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Lint transmute from ptr to ref

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This commit is contained in:
mcarton 2016-03-25 23:22:17 +01:00
parent ae24929cd6
commit 2d5e3f3118
4 changed files with 114 additions and 40 deletions
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3
README.md
View file

@ -14,7 +14,7 @@ Table of contents:
* [License](#license)
##Lints
There are 135 lints included in this crate:
There are 136 lints included in this crate:
name | default | meaning
---------------------------------------------------------------------------------------------------------------------|---------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
@ -133,6 +133,7 @@ name
[temporary_assignment](https://github.com/Manishearth/rust-clippy/wiki#temporary_assignment) | warn | assignments to temporaries
[too_many_arguments](https://github.com/Manishearth/rust-clippy/wiki#too_many_arguments) | warn | functions with too many arguments
[toplevel_ref_arg](https://github.com/Manishearth/rust-clippy/wiki#toplevel_ref_arg) | warn | An entire binding was declared as `ref`, in a function argument (`fn foo(ref x: Bar)`), or a `let` statement (`let ref x = foo()`). In such cases, it is preferred to take references with `&`.
[transmute_ptr_to_ref](https://github.com/Manishearth/rust-clippy/wiki#transmute_ptr_to_ref) | warn | transmutes from a pointer to a reference type
[trivial_regex](https://github.com/Manishearth/rust-clippy/wiki#trivial_regex) | warn | finds trivial regular expressions in `Regex::new(_)` invocations
[type_complexity](https://github.com/Manishearth/rust-clippy/wiki#type_complexity) | warn | usage of very complex types; recommends factoring out parts into `type` definitions
[unicode_not_nfc](https://github.com/Manishearth/rust-clippy/wiki#unicode_not_nfc) | allow | using a unicode literal not in NFC normal form (see http://www.unicode.org/reports/tr15/ for further information)

4
src/lib.rs
View file

@ -195,8 +195,7 @@ pub fn plugin_registrar(reg: &mut Registry) {
reg.register_late_lint_pass(box no_effect::NoEffectPass);
reg.register_late_lint_pass(box map_clone::MapClonePass);
reg.register_late_lint_pass(box temporary_assignment::TemporaryAssignmentPass);
reg.register_late_lint_pass(box transmute::CrosspointerTransmute);
reg.register_late_lint_pass(box transmute::UselessTransmute);
reg.register_late_lint_pass(box transmute::Transmute);
reg.register_late_lint_pass(box cyclomatic_complexity::CyclomaticComplexity::new(conf.cyclomatic_complexity_threshold));
reg.register_late_lint_pass(box escape::EscapePass);
reg.register_early_lint_pass(box misc_early::MiscEarly);
@ -352,6 +351,7 @@ pub fn plugin_registrar(reg: &mut Registry) {
swap::MANUAL_SWAP,
temporary_assignment::TEMPORARY_ASSIGNMENT,
transmute::CROSSPOINTER_TRANSMUTE,
transmute::TRANSMUTE_PTR_TO_REF,
transmute::USELESS_TRANSMUTE,
types::ABSURD_EXTREME_COMPARISONS,
types::BOX_VEC,

108
src/transmute.rs
View file

@ -1,9 +1,9 @@
use rustc::lint::*;
use rustc::ty::TypeVariants::{TyRawPtr, TyRef};
use rustc::ty;
use rustc_front::hir::*;
use rustc::ty::TyS;
use rustc::ty::TypeVariants::TyRawPtr;
use utils;
use utils::TRANSMUTE_PATH;
use utils::{match_def_path, snippet_opt, span_lint, span_lint_and_then};
/// **What it does:** This lint checks for transmutes to the original type of the object.
///
@ -31,28 +31,63 @@ declare_lint! {
"transmutes that have to or from types that are a pointer to the other"
}
pub struct UselessTransmute;
/// **What it does:*** This lint checks for transmutes from a pointer to a reference.
///
/// **Why is this bad?** This can always be rewritten with `&` and `*`.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// let _: &T = std::mem::transmute(p); // where p: *const T
/// // can be written:
/// let _: &T = &*p;
/// ```
declare_lint! {
pub TRANSMUTE_PTR_TO_REF,
Warn,
"transmutes from a pointer to a reference type"
}
impl LintPass for UselessTransmute {
pub struct Transmute;
impl LintPass for Transmute {
fn get_lints(&self) -> LintArray {
lint_array!(USELESS_TRANSMUTE)
lint_array! [
CROSSPOINTER_TRANSMUTE,
TRANSMUTE_PTR_TO_REF,
USELESS_TRANSMUTE
]
}
}
impl LateLintPass for UselessTransmute {
impl LateLintPass for Transmute {
fn check_expr(&mut self, cx: &LateContext, e: &Expr) {
if let ExprCall(ref path_expr, ref args) = e.node {
if let ExprPath(None, _) = path_expr.node {
let def_id = cx.tcx.def_map.borrow()[&path_expr.id].def_id();
if utils::match_def_path(cx, def_id, &TRANSMUTE_PATH) {
if match_def_path(cx, def_id, &TRANSMUTE_PATH) {
let from_ty = cx.tcx.expr_ty(&args[0]);
let to_ty = cx.tcx.expr_ty(e);
if from_ty == to_ty {
cx.span_lint(USELESS_TRANSMUTE,
e.span,
&format!("transmute from a type (`{}`) to itself", from_ty));
span_lint(cx,
USELESS_TRANSMUTE,
e.span,
&format!("transmute from a type (`{}`) to itself", from_ty));
} else if is_ptr_to(to_ty, from_ty) {
span_lint(cx,
CROSSPOINTER_TRANSMUTE,
e.span,
&format!("transmute from a type (`{}`) to a pointer to that type (`{}`)", from_ty, to_ty));
} else if is_ptr_to(from_ty, to_ty) {
span_lint(cx,
CROSSPOINTER_TRANSMUTE,
e.span,
&format!("transmute from a type (`{}`) to the type that it points to (`{}`)", from_ty, to_ty));
} else {
check_ptr_to_ref(cx, from_ty, to_ty, e, &args[0]);
}
}
}
@ -60,15 +95,7 @@ impl LateLintPass for UselessTransmute {
}
}
pub struct CrosspointerTransmute;
impl LintPass for CrosspointerTransmute {
fn get_lints(&self) -> LintArray {
lint_array!(CROSSPOINTER_TRANSMUTE)
}
}
fn is_ptr_to(from: &TyS, to: &TyS) -> bool {
fn is_ptr_to(from: ty::Ty, to: ty::Ty) -> bool {
if let TyRawPtr(from_ptr) = from.sty {
from_ptr.ty == to
} else {
@ -76,27 +103,34 @@ fn is_ptr_to(from: &TyS, to: &TyS) -> bool {
}
}
impl LateLintPass for CrosspointerTransmute {
fn check_expr(&mut self, cx: &LateContext, e: &Expr) {
if let ExprCall(ref path_expr, ref args) = e.node {
if let ExprPath(None, _) = path_expr.node {
let def_id = cx.tcx.def_map.borrow()[&path_expr.id].def_id();
fn check_ptr_to_ref<'tcx>(cx: &LateContext,
from_ty: ty::Ty<'tcx>,
to_ty: ty::Ty<'tcx>,
e: &Expr, arg: &Expr) {
if let TyRawPtr(ref from_pty) = from_ty.sty {
if let TyRef(_, ref to_rty) = to_ty.sty {
let mess = format!("transmute from a pointer type (`{}`) to a reference type (`{}`)",
from_ty,
to_ty);
span_lint_and_then(cx, TRANSMUTE_PTR_TO_REF, e.span, &mess, |db| {
if let Some(arg) = snippet_opt(cx, arg.span) {
let (deref, cast) = if to_rty.mutbl == Mutability::MutMutable {
("&mut *", "*mut")
} else {
("&*", "*const")
};
if utils::match_def_path(cx, def_id, &TRANSMUTE_PATH) {
let from_ty = cx.tcx.expr_ty(&args[0]);
let to_ty = cx.tcx.expr_ty(e);
if is_ptr_to(to_ty, from_ty) {
cx.span_lint(CROSSPOINTER_TRANSMUTE,
e.span,
&format!("transmute from a type (`{}`) to a pointer to that type (`{}`)", from_ty, to_ty));
} else if is_ptr_to(from_ty, to_ty) {
cx.span_lint(CROSSPOINTER_TRANSMUTE,
e.span,
&format!("transmute from a type (`{}`) to the type that it points to (`{}`)", from_ty, to_ty));
let sugg = if from_pty.ty == to_rty.ty {
format!("{}{}", deref, arg)
}
else {
format!("{}({} as {} {})", deref, arg, cast, to_rty.ty)
};
db.span_suggestion(e.span, "try", sugg);
}
}
});
}
}
}

39
tests/compile-fail/transmute.rs
View file

@ -19,6 +19,45 @@ unsafe fn _generic<'a, T, U: 'a>(t: &'a T) {
let _: &'a U = core::intrinsics::transmute(t);
}
#[deny(transmute_ptr_to_ref)]
unsafe fn _ptr_to_ref<T, U>(p: *const T, m: *mut T, o: *const U, om: *mut U) {
let _: &T = std::mem::transmute(p);
//~^ ERROR transmute from a pointer type (`*const T`) to a reference type (`&T`)
//~| HELP try
//~| SUGGESTION = &*p;
let _: &T = &*p;
let _: &mut T = std::mem::transmute(m);
//~^ ERROR transmute from a pointer type (`*mut T`) to a reference type (`&mut T`)
//~| HELP try
//~| SUGGESTION = &mut *m;
let _: &mut T = &mut *m;
let _: &T = std::mem::transmute(m);
//~^ ERROR transmute from a pointer type (`*mut T`) to a reference type (`&T`)
//~| HELP try
//~| SUGGESTION = &*m;
let _: &T = &*m;
let _: &T = std::mem::transmute(o);
//~^ ERROR transmute from a pointer type (`*const U`) to a reference type (`&T`)
//~| HELP try
//~| SUGGESTION = &*(o as *const T);
let _: &T = &*(o as *const T);
let _: &mut T = std::mem::transmute(om);
//~^ ERROR transmute from a pointer type (`*mut U`) to a reference type (`&mut T`)
//~| HELP try
//~| SUGGESTION = &mut *(om as *mut T);
let _: &mut T = &mut *(om as *mut T);
let _: &T = std::mem::transmute(om);
//~^ ERROR transmute from a pointer type (`*mut U`) to a reference type (`&T`)
//~| HELP try
//~| SUGGESTION = &*(om as *const T);
let _: &T = &*(om as *const T);
}
#[deny(useless_transmute)]
fn useless() {
unsafe {