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Make approx_const MSRV aware #7629

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merged 4 commits into from Sep 5, 2021
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Make approx_const MSRV aware #7629

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265b8ec
Reorder approx_consts constant to match rust docs
Sep 3, 2021
a23af89
Make `approx_const` MSRV aware
Sep 3, 2021
4ee9ec9
Add MSRV to `approx_constant` documentation
Sep 5, 2021
19d8a3e
Improve `approx_constant` output
Sep 5, 2021
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123 changes: 69 additions & 54 deletions clippy_lints/src/approx_const.rs
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Original file line number Diff line number Diff line change
@@ -1,8 +1,10 @@
use clippy_utils::diagnostics::span_lint;
use clippy_utils::diagnostics::span_lint_and_help;
use clippy_utils::{meets_msrv, msrvs};
use rustc_ast::ast::{FloatTy, LitFloatType, LitKind};
use rustc_hir::{Expr, ExprKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_lint::{LateContext, LateLintPass, LintContext};
use rustc_semver::RustcVersion;
use rustc_session::{declare_tool_lint, impl_lint_pass};
use rustc_span::symbol;
use std::f64::consts as f64;

Expand Down Expand Up @@ -36,68 +38,81 @@ declare_clippy_lint! {
"the approximate of a known float constant (in `std::fXX::consts`)"
}

// Tuples are of the form (constant, name, min_digits)
const KNOWN_CONSTS: [(f64, &str, usize); 18] = [
(f64::E, "E", 4),
(f64::FRAC_1_PI, "FRAC_1_PI", 4),
(f64::FRAC_1_SQRT_2, "FRAC_1_SQRT_2", 5),
(f64::FRAC_2_PI, "FRAC_2_PI", 5),
(f64::FRAC_2_SQRT_PI, "FRAC_2_SQRT_PI", 5),
(f64::FRAC_PI_2, "FRAC_PI_2", 5),
(f64::FRAC_PI_3, "FRAC_PI_3", 5),
(f64::FRAC_PI_4, "FRAC_PI_4", 5),
(f64::FRAC_PI_6, "FRAC_PI_6", 5),
(f64::FRAC_PI_8, "FRAC_PI_8", 5),
(f64::LN_10, "LN_10", 5),
(f64::LN_2, "LN_2", 5),
(f64::LOG10_E, "LOG10_E", 5),
(f64::LOG2_E, "LOG2_E", 5),
(f64::LOG2_10, "LOG2_10", 5),
(f64::LOG10_2, "LOG10_2", 5),
(f64::PI, "PI", 3),
(f64::SQRT_2, "SQRT_2", 5),
// Tuples are of the form (constant, name, min_digits, msrv)
const KNOWN_CONSTS: [(f64, &str, usize, Option<RustcVersion>); 18] = [
(f64::E, "E", 4, None),
(f64::FRAC_1_PI, "FRAC_1_PI", 4, None),
(f64::FRAC_1_SQRT_2, "FRAC_1_SQRT_2", 5, None),
(f64::FRAC_2_PI, "FRAC_2_PI", 5, None),
(f64::FRAC_2_SQRT_PI, "FRAC_2_SQRT_PI", 5, None),
(f64::FRAC_PI_2, "FRAC_PI_2", 5, None),
(f64::FRAC_PI_3, "FRAC_PI_3", 5, None),
(f64::FRAC_PI_4, "FRAC_PI_4", 5, None),
(f64::FRAC_PI_6, "FRAC_PI_6", 5, None),
(f64::FRAC_PI_8, "FRAC_PI_8", 5, None),
(f64::LN_2, "LN_2", 5, None),
(f64::LN_10, "LN_10", 5, None),
(f64::LOG2_10, "LOG2_10", 5, Some(msrvs::LOG2_10)),
(f64::LOG2_E, "LOG2_E", 5, None),
(f64::LOG10_2, "LOG10_2", 5, Some(msrvs::LOG10_2)),
(f64::LOG10_E, "LOG10_E", 5, None),
(f64::PI, "PI", 3, None),
(f64::SQRT_2, "SQRT_2", 5, None),
];

declare_lint_pass!(ApproxConstant => [APPROX_CONSTANT]);
pub struct ApproxConstant {
msrv: Option<RustcVersion>,
}

impl<'tcx> LateLintPass<'tcx> for ApproxConstant {
fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
if let ExprKind::Lit(lit) = &e.kind {
check_lit(cx, &lit.node, e);
impl ApproxConstant {
#[must_use]
pub fn new(msrv: Option<RustcVersion>) -> Self {
Self { msrv }
}

fn check_lit(&self, cx: &LateContext<'_>, lit: &LitKind, e: &Expr<'_>) {
match *lit {
LitKind::Float(s, LitFloatType::Suffixed(fty)) => match fty {
FloatTy::F32 => self.check_known_consts(cx, e, s, "f32"),
FloatTy::F64 => self.check_known_consts(cx, e, s, "f64"),
},
LitKind::Float(s, LitFloatType::Unsuffixed) => self.check_known_consts(cx, e, s, "f{32, 64}"),
_ => (),
}
}
}

fn check_lit(cx: &LateContext<'_>, lit: &LitKind, e: &Expr<'_>) {
match *lit {
LitKind::Float(s, LitFloatType::Suffixed(fty)) => match fty {
FloatTy::F32 => check_known_consts(cx, e, s, "f32"),
FloatTy::F64 => check_known_consts(cx, e, s, "f64"),
},
LitKind::Float(s, LitFloatType::Unsuffixed) => check_known_consts(cx, e, s, "f{32, 64}"),
_ => (),
fn check_known_consts(&self, cx: &LateContext<'_>, e: &Expr<'_>, s: symbol::Symbol, module: &str) {
let s = s.as_str();
if s.parse::<f64>().is_ok() {
for &(constant, name, min_digits, msrv) in &KNOWN_CONSTS {
if is_approx_const(constant, &s, min_digits)
&& msrv.as_ref().map_or(true, |msrv| meets_msrv(self.msrv.as_ref(), msrv))
{
span_lint_and_help(
cx,
APPROX_CONSTANT,
e.span,
&format!("approximate value of `{}::consts::{}` found", module, &name),
None,
"consider using the constant directly",
);
return;
}
}
}
}
}

fn check_known_consts(cx: &LateContext<'_>, e: &Expr<'_>, s: symbol::Symbol, module: &str) {
let s = s.as_str();
if s.parse::<f64>().is_ok() {
for &(constant, name, min_digits) in &KNOWN_CONSTS {
if is_approx_const(constant, &s, min_digits) {
span_lint(
cx,
APPROX_CONSTANT,
e.span,
&format!(
"approximate value of `{}::consts::{}` found. \
Consider using it directly",
module, &name
),
);
return;
}
impl_lint_pass!(ApproxConstant => [APPROX_CONSTANT]);

impl<'tcx> LateLintPass<'tcx> for ApproxConstant {
fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
if let ExprKind::Lit(lit) = &e.kind {
self.check_lit(cx, &lit.node, e);
}
}

extract_msrv_attr!(LateContext);
}

/// Returns `false` if the number of significant figures in `value` are
Expand Down
2 changes: 1 addition & 1 deletion clippy_lints/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1865,7 +1865,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
store.register_late_pass(|| Box::new(needless_bool::NeedlessBool));
store.register_late_pass(|| Box::new(needless_bool::BoolComparison));
store.register_late_pass(|| Box::new(needless_for_each::NeedlessForEach));
store.register_late_pass(|| Box::new(approx_const::ApproxConstant));
store.register_late_pass(|| Box::new(misc::MiscLints));
store.register_late_pass(|| Box::new(eta_reduction::EtaReduction));
store.register_late_pass(|| Box::new(identity_op::IdentityOp));
Expand Down Expand Up @@ -1894,6 +1893,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
});

let avoid_breaking_exported_api = conf.avoid_breaking_exported_api;
store.register_late_pass(move || Box::new(approx_const::ApproxConstant::new(msrv)));
store.register_late_pass(move || Box::new(methods::Methods::new(avoid_breaking_exported_api, msrv)));
store.register_late_pass(move || Box::new(matches::Matches::new(msrv)));
store.register_early_pass(move || Box::new(manual_non_exhaustive::ManualNonExhaustive::new(msrv)));
Expand Down
2 changes: 1 addition & 1 deletion clippy_lints/src/utils/conf.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -132,7 +132,7 @@ define_Conf! {
///
/// Suppress lints whenever the suggested change would cause breakage for other crates.
(avoid_breaking_exported_api: bool = true),
/// Lint: MANUAL_SPLIT_ONCE, MANUAL_STR_REPEAT, CLONED_INSTEAD_OF_COPIED, REDUNDANT_FIELD_NAMES, REDUNDANT_STATIC_LIFETIMES, FILTER_MAP_NEXT, CHECKED_CONVERSIONS, MANUAL_RANGE_CONTAINS, USE_SELF, MEM_REPLACE_WITH_DEFAULT, MANUAL_NON_EXHAUSTIVE, OPTION_AS_REF_DEREF, MAP_UNWRAP_OR, MATCH_LIKE_MATCHES_MACRO, MANUAL_STRIP, MISSING_CONST_FOR_FN, UNNESTED_OR_PATTERNS, FROM_OVER_INTO, PTR_AS_PTR, IF_THEN_SOME_ELSE_NONE.
/// Lint: MANUAL_SPLIT_ONCE, MANUAL_STR_REPEAT, CLONED_INSTEAD_OF_COPIED, REDUNDANT_FIELD_NAMES, REDUNDANT_STATIC_LIFETIMES, FILTER_MAP_NEXT, CHECKED_CONVERSIONS, MANUAL_RANGE_CONTAINS, USE_SELF, MEM_REPLACE_WITH_DEFAULT, MANUAL_NON_EXHAUSTIVE, OPTION_AS_REF_DEREF, MAP_UNWRAP_OR, MATCH_LIKE_MATCHES_MACRO, MANUAL_STRIP, MISSING_CONST_FOR_FN, UNNESTED_OR_PATTERNS, FROM_OVER_INTO, PTR_AS_PTR, IF_THEN_SOME_ELSE_NONE, APPROX_CONSTANT.
///
/// The minimum rust version that the project supports
(msrv: Option<String> = None),
Expand Down
1 change: 1 addition & 0 deletions clippy_utils/src/msrvs.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@ msrv_aliases! {
1,50,0 { BOOL_THEN }
1,46,0 { CONST_IF_MATCH }
1,45,0 { STR_STRIP_PREFIX }
1,43,0 { LOG2_10, LOG10_2 }
1,42,0 { MATCHES_MACRO }
1,41,0 { RE_REBALANCING_COHERENCE, RESULT_MAP_OR_ELSE }
1,40,0 { MEM_TAKE, NON_EXHAUSTIVE, OPTION_AS_DEREF }
Expand Down
83 changes: 62 additions & 21 deletions tests/ui/approx_const.stderr
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Original file line number Diff line number Diff line change
@@ -1,130 +1,171 @@
error: approximate value of `f{32, 64}::consts::E` found. Consider using it directly
error: approximate value of `f{32, 64}::consts::E` found
--> $DIR/approx_const.rs:4:16
|
LL | let my_e = 2.7182;
| ^^^^^^
|
= note: `-D clippy::approx-constant` implied by `-D warnings`
= help: consider using the constant directly

error: approximate value of `f{32, 64}::consts::E` found. Consider using it directly
error: approximate value of `f{32, 64}::consts::E` found
--> $DIR/approx_const.rs:5:20
|
LL | let almost_e = 2.718;
| ^^^^^
|
= help: consider using the constant directly

error: approximate value of `f{32, 64}::consts::FRAC_1_PI` found. Consider using it directly
error: approximate value of `f{32, 64}::consts::FRAC_1_PI` found
--> $DIR/approx_const.rs:8:24
|
LL | let my_1_frac_pi = 0.3183;
| ^^^^^^
|
= help: consider using the constant directly

error: approximate value of `f{32, 64}::consts::FRAC_1_SQRT_2` found. Consider using it directly
error: approximate value of `f{32, 64}::consts::FRAC_1_SQRT_2` found
--> $DIR/approx_const.rs:11:28
|
LL | let my_frac_1_sqrt_2 = 0.70710678;
| ^^^^^^^^^^
|
= help: consider using the constant directly

error: approximate value of `f{32, 64}::consts::FRAC_1_SQRT_2` found. Consider using it directly
error: approximate value of `f{32, 64}::consts::FRAC_1_SQRT_2` found
--> $DIR/approx_const.rs:12:32
|
LL | let almost_frac_1_sqrt_2 = 0.70711;
| ^^^^^^^
|
= help: consider using the constant directly

error: approximate value of `f{32, 64}::consts::FRAC_2_PI` found. Consider using it directly
error: approximate value of `f{32, 64}::consts::FRAC_2_PI` found
--> $DIR/approx_const.rs:15:24
|
LL | let my_frac_2_pi = 0.63661977;
| ^^^^^^^^^^
|
= help: consider using the constant directly

error: approximate value of `f{32, 64}::consts::FRAC_2_SQRT_PI` found. Consider using it directly
error: approximate value of `f{32, 64}::consts::FRAC_2_SQRT_PI` found
--> $DIR/approx_const.rs:18:27
|
LL | let my_frac_2_sq_pi = 1.128379;
| ^^^^^^^^
|
= help: consider using the constant directly

error: approximate value of `f{32, 64}::consts::FRAC_PI_2` found. Consider using it directly
error: approximate value of `f{32, 64}::consts::FRAC_PI_2` found
--> $DIR/approx_const.rs:21:24
|
LL | let my_frac_pi_2 = 1.57079632679;
| ^^^^^^^^^^^^^
|
= help: consider using the constant directly

error: approximate value of `f{32, 64}::consts::FRAC_PI_3` found. Consider using it directly
error: approximate value of `f{32, 64}::consts::FRAC_PI_3` found
--> $DIR/approx_const.rs:24:24
|
LL | let my_frac_pi_3 = 1.04719755119;
| ^^^^^^^^^^^^^
|
= help: consider using the constant directly

error: approximate value of `f{32, 64}::consts::FRAC_PI_4` found. Consider using it directly
error: approximate value of `f{32, 64}::consts::FRAC_PI_4` found
--> $DIR/approx_const.rs:27:24
|
LL | let my_frac_pi_4 = 0.785398163397;
| ^^^^^^^^^^^^^^
|
= help: consider using the constant directly

error: approximate value of `f{32, 64}::consts::FRAC_PI_6` found. Consider using it directly
error: approximate value of `f{32, 64}::consts::FRAC_PI_6` found
--> $DIR/approx_const.rs:30:24
|
LL | let my_frac_pi_6 = 0.523598775598;
| ^^^^^^^^^^^^^^
|
= help: consider using the constant directly

error: approximate value of `f{32, 64}::consts::FRAC_PI_8` found. Consider using it directly
error: approximate value of `f{32, 64}::consts::FRAC_PI_8` found
--> $DIR/approx_const.rs:33:24
|
LL | let my_frac_pi_8 = 0.3926990816987;
| ^^^^^^^^^^^^^^^
|
= help: consider using the constant directly

error: approximate value of `f{32, 64}::consts::LN_10` found. Consider using it directly
error: approximate value of `f{32, 64}::consts::LN_10` found
--> $DIR/approx_const.rs:36:20
|
LL | let my_ln_10 = 2.302585092994046;
| ^^^^^^^^^^^^^^^^^
|
= help: consider using the constant directly

error: approximate value of `f{32, 64}::consts::LN_2` found. Consider using it directly
error: approximate value of `f{32, 64}::consts::LN_2` found
--> $DIR/approx_const.rs:39:19
|
LL | let my_ln_2 = 0.6931471805599453;
| ^^^^^^^^^^^^^^^^^^
|
= help: consider using the constant directly

error: approximate value of `f{32, 64}::consts::LOG10_E` found. Consider using it directly
error: approximate value of `f{32, 64}::consts::LOG10_E` found
--> $DIR/approx_const.rs:42:22
|
LL | let my_log10_e = 0.4342944819032518;
| ^^^^^^^^^^^^^^^^^^
|
= help: consider using the constant directly

error: approximate value of `f{32, 64}::consts::LOG2_E` found. Consider using it directly
error: approximate value of `f{32, 64}::consts::LOG2_E` found
--> $DIR/approx_const.rs:45:21
|
LL | let my_log2_e = 1.4426950408889634;
| ^^^^^^^^^^^^^^^^^^
|
= help: consider using the constant directly

error: approximate value of `f{32, 64}::consts::LOG2_10` found. Consider using it directly
error: approximate value of `f{32, 64}::consts::LOG2_10` found
--> $DIR/approx_const.rs:48:19
|
LL | let log2_10 = 3.321928094887362;
| ^^^^^^^^^^^^^^^^^
|
= help: consider using the constant directly

error: approximate value of `f{32, 64}::consts::LOG10_2` found. Consider using it directly
error: approximate value of `f{32, 64}::consts::LOG10_2` found
--> $DIR/approx_const.rs:51:19
|
LL | let log10_2 = 0.301029995663981;
| ^^^^^^^^^^^^^^^^^
|
= help: consider using the constant directly

error: approximate value of `f{32, 64}::consts::PI` found. Consider using it directly
error: approximate value of `f{32, 64}::consts::PI` found
--> $DIR/approx_const.rs:54:17
|
LL | let my_pi = 3.1415;
| ^^^^^^
|
= help: consider using the constant directly

error: approximate value of `f{32, 64}::consts::PI` found. Consider using it directly
error: approximate value of `f{32, 64}::consts::PI` found
--> $DIR/approx_const.rs:55:21
|
LL | let almost_pi = 3.14;
| ^^^^
|
= help: consider using the constant directly

error: approximate value of `f{32, 64}::consts::SQRT_2` found. Consider using it directly
error: approximate value of `f{32, 64}::consts::SQRT_2` found
--> $DIR/approx_const.rs:58:18
|
LL | let my_sq2 = 1.4142;
| ^^^^^^
|
= help: consider using the constant directly

error: aborting due to 21 previous errors

5 changes: 5 additions & 0 deletions tests/ui/min_rust_version_attr.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,11 @@

use std::ops::{Deref, RangeFrom};

fn approx_const() {
let log2_10 = 3.321928094887362;
let log10_2 = 0.301029995663981;
}

fn cloned_instead_of_copied() {
let _ = [1].iter().cloned();
}
Expand Down
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