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Divide FN_TO_NUMERIC lint into two.

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FN_TO_NUMERIC_CAST_WITH_TRUNCATION is correctness check
FN_TO_NUMERIC_CAST is only style check
This commit is contained in:
Victor Korkin 2018-06-01 23:08:11 +07:00
parent ded2576957
commit 24ab207671
3 changed files with 109 additions and 27 deletions
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56
clippy_lints/src/types.rs
View File

@ -679,9 +679,9 @@ fn is_unit_literal(expr: &Expr) -> bool {
"cast to the same type, e.g. `x as i32` where `x: i32`"
}
/// **What it does:** Checks for casts of a function pointer to a numeric type except `usize`.
/// **What it does:** Checks for casts of a function pointer to a numeric type not enough to store address.
///
/// **Why is this bad?** Casting a function pointer to something other than `usize` could truncate the address value.
/// **Why is this bad?** Casting a function pointer to not eligable type could truncate the address value.
///
/// **Known problems:** None.
///
@ -691,8 +691,25 @@ fn is_unit_literal(expr: &Expr) -> bool {
/// let _ = test_fn as i32
/// ```
declare_clippy_lint! {
pub FN_TO_NUMERIC_CAST,
pub FN_TO_NUMERIC_CAST_WITH_TRUNCATION,
correctness,
"cast function pointer to the numeric type with value truncation"
}
/// **What it does:** Checks for casts of a function pointer to a numeric type except `usize`.
///
/// **Why is this bad?** Casting a function pointer to something other than `usize` is not a good style.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// fn test_fn() -> i16;
/// let _ = test_fn as i128
/// ```
declare_clippy_lint! {
pub FN_TO_NUMERIC_CAST,
style,
"cast function pointer to the numeric type"
}
@ -909,7 +926,8 @@ fn get_lints(&self) -> LintArray {
CAST_LOSSLESS,
UNNECESSARY_CAST,
CAST_PTR_ALIGNMENT,
FN_TO_NUMERIC_CAST
FN_TO_NUMERIC_CAST,
FN_TO_NUMERIC_CAST_WITH_TRUNCATION,
)
}
}
@ -998,14 +1016,28 @@ fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
ty::TyFnDef(..) |
ty::TyFnPtr(..) => {
if cast_to.is_numeric() && cast_to.sty != ty::TyUint(UintTy::Usize){
span_lint_and_sugg(
cx,
FN_TO_NUMERIC_CAST,
expr.span,
&format!("casting a `{}` to `{}` may truncate the function address value.", cast_from, cast_to),
"if you need the address of the function, consider",
format!("{} as usize", &snippet(cx, ex.span, "x"))
);
let to_nbits = int_ty_to_nbits(cast_to, cx.tcx);
let pointer_nbits = cx.tcx.data_layout.pointer_size.bits();
if to_nbits < pointer_nbits || (to_nbits == pointer_nbits && cast_to.is_signed()) {
span_lint_and_sugg(
cx,
FN_TO_NUMERIC_CAST_WITH_TRUNCATION,
expr.span,
&format!("casting a `{}` to `{}` may truncate the function address value.", cast_from, cast_to),
"if you need the address of the function, consider",
format!("{} as usize", &snippet(cx, ex.span, "x"))
);
} else {
span_lint_and_sugg(
cx,
FN_TO_NUMERIC_CAST,
expr.span,
&format!("casting a `{}` to `{}` is bad style.", cast_from, cast_to),
"if you need the address of the function, consider",
format!("{} as usize", &snippet(cx, ex.span, "x"))
);
};
}
}
_ => ()

14
tests/ui/types_fn_to_int.rs
View File

@ -9,8 +9,14 @@ fn bar() -> i32 {
fn main() {
let x = Foo::A;
let y = x as i32;
let y1 = Foo::A as i32;
let z = bar as u32;
let _y = x as i32;
let _y1 = Foo::A as i32;
let _y = x as u32;
let _z = bar as u32;
let _y = bar as i64;
let _y = bar as u64;
let _z = Foo::A as i128;
let _z = Foo::A as u128;
let _z = bar as i128;
let _z = bar as u128;
}

66
tests/ui/types_fn_to_int.stderr
View File

@ -1,22 +1,66 @@
error: casting a `fn(usize) -> Foo {Foo::A}` to `i32` may truncate the function address value.
--> $DIR/types_fn_to_int.rs:12:13
--> $DIR/types_fn_to_int.rs:12:14
|
12 | let y = x as i32;
| ^^^^^^^^ help: if you need the address of the function, consider: `x as usize`
12 | let _y = x as i32;
| ^^^^^^^^ help: if you need the address of the function, consider: `x as usize`
|
= note: #[deny(fn_to_numeric_cast)] on by default
= note: #[deny(fn_to_numeric_cast_with_truncation)] on by default
error: casting a `fn(usize) -> Foo {Foo::A}` to `i32` may truncate the function address value.
--> $DIR/types_fn_to_int.rs:13:14
--> $DIR/types_fn_to_int.rs:13:15
|
13 | let y1 = Foo::A as i32;
| ^^^^^^^^^^^^^ help: if you need the address of the function, consider: `Foo::A as usize`
13 | let _y1 = Foo::A as i32;
| ^^^^^^^^^^^^^ help: if you need the address of the function, consider: `Foo::A as usize`
error: casting a `fn(usize) -> Foo {Foo::A}` to `u32` may truncate the function address value.
--> $DIR/types_fn_to_int.rs:14:14
|
14 | let _y = x as u32;
| ^^^^^^^^ help: if you need the address of the function, consider: `x as usize`
error: casting a `fn() -> i32 {bar}` to `u32` may truncate the function address value.
--> $DIR/types_fn_to_int.rs:15:13
--> $DIR/types_fn_to_int.rs:15:14
|
15 | let z = bar as u32;
| ^^^^^^^^^^ help: if you need the address of the function, consider: `bar as usize`
15 | let _z = bar as u32;
| ^^^^^^^^^^ help: if you need the address of the function, consider: `bar as usize`
error: aborting due to 3 previous errors
error: casting a `fn() -> i32 {bar}` to `i64` may truncate the function address value.
--> $DIR/types_fn_to_int.rs:16:14
|
16 | let _y = bar as i64;
| ^^^^^^^^^^ help: if you need the address of the function, consider: `bar as usize`
error: casting a `fn() -> i32 {bar}` to `u64` is bad style.
--> $DIR/types_fn_to_int.rs:17:14
|
17 | let _y = bar as u64;
| ^^^^^^^^^^ help: if you need the address of the function, consider: `bar as usize`
|
= note: `-D fn-to-numeric-cast` implied by `-D warnings`
error: casting a `fn(usize) -> Foo {Foo::A}` to `i128` is bad style.
--> $DIR/types_fn_to_int.rs:18:14
|
18 | let _z = Foo::A as i128;
| ^^^^^^^^^^^^^^ help: if you need the address of the function, consider: `Foo::A as usize`
error: casting a `fn(usize) -> Foo {Foo::A}` to `u128` is bad style.
--> $DIR/types_fn_to_int.rs:19:14
|
19 | let _z = Foo::A as u128;
| ^^^^^^^^^^^^^^ help: if you need the address of the function, consider: `Foo::A as usize`
error: casting a `fn() -> i32 {bar}` to `i128` is bad style.
--> $DIR/types_fn_to_int.rs:20:14
|
20 | let _z = bar as i128;
| ^^^^^^^^^^^ help: if you need the address of the function, consider: `bar as usize`
error: casting a `fn() -> i32 {bar}` to `u128` is bad style.
--> $DIR/types_fn_to_int.rs:21:14
|
21 | let _z = bar as u128;
| ^^^^^^^^^^^ help: if you need the address of the function, consider: `bar as usize`
error: aborting due to 10 previous errors