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Auto merge of #5919 - ebroto:5747_from_bits_in_const, r=matthiaskrgr
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transmute: avoid suggesting from/to bits in const

changelog: Avoid suggesting from/to bits in const contexts in [`transmute_int_to_float`]

Fixes #5747
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@bors
bors committed Aug 20, 2020
2 parents 6220dff + 6a12bae commit d891954
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Showing 5 changed files with 88 additions and 40 deletions.
10 changes: 7 additions & 3 deletions clippy_lints/src/transmute.rs
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
use crate::utils::{
is_normalizable, last_path_segment, match_def_path, paths, snippet, span_lint, span_lint_and_sugg,
in_constant, is_normalizable, last_path_segment, match_def_path, paths, snippet, span_lint, span_lint_and_sugg,
span_lint_and_then, sugg,
};
use if_chain::if_chain;
Expand Down Expand Up @@ -331,6 +331,10 @@ impl<'tcx> LateLintPass<'tcx> for Transmute {
if let Some(def_id) = cx.qpath_res(qpath, path_expr.hir_id).opt_def_id();
if match_def_path(cx, def_id, &paths::TRANSMUTE);
then {
// Avoid suggesting from/to bits in const contexts.
// See https://github.com/rust-lang/rust/issues/73736 for progress on making them `const fn`.
let const_context = in_constant(cx, e.hir_id);

let from_ty = cx.typeck_results().expr_ty(&args[0]);
let to_ty = cx.typeck_results().expr_ty(e);

Expand Down Expand Up @@ -544,7 +548,7 @@ impl<'tcx> LateLintPass<'tcx> for Transmute {
},
)
},
(ty::Int(_) | ty::Uint(_), ty::Float(_)) => span_lint_and_then(
(ty::Int(_) | ty::Uint(_), ty::Float(_)) if !const_context => span_lint_and_then(
cx,
TRANSMUTE_INT_TO_FLOAT,
e.span,
Expand All @@ -567,7 +571,7 @@ impl<'tcx> LateLintPass<'tcx> for Transmute {
);
},
),
(ty::Float(float_ty), ty::Int(_) | ty::Uint(_)) => span_lint_and_then(
(ty::Float(float_ty), ty::Int(_) | ty::Uint(_)) if !const_context => span_lint_and_then(
cx,
TRANSMUTE_FLOAT_TO_INT,
e.span,
Expand Down
24 changes: 21 additions & 3 deletions tests/ui/transmute.rs
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Original file line number Diff line number Diff line change
@@ -1,3 +1,4 @@
#![feature(const_fn_transmute)]
#![allow(dead_code)]

extern crate core;
Expand Down Expand Up @@ -81,9 +82,26 @@ fn int_to_bool() {
}

#[warn(clippy::transmute_int_to_float)]
fn int_to_float() {
let _: f32 = unsafe { std::mem::transmute(0_u32) };
let _: f32 = unsafe { std::mem::transmute(0_i32) };
mod int_to_float {
fn test() {
let _: f32 = unsafe { std::mem::transmute(0_u32) };
let _: f32 = unsafe { std::mem::transmute(0_i32) };
let _: f64 = unsafe { std::mem::transmute(0_u64) };
let _: f64 = unsafe { std::mem::transmute(0_i64) };
}

mod issue_5747 {
const VALUE32: f32 = unsafe { std::mem::transmute(0_u32) };
const VALUE64: f64 = unsafe { std::mem::transmute(0_i64) };

const fn from_bits_32(v: i32) -> f32 {
unsafe { std::mem::transmute(v) }
}

const fn from_bits_64(v: u64) -> f64 {
unsafe { std::mem::transmute(v) }
}
}
}

fn bytes_to_str(b: &[u8], mb: &mut [u8]) {
Expand Down
66 changes: 39 additions & 27 deletions tests/ui/transmute.stderr
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Original file line number Diff line number Diff line change
@@ -1,146 +1,158 @@
error: transmute from a type (`&T`) to itself
--> $DIR/transmute.rs:19:20
--> $DIR/transmute.rs:20:20
|
LL | let _: &'a T = core::intrinsics::transmute(t);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: `-D clippy::useless-transmute` implied by `-D warnings`

error: transmute from a reference to a pointer
--> $DIR/transmute.rs:23:23
--> $DIR/transmute.rs:24:23
|
LL | let _: *const T = core::intrinsics::transmute(t);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `t as *const T`

error: transmute from a reference to a pointer
--> $DIR/transmute.rs:25:21
--> $DIR/transmute.rs:26:21
|
LL | let _: *mut T = core::intrinsics::transmute(t);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `t as *const T as *mut T`

error: transmute from a reference to a pointer
--> $DIR/transmute.rs:27:23
--> $DIR/transmute.rs:28:23
|
LL | let _: *const U = core::intrinsics::transmute(t);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `t as *const T as *const U`

error: transmute from a type (`std::vec::Vec<i32>`) to itself
--> $DIR/transmute.rs:33:27
--> $DIR/transmute.rs:34:27
|
LL | let _: Vec<i32> = core::intrinsics::transmute(my_vec());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: transmute from a type (`std::vec::Vec<i32>`) to itself
--> $DIR/transmute.rs:35:27
--> $DIR/transmute.rs:36:27
|
LL | let _: Vec<i32> = core::mem::transmute(my_vec());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: transmute from a type (`std::vec::Vec<i32>`) to itself
--> $DIR/transmute.rs:37:27
--> $DIR/transmute.rs:38:27
|
LL | let _: Vec<i32> = std::intrinsics::transmute(my_vec());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: transmute from a type (`std::vec::Vec<i32>`) to itself
--> $DIR/transmute.rs:39:27
--> $DIR/transmute.rs:40:27
|
LL | let _: Vec<i32> = std::mem::transmute(my_vec());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: transmute from a type (`std::vec::Vec<i32>`) to itself
--> $DIR/transmute.rs:41:27
--> $DIR/transmute.rs:42:27
|
LL | let _: Vec<i32> = my_transmute(my_vec());
| ^^^^^^^^^^^^^^^^^^^^^^

error: transmute from an integer to a pointer
--> $DIR/transmute.rs:43:31
--> $DIR/transmute.rs:44:31
|
LL | let _: *const usize = std::mem::transmute(5_isize);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `5_isize as *const usize`

error: transmute from an integer to a pointer
--> $DIR/transmute.rs:47:31
--> $DIR/transmute.rs:48:31
|
LL | let _: *const usize = std::mem::transmute(1 + 1usize);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `(1 + 1usize) as *const usize`

error: transmute from a type (`*const Usize`) to the type that it points to (`Usize`)
--> $DIR/transmute.rs:62:24
--> $DIR/transmute.rs:63:24
|
LL | let _: Usize = core::intrinsics::transmute(int_const_ptr);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: `-D clippy::crosspointer-transmute` implied by `-D warnings`

error: transmute from a type (`*mut Usize`) to the type that it points to (`Usize`)
--> $DIR/transmute.rs:64:24
--> $DIR/transmute.rs:65:24
|
LL | let _: Usize = core::intrinsics::transmute(int_mut_ptr);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: transmute from a type (`Usize`) to a pointer to that type (`*const Usize`)
--> $DIR/transmute.rs:66:31
--> $DIR/transmute.rs:67:31
|
LL | let _: *const Usize = core::intrinsics::transmute(my_int());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: transmute from a type (`Usize`) to a pointer to that type (`*mut Usize`)
--> $DIR/transmute.rs:68:29
--> $DIR/transmute.rs:69:29
|
LL | let _: *mut Usize = core::intrinsics::transmute(my_int());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: transmute from a `u32` to a `char`
--> $DIR/transmute.rs:74:28
--> $DIR/transmute.rs:75:28
|
LL | let _: char = unsafe { std::mem::transmute(0_u32) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::char::from_u32(0_u32).unwrap()`
|
= note: `-D clippy::transmute-int-to-char` implied by `-D warnings`

error: transmute from a `i32` to a `char`
--> $DIR/transmute.rs:75:28
--> $DIR/transmute.rs:76:28
|
LL | let _: char = unsafe { std::mem::transmute(0_i32) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::char::from_u32(0_i32 as u32).unwrap()`

error: transmute from a `u8` to a `bool`
--> $DIR/transmute.rs:80:28
--> $DIR/transmute.rs:81:28
|
LL | let _: bool = unsafe { std::mem::transmute(0_u8) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `0_u8 != 0`
|
= note: `-D clippy::transmute-int-to-bool` implied by `-D warnings`

error: transmute from a `u32` to a `f32`
--> $DIR/transmute.rs:85:27
--> $DIR/transmute.rs:87:31
|
LL | let _: f32 = unsafe { std::mem::transmute(0_u32) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `f32::from_bits(0_u32)`
LL | let _: f32 = unsafe { std::mem::transmute(0_u32) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `f32::from_bits(0_u32)`
|
= note: `-D clippy::transmute-int-to-float` implied by `-D warnings`

error: transmute from a `i32` to a `f32`
--> $DIR/transmute.rs:86:27
--> $DIR/transmute.rs:88:31
|
LL | let _: f32 = unsafe { std::mem::transmute(0_i32) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `f32::from_bits(0_i32 as u32)`

error: transmute from a `u64` to a `f64`
--> $DIR/transmute.rs:89:31
|
LL | let _: f64 = unsafe { std::mem::transmute(0_u64) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `f64::from_bits(0_u64)`

error: transmute from a `i64` to a `f64`
--> $DIR/transmute.rs:90:31
|
LL | let _: f32 = unsafe { std::mem::transmute(0_i32) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `f32::from_bits(0_i32 as u32)`
LL | let _: f64 = unsafe { std::mem::transmute(0_i64) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `f64::from_bits(0_i64 as u64)`

error: transmute from a `&[u8]` to a `&str`
--> $DIR/transmute.rs:90:28
--> $DIR/transmute.rs:108:28
|
LL | let _: &str = unsafe { std::mem::transmute(b) };
| ^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::str::from_utf8(b).unwrap()`
|
= note: `-D clippy::transmute-bytes-to-str` implied by `-D warnings`

error: transmute from a `&mut [u8]` to a `&mut str`
--> $DIR/transmute.rs:91:32
--> $DIR/transmute.rs:109:32
|
LL | let _: &mut str = unsafe { std::mem::transmute(mb) };
| ^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::str::from_utf8_mut(mb).unwrap()`

error: aborting due to 22 previous errors
error: aborting due to 24 previous errors

16 changes: 15 additions & 1 deletion tests/ui/transmute_float_to_int.rs
View file
Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
#[warn(clippy::transmute_float_to_int)]
#![feature(const_fn_transmute)]
#![warn(clippy::transmute_float_to_int)]

fn float_to_int() {
let _: u32 = unsafe { std::mem::transmute(1f32) };
Expand All @@ -9,4 +10,17 @@ fn float_to_int() {
let _: u64 = unsafe { std::mem::transmute(-1.0) };
}

mod issue_5747 {
const VALUE32: i32 = unsafe { std::mem::transmute(1f32) };
const VALUE64: u64 = unsafe { std::mem::transmute(1f64) };

const fn to_bits_32(v: f32) -> u32 {
unsafe { std::mem::transmute(v) }
}

const fn to_bits_64(v: f64) -> i64 {
unsafe { std::mem::transmute(v) }
}
}

fn main() {}
12 changes: 6 additions & 6 deletions tests/ui/transmute_float_to_int.stderr
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Original file line number Diff line number Diff line change
@@ -1,37 +1,37 @@
error: transmute from a `f32` to a `u32`
--> $DIR/transmute_float_to_int.rs:4:27
--> $DIR/transmute_float_to_int.rs:5:27
|
LL | let _: u32 = unsafe { std::mem::transmute(1f32) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `1f32.to_bits()`
|
= note: `-D clippy::transmute-float-to-int` implied by `-D warnings`

error: transmute from a `f32` to a `i32`
--> $DIR/transmute_float_to_int.rs:5:27
--> $DIR/transmute_float_to_int.rs:6:27
|
LL | let _: i32 = unsafe { std::mem::transmute(1f32) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `1f32.to_bits() as i32`

error: transmute from a `f64` to a `u64`
--> $DIR/transmute_float_to_int.rs:6:27
--> $DIR/transmute_float_to_int.rs:7:27
|
LL | let _: u64 = unsafe { std::mem::transmute(1f64) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `1f64.to_bits()`

error: transmute from a `f64` to a `i64`
--> $DIR/transmute_float_to_int.rs:7:27
--> $DIR/transmute_float_to_int.rs:8:27
|
LL | let _: i64 = unsafe { std::mem::transmute(1f64) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `1f64.to_bits() as i64`

error: transmute from a `f64` to a `u64`
--> $DIR/transmute_float_to_int.rs:8:27
--> $DIR/transmute_float_to_int.rs:9:27
|
LL | let _: u64 = unsafe { std::mem::transmute(1.0) };
| ^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `1.0f64.to_bits()`

error: transmute from a `f64` to a `u64`
--> $DIR/transmute_float_to_int.rs:9:27
--> $DIR/transmute_float_to_int.rs:10:27
|
LL | let _: u64 = unsafe { std::mem::transmute(-1.0) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `(-1.0f64).to_bits()`
Expand Down

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