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lint on unnecessary and plain wrong transmutes

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This commit is contained in:
Oliver Schneider 2016-06-28 14:08:08 +02:00
parent 5aea20da7f
commit e06bc37477
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GPG key ID: 56D6EEA0FC67AC46
7 changed files with 102 additions and 19 deletions
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1
clippy_lints/src/lib.rs
View file

@ -403,6 +403,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry) {
transmute::CROSSPOINTER_TRANSMUTE,
transmute::TRANSMUTE_PTR_TO_REF,
transmute::USELESS_TRANSMUTE,
transmute::WRONG_TRANSMUTE,
types::ABSURD_EXTREME_COMPARISONS,
types::BOX_VEC,
types::CHAR_LIT_AS_U8,

43
clippy_lints/src/transmute.rs
View file

@ -1,11 +1,25 @@
use rustc::lint::*;
use rustc::ty::TypeVariants::{TyRawPtr, TyRef};
use rustc::ty;
use rustc::hir::*;
use utils::{match_def_path, paths, snippet_opt, span_lint, span_lint_and_then};
/// **What it does:** This lint checks for transmutes to the original type of the object.
/// **What it does:** This lint checks for transmutes that can't ever be correct on any architecture
///
/// **Why is this bad?** Readability. The code tricks people into thinking that the original value was of some other type.
/// **Why is this bad?** It's basically guaranteed to be undefined behaviour
///
/// **Known problems:** When accessing C, users might want to store pointer sized objects in `extradata` arguments to save an allocation.
///
/// **Example:** `let ptr: *const T = core::intrinsics::transmute('x')`.
declare_lint! {
pub WRONG_TRANSMUTE,
Warn,
"transmutes that are confusing at best, undefined behaviour at worst and always useless"
}
/// **What it does:** This lint checks for transmutes to the original type of the object and transmutes that could be a cast.
///
/// **Why is this bad?** Readability. The code tricks people into thinking that something complex is going on
///
/// **Known problems:** None.
///
@ -13,7 +27,7 @@ use utils::{match_def_path, paths, snippet_opt, span_lint, span_lint_and_then};
declare_lint! {
pub USELESS_TRANSMUTE,
Warn,
"transmutes that have the same to and from types"
"transmutes that have the same to and from types or could be a cast/coercion"
}
/// **What it does:*** This lint checks for transmutes between a type `T` and `*T`.
@ -51,7 +65,7 @@ pub struct Transmute;
impl LintPass for Transmute {
fn get_lints(&self) -> LintArray {
lint_array![CROSSPOINTER_TRANSMUTE, TRANSMUTE_PTR_TO_REF, USELESS_TRANSMUTE]
lint_array![CROSSPOINTER_TRANSMUTE, TRANSMUTE_PTR_TO_REF, USELESS_TRANSMUTE, WRONG_TRANSMUTE]
}
}
@ -89,6 +103,27 @@ impl LateLintPass for Transmute {
}
},
),
(&ty::TyInt(_), &TyRawPtr(_)) |
(&ty::TyUint(_), &TyRawPtr(_)) => span_lint_and_then(
cx,
USELESS_TRANSMUTE,
e.span,
"transmute from an integer to a pointer",
|db| {
if let Some(arg) = snippet_opt(cx, args[0].span) {
db.span_suggestion(e.span, "try", format!("{} as {}", arg, to_ty));
}
},
),
(&ty::TyFloat(_), &TyRef(..)) |
(&ty::TyFloat(_), &TyRawPtr(_)) |
(&ty::TyChar, &TyRef(..)) |
(&ty::TyChar, &TyRawPtr(_)) => span_lint(
cx,
WRONG_TRANSMUTE,
e.span,
&format!("transmute from a `{}` to a pointer", from_ty),
),
(&TyRawPtr(from_ptr), _) if from_ptr.ty == to_ty => span_lint(
cx,
CROSSPOINTER_TRANSMUTE,