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Auto merge of #5202 - krishna-veerareddy:issue-5201-move-lossy-float-literal-restriction, r=flip1995

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Move check for lossy whole-number floats out of `excessive_precision`

changelog: Add new lint `lossy_float_literal` to detect lossy whole number float literals and move it out of `excessive_precision` again.

Fixes #5201
This commit is contained in:
bors 2020-02-21 09:43:55 +00:00
commit acfcbee4a2
11 changed files with 214 additions and 145 deletions
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1
CHANGELOG.md
View file

@ -1207,6 +1207,7 @@ Released 2018-09-13
[`let_unit_value`]: https://rust-lang.github.io/rust-clippy/master/index.html#let_unit_value
[`linkedlist`]: https://rust-lang.github.io/rust-clippy/master/index.html#linkedlist
[`logic_bug`]: https://rust-lang.github.io/rust-clippy/master/index.html#logic_bug
[`lossy_float_literal`]: https://rust-lang.github.io/rust-clippy/master/index.html#lossy_float_literal
[`main_recursion`]: https://rust-lang.github.io/rust-clippy/master/index.html#main_recursion
[`manual_memcpy`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_memcpy
[`manual_mul_add`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_mul_add

2
README.md
View file

@ -5,7 +5,7 @@
A collection of lints to catch common mistakes and improve your [Rust](https://github.com/rust-lang/rust) code.
[There are 355 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
[There are 356 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
We have a bunch of lint categories to allow you to choose how much Clippy is supposed to ~~annoy~~ help you:

79
clippy_lints/src/excessive_precision.rs → clippy_lints/src/float_literal.rs
View file

@ -13,8 +13,7 @@ declare_clippy_lint! {
/// **What it does:** Checks for float literals with a precision greater
/// than that supported by the underlying type.
///
/// **Why is this bad?** Rust will silently lose precision during conversion
/// to a float.
/// **Why is this bad?** Rust will truncate the literal silently.
///
/// **Known problems:** None.
///
@ -22,21 +21,45 @@ declare_clippy_lint! {
///
/// ```rust
/// // Bad
/// let a: f32 = 0.123_456_789_9; // 0.123_456_789
/// let b: f32 = 16_777_217.0; // 16_777_216.0
/// let v: f32 = 0.123_456_789_9;
/// println!("{}", v); // 0.123_456_789
///
/// // Good
/// let a: f64 = 0.123_456_789_9;
/// let b: f64 = 16_777_216.0;
/// let v: f64 = 0.123_456_789_9;
/// println!("{}", v); // 0.123_456_789_9
/// ```
pub EXCESSIVE_PRECISION,
correctness,
style,
"excessive precision for float literal"
}
declare_lint_pass!(ExcessivePrecision => [EXCESSIVE_PRECISION]);
declare_clippy_lint! {
/// **What it does:** Checks for whole number float literals that
/// cannot be represented as the underlying type without loss.
///
/// **Why is this bad?** Rust will silently lose precision during
/// conversion to a float.
///
/// **Known problems:** None.
///
/// **Example:**
///
/// ```rust
/// // Bad
/// let _: f32 = 16_777_217.0; // 16_777_216.0
///
/// // Good
/// let _: f32 = 16_777_216.0;
/// let _: f64 = 16_777_217.0;
/// ```
pub LOSSY_FLOAT_LITERAL,
restriction,
"lossy whole number float literals"
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ExcessivePrecision {
declare_lint_pass!(FloatLiteral => [EXCESSIVE_PRECISION, LOSSY_FLOAT_LITERAL]);
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for FloatLiteral {
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr<'_>) {
if_chain! {
let ty = cx.tables.expr_ty(expr);
@ -52,26 +75,41 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ExcessivePrecision {
// since we'll need the truncated string anyway.
let digits = count_digits(&sym_str);
let max = max_digits(fty);
let float_str = match fty {
FloatTy::F32 => sym_str.parse::<f32>().map(|f| formatter.format(f)),
FloatTy::F64 => sym_str.parse::<f64>().map(|f| formatter.format(f)),
}.unwrap();
let type_suffix = match lit_float_ty {
LitFloatType::Suffixed(FloatTy::F32) => Some("f32"),
LitFloatType::Suffixed(FloatTy::F64) => Some("f64"),
_ => None
};
let (is_whole, mut float_str) = match fty {
FloatTy::F32 => {
let value = sym_str.parse::<f32>().unwrap();
if is_whole_number(&sym_str, fty) {
(value.fract() == 0.0, formatter.format(value))
},
FloatTy::F64 => {
let value = sym_str.parse::<f64>().unwrap();
(value.fract() == 0.0, formatter.format(value))
},
};
if is_whole && !sym_str.contains(|c| c == 'e' || c == 'E') {
// Normalize the literal by stripping the fractional portion
if sym_str.split('.').next().unwrap() != float_str {
// If the type suffix is missing the suggestion would be
// incorrectly interpreted as an integer so adding a `.0`
// suffix to prevent that.
if type_suffix.is_none() {
float_str.push_str(".0");
}
span_lint_and_sugg(
cx,
EXCESSIVE_PRECISION,
LOSSY_FLOAT_LITERAL,
expr.span,
"literal cannot be represented as the underlying type without loss of precision",
"consider changing the type or replacing it with",
format_numeric_literal(format!("{}.0", float_str).as_str(), type_suffix, true),
format_numeric_literal(&float_str, type_suffix, true),
Applicability::MachineApplicable,
);
}
@ -91,15 +129,6 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ExcessivePrecision {
}
}
// Checks whether a float literal is a whole number
#[must_use]
fn is_whole_number(sym_str: &str, fty: FloatTy) -> bool {
match fty {
FloatTy::F32 => sym_str.parse::<f32>().unwrap().fract() == 0.0,
FloatTy::F64 => sym_str.parse::<f64>().unwrap().fract() == 0.0,
}
}
#[must_use]
fn max_digits(fty: FloatTy) -> u32 {
match fty {

12
clippy_lints/src/lib.rs
View file

@ -205,10 +205,10 @@ pub mod escape;
pub mod eta_reduction;
pub mod eval_order_dependence;
pub mod excessive_bools;
pub mod excessive_precision;
pub mod exit;
pub mod explicit_write;
pub mod fallible_impl_from;
pub mod float_literal;
pub mod format;
pub mod formatting;
pub mod functions;
@ -534,10 +534,11 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
&eval_order_dependence::EVAL_ORDER_DEPENDENCE,
&excessive_bools::FN_PARAMS_EXCESSIVE_BOOLS,
&excessive_bools::STRUCT_EXCESSIVE_BOOLS,
&excessive_precision::EXCESSIVE_PRECISION,
&exit::EXIT,
&explicit_write::EXPLICIT_WRITE,
&fallible_impl_from::FALLIBLE_IMPL_FROM,
&float_literal::EXCESSIVE_PRECISION,
&float_literal::LOSSY_FLOAT_LITERAL,
&format::USELESS_FORMAT,
&formatting::POSSIBLE_MISSING_COMMA,
&formatting::SUSPICIOUS_ASSIGNMENT_FORMATTING,
@ -836,7 +837,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
store.register_late_pass(|| box eq_op::EqOp);
store.register_late_pass(|| box enum_glob_use::EnumGlobUse);
store.register_late_pass(|| box enum_clike::UnportableVariant);
store.register_late_pass(|| box excessive_precision::ExcessivePrecision);
store.register_late_pass(|| box float_literal::FloatLiteral);
let verbose_bit_mask_threshold = conf.verbose_bit_mask_threshold;
store.register_late_pass(move || box bit_mask::BitMask::new(verbose_bit_mask_threshold));
store.register_late_pass(|| box ptr::Ptr);
@ -1016,6 +1017,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&dbg_macro::DBG_MACRO),
LintId::of(&else_if_without_else::ELSE_IF_WITHOUT_ELSE),
LintId::of(&exit::EXIT),
LintId::of(&float_literal::LOSSY_FLOAT_LITERAL),
LintId::of(&implicit_return::IMPLICIT_RETURN),
LintId::of(&indexing_slicing::INDEXING_SLICING),
LintId::of(&inherent_impl::MULTIPLE_INHERENT_IMPL),
@ -1160,8 +1162,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&eta_reduction::REDUNDANT_CLOSURE),
LintId::of(&eval_order_dependence::DIVERGING_SUB_EXPRESSION),
LintId::of(&eval_order_dependence::EVAL_ORDER_DEPENDENCE),
LintId::of(&excessive_precision::EXCESSIVE_PRECISION),
LintId::of(&explicit_write::EXPLICIT_WRITE),
LintId::of(&float_literal::EXCESSIVE_PRECISION),
LintId::of(&format::USELESS_FORMAT),
LintId::of(&formatting::POSSIBLE_MISSING_COMMA),
LintId::of(&formatting::SUSPICIOUS_ASSIGNMENT_FORMATTING),
@ -1386,6 +1388,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&enum_variants::MODULE_INCEPTION),
LintId::of(&eq_op::OP_REF),
LintId::of(&eta_reduction::REDUNDANT_CLOSURE),
LintId::of(&float_literal::EXCESSIVE_PRECISION),
LintId::of(&formatting::SUSPICIOUS_ASSIGNMENT_FORMATTING),
LintId::of(&formatting::SUSPICIOUS_ELSE_FORMATTING),
LintId::of(&formatting::SUSPICIOUS_UNARY_OP_FORMATTING),
@ -1565,7 +1568,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&enum_clike::ENUM_CLIKE_UNPORTABLE_VARIANT),
LintId::of(&eq_op::EQ_OP),
LintId::of(&erasing_op::ERASING_OP),
LintId::of(&excessive_precision::EXCESSIVE_PRECISION),
LintId::of(&formatting::POSSIBLE_MISSING_COMMA),
LintId::of(&functions::NOT_UNSAFE_PTR_ARG_DEREF),
LintId::of(&indexing_slicing::OUT_OF_BOUNDS_INDEXING),

13
src/lintlist/mod.rs
View file

@ -6,7 +6,7 @@ pub use lint::Lint;
pub use lint::LINT_LEVELS;
// begin lint list, do not remove this comment, it’s used in `update_lints`
pub const ALL_LINTS: [Lint; 355] = [
pub const ALL_LINTS: [Lint; 356] = [
Lint {
name: "absurd_extreme_comparisons",
group: "correctness",
@ -492,10 +492,10 @@ pub const ALL_LINTS: [Lint; 355] = [
},
Lint {
name: "excessive_precision",
group: "correctness",
group: "style",
desc: "excessive precision for float literal",
deprecation: None,
module: "excessive_precision",
module: "float_literal",
},
Lint {
name: "exit",
@ -1001,6 +1001,13 @@ pub const ALL_LINTS: [Lint; 355] = [
deprecation: None,
module: "booleans",
},
Lint {
name: "lossy_float_literal",
group: "restriction",
desc: "lossy whole number float literals",
deprecation: None,
module: "float_literal",
},
Lint {
name: "main_recursion",
group: "style",

22
tests/ui/excessive_precision.fixed
View file

@ -60,26 +60,4 @@ fn main() {
// issue #2840
let num = 0.000_000_000_01e-10f64;
// Lossy whole-number float literals
let _: f32 = 16_777_216.0;
let _: f32 = 16_777_220.0;
let _: f32 = 16_777_220.0;
let _: f32 = 16_777_220.0;
let _ = 16_777_220.0_f32;
let _: f32 = -16_777_220.0;
let _: f64 = 9_007_199_254_740_992.0;
let _: f64 = 9_007_199_254_740_992.0;
let _: f64 = 9_007_199_254_740_992.0;
let _ = 9_007_199_254_740_992.0_f64;
let _: f64 = -9_007_199_254_740_992.0;
// Lossless whole number float literals
let _: f32 = 16_777_216.0;
let _: f32 = 16_777_218.0;
let _: f32 = 16_777_220.0;
let _: f32 = -16_777_216.0;
let _: f32 = -16_777_220.0;
let _: f64 = 9_007_199_254_740_992.0;
let _: f64 = -9_007_199_254_740_992.0;
}

22
tests/ui/excessive_precision.rs
View file

@ -60,26 +60,4 @@ fn main() {
// issue #2840
let num = 0.000_000_000_01e-10f64;
// Lossy whole-number float literals
let _: f32 = 16_777_217.0;
let _: f32 = 16_777_219.0;
let _: f32 = 16_777_219.;
let _: f32 = 16_777_219.000;
let _ = 16_777_219f32;
let _: f32 = -16_777_219.0;
let _: f64 = 9_007_199_254_740_993.0;
let _: f64 = 9_007_199_254_740_993.;
let _: f64 = 9_007_199_254_740_993.000;
let _ = 9_007_199_254_740_993f64;
let _: f64 = -9_007_199_254_740_993.0;
// Lossless whole number float literals
let _: f32 = 16_777_216.0;
let _: f32 = 16_777_218.0;
let _: f32 = 16_777_220.0;
let _: f32 = -16_777_216.0;
let _: f32 = -16_777_220.0;
let _: f64 = 9_007_199_254_740_992.0;
let _: f64 = -9_007_199_254_740_992.0;
}

68
tests/ui/excessive_precision.stderr
View file

@ -108,71 +108,5 @@ error: float has excessive precision
LL | let bad_bige32: f32 = 1.123_456_788_888E-10;
| ^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `1.123_456_8E-10`
error: literal cannot be represented as the underlying type without loss of precision
--> $DIR/excessive_precision.rs:65:18
|
LL | let _: f32 = 16_777_217.0;
| ^^^^^^^^^^^^ help: consider changing the type or replacing it with: `16_777_216.0`
error: literal cannot be represented as the underlying type without loss of precision
--> $DIR/excessive_precision.rs:66:18
|
LL | let _: f32 = 16_777_219.0;
| ^^^^^^^^^^^^ help: consider changing the type or replacing it with: `16_777_220.0`
error: literal cannot be represented as the underlying type without loss of precision
--> $DIR/excessive_precision.rs:67:18
|
LL | let _: f32 = 16_777_219.;
| ^^^^^^^^^^^ help: consider changing the type or replacing it with: `16_777_220.0`
error: literal cannot be represented as the underlying type without loss of precision
--> $DIR/excessive_precision.rs:68:18
|
LL | let _: f32 = 16_777_219.000;
| ^^^^^^^^^^^^^^ help: consider changing the type or replacing it with: `16_777_220.0`
error: literal cannot be represented as the underlying type without loss of precision
--> $DIR/excessive_precision.rs:69:13
|
LL | let _ = 16_777_219f32;
| ^^^^^^^^^^^^^ help: consider changing the type or replacing it with: `16_777_220.0_f32`
error: literal cannot be represented as the underlying type without loss of precision
--> $DIR/excessive_precision.rs:70:19
|
LL | let _: f32 = -16_777_219.0;
| ^^^^^^^^^^^^ help: consider changing the type or replacing it with: `16_777_220.0`
error: literal cannot be represented as the underlying type without loss of precision
--> $DIR/excessive_precision.rs:71:18
|
LL | let _: f64 = 9_007_199_254_740_993.0;
| ^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or replacing it with: `9_007_199_254_740_992.0`
error: literal cannot be represented as the underlying type without loss of precision
--> $DIR/excessive_precision.rs:72:18
|
LL | let _: f64 = 9_007_199_254_740_993.;
| ^^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or replacing it with: `9_007_199_254_740_992.0`
error: literal cannot be represented as the underlying type without loss of precision
--> $DIR/excessive_precision.rs:73:18
|
LL | let _: f64 = 9_007_199_254_740_993.000;
| ^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or replacing it with: `9_007_199_254_740_992.0`
error: literal cannot be represented as the underlying type without loss of precision
--> $DIR/excessive_precision.rs:74:13
|
LL | let _ = 9_007_199_254_740_993f64;
| ^^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or replacing it with: `9_007_199_254_740_992.0_f64`
error: literal cannot be represented as the underlying type without loss of precision
--> $DIR/excessive_precision.rs:75:19
|
LL | let _: f64 = -9_007_199_254_740_993.0;
| ^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or replacing it with: `9_007_199_254_740_992.0`
error: aborting due to 29 previous errors
error: aborting due to 18 previous errors

35
tests/ui/lossy_float_literal.fixed Normal file
View file

@ -0,0 +1,35 @@
// run-rustfix
#![warn(clippy::lossy_float_literal)]
fn main() {
// Lossy whole-number float literals
let _: f32 = 16_777_216.0;
let _: f32 = 16_777_220.0;
let _: f32 = 16_777_220.0;
let _: f32 = 16_777_220.0;
let _ = 16_777_220_f32;
let _: f32 = -16_777_220.0;
let _: f64 = 9_007_199_254_740_992.0;
let _: f64 = 9_007_199_254_740_992.0;
let _: f64 = 9_007_199_254_740_992.0;
let _ = 9_007_199_254_740_992_f64;
let _: f64 = -9_007_199_254_740_992.0;
// Lossless whole number float literals
let _: f32 = 16_777_216.0;
let _: f32 = 16_777_218.0;
let _: f32 = 16_777_220.0;
let _: f32 = -16_777_216.0;
let _: f32 = -16_777_220.0;
let _: f64 = 16_777_217.0;
let _: f64 = -16_777_217.0;
let _: f64 = 9_007_199_254_740_992.0;
let _: f64 = -9_007_199_254_740_992.0;
// Ignored whole number float literals
let _: f32 = 1e25;
let _: f32 = 1E25;
let _: f64 = 1e99;
let _: f64 = 1E99;
let _: f32 = 0.1;
}

35
tests/ui/lossy_float_literal.rs Normal file
View file

@ -0,0 +1,35 @@
// run-rustfix
#![warn(clippy::lossy_float_literal)]
fn main() {
// Lossy whole-number float literals
let _: f32 = 16_777_217.0;
let _: f32 = 16_777_219.0;
let _: f32 = 16_777_219.;
let _: f32 = 16_777_219.000;
let _ = 16_777_219f32;
let _: f32 = -16_777_219.0;
let _: f64 = 9_007_199_254_740_993.0;
let _: f64 = 9_007_199_254_740_993.;
let _: f64 = 9_007_199_254_740_993.00;
let _ = 9_007_199_254_740_993f64;
let _: f64 = -9_007_199_254_740_993.0;
// Lossless whole number float literals
let _: f32 = 16_777_216.0;
let _: f32 = 16_777_218.0;
let _: f32 = 16_777_220.0;
let _: f32 = -16_777_216.0;
let _: f32 = -16_777_220.0;
let _: f64 = 16_777_217.0;
let _: f64 = -16_777_217.0;
let _: f64 = 9_007_199_254_740_992.0;
let _: f64 = -9_007_199_254_740_992.0;
// Ignored whole number float literals
let _: f32 = 1e25;
let _: f32 = 1E25;
let _: f64 = 1e99;
let _: f64 = 1E99;
let _: f32 = 0.1;
}

70
tests/ui/lossy_float_literal.stderr Normal file
View file

@ -0,0 +1,70 @@
error: literal cannot be represented as the underlying type without loss of precision
--> $DIR/lossy_float_literal.rs:6:18
|
LL | let _: f32 = 16_777_217.0;
| ^^^^^^^^^^^^ help: consider changing the type or replacing it with: `16_777_216.0`
|
= note: `-D clippy::lossy-float-literal` implied by `-D warnings`
error: literal cannot be represented as the underlying type without loss of precision
--> $DIR/lossy_float_literal.rs:7:18
|
LL | let _: f32 = 16_777_219.0;
| ^^^^^^^^^^^^ help: consider changing the type or replacing it with: `16_777_220.0`
error: literal cannot be represented as the underlying type without loss of precision
--> $DIR/lossy_float_literal.rs:8:18
|
LL | let _: f32 = 16_777_219.;
| ^^^^^^^^^^^ help: consider changing the type or replacing it with: `16_777_220.0`
error: literal cannot be represented as the underlying type without loss of precision
--> $DIR/lossy_float_literal.rs:9:18
|
LL | let _: f32 = 16_777_219.000;
| ^^^^^^^^^^^^^^ help: consider changing the type or replacing it with: `16_777_220.0`
error: literal cannot be represented as the underlying type without loss of precision
--> $DIR/lossy_float_literal.rs:10:13
|
LL | let _ = 16_777_219f32;
| ^^^^^^^^^^^^^ help: consider changing the type or replacing it with: `16_777_220_f32`
error: literal cannot be represented as the underlying type without loss of precision
--> $DIR/lossy_float_literal.rs:11:19
|
LL | let _: f32 = -16_777_219.0;
| ^^^^^^^^^^^^ help: consider changing the type or replacing it with: `16_777_220.0`
error: literal cannot be represented as the underlying type without loss of precision
--> $DIR/lossy_float_literal.rs:12:18
|
LL | let _: f64 = 9_007_199_254_740_993.0;
| ^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or replacing it with: `9_007_199_254_740_992.0`
error: literal cannot be represented as the underlying type without loss of precision
--> $DIR/lossy_float_literal.rs:13:18
|
LL | let _: f64 = 9_007_199_254_740_993.;
| ^^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or replacing it with: `9_007_199_254_740_992.0`
error: literal cannot be represented as the underlying type without loss of precision
--> $DIR/lossy_float_literal.rs:14:18
|
LL | let _: f64 = 9_007_199_254_740_993.00;
| ^^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or replacing it with: `9_007_199_254_740_992.0`
error: literal cannot be represented as the underlying type without loss of precision
--> $DIR/lossy_float_literal.rs:15:13
|
LL | let _ = 9_007_199_254_740_993f64;
| ^^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or replacing it with: `9_007_199_254_740_992_f64`
error: literal cannot be represented as the underlying type without loss of precision
--> $DIR/lossy_float_literal.rs:16:19
|
LL | let _: f64 = -9_007_199_254_740_993.0;
| ^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or replacing it with: `9_007_199_254_740_992.0`
error: aborting due to 11 previous errors