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Auto merge of #5470 - flip1995:rollup-cvkuiza, r=flip1995
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Rollup of 5 pull requests

Successful merges:

 - #5226 (Add lint for explicit deref and deref_mut method calls)
 - #5248 (Add lint on large non scalar const)
 - #5430 (Disallow bit-shifting in integer_arithmetic)
 - #5466 (large_enum_variant: Report sizes of variants)
 - #5468 (Zero single char names)

Failed merges:

r? @ghost

changelog: rollup
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bors committed Apr 15, 2020
2 parents a9a4c8e + 19183a6 commit 6651c1b
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2 changes: 2 additions & 0 deletions CHANGELOG.md
Original file line number Diff line number Diff line change
Expand Up @@ -1256,6 +1256,7 @@ Released 2018-09-13
[`expect_fun_call`]: https://rust-lang.github.io/rust-clippy/master/index.html#expect_fun_call
[`expl_impl_clone_on_copy`]: https://rust-lang.github.io/rust-clippy/master/index.html#expl_impl_clone_on_copy
[`explicit_counter_loop`]: https://rust-lang.github.io/rust-clippy/master/index.html#explicit_counter_loop
[`explicit_deref_methods`]: https://rust-lang.github.io/rust-clippy/master/index.html#explicit_deref_methods
[`explicit_into_iter_loop`]: https://rust-lang.github.io/rust-clippy/master/index.html#explicit_into_iter_loop
[`explicit_iter_loop`]: https://rust-lang.github.io/rust-clippy/master/index.html#explicit_iter_loop
[`explicit_write`]: https://rust-lang.github.io/rust-clippy/master/index.html#explicit_write
Expand Down Expand Up @@ -1319,6 +1320,7 @@ Released 2018-09-13
[`iter_skip_next`]: https://rust-lang.github.io/rust-clippy/master/index.html#iter_skip_next
[`iterator_step_by_zero`]: https://rust-lang.github.io/rust-clippy/master/index.html#iterator_step_by_zero
[`just_underscores_and_digits`]: https://rust-lang.github.io/rust-clippy/master/index.html#just_underscores_and_digits
[`large_const_arrays`]: https://rust-lang.github.io/rust-clippy/master/index.html#large_const_arrays
[`large_digit_groups`]: https://rust-lang.github.io/rust-clippy/master/index.html#large_digit_groups
[`large_enum_variant`]: https://rust-lang.github.io/rust-clippy/master/index.html#large_enum_variant
[`large_stack_arrays`]: https://rust-lang.github.io/rust-clippy/master/index.html#large_stack_arrays
Expand Down
18 changes: 11 additions & 7 deletions clippy_lints/src/arithmetic.rs
Original file line number Diff line number Diff line change
Expand Up @@ -6,11 +6,17 @@ use rustc_session::{declare_tool_lint, impl_lint_pass};
use rustc_span::source_map::Span;

declare_clippy_lint! {
/// **What it does:** Checks for plain integer arithmetic.
/// **What it does:** Checks for integer arithmetic operations which could overflow or panic.
///
/// **Why is this bad?** This is only checked against overflow in debug builds.
/// In some applications one wants explicitly checked, wrapping or saturating
/// arithmetic.
/// Specifically, checks for any operators (`+`, `-`, `*`, `<<`, etc) which are capable
/// of overflowing according to the [Rust
/// Reference](https://doc.rust-lang.org/reference/expressions/operator-expr.html#overflow),
/// or which can panic (`/`, `%`). No bounds analysis or sophisticated reasoning is
/// attempted.
///
/// **Why is this bad?** Integer overflow will trigger a panic in debug builds or will wrap in
/// release mode. Division by zero will cause a panic in either mode. In some applications one
/// wants explicitly checked, wrapping or saturating arithmetic.
///
/// **Known problems:** None.
///
Expand All @@ -21,7 +27,7 @@ declare_clippy_lint! {
/// ```
pub INTEGER_ARITHMETIC,
restriction,
"any integer arithmetic statement"
"any integer arithmetic expression which could overflow or panic"
}

declare_clippy_lint! {
Expand Down Expand Up @@ -71,8 +77,6 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Arithmetic {
| hir::BinOpKind::BitAnd
| hir::BinOpKind::BitOr
| hir::BinOpKind::BitXor
| hir::BinOpKind::Shl
| hir::BinOpKind::Shr
| hir::BinOpKind::Eq
| hir::BinOpKind::Lt
| hir::BinOpKind::Le
Expand Down
113 changes: 113 additions & 0 deletions clippy_lints/src/dereference.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,113 @@
use crate::utils::{get_parent_expr, implements_trait, snippet, span_lint_and_sugg};
use if_chain::if_chain;
use rustc_ast::util::parser::{ExprPrecedence, PREC_POSTFIX, PREC_PREFIX};
use rustc_errors::Applicability;
use rustc_hir::{Expr, ExprKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::source_map::Span;

declare_clippy_lint! {
/// **What it does:** Checks for explicit `deref()` or `deref_mut()` method calls.
///
/// **Why is this bad?** Derefencing by `&*x` or `&mut *x` is clearer and more concise,
/// when not part of a method chain.
///
/// **Example:**
/// ```rust
/// use std::ops::Deref;
/// let a: &mut String = &mut String::from("foo");
/// let b: &str = a.deref();
/// ```
/// Could be written as:
/// ```rust
/// let a: &mut String = &mut String::from("foo");
/// let b = &*a;
/// ```
///
/// This lint excludes
/// ```rust,ignore
/// let _ = d.unwrap().deref();
/// ```
pub EXPLICIT_DEREF_METHODS,
pedantic,
"Explicit use of deref or deref_mut method while not in a method chain."
}

declare_lint_pass!(Dereferencing => [
EXPLICIT_DEREF_METHODS
]);

impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Dereferencing {
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr<'_>) {
if_chain! {
if !expr.span.from_expansion();
if let ExprKind::MethodCall(ref method_name, _, ref args) = &expr.kind;
if args.len() == 1;

then {
if let Some(parent_expr) = get_parent_expr(cx, expr) {
// Check if we have the whole call chain here
if let ExprKind::MethodCall(..) = parent_expr.kind {
return;
}
// Check for Expr that we don't want to be linted
let precedence = parent_expr.precedence();
match precedence {
// Lint a Call is ok though
ExprPrecedence::Call | ExprPrecedence::AddrOf => (),
_ => {
if precedence.order() >= PREC_PREFIX && precedence.order() <= PREC_POSTFIX {
return;
}
}
}
}
let name = method_name.ident.as_str();
lint_deref(cx, &*name, &args[0], args[0].span, expr.span);
}
}
}
}

fn lint_deref(cx: &LateContext<'_, '_>, method_name: &str, call_expr: &Expr<'_>, var_span: Span, expr_span: Span) {
match method_name {
"deref" => {
if cx
.tcx
.lang_items()
.deref_trait()
.map_or(false, |id| implements_trait(cx, cx.tables.expr_ty(&call_expr), id, &[]))
{
span_lint_and_sugg(
cx,
EXPLICIT_DEREF_METHODS,
expr_span,
"explicit deref method call",
"try this",
format!("&*{}", &snippet(cx, var_span, "..")),
Applicability::MachineApplicable,
);
}
},
"deref_mut" => {
if cx
.tcx
.lang_items()
.deref_mut_trait()
.map_or(false, |id| implements_trait(cx, cx.tables.expr_ty(&call_expr), id, &[]))
{
span_lint_and_sugg(
cx,
EXPLICIT_DEREF_METHODS,
expr_span,
"explicit deref_mut method call",
"try this",
format!("&mut *{}", &snippet(cx, var_span, "..")),
Applicability::MachineApplicable,
);
}
},
_ => (),
}
}
85 changes: 85 additions & 0 deletions clippy_lints/src/large_const_arrays.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,85 @@
use crate::rustc_target::abi::LayoutOf;
use crate::utils::span_lint_and_then;
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::{Item, ItemKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::mir::interpret::ConstValue;
use rustc_middle::ty::{self, ConstKind};
use rustc_session::{declare_tool_lint, impl_lint_pass};
use rustc_span::{BytePos, Pos, Span};
use rustc_typeck::hir_ty_to_ty;

declare_clippy_lint! {
/// **What it does:** Checks for large `const` arrays that should
/// be defined as `static` instead.
///
/// **Why is this bad?** Performance: const variables are inlined upon use.
/// Static items result in only one instance and has a fixed location in memory.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust,ignore
/// // Bad
/// pub const a = [0u32; 1_000_000];
///
/// // Good
/// pub static a = [0u32; 1_000_000];
/// ```
pub LARGE_CONST_ARRAYS,
perf,
"large non-scalar const array may cause performance overhead"
}

pub struct LargeConstArrays {
maximum_allowed_size: u64,
}

impl LargeConstArrays {
#[must_use]
pub fn new(maximum_allowed_size: u64) -> Self {
Self { maximum_allowed_size }
}
}

impl_lint_pass!(LargeConstArrays => [LARGE_CONST_ARRAYS]);

impl<'a, 'tcx> LateLintPass<'a, 'tcx> for LargeConstArrays {
fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx Item<'_>) {
if_chain! {
if !item.span.from_expansion();
if let ItemKind::Const(hir_ty, _) = &item.kind;
let ty = hir_ty_to_ty(cx.tcx, hir_ty);
if let ty::Array(element_type, cst) = ty.kind;
if let ConstKind::Value(val) = cst.val;
if let ConstValue::Scalar(element_count) = val;
if let Ok(element_count) = element_count.to_machine_usize(&cx.tcx);
if let Ok(element_size) = cx.layout_of(element_type).map(|l| l.size.bytes());
if self.maximum_allowed_size < element_count * element_size;

then {
let hi_pos = item.ident.span.lo() - BytePos::from_usize(1);
let sugg_span = Span::new(
hi_pos - BytePos::from_usize("const".len()),
hi_pos,
item.span.ctxt(),
);
span_lint_and_then(
cx,
LARGE_CONST_ARRAYS,
item.span,
"large array defined as const",
|db| {
db.span_suggestion(
sugg_span,
"make this a static item",
"static".to_string(),
Applicability::MachineApplicable,
);
}
);
}
}
}
}
25 changes: 19 additions & 6 deletions clippy_lints/src/large_enum_variant.rs
Original file line number Diff line number Diff line change
Expand Up @@ -21,11 +21,19 @@ declare_clippy_lint! {
/// measure the change this lint suggests.
///
/// **Example:**
///
/// ```rust
/// // Bad
/// enum Test {
/// A(i32),
/// B([i32; 8000]),
/// }
///
/// // Possibly better
/// enum Test2 {
/// A(i32),
/// B(Box<[i32; 8000]>),
/// }
/// ```
pub LARGE_ENUM_VARIANT,
perf,
Expand Down Expand Up @@ -84,12 +92,21 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for LargeEnumVariant {
if difference > self.maximum_size_difference_allowed {
let (i, variant) = largest.1;

let help_text = "consider boxing the large fields to reduce the total size of the enum";
span_lint_and_then(
cx,
LARGE_ENUM_VARIANT,
def.variants[i].span,
"large size difference between variants",
|db| {
db.span_label(
def.variants[(largest.1).0].span,
&format!("this variant is {} bytes", largest.0),
);
db.span_note(
def.variants[(second.1).0].span,
&format!("and the second-largest variant is {} bytes:", second.0),
);
if variant.fields.len() == 1 {
let span = match def.variants[i].data {
VariantData::Struct(ref fields, ..) | VariantData::Tuple(ref fields, ..) => {
Expand All @@ -100,18 +117,14 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for LargeEnumVariant {
if let Some(snip) = snippet_opt(cx, span) {
db.span_suggestion(
span,
"consider boxing the large fields to reduce the total size of the \
enum",
help_text,
format!("Box<{}>", snip),
Applicability::MaybeIncorrect,
);
return;
}
}
db.span_help(
def.variants[i].span,
"consider boxing the large fields to reduce the total size of the enum",
);
db.span_help(def.variants[i].span, help_text);
},
);
}
Expand Down
9 changes: 9 additions & 0 deletions clippy_lints/src/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -191,6 +191,7 @@ mod copies;
mod copy_iterator;
mod dbg_macro;
mod default_trait_access;
mod dereference;
mod derive;
mod doc;
mod double_comparison;
Expand Down Expand Up @@ -231,6 +232,7 @@ mod inline_fn_without_body;
mod int_plus_one;
mod integer_division;
mod items_after_statements;
mod large_const_arrays;
mod large_enum_variant;
mod large_stack_arrays;
mod len_zero;
Expand Down Expand Up @@ -513,6 +515,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
&copy_iterator::COPY_ITERATOR,
&dbg_macro::DBG_MACRO,
&default_trait_access::DEFAULT_TRAIT_ACCESS,
&dereference::EXPLICIT_DEREF_METHODS,
&derive::DERIVE_HASH_XOR_EQ,
&derive::EXPL_IMPL_CLONE_ON_COPY,
&doc::DOC_MARKDOWN,
Expand Down Expand Up @@ -580,6 +583,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
&int_plus_one::INT_PLUS_ONE,
&integer_division::INTEGER_DIVISION,
&items_after_statements::ITEMS_AFTER_STATEMENTS,
&large_const_arrays::LARGE_CONST_ARRAYS,
&large_enum_variant::LARGE_ENUM_VARIANT,
&large_stack_arrays::LARGE_STACK_ARRAYS,
&len_zero::LEN_WITHOUT_IS_EMPTY,
Expand Down Expand Up @@ -1024,6 +1028,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
store.register_late_pass(|| box to_digit_is_some::ToDigitIsSome);
let array_size_threshold = conf.array_size_threshold;
store.register_late_pass(move || box large_stack_arrays::LargeStackArrays::new(array_size_threshold));
store.register_late_pass(move || box large_const_arrays::LargeConstArrays::new(array_size_threshold));
store.register_late_pass(move || box floating_point_arithmetic::FloatingPointArithmetic);
store.register_early_pass(|| box as_conversions::AsConversions);
store.register_early_pass(|| box utils::internal_lints::ProduceIce);
Expand All @@ -1039,6 +1044,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
store.register_late_pass(|| box verbose_file_reads::VerboseFileReads);
store.register_late_pass(|| box redundant_pub_crate::RedundantPubCrate::default());
store.register_late_pass(|| box unnamed_address::UnnamedAddress);
store.register_late_pass(|| box dereference::Dereferencing);

store.register_group(true, "clippy::restriction", Some("clippy_restriction"), vec![
LintId::of(&arithmetic::FLOAT_ARITHMETIC),
Expand Down Expand Up @@ -1089,6 +1095,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&copies::SAME_FUNCTIONS_IN_IF_CONDITION),
LintId::of(&copy_iterator::COPY_ITERATOR),
LintId::of(&default_trait_access::DEFAULT_TRAIT_ACCESS),
LintId::of(&dereference::EXPLICIT_DEREF_METHODS),
LintId::of(&derive::EXPL_IMPL_CLONE_ON_COPY),
LintId::of(&doc::DOC_MARKDOWN),
LintId::of(&doc::MISSING_ERRORS_DOC),
Expand Down Expand Up @@ -1221,6 +1228,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&inherent_to_string::INHERENT_TO_STRING_SHADOW_DISPLAY),
LintId::of(&inline_fn_without_body::INLINE_FN_WITHOUT_BODY),
LintId::of(&int_plus_one::INT_PLUS_ONE),
LintId::of(&large_const_arrays::LARGE_CONST_ARRAYS),
LintId::of(&large_enum_variant::LARGE_ENUM_VARIANT),
LintId::of(&len_zero::LEN_WITHOUT_IS_EMPTY),
LintId::of(&len_zero::LEN_ZERO),
Expand Down Expand Up @@ -1652,6 +1660,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&bytecount::NAIVE_BYTECOUNT),
LintId::of(&entry::MAP_ENTRY),
LintId::of(&escape::BOXED_LOCAL),
LintId::of(&large_const_arrays::LARGE_CONST_ARRAYS),
LintId::of(&large_enum_variant::LARGE_ENUM_VARIANT),
LintId::of(&loops::MANUAL_MEMCPY),
LintId::of(&loops::NEEDLESS_COLLECT),
Expand Down
2 changes: 1 addition & 1 deletion clippy_lints/src/non_expressive_names.rs
Original file line number Diff line number Diff line change
Expand Up @@ -93,7 +93,7 @@ impl<'a, 'tcx> SimilarNamesLocalVisitor<'a, 'tcx> {
fn check_single_char_names(&self) {
let num_single_char_names = self.single_char_names.iter().flatten().count();
let threshold = self.lint.single_char_binding_names_threshold;
if num_single_char_names as u64 >= threshold {
if num_single_char_names as u64 > threshold {
let span = self
.single_char_names
.iter()
Expand Down
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