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Move invalid_upcast_comparisons to its own module

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This commit is contained in:
Yoshitomo Nakanishi 2021-03-18 16:15:19 +09:00
parent caa49c85d6
commit f231b59b9e
3 changed files with 227 additions and 216 deletions
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221
clippy_lints/src/invalid_upcast_comparisons.rs Normal file
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@ -0,0 +1,221 @@
use std::cmp::Ordering;
use rustc_hir::{Expr, ExprKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::ty::{self, IntTy, UintTy};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::Span;
use rustc_target::abi::LayoutOf;
use crate::consts::{constant, Constant};
use clippy_utils::comparisons::Rel;
use clippy_utils::diagnostics::span_lint;
use clippy_utils::source::snippet;
use clippy_utils::{comparisons, sext};
declare_clippy_lint! {
/// **What it does:** Checks for comparisons where the relation is always either
/// true or false, but where one side has been upcast so that the comparison is
/// necessary. Only integer types are checked.
///
/// **Why is this bad?** An expression like `let x : u8 = ...; (x as u32) > 300`
/// will mistakenly imply that it is possible for `x` to be outside the range of
/// `u8`.
///
/// **Known problems:**
/// https://github.com/rust-lang/rust-clippy/issues/886
///
/// **Example:**
/// ```rust
/// let x: u8 = 1;
/// (x as u32) > 300;
/// ```
pub INVALID_UPCAST_COMPARISONS,
pedantic,
"a comparison involving an upcast which is always true or false"
}
declare_lint_pass!(InvalidUpcastComparisons => [INVALID_UPCAST_COMPARISONS]);
#[derive(Copy, Clone, Debug, Eq)]
enum FullInt {
S(i128),
U(u128),
}
impl FullInt {
#[allow(clippy::cast_sign_loss)]
#[must_use]
fn cmp_s_u(s: i128, u: u128) -> Ordering {
if s < 0 {
Ordering::Less
} else if u > (i128::MAX as u128) {
Ordering::Greater
} else {
(s as u128).cmp(&u)
}
}
}
impl PartialEq for FullInt {
#[must_use]
fn eq(&self, other: &Self) -> bool {
self.partial_cmp(other).expect("`partial_cmp` only returns `Some(_)`") == Ordering::Equal
}
}
impl PartialOrd for FullInt {
#[must_use]
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
Some(match (self, other) {
(&Self::S(s), &Self::S(o)) => s.cmp(&o),
(&Self::U(s), &Self::U(o)) => s.cmp(&o),
(&Self::S(s), &Self::U(o)) => Self::cmp_s_u(s, o),
(&Self::U(s), &Self::S(o)) => Self::cmp_s_u(o, s).reverse(),
})
}
}
impl Ord for FullInt {
#[must_use]
fn cmp(&self, other: &Self) -> Ordering {
self.partial_cmp(other)
.expect("`partial_cmp` for FullInt can never return `None`")
}
}
fn numeric_cast_precast_bounds<'a>(cx: &LateContext<'_>, expr: &'a Expr<'_>) -> Option<(FullInt, FullInt)> {
if let ExprKind::Cast(ref cast_exp, _) = expr.kind {
let pre_cast_ty = cx.typeck_results().expr_ty(cast_exp);
let cast_ty = cx.typeck_results().expr_ty(expr);
// if it's a cast from i32 to u32 wrapping will invalidate all these checks
if cx.layout_of(pre_cast_ty).ok().map(|l| l.size) == cx.layout_of(cast_ty).ok().map(|l| l.size) {
return None;
}
match pre_cast_ty.kind() {
ty::Int(int_ty) => Some(match int_ty {
IntTy::I8 => (FullInt::S(i128::from(i8::MIN)), FullInt::S(i128::from(i8::MAX))),
IntTy::I16 => (FullInt::S(i128::from(i16::MIN)), FullInt::S(i128::from(i16::MAX))),
IntTy::I32 => (FullInt::S(i128::from(i32::MIN)), FullInt::S(i128::from(i32::MAX))),
IntTy::I64 => (FullInt::S(i128::from(i64::MIN)), FullInt::S(i128::from(i64::MAX))),
IntTy::I128 => (FullInt::S(i128::MIN), FullInt::S(i128::MAX)),
IntTy::Isize => (FullInt::S(isize::MIN as i128), FullInt::S(isize::MAX as i128)),
}),
ty::Uint(uint_ty) => Some(match uint_ty {
UintTy::U8 => (FullInt::U(u128::from(u8::MIN)), FullInt::U(u128::from(u8::MAX))),
UintTy::U16 => (FullInt::U(u128::from(u16::MIN)), FullInt::U(u128::from(u16::MAX))),
UintTy::U32 => (FullInt::U(u128::from(u32::MIN)), FullInt::U(u128::from(u32::MAX))),
UintTy::U64 => (FullInt::U(u128::from(u64::MIN)), FullInt::U(u128::from(u64::MAX))),
UintTy::U128 => (FullInt::U(u128::MIN), FullInt::U(u128::MAX)),
UintTy::Usize => (FullInt::U(usize::MIN as u128), FullInt::U(usize::MAX as u128)),
}),
_ => None,
}
} else {
None
}
}
fn node_as_const_fullint<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<FullInt> {
let val = constant(cx, cx.typeck_results(), expr)?.0;
if let Constant::Int(const_int) = val {
match *cx.typeck_results().expr_ty(expr).kind() {
ty::Int(ity) => Some(FullInt::S(sext(cx.tcx, const_int, ity))),
ty::Uint(_) => Some(FullInt::U(const_int)),
_ => None,
}
} else {
None
}
}
fn err_upcast_comparison(cx: &LateContext<'_>, span: Span, expr: &Expr<'_>, always: bool) {
if let ExprKind::Cast(ref cast_val, _) = expr.kind {
span_lint(
cx,
INVALID_UPCAST_COMPARISONS,
span,
&format!(
"because of the numeric bounds on `{}` prior to casting, this expression is always {}",
snippet(cx, cast_val.span, "the expression"),
if always { "true" } else { "false" },
),
);
}
}
fn upcast_comparison_bounds_err<'tcx>(
cx: &LateContext<'tcx>,
span: Span,
rel: comparisons::Rel,
lhs_bounds: Option<(FullInt, FullInt)>,
lhs: &'tcx Expr<'_>,
rhs: &'tcx Expr<'_>,
invert: bool,
) {
if let Some((lb, ub)) = lhs_bounds {
if let Some(norm_rhs_val) = node_as_const_fullint(cx, rhs) {
if rel == Rel::Eq || rel == Rel::Ne {
if norm_rhs_val < lb || norm_rhs_val > ub {
err_upcast_comparison(cx, span, lhs, rel == Rel::Ne);
}
} else if match rel {
Rel::Lt => {
if invert {
norm_rhs_val < lb
} else {
ub < norm_rhs_val
}
},
Rel::Le => {
if invert {
norm_rhs_val <= lb
} else {
ub <= norm_rhs_val
}
},
Rel::Eq | Rel::Ne => unreachable!(),
} {
err_upcast_comparison(cx, span, lhs, true)
} else if match rel {
Rel::Lt => {
if invert {
norm_rhs_val >= ub
} else {
lb >= norm_rhs_val
}
},
Rel::Le => {
if invert {
norm_rhs_val > ub
} else {
lb > norm_rhs_val
}
},
Rel::Eq | Rel::Ne => unreachable!(),
} {
err_upcast_comparison(cx, span, lhs, false)
}
}
}
}
impl<'tcx> LateLintPass<'tcx> for InvalidUpcastComparisons {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
if let ExprKind::Binary(ref cmp, ref lhs, ref rhs) = expr.kind {
let normalized = comparisons::normalize_comparison(cmp.node, lhs, rhs);
let (rel, normalized_lhs, normalized_rhs) = if let Some(val) = normalized {
val
} else {
return;
};
let lhs_bounds = numeric_cast_precast_bounds(cx, normalized_lhs);
let rhs_bounds = numeric_cast_precast_bounds(cx, normalized_rhs);
upcast_comparison_bounds_err(cx, expr.span, rel, lhs_bounds, normalized_lhs, normalized_rhs, false);
upcast_comparison_bounds_err(cx, expr.span, rel, rhs_bounds, normalized_rhs, normalized_lhs, true);
}
}
}

7
clippy_lints/src/lib.rs
View File

@ -242,6 +242,7 @@ mod inherent_to_string;
mod inline_fn_without_body;
mod int_plus_one;
mod integer_division;
mod invalid_upcast_comparisons;
mod items_after_statements;
mod large_const_arrays;
mod large_enum_variant;
@ -697,6 +698,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
&inline_fn_without_body::INLINE_FN_WITHOUT_BODY,
&int_plus_one::INT_PLUS_ONE,
&integer_division::INTEGER_DIVISION,
&invalid_upcast_comparisons::INVALID_UPCAST_COMPARISONS,
&items_after_statements::ITEMS_AFTER_STATEMENTS,
&large_const_arrays::LARGE_CONST_ARRAYS,
&large_enum_variant::LARGE_ENUM_VARIANT,
@ -960,7 +962,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
&types::BORROWED_BOX,
&types::BOX_VEC,
&types::IMPLICIT_HASHER,
&types::INVALID_UPCAST_COMPARISONS,
&types::LINKEDLIST,
&types::OPTION_OPTION,
&types::RC_BUFFER,
@ -1114,7 +1115,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
store.register_late_pass(|| box drop_forget_ref::DropForgetRef);
store.register_late_pass(|| box empty_enum::EmptyEnum);
store.register_late_pass(|| box absurd_extreme_comparisons::AbsurdExtremeComparisons);
store.register_late_pass(|| box types::InvalidUpcastComparisons);
store.register_late_pass(|| box invalid_upcast_comparisons::InvalidUpcastComparisons);
store.register_late_pass(|| box regex::Regex::default());
store.register_late_pass(|| box copies::CopyAndPaste);
store.register_late_pass(|| box copy_iterator::CopyIterator);
@ -1374,6 +1375,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&if_not_else::IF_NOT_ELSE),
LintId::of(&implicit_saturating_sub::IMPLICIT_SATURATING_SUB),
LintId::of(&infinite_iter::MAYBE_INFINITE_ITER),
LintId::of(&invalid_upcast_comparisons::INVALID_UPCAST_COMPARISONS),
LintId::of(&items_after_statements::ITEMS_AFTER_STATEMENTS),
LintId::of(&large_stack_arrays::LARGE_STACK_ARRAYS),
LintId::of(&let_underscore::LET_UNDERSCORE_DROP),
@ -1413,7 +1415,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&trait_bounds::TRAIT_DUPLICATION_IN_BOUNDS),
LintId::of(&trait_bounds::TYPE_REPETITION_IN_BOUNDS),
LintId::of(&types::IMPLICIT_HASHER),
LintId::of(&types::INVALID_UPCAST_COMPARISONS),
LintId::of(&types::LINKEDLIST),
LintId::of(&types::OPTION_OPTION),
LintId::of(&unicode::NON_ASCII_LITERAL),

215
clippy_lints/src/types/mod.rs
View File

@ -10,7 +10,6 @@ mod utils;
mod vec_box;
use std::borrow::Cow;
use std::cmp::Ordering;
use std::collections::BTreeMap;
use clippy_utils::diagnostics::{multispan_sugg, span_lint, span_lint_and_then};
@ -27,17 +26,15 @@ use rustc_hir::{
use rustc_lint::{LateContext, LateLintPass, LintContext};
use rustc_middle::hir::map::Map;
use rustc_middle::lint::in_external_macro;
use rustc_middle::ty::{self, IntTy, Ty, TyS, TypeckResults, UintTy};
use rustc_middle::ty::{Ty, TyS, TypeckResults};
use rustc_session::{declare_lint_pass, declare_tool_lint, impl_lint_pass};
use rustc_span::source_map::Span;
use rustc_span::symbol::sym;
use rustc_target::abi::LayoutOf;
use rustc_target::spec::abi::Abi;
use rustc_typeck::hir_ty_to_ty;
use crate::consts::{constant, Constant};
use clippy_utils::paths;
use clippy_utils::{comparisons, differing_macro_contexts, match_path, sext};
use clippy_utils::{differing_macro_contexts, match_path};
declare_clippy_lint! {
/// **What it does:** Checks for use of `Box<Vec<_>>` anywhere in the code.
@ -552,214 +549,6 @@ impl<'tcx> Visitor<'tcx> for TypeComplexityVisitor {
}
}
declare_clippy_lint! {
/// **What it does:** Checks for comparisons where the relation is always either
/// true or false, but where one side has been upcast so that the comparison is
/// necessary. Only integer types are checked.
///
/// **Why is this bad?** An expression like `let x : u8 = ...; (x as u32) > 300`
/// will mistakenly imply that it is possible for `x` to be outside the range of
/// `u8`.
///
/// **Known problems:**
/// https://github.com/rust-lang/rust-clippy/issues/886
///
/// **Example:**
/// ```rust
/// let x: u8 = 1;
/// (x as u32) > 300;
/// ```
pub INVALID_UPCAST_COMPARISONS,
pedantic,
"a comparison involving an upcast which is always true or false"
}
declare_lint_pass!(InvalidUpcastComparisons => [INVALID_UPCAST_COMPARISONS]);
#[derive(Copy, Clone, Debug, Eq)]
enum FullInt {
S(i128),
U(u128),
}
impl FullInt {
#[allow(clippy::cast_sign_loss)]
#[must_use]
fn cmp_s_u(s: i128, u: u128) -> Ordering {
if s < 0 {
Ordering::Less
} else if u > (i128::MAX as u128) {
Ordering::Greater
} else {
(s as u128).cmp(&u)
}
}
}
impl PartialEq for FullInt {
#[must_use]
fn eq(&self, other: &Self) -> bool {
self.partial_cmp(other).expect("`partial_cmp` only returns `Some(_)`") == Ordering::Equal
}
}
impl PartialOrd for FullInt {
#[must_use]
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
Some(match (self, other) {
(&Self::S(s), &Self::S(o)) => s.cmp(&o),
(&Self::U(s), &Self::U(o)) => s.cmp(&o),
(&Self::S(s), &Self::U(o)) => Self::cmp_s_u(s, o),
(&Self::U(s), &Self::S(o)) => Self::cmp_s_u(o, s).reverse(),
})
}
}
impl Ord for FullInt {
#[must_use]
fn cmp(&self, other: &Self) -> Ordering {
self.partial_cmp(other)
.expect("`partial_cmp` for FullInt can never return `None`")
}
}
fn numeric_cast_precast_bounds<'a>(cx: &LateContext<'_>, expr: &'a Expr<'_>) -> Option<(FullInt, FullInt)> {
if let ExprKind::Cast(ref cast_exp, _) = expr.kind {
let pre_cast_ty = cx.typeck_results().expr_ty(cast_exp);
let cast_ty = cx.typeck_results().expr_ty(expr);
// if it's a cast from i32 to u32 wrapping will invalidate all these checks
if cx.layout_of(pre_cast_ty).ok().map(|l| l.size) == cx.layout_of(cast_ty).ok().map(|l| l.size) {
return None;
}
match pre_cast_ty.kind() {
ty::Int(int_ty) => Some(match int_ty {
IntTy::I8 => (FullInt::S(i128::from(i8::MIN)), FullInt::S(i128::from(i8::MAX))),
IntTy::I16 => (FullInt::S(i128::from(i16::MIN)), FullInt::S(i128::from(i16::MAX))),
IntTy::I32 => (FullInt::S(i128::from(i32::MIN)), FullInt::S(i128::from(i32::MAX))),
IntTy::I64 => (FullInt::S(i128::from(i64::MIN)), FullInt::S(i128::from(i64::MAX))),
IntTy::I128 => (FullInt::S(i128::MIN), FullInt::S(i128::MAX)),
IntTy::Isize => (FullInt::S(isize::MIN as i128), FullInt::S(isize::MAX as i128)),
}),
ty::Uint(uint_ty) => Some(match uint_ty {
UintTy::U8 => (FullInt::U(u128::from(u8::MIN)), FullInt::U(u128::from(u8::MAX))),
UintTy::U16 => (FullInt::U(u128::from(u16::MIN)), FullInt::U(u128::from(u16::MAX))),
UintTy::U32 => (FullInt::U(u128::from(u32::MIN)), FullInt::U(u128::from(u32::MAX))),
UintTy::U64 => (FullInt::U(u128::from(u64::MIN)), FullInt::U(u128::from(u64::MAX))),
UintTy::U128 => (FullInt::U(u128::MIN), FullInt::U(u128::MAX)),
UintTy::Usize => (FullInt::U(usize::MIN as u128), FullInt::U(usize::MAX as u128)),
}),
_ => None,
}
} else {
None
}
}
fn node_as_const_fullint<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<FullInt> {
let val = constant(cx, cx.typeck_results(), expr)?.0;
if let Constant::Int(const_int) = val {
match *cx.typeck_results().expr_ty(expr).kind() {
ty::Int(ity) => Some(FullInt::S(sext(cx.tcx, const_int, ity))),
ty::Uint(_) => Some(FullInt::U(const_int)),
_ => None,
}
} else {
None
}
}
fn err_upcast_comparison(cx: &LateContext<'_>, span: Span, expr: &Expr<'_>, always: bool) {
if let ExprKind::Cast(ref cast_val, _) = expr.kind {
span_lint(
cx,
INVALID_UPCAST_COMPARISONS,
span,
&format!(
"because of the numeric bounds on `{}` prior to casting, this expression is always {}",
snippet(cx, cast_val.span, "the expression"),
if always { "true" } else { "false" },
),
);
}
}
fn upcast_comparison_bounds_err<'tcx>(
cx: &LateContext<'tcx>,
span: Span,
rel: comparisons::Rel,
lhs_bounds: Option<(FullInt, FullInt)>,
lhs: &'tcx Expr<'_>,
rhs: &'tcx Expr<'_>,
invert: bool,
) {
use clippy_utils::comparisons::Rel;
if let Some((lb, ub)) = lhs_bounds {
if let Some(norm_rhs_val) = node_as_const_fullint(cx, rhs) {
if rel == Rel::Eq || rel == Rel::Ne {
if norm_rhs_val < lb || norm_rhs_val > ub {
err_upcast_comparison(cx, span, lhs, rel == Rel::Ne);
}
} else if match rel {
Rel::Lt => {
if invert {
norm_rhs_val < lb
} else {
ub < norm_rhs_val
}
},
Rel::Le => {
if invert {
norm_rhs_val <= lb
} else {
ub <= norm_rhs_val
}
},
Rel::Eq | Rel::Ne => unreachable!(),
} {
err_upcast_comparison(cx, span, lhs, true)
} else if match rel {
Rel::Lt => {
if invert {
norm_rhs_val >= ub
} else {
lb >= norm_rhs_val
}
},
Rel::Le => {
if invert {
norm_rhs_val > ub
} else {
lb > norm_rhs_val
}
},
Rel::Eq | Rel::Ne => unreachable!(),
} {
err_upcast_comparison(cx, span, lhs, false)
}
}
}
}
impl<'tcx> LateLintPass<'tcx> for InvalidUpcastComparisons {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
if let ExprKind::Binary(ref cmp, ref lhs, ref rhs) = expr.kind {
let normalized = comparisons::normalize_comparison(cmp.node, lhs, rhs);
let (rel, normalized_lhs, normalized_rhs) = if let Some(val) = normalized {
val
} else {
return;
};
let lhs_bounds = numeric_cast_precast_bounds(cx, normalized_lhs);
let rhs_bounds = numeric_cast_precast_bounds(cx, normalized_rhs);
upcast_comparison_bounds_err(cx, expr.span, rel, lhs_bounds, normalized_lhs, normalized_rhs, false);
upcast_comparison_bounds_err(cx, expr.span, rel, rhs_bounds, normalized_rhs, normalized_lhs, true);
}
}
}
declare_clippy_lint! {
/// **What it does:** Checks for public `impl` or `fn` missing generalization
/// over different hashers and implicitly defaulting to the default hashing