use rustc::lint::*;
use syntax::ast::*;
use syntax::ast_util as ast_util;
use syntax::ptr::P;
use syntax::codemap as code;
use utils::span_lint;
declare_lint! {
pub EQ_OP,
Warn,
"warn about comparing equal expressions (e.g. x == x)"
}
#[derive(Copy,Clone)]
pub struct EqOp;
impl LintPass for EqOp {
fn get_lints(&self) -> LintArray {
lint_array!(EQ_OP)
}
fn check_expr(&mut self, cx: &Context, e: &Expr) {
if let ExprBinary(ref op, ref left, ref right) = e.node {
if is_cmp_or_bit(op) && is_exp_equal(left, right) {
span_lint(cx, EQ_OP, e.span, &format!(
"equal expressions as operands to {}",
ast_util::binop_to_string(op.node)));
}
}
}
}
pub fn is_exp_equal(left : &Expr, right : &Expr) -> bool {
match (&left.node, &right.node) {
(&ExprBinary(ref lop, ref ll, ref lr),
&ExprBinary(ref rop, ref rl, ref rr)) =>
lop.node == rop.node &&
is_exp_equal(ll, rl) && is_exp_equal(lr, rr),
(&ExprBox(ref lpl, ref lbox), &ExprBox(ref rpl, ref rbox)) =>
both(lpl, rpl, |l, r| is_exp_equal(l, r)) &&
is_exp_equal(lbox, rbox),
(&ExprCall(ref lcallee, ref largs),
&ExprCall(ref rcallee, ref rargs)) => is_exp_equal(lcallee,
rcallee) && is_exps_equal(largs, rargs),
(&ExprCast(ref lc, ref lty), &ExprCast(ref rc, ref rty)) =>
is_ty_equal(lty, rty) && is_exp_equal(lc, rc),
(&ExprField(ref lfexp, ref lfident),
&ExprField(ref rfexp, ref rfident)) =>
lfident.node == rfident.node && is_exp_equal(lfexp, rfexp),
(&ExprLit(ref l), &ExprLit(ref r)) => l.node == r.node,
(&ExprMethodCall(ref lident, ref lcty, ref lmargs),
&ExprMethodCall(ref rident, ref rcty, ref rmargs)) =>
lident.node == rident.node && is_tys_equal(lcty, rcty) &&
is_exps_equal(lmargs, rmargs),
(&ExprParen(ref lparen), _) => is_exp_equal(lparen, right),
(_, &ExprParen(ref rparen)) => is_exp_equal(left, rparen),
(&ExprPath(ref lqself, ref lsubpath),
&ExprPath(ref rqself, ref rsubpath)) =>
both(lqself, rqself, |l, r| is_qself_equal(l, r)) &&
is_path_equal(lsubpath, rsubpath),
(&ExprTup(ref ltup), &ExprTup(ref rtup)) =>
is_exps_equal(ltup, rtup),
(&ExprUnary(lunop, ref l), &ExprUnary(runop, ref r)) =>
lunop == runop && is_exp_equal(l, r),
(&ExprVec(ref l), &ExprVec(ref r)) => is_exps_equal(l, r),
_ => false
}
}
fn is_exps_equal(left : &[P<Expr>], right : &[P<Expr>]) -> bool {
over(left, right, |l, r| is_exp_equal(l, r))
}
fn is_path_equal(left : &Path, right : &Path) -> bool {
left.global == right.global && over(&left.segments, &right.segments,
|l, r| l.identifier.name == r.identifier.name
&& l.identifier.ctxt == r.identifier.ctxt
&& l.parameters == r.parameters)
}
fn is_qself_equal(left : &QSelf, right : &QSelf) -> bool {
left.ty.node == right.ty.node && left.position == right.position
}
fn is_ty_equal(left : &Ty, right : &Ty) -> bool {
match (&left.node, &right.node) {
(&TyVec(ref lvec), &TyVec(ref rvec)) => is_ty_equal(lvec, rvec),
(&TyFixedLengthVec(ref lfvty, ref lfvexp),
&TyFixedLengthVec(ref rfvty, ref rfvexp)) =>
is_ty_equal(lfvty, rfvty) && is_exp_equal(lfvexp, rfvexp),
(&TyPtr(ref lmut), &TyPtr(ref rmut)) => is_mut_ty_equal(lmut, rmut),
(&TyRptr(ref ltime, ref lrmut), &TyRptr(ref rtime, ref rrmut)) =>
both(ltime, rtime, is_lifetime_equal) &&
is_mut_ty_equal(lrmut, rrmut),
(&TyBareFn(ref lbare), &TyBareFn(ref rbare)) =>
is_bare_fn_ty_equal(lbare, rbare),
(&TyTup(ref ltup), &TyTup(ref rtup)) => is_tys_equal(ltup, rtup),
(&TyPath(ref lq, ref lpath), &TyPath(ref rq, ref rpath)) =>
both(lq, rq, is_qself_equal) && is_path_equal(lpath, rpath),
(&TyObjectSum(ref lsumty, ref lobounds),
&TyObjectSum(ref rsumty, ref robounds)) =>
is_ty_equal(lsumty, rsumty) &&
is_param_bounds_equal(lobounds, robounds),
(&TyPolyTraitRef(ref ltbounds), &TyPolyTraitRef(ref rtbounds)) =>
is_param_bounds_equal(ltbounds, rtbounds),
(&TyParen(ref lty), &TyParen(ref rty)) => is_ty_equal(lty, rty),
(&TyTypeof(ref lof), &TyTypeof(ref rof)) => is_exp_equal(lof, rof),
(&TyInfer, &TyInfer) => true,
_ => false
}
}
fn is_param_bound_equal(left : &TyParamBound, right : &TyParamBound)
-> bool {
match(left, right) {
(&TraitTyParamBound(ref lpoly, ref lmod),
&TraitTyParamBound(ref rpoly, ref rmod)) =>
lmod == rmod && is_poly_traitref_equal(lpoly, rpoly),
(&RegionTyParamBound(ref ltime), &RegionTyParamBound(ref rtime)) =>
is_lifetime_equal(ltime, rtime),
_ => false
}
}
fn is_poly_traitref_equal(left : &PolyTraitRef, right : &PolyTraitRef)
-> bool {
is_lifetimedefs_equal(&left.bound_lifetimes, &right.bound_lifetimes)
&& is_path_equal(&left.trait_ref.path, &right.trait_ref.path)
}
fn is_param_bounds_equal(left : &TyParamBounds, right : &TyParamBounds)
-> bool {
over(left, right, is_param_bound_equal)
}
fn is_mut_ty_equal(left : &MutTy, right : &MutTy) -> bool {
left.mutbl == right.mutbl && is_ty_equal(&left.ty, &right.ty)
}
fn is_bare_fn_ty_equal(left : &BareFnTy, right : &BareFnTy) -> bool {
left.unsafety == right.unsafety && left.abi == right.abi &&
is_lifetimedefs_equal(&left.lifetimes, &right.lifetimes) &&
is_fndecl_equal(&left.decl, &right.decl)
}
fn is_fndecl_equal(left : &P<FnDecl>, right : &P<FnDecl>) -> bool {
left.variadic == right.variadic &&
is_args_equal(&left.inputs, &right.inputs) &&
is_fnret_ty_equal(&left.output, &right.output)
}
fn is_fnret_ty_equal(left : &FunctionRetTy, right : &FunctionRetTy)
-> bool {
match (left, right) {
(&NoReturn(_), &NoReturn(_)) |
(&DefaultReturn(_), &DefaultReturn(_)) => true,
(&Return(ref lty), &Return(ref rty)) => is_ty_equal(lty, rty),
_ => false
}
}
fn is_arg_equal(l: &Arg, r : &Arg) -> bool {
is_ty_equal(&l.ty, &r.ty) && is_pat_equal(&l.pat, &r.pat)
}
fn is_args_equal(left : &[Arg], right : &[Arg]) -> bool {
over(left, right, is_arg_equal)
}
fn is_pat_equal(left : &Pat, right : &Pat) -> bool {
match(&left.node, &right.node) {
(&PatWild(lwild), &PatWild(rwild)) => lwild == rwild,
(&PatIdent(ref lmode, ref lident, Option::None),
&PatIdent(ref rmode, ref rident, Option::None)) =>
lmode == rmode && is_ident_equal(&lident.node, &rident.node),
(&PatIdent(ref lmode, ref lident, Option::Some(ref lpat)),
&PatIdent(ref rmode, ref rident, Option::Some(ref rpat))) =>
lmode == rmode && is_ident_equal(&lident.node, &rident.node) &&
is_pat_equal(lpat, rpat),
(&PatEnum(ref lpath, ref lenum), &PatEnum(ref rpath, ref renum)) =>
is_path_equal(lpath, rpath) && both(lenum, renum, |l, r|
is_pats_equal(l, r)),
(&PatStruct(ref lpath, ref lfieldpat, lbool),
&PatStruct(ref rpath, ref rfieldpat, rbool)) =>
lbool == rbool && is_path_equal(lpath, rpath) &&
is_spanned_fieldpats_equal(lfieldpat, rfieldpat),
(&PatTup(ref ltup), &PatTup(ref rtup)) => is_pats_equal(ltup, rtup),
(&PatBox(ref lboxed), &PatBox(ref rboxed)) =>
is_pat_equal(lboxed, rboxed),
(&PatRegion(ref lpat, ref lmut), &PatRegion(ref rpat, ref rmut)) =>
is_pat_equal(lpat, rpat) && lmut == rmut,
(&PatLit(ref llit), &PatLit(ref rlit)) => is_exp_equal(llit, rlit),
(&PatRange(ref lfrom, ref lto), &PatRange(ref rfrom, ref rto)) =>
is_exp_equal(lfrom, rfrom) && is_exp_equal(lto, rto),
(&PatVec(ref lfirst, Option::None, ref llast),
&PatVec(ref rfirst, Option::None, ref rlast)) =>
is_pats_equal(lfirst, rfirst) && is_pats_equal(llast, rlast),
(&PatVec(ref lfirst, Option::Some(ref lpat), ref llast),
&PatVec(ref rfirst, Option::Some(ref rpat), ref rlast)) =>
is_pats_equal(lfirst, rfirst) && is_pat_equal(lpat, rpat) &&
is_pats_equal(llast, rlast),
_ => false
}
}
fn is_spanned_fieldpats_equal(left : &[code::Spanned<FieldPat>],
right : &[code::Spanned<FieldPat>]) -> bool {
over(left, right, |l, r| is_fieldpat_equal(&l.node, &r.node))
}
fn is_fieldpat_equal(left : &FieldPat, right : &FieldPat) -> bool {
left.is_shorthand == right.is_shorthand &&
is_ident_equal(&left.ident, &right.ident) &&
is_pat_equal(&left.pat, &right.pat)
}
fn is_ident_equal(left : &Ident, right : &Ident) -> bool {
&left.name == &right.name && left.ctxt == right.ctxt
}
fn is_pats_equal(left : &[P<Pat>], right : &[P<Pat>]) -> bool {
over(left, right, |l, r| is_pat_equal(l, r))
}
fn is_lifetimedef_equal(left : &LifetimeDef, right : &LifetimeDef)
-> bool {
is_lifetime_equal(&left.lifetime, &right.lifetime) &&
over(&left.bounds, &right.bounds, is_lifetime_equal)
}
fn is_lifetimedefs_equal(left : &[LifetimeDef], right : &[LifetimeDef])
-> bool {
over(left, right, is_lifetimedef_equal)
}
fn is_lifetime_equal(left : &Lifetime, right : &Lifetime) -> bool {
left.name == right.name
}
fn is_tys_equal(left : &[P<Ty>], right : &[P<Ty>]) -> bool {
over(left, right, |l, r| is_ty_equal(l, r))
}
fn over<X, F>(left: &[X], right: &[X], mut eq_fn: F) -> bool
where F: FnMut(&X, &X) -> bool {
left.len() == right.len() && left.iter().zip(right).all(|(x, y)|
eq_fn(x, y))
}
fn both<X, F>(l: &Option<X>, r: &Option<X>, mut eq_fn : F) -> bool
where F: FnMut(&X, &X) -> bool {
l.as_ref().map_or_else(|| r.is_none(), |x| r.as_ref().map_or(false,
|y| eq_fn(x, y)))
}
fn is_cmp_or_bit(op : &BinOp) -> bool {
match op.node {
BiEq | BiLt | BiLe | BiGt | BiGe | BiNe | BiAnd | BiOr |
BiBitXor | BiBitAnd | BiBitOr => true,
_ => false
}
}