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Auto merge of rust-lang#9980 - Jarcho:issue_9960, r=xFrednet
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Don't lint `unnecessary_cast` in mixed macro context

fixes rust-lang#9960

Time to start making a dent in this onslaught.

changelog: `unnecessary_cast`: Don't lint when the identifiers context differs from its binding's context for locals
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@bors
bors committed Nov 29, 2022
2 parents 1207480 + f44b7aa commit e9a8b8c
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Showing 4 changed files with 54 additions and 23 deletions.
11 changes: 10 additions & 1 deletion clippy_lints/src/casts/unnecessary_cast.rs
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::get_parent_expr;
use clippy_utils::numeric_literal::NumericLiteral;
use clippy_utils::source::snippet_opt;
use clippy_utils::{get_parent_expr, path_to_local};
use if_chain::if_chain;
use rustc_ast::{LitFloatType, LitIntType, LitKind};
use rustc_errors::Applicability;
Expand Down Expand Up @@ -75,6 +75,15 @@ pub(super) fn check<'tcx>(
}

if cast_from.kind() == cast_to.kind() && !in_external_macro(cx.sess(), expr.span) {
if let Some(id) = path_to_local(cast_expr)
&& let Some(span) = cx.tcx.hir().opt_span(id)
&& span.ctxt() != cast_expr.span.ctxt()
{
// Binding context is different than the identifiers context.
// Weird macro wizardry could be involved here.
return false;
}

span_lint_and_sugg(
cx,
UNNECESSARY_CAST,
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11 changes: 11 additions & 0 deletions tests/ui/unnecessary_cast.fixed
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Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,17 @@ fn main() {
// do not lint cast to alias type
1 as I32Alias;
&1 as &I32Alias;

// issue #9960
macro_rules! bind_var {
($id:ident, $e:expr) => {{
let $id = 0usize;
let _ = $e != 0usize;
let $id = 0isize;
let _ = $e != 0usize;
}}
}
bind_var!(x, (x as usize) + 1);
}

type I32Alias = i32;
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11 changes: 11 additions & 0 deletions tests/ui/unnecessary_cast.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,17 @@ fn main() {
// do not lint cast to alias type
1 as I32Alias;
&1 as &I32Alias;

// issue #9960
macro_rules! bind_var {
($id:ident, $e:expr) => {{
let $id = 0usize;
let _ = $e != 0usize;
let $id = 0isize;
let _ = $e != 0usize;
}}
}
bind_var!(x, (x as usize) + 1);
}

type I32Alias = i32;
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44 changes: 22 additions & 22 deletions tests/ui/unnecessary_cast.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -49,133 +49,133 @@ LL | 1_f32 as f32;
| ^^^^^^^^^^^^ help: try: `1_f32`

error: casting integer literal to `f32` is unnecessary
--> $DIR/unnecessary_cast.rs:53:9
--> $DIR/unnecessary_cast.rs:64:9
|
LL | 100 as f32;
| ^^^^^^^^^^ help: try: `100_f32`

error: casting integer literal to `f64` is unnecessary
--> $DIR/unnecessary_cast.rs:54:9
--> $DIR/unnecessary_cast.rs:65:9
|
LL | 100 as f64;
| ^^^^^^^^^^ help: try: `100_f64`

error: casting integer literal to `f64` is unnecessary
--> $DIR/unnecessary_cast.rs:55:9
--> $DIR/unnecessary_cast.rs:66:9
|
LL | 100_i32 as f64;
| ^^^^^^^^^^^^^^ help: try: `100_f64`

error: casting integer literal to `f32` is unnecessary
--> $DIR/unnecessary_cast.rs:56:17
--> $DIR/unnecessary_cast.rs:67:17
|
LL | let _ = -100 as f32;
| ^^^^^^^^^^^ help: try: `-100_f32`

error: casting integer literal to `f64` is unnecessary
--> $DIR/unnecessary_cast.rs:57:17
--> $DIR/unnecessary_cast.rs:68:17
|
LL | let _ = -100 as f64;
| ^^^^^^^^^^^ help: try: `-100_f64`

error: casting integer literal to `f64` is unnecessary
--> $DIR/unnecessary_cast.rs:58:17
--> $DIR/unnecessary_cast.rs:69:17
|
LL | let _ = -100_i32 as f64;
| ^^^^^^^^^^^^^^^ help: try: `-100_f64`

error: casting float literal to `f32` is unnecessary
--> $DIR/unnecessary_cast.rs:59:9
--> $DIR/unnecessary_cast.rs:70:9
|
LL | 100. as f32;
| ^^^^^^^^^^^ help: try: `100_f32`

error: casting float literal to `f64` is unnecessary
--> $DIR/unnecessary_cast.rs:60:9
--> $DIR/unnecessary_cast.rs:71:9
|
LL | 100. as f64;
| ^^^^^^^^^^^ help: try: `100_f64`

error: casting integer literal to `u32` is unnecessary
--> $DIR/unnecessary_cast.rs:72:9
--> $DIR/unnecessary_cast.rs:83:9
|
LL | 1 as u32;
| ^^^^^^^^ help: try: `1_u32`

error: casting integer literal to `i32` is unnecessary
--> $DIR/unnecessary_cast.rs:73:9
--> $DIR/unnecessary_cast.rs:84:9
|
LL | 0x10 as i32;
| ^^^^^^^^^^^ help: try: `0x10_i32`

error: casting integer literal to `usize` is unnecessary
--> $DIR/unnecessary_cast.rs:74:9
--> $DIR/unnecessary_cast.rs:85:9
|
LL | 0b10 as usize;
| ^^^^^^^^^^^^^ help: try: `0b10_usize`

error: casting integer literal to `u16` is unnecessary
--> $DIR/unnecessary_cast.rs:75:9
--> $DIR/unnecessary_cast.rs:86:9
|
LL | 0o73 as u16;
| ^^^^^^^^^^^ help: try: `0o73_u16`

error: casting integer literal to `u32` is unnecessary
--> $DIR/unnecessary_cast.rs:76:9
--> $DIR/unnecessary_cast.rs:87:9
|
LL | 1_000_000_000 as u32;
| ^^^^^^^^^^^^^^^^^^^^ help: try: `1_000_000_000_u32`

error: casting float literal to `f64` is unnecessary
--> $DIR/unnecessary_cast.rs:78:9
--> $DIR/unnecessary_cast.rs:89:9
|
LL | 1.0 as f64;
| ^^^^^^^^^^ help: try: `1.0_f64`

error: casting float literal to `f32` is unnecessary
--> $DIR/unnecessary_cast.rs:79:9
--> $DIR/unnecessary_cast.rs:90:9
|
LL | 0.5 as f32;
| ^^^^^^^^^^ help: try: `0.5_f32`

error: casting integer literal to `i32` is unnecessary
--> $DIR/unnecessary_cast.rs:83:17
--> $DIR/unnecessary_cast.rs:94:17
|
LL | let _ = -1 as i32;
| ^^^^^^^^^ help: try: `-1_i32`

error: casting float literal to `f32` is unnecessary
--> $DIR/unnecessary_cast.rs:84:17
--> $DIR/unnecessary_cast.rs:95:17
|
LL | let _ = -1.0 as f32;
| ^^^^^^^^^^^ help: try: `-1.0_f32`

error: casting integer literal to `i32` is unnecessary
--> $DIR/unnecessary_cast.rs:93:22
--> $DIR/unnecessary_cast.rs:104:22
|
LL | let _: i32 = -(1) as i32;
| ^^^^^^^^^^^ help: try: `-1_i32`

error: casting integer literal to `i64` is unnecessary
--> $DIR/unnecessary_cast.rs:95:22
--> $DIR/unnecessary_cast.rs:106:22
|
LL | let _: i64 = -(1) as i64;
| ^^^^^^^^^^^ help: try: `-1_i64`

error: casting float literal to `f64` is unnecessary
--> $DIR/unnecessary_cast.rs:102:22
--> $DIR/unnecessary_cast.rs:113:22
|
LL | let _: f64 = (-8.0 as f64).exp();
| ^^^^^^^^^^^^^ help: try: `(-8.0_f64)`

error: casting float literal to `f64` is unnecessary
--> $DIR/unnecessary_cast.rs:104:23
--> $DIR/unnecessary_cast.rs:115:23
|
LL | let _: f64 = -(8.0 as f64).exp(); // should suggest `-8.0_f64.exp()` here not to change code behavior
| ^^^^^^^^^^^^ help: try: `8.0_f64`

error: casting to the same type is unnecessary (`f32` -> `f32`)
--> $DIR/unnecessary_cast.rs:112:20
--> $DIR/unnecessary_cast.rs:123:20
|
LL | let _num = foo() as f32;
| ^^^^^^^^^^^^ help: try: `foo()`
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