diff options
| -rw-r--r-- | CHANGELOG.md | 1 | ||||
| -rw-r--r-- | clippy_lints/src/casts/fn_to_numeric_cast_any.rs | 34 | ||||
| -rw-r--r-- | clippy_lints/src/casts/mod.rs | 39 | ||||
| -rw-r--r-- | clippy_lints/src/lib.register_lints.rs | 1 | ||||
| -rw-r--r-- | clippy_lints/src/lib.register_restriction.rs | 1 | ||||
| -rw-r--r-- | tests/ui/fn_to_numeric_cast_any.rs | 76 | ||||
| -rw-r--r-- | tests/ui/fn_to_numeric_cast_any.stderr | 106 |
7 files changed, 258 insertions, 0 deletions
diff --git a/CHANGELOG.md b/CHANGELOG.md index 7fdb300c977..b13a5d76002 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -2730,6 +2730,7 @@ Released 2018-09-13 [`fn_address_comparisons`]: https://rust-lang.github.io/rust-clippy/master/index.html#fn_address_comparisons [`fn_params_excessive_bools`]: https://rust-lang.github.io/rust-clippy/master/index.html#fn_params_excessive_bools [`fn_to_numeric_cast`]: https://rust-lang.github.io/rust-clippy/master/index.html#fn_to_numeric_cast +[`fn_to_numeric_cast_any`]: https://rust-lang.github.io/rust-clippy/master/index.html#fn_to_numeric_cast_any [`fn_to_numeric_cast_with_truncation`]: https://rust-lang.github.io/rust-clippy/master/index.html#fn_to_numeric_cast_with_truncation [`for_kv_map`]: https://rust-lang.github.io/rust-clippy/master/index.html#for_kv_map [`for_loops_over_fallibles`]: https://rust-lang.github.io/rust-clippy/master/index.html#for_loops_over_fallibles diff --git a/clippy_lints/src/casts/fn_to_numeric_cast_any.rs b/clippy_lints/src/casts/fn_to_numeric_cast_any.rs new file mode 100644 index 00000000000..03621887a34 --- /dev/null +++ b/clippy_lints/src/casts/fn_to_numeric_cast_any.rs @@ -0,0 +1,34 @@ +use clippy_utils::diagnostics::span_lint_and_sugg; +use clippy_utils::source::snippet_with_applicability; +use rustc_errors::Applicability; +use rustc_hir::Expr; +use rustc_lint::LateContext; +use rustc_middle::ty::{self, Ty}; + +use super::FN_TO_NUMERIC_CAST_ANY; + +pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_expr: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) { + // We allow casts from any function type to any function type. + match cast_to.kind() { + ty::FnDef(..) | ty::FnPtr(..) => return, + _ => { /* continue to checks */ }, + } + + match cast_from.kind() { + ty::FnDef(..) | ty::FnPtr(_) => { + let mut applicability = Applicability::MaybeIncorrect; + let from_snippet = snippet_with_applicability(cx, cast_expr.span, "..", &mut applicability); + + span_lint_and_sugg( + cx, + FN_TO_NUMERIC_CAST_ANY, + expr.span, + &format!("casting function pointer `{}` to `{}`", from_snippet, cast_to), + "did you mean to invoke the function?", + format!("{}() as {}", from_snippet, cast_to), + applicability, + ); + }, + _ => {}, + } +} diff --git a/clippy_lints/src/casts/mod.rs b/clippy_lints/src/casts/mod.rs index 27e1bea7993..f0800c6a6f1 100644 --- a/clippy_lints/src/casts/mod.rs +++ b/clippy_lints/src/casts/mod.rs @@ -7,6 +7,7 @@ mod cast_ref_to_mut; mod cast_sign_loss; mod char_lit_as_u8; mod fn_to_numeric_cast; +mod fn_to_numeric_cast_any; mod fn_to_numeric_cast_with_truncation; mod ptr_as_ptr; mod unnecessary_cast; @@ -253,6 +254,42 @@ declare_clippy_lint! { declare_clippy_lint! { /// ### What it does + /// Checks for casts of a function pointer to any integer type. + /// + /// ### Why is this bad? + /// Casting a function pointer to an integer can have surprising results and can occur + /// accidentally if parantheses are omitted from a function call. If you aren't doing anything + /// low-level with function pointers then you can opt-out of casting functions to integers in + /// order to avoid mistakes. Alternatively, you can use this lint to audit all uses of function + /// pointer casts in your code. + /// + /// ### Example + /// ```rust + /// // Bad: fn1 is cast as `usize` + /// fn fn1() -> u16 { + /// 1 + /// }; + /// let _ = fn1 as usize; + /// + /// // Good: maybe you intended to call the function? + /// fn fn2() -> u16 { + /// 1 + /// }; + /// let _ = fn2() as usize; + /// + /// // Good: maybe you intended to cast it to a function type? + /// fn fn3() -> u16 { + /// 1 + /// } + /// let _ = fn3 as fn() -> u16; + /// ``` + pub FN_TO_NUMERIC_CAST_ANY, + restriction, + "casting a function pointer to any integer type" +} + +declare_clippy_lint! { + /// ### What it does /// Checks for casts of `&T` to `&mut T` anywhere in the code. /// /// ### Why is this bad? @@ -360,6 +397,7 @@ impl_lint_pass!(Casts => [ CAST_REF_TO_MUT, CAST_PTR_ALIGNMENT, UNNECESSARY_CAST, + FN_TO_NUMERIC_CAST_ANY, FN_TO_NUMERIC_CAST, FN_TO_NUMERIC_CAST_WITH_TRUNCATION, CHAR_LIT_AS_U8, @@ -385,6 +423,7 @@ impl<'tcx> LateLintPass<'tcx> for Casts { return; } + fn_to_numeric_cast_any::check(cx, expr, cast_expr, cast_from, cast_to); fn_to_numeric_cast::check(cx, expr, cast_expr, cast_from, cast_to); fn_to_numeric_cast_with_truncation::check(cx, expr, cast_expr, cast_from, cast_to); if cast_from.is_numeric() && cast_to.is_numeric() && !in_external_macro(cx.sess(), expr.span) { diff --git a/clippy_lints/src/lib.register_lints.rs b/clippy_lints/src/lib.register_lints.rs index 2ba2b3da55c..3c6d8103b6d 100644 --- a/clippy_lints/src/lib.register_lints.rs +++ b/clippy_lints/src/lib.register_lints.rs @@ -67,6 +67,7 @@ store.register_lints(&[ casts::CAST_SIGN_LOSS, casts::CHAR_LIT_AS_U8, casts::FN_TO_NUMERIC_CAST, + casts::FN_TO_NUMERIC_CAST_ANY, casts::FN_TO_NUMERIC_CAST_WITH_TRUNCATION, casts::PTR_AS_PTR, casts::UNNECESSARY_CAST, diff --git a/clippy_lints/src/lib.register_restriction.rs b/clippy_lints/src/lib.register_restriction.rs index 4463dea5fcb..503f4f64a0e 100644 --- a/clippy_lints/src/lib.register_restriction.rs +++ b/clippy_lints/src/lib.register_restriction.rs @@ -8,6 +8,7 @@ store.register_group(true, "clippy::restriction", Some("clippy_restriction"), ve LintId::of(as_conversions::AS_CONVERSIONS), LintId::of(asm_syntax::INLINE_ASM_X86_ATT_SYNTAX), LintId::of(asm_syntax::INLINE_ASM_X86_INTEL_SYNTAX), + LintId::of(casts::FN_TO_NUMERIC_CAST_ANY), LintId::of(create_dir::CREATE_DIR), LintId::of(dbg_macro::DBG_MACRO), LintId::of(default_numeric_fallback::DEFAULT_NUMERIC_FALLBACK), diff --git a/tests/ui/fn_to_numeric_cast_any.rs b/tests/ui/fn_to_numeric_cast_any.rs new file mode 100644 index 00000000000..46704683926 --- /dev/null +++ b/tests/ui/fn_to_numeric_cast_any.rs @@ -0,0 +1,76 @@ +#![warn(clippy::fn_to_numeric_cast_any)] +#![allow(clippy::fn_to_numeric_cast, clippy::fn_to_numeric_cast_with_truncation)] + +fn foo() -> u8 { + 0 +} + +fn generic_foo<T>(x: T) -> T { + x +} + +trait Trait { + fn static_method() -> u32 { + 2 + } +} + +struct Struct; + +impl Trait for Struct {} + +fn fn_pointer_to_integer() { + let _ = foo as i8; + let _ = foo as i16; + let _ = foo as i32; + let _ = foo as i64; + let _ = foo as i128; + let _ = foo as isize; + + let _ = foo as u8; + let _ = foo as u16; + let _ = foo as u32; + let _ = foo as u64; + let _ = foo as u128; + let _ = foo as usize; +} + +fn static_method_to_integer() { + let _ = Struct::static_method as usize; +} + +fn fn_with_fn_arg(f: fn(i32) -> u32) -> usize { + f as usize +} + +fn fn_with_generic_static_trait_method<T: Trait>() -> usize { + T::static_method as usize +} + +fn closure_to_fn_to_integer() { + let clos = |x| x * 2_u32; + + let _ = (clos as fn(u32) -> u32) as usize; +} + +fn fn_to_raw_ptr() { + let _ = foo as *const (); +} + +fn cast_fn_to_self() { + // Casting to the same function pointer type should be permitted. + let _ = foo as fn() -> u8; +} + +fn cast_generic_to_concrete() { + // Casting to a more concrete function pointer type should be permitted. + let _ = generic_foo as fn(usize) -> usize; +} + +fn cast_closure_to_fn() { + // Casting a closure to a function pointer should be permitted. + let id = |x| x; + let _ = id as fn(usize) -> usize; +} + +fn main() {} diff --git a/tests/ui/fn_to_numeric_cast_any.stderr b/tests/ui/fn_to_numeric_cast_any.stderr new file mode 100644 index 00000000000..a6c4a77672f --- /dev/null +++ b/tests/ui/fn_to_numeric_cast_any.stderr @@ -0,0 +1,106 @@ +error: casting function pointer `foo` to `i8` + --> $DIR/fn_to_numeric_cast_any.rs:23:13 + | +LL | let _ = foo as i8; + | ^^^^^^^^^ help: did you mean to invoke the function?: `foo() as i8` + | + = note: `-D clippy::fn-to-numeric-cast-any` implied by `-D warnings` + +error: casting function pointer `foo` to `i16` + --> $DIR/fn_to_numeric_cast_any.rs:24:13 + | +LL | let _ = foo as i16; + | ^^^^^^^^^^ help: did you mean to invoke the function?: `foo() as i16` + +error: casting function pointer `foo` to `i32` + --> $DIR/fn_to_numeric_cast_any.rs:25:13 + | +LL | let _ = foo as i32; + | ^^^^^^^^^^ help: did you mean to invoke the function?: `foo() as i32` + +error: casting function pointer `foo` to `i64` + --> $DIR/fn_to_numeric_cast_any.rs:26:13 + | +LL | let _ = foo as i64; + | ^^^^^^^^^^ help: did you mean to invoke the function?: `foo() as i64` + +error: casting function pointer `foo` to `i128` + --> $DIR/fn_to_numeric_cast_any.rs:27:13 + | +LL | let _ = foo as i128; + | ^^^^^^^^^^^ help: did you mean to invoke the function?: `foo() as i128` + +error: casting function pointer `foo` to `isize` + --> $DIR/fn_to_numeric_cast_any.rs:28:13 + | +LL | let _ = foo as isize; + | ^^^^^^^^^^^^ help: did you mean to invoke the function?: `foo() as isize` + +error: casting function pointer `foo` to `u8` + --> $DIR/fn_to_numeric_cast_any.rs:30:13 + | +LL | let _ = foo as u8; + | ^^^^^^^^^ help: did you mean to invoke the function?: `foo() as u8` + +error: casting function pointer `foo` to `u16` + --> $DIR/fn_to_numeric_cast_any.rs:31:13 + | +LL | let _ = foo as u16; + | ^^^^^^^^^^ help: did you mean to invoke the function?: `foo() as u16` + +error: casting function pointer `foo` to `u32` + --> $DIR/fn_to_numeric_cast_any.rs:32:13 + | +LL | let _ = foo as u32; + | ^^^^^^^^^^ help: did you mean to invoke the function?: `foo() as u32` + +error: casting function pointer `foo` to `u64` + --> $DIR/fn_to_numeric_cast_any.rs:33:13 + | +LL | let _ = foo as u64; + | ^^^^^^^^^^ help: did you mean to invoke the function?: `foo() as u64` + +error: casting function pointer `foo` to `u128` + --> $DIR/fn_to_numeric_cast_any.rs:34:13 + | +LL | let _ = foo as u128; + | ^^^^^^^^^^^ help: did you mean to invoke the function?: `foo() as u128` + +error: casting function pointer `foo` to `usize` + --> $DIR/fn_to_numeric_cast_any.rs:35:13 + | +LL | let _ = foo as usize; + | ^^^^^^^^^^^^ help: did you mean to invoke the function?: `foo() as usize` + +error: casting function pointer `Struct::static_method` to `usize` + --> $DIR/fn_to_numeric_cast_any.rs:39:13 + | +LL | let _ = Struct::static_method as usize; + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: did you mean to invoke the function?: `Struct::static_method() as usize` + +error: casting function pointer `f` to `usize` + --> $DIR/fn_to_numeric_cast_any.rs:43:5 + | +LL | f as usize + | ^^^^^^^^^^ help: did you mean to invoke the function?: `f() as usize` + +error: casting function pointer `T::static_method` to `usize` + --> $DIR/fn_to_numeric_cast_any.rs:47:5 + | +LL | T::static_method as usize + | ^^^^^^^^^^^^^^^^^^^^^^^^^ help: did you mean to invoke the function?: `T::static_method() as usize` + +error: casting function pointer `(clos as fn(u32) -> u32)` to `usize` + --> $DIR/fn_to_numeric_cast_any.rs:53:13 + | +LL | let _ = (clos as fn(u32) -> u32) as usize; + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: did you mean to invoke the function?: `(clos as fn(u32) -> u32)() as usize` + +error: casting function pointer `foo` to `*const ()` + --> $DIR/fn_to_numeric_cast_any.rs:57:13 + | +LL | let _ = foo as *const (); + | ^^^^^^^^^^^^^^^^ help: did you mean to invoke the function?: `foo() as *const ()` + +error: aborting due to 17 previous errors + |