ => bug!(),
|
||
}
|
||
},
|
||
LitKind::Float(ref is, ty) => Constant::Float(is.to_string(), ty.into()),
|
||
LitKind::FloatUnsuffixed(ref is) => Constant::Float(is.to_string(), FloatWidth::Any),
|
||
LitKind::Bool(b) => Constant::Bool(b),
|
||
}
|
||
}
|
||
|
||
fn constant_not(o: &Constant) -> Option<Constant> {
|
||
use self::Constant::*;
|
||
match *o {
|
||
Bool(b) => Some(Bool(!b)),
|
||
Int(value) => (!value).ok().map(Int),
|
||
_ => None,
|
||
}
|
||
}
|
||
|
||
fn constant_negate(o: Constant) -> Option<Constant> {
|
||
use self::Constant::*;
|
||
match o {
|
||
Int(value) => (-value).ok().map(Int),
|
||
Float(is, ty) => Some(Float(neg_float_str(&is), ty)),
|
||
_ => None,
|
||
}
|
||
}
|
||
|
||
fn neg_float_str(s: &str) -> String {
|
||
if s.starts_with('-') {
|
||
s[1..].to_owned()
|
||
} else {
|
||
format!("-{}", s)
|
||
}
|
||
}
|
||
|
||
pub fn constant(lcx: &LateContext, e: &Expr) -> Option<(Constant, bool)> {
|
||
let mut cx = ConstEvalLateContext {
|
||
tcx: lcx.tcx,
|
||
tables: lcx.tables,
|
||
needed_resolution: false,
|
||
substs: lcx.tcx.intern_substs(&[]),
|
||
};
|
||
cx.expr(e).map(|cst| (cst, cx.needed_resolution))
|
||
}
|
||
|
||
pub fn constant_simple(lcx: &LateContext, e: &Expr) -> Option<Constant> {
|
||
constant(lcx, e).and_then(|(cst, res)| if res { None } else { Some(cst) })
|
||
}
|
||
|
||
struct ConstEvalLateContext<'a, 'tcx: 'a> {
|
||
tcx: TyCtxt<'a, 'tcx, 'tcx>,
|
||
tables: &'a ty::TypeckTables<'tcx>,
|
||
needed_resolution: bool,
|
||
substs: &'tcx Substs<'tcx>,
|
||
}
|
||
|
||
impl<'c, 'cc> ConstEvalLateContext<'c, 'cc> {
|
||
/// simple constant folding: Insert an expression, get a constant or none.
|
||
fn expr(&mut self, e: &Expr) -> Option<Constant> {
|
||
match e.node {
|
||
ExprPath(ref qpath) => self.fetch_path(qpath, e.id),
|
||
ExprBlock(ref block) => self.block(block),
|
||
ExprIf(ref cond, ref then, ref otherwise) => self.ifthenelse(cond, then, otherwise),
|
||
ExprLit(ref lit) => Some(lit_to_constant(&lit.node, self.tcx, self.tables.expr_ty(e))),
|
||
ExprArray(ref vec) => self.multi(vec).map(Constant::Vec),
|
||
ExprTup(ref tup) => self.multi(tup).map(Constant::Tuple),
|
||
ExprRepeat(ref value, _) => {
|
||
let n = match self.tables.expr_ty(e).sty {
|
||
ty::TyArray(_, n) => n,
|
||
_ => span_bug!(e.span, "typeck error"),
|
||
};
|
||
self.expr(value).map(|v| Constant::Repeat(Box::new(v), n))
|
||
},
|
||
ExprUnary(op, ref operand) => {
|
||
self.expr(operand).and_then(|o| match op {
|
||
UnNot => constant_not(&o),
|
||
UnNeg => constant_negate(o),
|
||
UnDeref => Some(o),
|
||
})
|
||
},
|
||
ExprBinary(op, ref left, ref right) => self.binop(op, left, right),
|
||
// TODO: add other expressions
|
||
_ => 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 ExprPath
|
||
fn fetch_path(&mut self, qpath: &QPath, id: NodeId) -> Option<Constant> {
|
||
let def = self.tables.qpath_def(qpath, id);
|
||
match def {
|
||
Def::Const(def_id) |
|
||
Def::AssociatedConst(def_id) => {
|
||
let substs = self.tables.node_substs(id);
|
||
let substs = if self.substs.is_empty() {
|
||
substs
|
||
} else {
|
||
substs.subst(self.tcx, self.substs)
|
||
};
|
||
if let Some((def_id, substs)) = lookup_const_by_id(self.tcx, def_id, substs) {
|
||
let mut cx = ConstEvalLateContext {
|
||
tcx: self.tcx,
|
||
tables: self.tcx.typeck_tables_of(def_id),
|
||
needed_resolution: false,
|
||
substs: substs,
|
||
};
|
||
let body = if let Some(id) = self.tcx.hir.as_local_node_id(def_id) {
|
||
self.tcx.mir_const_qualif(def_id);
|
||
self.tcx.hir.body(self.tcx.hir.body_owned_by(id))
|
||
} else {
|
||
self.tcx.sess.cstore.item_body(self.tcx, def_id)
|
||
};
|
||
let ret = cx.expr(&body.value);
|
||
if ret.is_some() {
|
||
self.needed_resolution = true;
|
||
}
|
||
return ret;
|
||
}
|
||
},
|
||
_ => {},
|
||
}
|
||
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: &P<Expr>, otherwise: &Option<P<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 = if let Some(l) = self.expr(left) {
|
||
l
|
||
} else {
|
||
return None;
|
||
};
|
||
let r = self.expr(right);
|
||
match (op.node, l, r) {
|
||
(BiAdd, Constant::Int(l), Some(Constant::Int(r))) => (l + r).ok().map(Constant::Int),
|
||
(BiSub, Constant::Int(l), Some(Constant::Int(r))) => (l - r).ok().map(Constant::Int),
|
||
(BiMul, Constant::Int(l), Some(Constant::Int(r))) => (l * r).ok().map(Constant::Int),
|
||
(BiDiv, Constant::Int(l), Some(Constant::Int(r))) => (l / r).ok().map(Constant::Int),
|
||
(BiRem, Constant::Int(l), Some(Constant::Int(r))) => (l % r).ok().map(Constant::Int),
|
||
(BiAnd, Constant::Bool(false), _) => Some(Constant::Bool(false)),
|
||
(BiOr, Constant::Bool(true), _) => Some(Constant::Bool(true)),
|
||
(BiAnd, Constant::Bool(true), Some(r)) |
|
||
(BiOr, Constant::Bool(false), Some(r)) => Some(r),
|
||
(BiBitXor, Constant::Bool(l), Some(Constant::Bool(r))) => Some(Constant::Bool(l ^ r)),
|
||
(BiBitXor, Constant::Int(l), Some(Constant::Int(r))) => (l ^ r).ok().map(Constant::Int),
|
||
(BiBitAnd, Constant::Bool(l), Some(Constant::Bool(r))) => Some(Constant::Bool(l & r)),
|
||
(BiBitAnd, Constant::Int(l), Some(Constant::Int(r))) => (l & r).ok().map(Constant::Int),
|
||
(BiBitOr, Constant::Bool(l), Some(Constant::Bool(r))) => Some(Constant::Bool(l | r)),
|
||
(BiBitOr, Constant::Int(l), Some(Constant::Int(r))) => (l | r).ok().map(Constant::Int),
|
||
(BiShl, Constant::Int(l), Some(Constant::Int(r))) => (l << r).ok().map(Constant::Int),
|
||
(BiShr, Constant::Int(l), Some(Constant::Int(r))) => (l >> r).ok().map(Constant::Int),
|
||
(BiEq, Constant::Int(l), Some(Constant::Int(r))) => Some(Constant::Bool(l == r)),
|
||
(BiNe, Constant::Int(l), Some(Constant::Int(r))) => Some(Constant::Bool(l != r)),
|
||
(BiLt, Constant::Int(l), Some(Constant::Int(r))) => Some(Constant::Bool(l < r)),
|
||
(BiLe, Constant::Int(l), Some(Constant::Int(r))) => Some(Constant::Bool(l <= r)),
|
||
(BiGe, Constant::Int(l), Some(Constant::Int(r))) => Some(Constant::Bool(l >= r)),
|
||
(BiGt, Constant::Int(l), Some(Constant::Int(r))) => Some(Constant::Bool(l > r)),
|
||
_ => None,
|
||
}
|
||
}
|
||
}
|