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Rollup merge of #113657 - Urgau:expand-incorrect_fn_null_check-lint, r=cjgillot

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Expand, rename and improve `incorrect_fn_null_checks` lint

This PR,

 - firstly, expand the lint by now linting on references
 - secondly, it renames the lint `incorrect_fn_null_checks` -> `useless_ptr_null_checks`
 - and thirdly it improves the lint by catching `ptr::from_mut`, `ptr::from_ref`, as well as `<*mut _>::cast` and `<*const _>::cast_mut`

Fixes https://github.com/rust-lang/rust/issues/113601
cc ```@est31```
This commit is contained in:
Matthias Krüger 2023-08-03 17:29:06 +02:00 • committed by GitHub
commit 7518ae566e
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GPG key ID: 4AEE18F83AFDEB23
17 changed files with 484 additions and 225 deletions
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10
compiler/rustc_lint/messages.ftl
View file

@ -213,9 +213,6 @@ lint_expectation = this lint expectation is unfulfilled
.note = the `unfulfilled_lint_expectations` lint can't be expected and will always produce this message .note = the `unfulfilled_lint_expectations` lint can't be expected and will always produce this message
.rationale = {$rationale} .rationale = {$rationale}
lint_fn_null_check = function pointers are not nullable, so checking them for null will always return false
.help = wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value
lint_for_loops_over_fallibles = lint_for_loops_over_fallibles =
for loop over {$article} `{$ty}`. This is more readably written as an `if let` statement for loop over {$article} `{$ty}`. This is more readably written as an `if let` statement
.suggestion = consider using `if let` to clear intent .suggestion = consider using `if let` to clear intent
@ -454,6 +451,13 @@ lint_path_statement_drop = path statement drops value
lint_path_statement_no_effect = path statement with no effect lint_path_statement_no_effect = path statement with no effect
lint_ptr_null_checks_fn_ptr = function pointers are not nullable, so checking them for null will always return false
.help = wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value
.label = expression has type `{$orig_ty}`
lint_ptr_null_checks_ref = references are not nullable, so checking them for null will always return false
.label = expression has type `{$orig_ty}`
lint_query_instability = using `{$query}` can result in unstable query results lint_query_instability = using `{$query}` can result in unstable query results
.note = if you believe this case to be fine, allow this lint and add a comment explaining your rationale .note = if you believe this case to be fine, allow this lint and add a comment explaining your rationale

112
compiler/rustc_lint/src/fn_null_check.rs
View file

@ -1,112 +0,0 @@
use crate::{lints::FnNullCheckDiag, LateContext, LateLintPass, LintContext};
use rustc_ast::LitKind;
use rustc_hir::{BinOpKind, Expr, ExprKind, TyKind};
use rustc_session::{declare_lint, declare_lint_pass};
use rustc_span::sym;
declare_lint! {
/// The `incorrect_fn_null_checks` lint checks for expression that checks if a
/// function pointer is null.
///
/// ### Example
///
/// ```rust
/// # fn test() {}
/// let fn_ptr: fn() = /* somehow obtained nullable function pointer */
/// # test;
///
/// if (fn_ptr as *const ()).is_null() { /* ... */ }
/// ```
///
/// {{produces}}
///
/// ### Explanation
///
/// Function pointers are assumed to be non-null, checking them for null will always
/// return false.
INCORRECT_FN_NULL_CHECKS,
Warn,
"incorrect checking of null function pointer"
}
declare_lint_pass!(IncorrectFnNullChecks => [INCORRECT_FN_NULL_CHECKS]);
fn is_fn_ptr_cast(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
let mut expr = expr.peel_blocks();
let mut had_at_least_one_cast = false;
while let ExprKind::Cast(cast_expr, cast_ty) = expr.kind
&& let TyKind::Ptr(_) = cast_ty.kind {
expr = cast_expr.peel_blocks();
had_at_least_one_cast = true;
}
had_at_least_one_cast && cx.typeck_results().expr_ty_adjusted(expr).is_fn()
}
impl<'tcx> LateLintPass<'tcx> for IncorrectFnNullChecks {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
match expr.kind {
// Catching:
// <*<const/mut> <ty>>::is_null(fn_ptr as *<const/mut> <ty>)
ExprKind::Call(path, [arg])
if let ExprKind::Path(ref qpath) = path.kind
&& let Some(def_id) = cx.qpath_res(qpath, path.hir_id).opt_def_id()
&& matches!(
cx.tcx.get_diagnostic_name(def_id),
Some(sym::ptr_const_is_null | sym::ptr_is_null)
)
&& is_fn_ptr_cast(cx, arg) =>
{
cx.emit_spanned_lint(INCORRECT_FN_NULL_CHECKS, expr.span, FnNullCheckDiag)
}
// Catching:
// (fn_ptr as *<const/mut> <ty>).is_null()
ExprKind::MethodCall(_, receiver, _, _)
if let Some(def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id)
&& matches!(
cx.tcx.get_diagnostic_name(def_id),
Some(sym::ptr_const_is_null | sym::ptr_is_null)
)
&& is_fn_ptr_cast(cx, receiver) =>
{
cx.emit_spanned_lint(INCORRECT_FN_NULL_CHECKS, expr.span, FnNullCheckDiag)
}
ExprKind::Binary(op, left, right) if matches!(op.node, BinOpKind::Eq) => {
let to_check: &Expr<'_>;
if is_fn_ptr_cast(cx, left) {
to_check = right;
} else if is_fn_ptr_cast(cx, right) {
to_check = left;
} else {
return;
}
match to_check.kind {
// Catching:
// (fn_ptr as *<const/mut> <ty>) == (0 as <ty>)
ExprKind::Cast(cast_expr, _)
if let ExprKind::Lit(spanned) = cast_expr.kind
&& let LitKind::Int(v, _) = spanned.node && v == 0 =>
{
cx.emit_spanned_lint(INCORRECT_FN_NULL_CHECKS, expr.span, FnNullCheckDiag)
},
// Catching:
// (fn_ptr as *<const/mut> <ty>) == std::ptr::null()
ExprKind::Call(path, [])
if let ExprKind::Path(ref qpath) = path.kind
&& let Some(def_id) = cx.qpath_res(qpath, path.hir_id).opt_def_id()
&& let Some(diag_item) = cx.tcx.get_diagnostic_name(def_id)
&& (diag_item == sym::ptr_null || diag_item == sym::ptr_null_mut) =>
{
cx.emit_spanned_lint(INCORRECT_FN_NULL_CHECKS, expr.span, FnNullCheckDiag)
},
_ => {},
}
}
_ => {}
}
}
}

6
compiler/rustc_lint/src/lib.rs
View file

@ -57,7 +57,6 @@ mod early;
mod enum_intrinsics_non_enums; mod enum_intrinsics_non_enums;
mod errors; mod errors;
mod expect; mod expect;
mod fn_null_check;
mod for_loops_over_fallibles; mod for_loops_over_fallibles;
pub mod hidden_unicode_codepoints; pub mod hidden_unicode_codepoints;
mod internal; mod internal;
@ -76,6 +75,7 @@ mod noop_method_call;
mod opaque_hidden_inferred_bound; mod opaque_hidden_inferred_bound;
mod pass_by_value; mod pass_by_value;
mod passes; mod passes;
mod ptr_nulls;
mod redundant_semicolon; mod redundant_semicolon;
mod reference_casting; mod reference_casting;
mod traits; mod traits;
@ -102,7 +102,6 @@ use builtin::*;
use deref_into_dyn_supertrait::*; use deref_into_dyn_supertrait::*;
use drop_forget_useless::*; use drop_forget_useless::*;
use enum_intrinsics_non_enums::EnumIntrinsicsNonEnums; use enum_intrinsics_non_enums::EnumIntrinsicsNonEnums;
use fn_null_check::*;
use for_loops_over_fallibles::*; use for_loops_over_fallibles::*;
use hidden_unicode_codepoints::*; use hidden_unicode_codepoints::*;
use internal::*; use internal::*;
@ -117,6 +116,7 @@ use nonstandard_style::*;
use noop_method_call::*; use noop_method_call::*;
use opaque_hidden_inferred_bound::*; use opaque_hidden_inferred_bound::*;
use pass_by_value::*; use pass_by_value::*;
use ptr_nulls::*;
use redundant_semicolon::*; use redundant_semicolon::*;
use reference_casting::*; use reference_casting::*;
use traits::*; use traits::*;
@ -227,7 +227,7 @@ late_lint_methods!(
// Depends on types used in type definitions // Depends on types used in type definitions
MissingCopyImplementations: MissingCopyImplementations, MissingCopyImplementations: MissingCopyImplementations,
// Depends on referenced function signatures in expressions // Depends on referenced function signatures in expressions
IncorrectFnNullChecks: IncorrectFnNullChecks, PtrNullChecks: PtrNullChecks,
MutableTransmutes: MutableTransmutes, MutableTransmutes: MutableTransmutes,
TypeAliasBounds: TypeAliasBounds, TypeAliasBounds: TypeAliasBounds,
TrivialConstraints: TrivialConstraints, TrivialConstraints: TrivialConstraints,

20
compiler/rustc_lint/src/lints.rs
View file

@ -613,11 +613,23 @@ pub struct ExpectationNote {
pub rationale: Symbol, pub rationale: Symbol,
} }
// fn_null_check.rs // ptr_nulls.rs
#[derive(LintDiagnostic)] #[derive(LintDiagnostic)]
#[diag(lint_fn_null_check)] pub enum PtrNullChecksDiag<'a> {
#[help] #[diag(lint_ptr_null_checks_fn_ptr)]
pub struct FnNullCheckDiag; #[help(lint_help)]
FnPtr {
orig_ty: Ty<'a>,
#[label]
label: Span,
},
#[diag(lint_ptr_null_checks_ref)]
Ref {
orig_ty: Ty<'a>,
#[label]
label: Span,
},
}
// for_loops_over_fallibles.rs // for_loops_over_fallibles.rs
#[derive(LintDiagnostic)] #[derive(LintDiagnostic)]

146
compiler/rustc_lint/src/ptr_nulls.rs Normal file
View file

@ -0,0 +1,146 @@
use crate::{lints::PtrNullChecksDiag, LateContext, LateLintPass, LintContext};
use rustc_ast::LitKind;
use rustc_hir::{BinOpKind, Expr, ExprKind, TyKind};
use rustc_session::{declare_lint, declare_lint_pass};
use rustc_span::sym;
declare_lint! {
/// The `useless_ptr_null_checks` lint checks for useless null checks against pointers
/// obtained from non-null types.
///
/// ### Example
///
/// ```rust
/// # fn test() {}
/// let fn_ptr: fn() = /* somehow obtained nullable function pointer */
/// # test;
///
/// if (fn_ptr as *const ()).is_null() { /* ... */ }
/// ```
///
/// {{produces}}
///
/// ### Explanation
///
/// Function pointers and references are assumed to be non-null, checking them for null
/// will always return false.
USELESS_PTR_NULL_CHECKS,
Warn,
"useless checking of non-null-typed pointer"
}
declare_lint_pass!(PtrNullChecks => [USELESS_PTR_NULL_CHECKS]);
/// This function detects and returns the original expression from a series of consecutive casts,
/// ie. `(my_fn as *const _ as *mut _).cast_mut()` would return the expression for `my_fn`.
fn ptr_cast_chain<'a>(cx: &'a LateContext<'_>, mut e: &'a Expr<'a>) -> Option<&'a Expr<'a>> {
let mut had_at_least_one_cast = false;
loop {
e = e.peel_blocks();
e = if let ExprKind::Cast(expr, t) = e.kind
&& let TyKind::Ptr(_) = t.kind {
had_at_least_one_cast = true;
expr
} else if let ExprKind::MethodCall(_, expr, [], _) = e.kind
&& let Some(def_id) = cx.typeck_results().type_dependent_def_id(e.hir_id)
&& matches!(cx.tcx.get_diagnostic_name(def_id), Some(sym::ptr_cast | sym::ptr_cast_mut)) {
had_at_least_one_cast = true;
expr
} else if let ExprKind::Call(path, [arg]) = e.kind
&& let ExprKind::Path(ref qpath) = path.kind
&& let Some(def_id) = cx.qpath_res(qpath, path.hir_id).opt_def_id()
&& matches!(cx.tcx.get_diagnostic_name(def_id), Some(sym::ptr_from_ref | sym::ptr_from_mut)) {
had_at_least_one_cast = true;
arg
} else if had_at_least_one_cast {
return Some(e);
} else {
return None;
};
}
}
fn incorrect_check<'a>(cx: &LateContext<'a>, expr: &Expr<'_>) -> Option<PtrNullChecksDiag<'a>> {
let expr = ptr_cast_chain(cx, expr)?;
let orig_ty = cx.typeck_results().expr_ty(expr);
if orig_ty.is_fn() {
Some(PtrNullChecksDiag::FnPtr { orig_ty, label: expr.span })
} else if orig_ty.is_ref() {
Some(PtrNullChecksDiag::Ref { orig_ty, label: expr.span })
} else {
None
}
}
impl<'tcx> LateLintPass<'tcx> for PtrNullChecks {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
match expr.kind {
// Catching:
// <*<const/mut> <ty>>::is_null(fn_ptr as *<const/mut> <ty>)
ExprKind::Call(path, [arg])
if let ExprKind::Path(ref qpath) = path.kind
&& let Some(def_id) = cx.qpath_res(qpath, path.hir_id).opt_def_id()
&& matches!(
cx.tcx.get_diagnostic_name(def_id),
Some(sym::ptr_const_is_null | sym::ptr_is_null)
)
&& let Some(diag) = incorrect_check(cx, arg) =>
{
cx.emit_spanned_lint(USELESS_PTR_NULL_CHECKS, expr.span, diag)
}
// Catching:
// (fn_ptr as *<const/mut> <ty>).is_null()
ExprKind::MethodCall(_, receiver, _, _)
if let Some(def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id)
&& matches!(
cx.tcx.get_diagnostic_name(def_id),
Some(sym::ptr_const_is_null | sym::ptr_is_null)
)
&& let Some(diag) = incorrect_check(cx, receiver) =>
{
cx.emit_spanned_lint(USELESS_PTR_NULL_CHECKS, expr.span, diag)
}
ExprKind::Binary(op, left, right) if matches!(op.node, BinOpKind::Eq) => {
let to_check: &Expr<'_>;
let diag: PtrNullChecksDiag<'_>;
if let Some(ddiag) = incorrect_check(cx, left) {
to_check = right;
diag = ddiag;
} else if let Some(ddiag) = incorrect_check(cx, right) {
to_check = left;
diag = ddiag;
} else {
return;
}
match to_check.kind {
// Catching:
// (fn_ptr as *<const/mut> <ty>) == (0 as <ty>)
ExprKind::Cast(cast_expr, _)
if let ExprKind::Lit(spanned) = cast_expr.kind
&& let LitKind::Int(v, _) = spanned.node && v == 0 =>
{
cx.emit_spanned_lint(USELESS_PTR_NULL_CHECKS, expr.span, diag)
},
// Catching:
// (fn_ptr as *<const/mut> <ty>) == std::ptr::null()
ExprKind::Call(path, [])
if let ExprKind::Path(ref qpath) = path.kind
&& let Some(def_id) = cx.qpath_res(qpath, path.hir_id).opt_def_id()
&& let Some(diag_item) = cx.tcx.get_diagnostic_name(def_id)
&& (diag_item == sym::ptr_null || diag_item == sym::ptr_null_mut) =>
{
cx.emit_spanned_lint(USELESS_PTR_NULL_CHECKS, expr.span, diag)
},
_ => {},
}
}
_ => {}
}
}
}

2
compiler/rustc_span/src/symbol.rs
View file

@ -1155,8 +1155,10 @@ symbols! {
profiler_builtins, profiler_builtins,
profiler_runtime, profiler_runtime,
ptr, ptr,
ptr_cast,
ptr_cast_mut, ptr_cast_mut,
ptr_const_is_null, ptr_const_is_null,
ptr_from_mut,
ptr_from_ref, ptr_from_ref,
ptr_guaranteed_cmp, ptr_guaranteed_cmp,
ptr_is_null, ptr_is_null,

1
library/core/src/ptr/mod.rs
View file

@ -710,6 +710,7 @@ pub const fn from_ref<T: ?Sized>(r: &T) -> *const T {
#[inline(always)] #[inline(always)]
#[must_use] #[must_use]
#[unstable(feature = "ptr_from_ref", issue = "106116")] #[unstable(feature = "ptr_from_ref", issue = "106116")]
#[rustc_diagnostic_item = "ptr_from_mut"]
pub const fn from_mut<T: ?Sized>(r: &mut T) -> *mut T { pub const fn from_mut<T: ?Sized>(r: &mut T) -> *mut T {
r r
} }

1
library/core/src/ptr/mut_ptr.rs
View file

@ -54,6 +54,7 @@ impl<T: ?Sized> *mut T {
/// Casts to a pointer of another type. /// Casts to a pointer of another type.
#[stable(feature = "ptr_cast", since = "1.38.0")] #[stable(feature = "ptr_cast", since = "1.38.0")]
#[rustc_const_stable(feature = "const_ptr_cast", since = "1.38.0")] #[rustc_const_stable(feature = "const_ptr_cast", since = "1.38.0")]
#[rustc_diagnostic_item = "ptr_cast"]
#[inline(always)] #[inline(always)]
pub const fn cast<U>(self) -> *mut U { pub const fn cast<U>(self) -> *mut U {
self as _ self as _

2
src/tools/clippy/clippy_lints/src/renamed_lints.rs
View file

@ -43,7 +43,7 @@ pub static RENAMED_LINTS: &[(&str, &str)] = &[
("clippy::for_loops_over_fallibles", "for_loops_over_fallibles"), ("clippy::for_loops_over_fallibles", "for_loops_over_fallibles"),
("clippy::forget_copy", "forgetting_copy_types"), ("clippy::forget_copy", "forgetting_copy_types"),
("clippy::forget_ref", "forgetting_references"), ("clippy::forget_ref", "forgetting_references"),
("clippy::fn_null_check", "incorrect_fn_null_checks"), ("clippy::fn_null_check", "useless_ptr_null_checks"),
("clippy::into_iter_on_array", "array_into_iter"), ("clippy::into_iter_on_array", "array_into_iter"),
("clippy::invalid_atomic_ordering", "invalid_atomic_ordering"), ("clippy::invalid_atomic_ordering", "invalid_atomic_ordering"),
("clippy::invalid_ref", "invalid_value"), ("clippy::invalid_ref", "invalid_value"),

4
src/tools/clippy/tests/ui/rename.fixed
View file

@ -38,7 +38,7 @@
#![allow(for_loops_over_fallibles)] #![allow(for_loops_over_fallibles)]
#![allow(forgetting_copy_types)] #![allow(forgetting_copy_types)]
#![allow(forgetting_references)] #![allow(forgetting_references)]
#![allow(incorrect_fn_null_checks)] #![allow(useless_ptr_null_checks)]
#![allow(array_into_iter)] #![allow(array_into_iter)]
#![allow(invalid_atomic_ordering)] #![allow(invalid_atomic_ordering)]
#![allow(invalid_value)] #![allow(invalid_value)]
@ -92,7 +92,7 @@
#![warn(for_loops_over_fallibles)] #![warn(for_loops_over_fallibles)]
#![warn(forgetting_copy_types)] #![warn(forgetting_copy_types)]
#![warn(forgetting_references)] #![warn(forgetting_references)]
#![warn(incorrect_fn_null_checks)] #![warn(useless_ptr_null_checks)]
#![warn(array_into_iter)] #![warn(array_into_iter)]
#![warn(invalid_atomic_ordering)] #![warn(invalid_atomic_ordering)]
#![warn(invalid_value)] #![warn(invalid_value)]

2
src/tools/clippy/tests/ui/rename.rs
View file

@ -38,7 +38,7 @@
#![allow(for_loops_over_fallibles)] #![allow(for_loops_over_fallibles)]
#![allow(forgetting_copy_types)] #![allow(forgetting_copy_types)]
#![allow(forgetting_references)] #![allow(forgetting_references)]
#![allow(incorrect_fn_null_checks)] #![allow(useless_ptr_null_checks)]
#![allow(array_into_iter)] #![allow(array_into_iter)]
#![allow(invalid_atomic_ordering)] #![allow(invalid_atomic_ordering)]
#![allow(invalid_value)] #![allow(invalid_value)]

4
src/tools/clippy/tests/ui/rename.stderr
View file

@ -246,11 +246,11 @@ error: lint `clippy::forget_ref` has been renamed to `forgetting_references`
LL | #![warn(clippy::forget_ref)] LL | #![warn(clippy::forget_ref)]
| ^^^^^^^^^^^^^^^^^^ help: use the new name: `forgetting_references` | ^^^^^^^^^^^^^^^^^^ help: use the new name: `forgetting_references`
error: lint `clippy::fn_null_check` has been renamed to `incorrect_fn_null_checks` error: lint `clippy::fn_null_check` has been renamed to `useless_ptr_null_checks`
--> $DIR/rename.rs:95:9 --> $DIR/rename.rs:95:9
| |
LL | #![warn(clippy::fn_null_check)] LL | #![warn(clippy::fn_null_check)]
| ^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `incorrect_fn_null_checks` | ^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `useless_ptr_null_checks`
error: lint `clippy::into_iter_on_array` has been renamed to `array_into_iter` error: lint `clippy::into_iter_on_array` has been renamed to `array_into_iter`
--> $DIR/rename.rs:96:9 --> $DIR/rename.rs:96:9

1
tests/ui/consts/ptr_is_null.rs
View file

@ -2,6 +2,7 @@
// check-pass // check-pass
#![feature(const_ptr_is_null)] #![feature(const_ptr_is_null)]
#![allow(useless_ptr_null_checks)]
const FOO: &usize = &42; const FOO: &usize = &42;

30
tests/ui/lint/fn_null_check.rs
View file

@ -1,30 +0,0 @@
// check-pass
fn main() {
let fn_ptr = main;
if (fn_ptr as *mut ()).is_null() {}
//~^ WARN function pointers are not nullable
if (fn_ptr as *const u8).is_null() {}
//~^ WARN function pointers are not nullable
if (fn_ptr as *const ()) == std::ptr::null() {}
//~^ WARN function pointers are not nullable
if (fn_ptr as *mut ()) == std::ptr::null_mut() {}
//~^ WARN function pointers are not nullable
if (fn_ptr as *const ()) == (0 as *const ()) {}
//~^ WARN function pointers are not nullable
if <*const _>::is_null(fn_ptr as *const ()) {}
//~^ WARN function pointers are not nullable
if (fn_ptr as *mut fn() as *const fn() as *const ()).is_null() {}
//~^ WARN function pointers are not nullable
if (fn_ptr as fn() as *const ()).is_null() {}
//~^ WARN function pointers are not nullable
const ZPTR: *const () = 0 as *const _;
const NOT_ZPTR: *const () = 1 as *const _;
// unlike the uplifted clippy::fn_null_check lint we do
// not lint on them
if (fn_ptr as *const ()) == ZPTR {}
if (fn_ptr as *const ()) == NOT_ZPTR {}
}

67
tests/ui/lint/fn_null_check.stderr
View file

@ -1,67 +0,0 @@
warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/fn_null_check.rs:6:8
|
LL | if (fn_ptr as *mut ()).is_null() {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value
= note: `#[warn(incorrect_fn_null_checks)]` on by default
warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/fn_null_check.rs:8:8
|
LL | if (fn_ptr as *const u8).is_null() {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value
warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/fn_null_check.rs:10:8
|
LL | if (fn_ptr as *const ()) == std::ptr::null() {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value
warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/fn_null_check.rs:12:8
|
LL | if (fn_ptr as *mut ()) == std::ptr::null_mut() {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value
warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/fn_null_check.rs:14:8
|
LL | if (fn_ptr as *const ()) == (0 as *const ()) {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value
warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/fn_null_check.rs:16:8
|
LL | if <*const _>::is_null(fn_ptr as *const ()) {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value
warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/fn_null_check.rs:18:8
|
LL | if (fn_ptr as *mut fn() as *const fn() as *const ()).is_null() {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value
warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/fn_null_check.rs:20:8
|
LL | if (fn_ptr as fn() as *const ()).is_null() {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value
warning: 8 warnings emitted

76
tests/ui/lint/ptr_null_checks.rs Normal file
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@ -0,0 +1,76 @@
// check-pass
#![feature(ptr_from_ref)]
use std::ptr;
extern "C" fn c_fn() {}
fn static_i32() -> &'static i32 { &1 }
fn main() {
let fn_ptr = main;
// ------------- Function pointers ---------------
if (fn_ptr as *mut ()).is_null() {}
//~^ WARN function pointers are not nullable
if (fn_ptr as *const u8).is_null() {}
//~^ WARN function pointers are not nullable
if (fn_ptr as *const ()) == std::ptr::null() {}
//~^ WARN function pointers are not nullable
if (fn_ptr as *mut ()) == std::ptr::null_mut() {}
//~^ WARN function pointers are not nullable
if (fn_ptr as *const ()) == (0 as *const ()) {}
//~^ WARN function pointers are not nullable
if <*const _>::is_null(fn_ptr as *const ()) {}
//~^ WARN function pointers are not nullable
if (fn_ptr as *mut fn() as *const fn() as *const ()).is_null() {}
//~^ WARN function pointers are not nullable
if (fn_ptr as *mut fn() as *const fn()).cast_mut().is_null() {}
//~^ WARN function pointers are not nullable
if ((fn_ptr as *mut fn()).cast() as *const fn()).cast_mut().is_null() {}
//~^ WARN function pointers are not nullable
if (fn_ptr as fn() as *const ()).is_null() {}
//~^ WARN function pointers are not nullable
if (c_fn as *const fn()).is_null() {}
//~^ WARN function pointers are not nullable
// ---------------- References ------------------
if (&mut 8 as *mut i32).is_null() {}
//~^ WARN references are not nullable
if ptr::from_mut(&mut 8).is_null() {}
//~^ WARN references are not nullable
if (&8 as *const i32).is_null() {}
//~^ WARN references are not nullable
if ptr::from_ref(&8).is_null() {}
//~^ WARN references are not nullable
if ptr::from_ref(&8).cast_mut().is_null() {}
//~^ WARN references are not nullable
if (ptr::from_ref(&8).cast_mut() as *mut i32).is_null() {}
//~^ WARN references are not nullable
if (&8 as *const i32) == std::ptr::null() {}
//~^ WARN references are not nullable
let ref_num = &8;
if (ref_num as *const i32) == std::ptr::null() {}
//~^ WARN references are not nullable
if (b"\0" as *const u8).is_null() {}
//~^ WARN references are not nullable
if ("aa" as *const str).is_null() {}
//~^ WARN references are not nullable
if (&[1, 2] as *const i32).is_null() {}
//~^ WARN references are not nullable
if (&mut [1, 2] as *mut i32) == std::ptr::null_mut() {}
//~^ WARN references are not nullable
if (static_i32() as *const i32).is_null() {}
//~^ WARN references are not nullable
if (&*{ static_i32() } as *const i32).is_null() {}
//~^ WARN references are not nullable
// ----------------------------------------------
const ZPTR: *const () = 0 as *const _;
const NOT_ZPTR: *const () = 1 as *const _;
// unlike the uplifted clippy::fn_null_check lint we do
// not lint on them
if (fn_ptr as *const ()) == ZPTR {}
if (fn_ptr as *const ()) == NOT_ZPTR {}
}

225
tests/ui/lint/ptr_null_checks.stderr Normal file
View file

@ -0,0 +1,225 @@
warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:14:8
|
LL | if (fn_ptr as *mut ()).is_null() {}
| ^------^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `fn() {main}`
|
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value
= note: `#[warn(useless_ptr_null_checks)]` on by default
warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:16:8
|
LL | if (fn_ptr as *const u8).is_null() {}
| ^------^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `fn() {main}`
|
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value
warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:18:8
|
LL | if (fn_ptr as *const ()) == std::ptr::null() {}
| ^------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `fn() {main}`
|
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value
warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:20:8
|
LL | if (fn_ptr as *mut ()) == std::ptr::null_mut() {}
| ^------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `fn() {main}`
|
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value
warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:22:8
|
LL | if (fn_ptr as *const ()) == (0 as *const ()) {}
| ^------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `fn() {main}`
|
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value
warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:24:8
|
LL | if <*const _>::is_null(fn_ptr as *const ()) {}
| ^^^^^^^^^^^^^^^^^^^^------^^^^^^^^^^^^^^
| |
| expression has type `fn() {main}`
|
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value
warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:26:8
|
LL | if (fn_ptr as *mut fn() as *const fn() as *const ()).is_null() {}
| ^------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `fn() {main}`
|
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value
warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:28:8
|
LL | if (fn_ptr as *mut fn() as *const fn()).cast_mut().is_null() {}
| ^------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `fn() {main}`
|
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value
warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:30:8
|
LL | if ((fn_ptr as *mut fn()).cast() as *const fn()).cast_mut().is_null() {}
| ^^------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `fn() {main}`
|
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value
warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:32:8
|
LL | if (fn_ptr as fn() as *const ()).is_null() {}
| ^--------------^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `fn()`
|
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value
warning: function pointers are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:34:8
|
LL | if (c_fn as *const fn()).is_null() {}
| ^----^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `extern "C" fn() {c_fn}`
|
= help: wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value
warning: references are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:38:8
|
LL | if (&mut 8 as *mut i32).is_null() {}
| ^------^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `&mut i32`
warning: references are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:40:8
|
LL | if ptr::from_mut(&mut 8).is_null() {}
| ^^^^^^^^^^^^^^------^^^^^^^^^^^
| |
| expression has type `&mut i32`
warning: references are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:42:8
|
LL | if (&8 as *const i32).is_null() {}
| ^--^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `&i32`
warning: references are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:44:8
|
LL | if ptr::from_ref(&8).is_null() {}
| ^^^^^^^^^^^^^^--^^^^^^^^^^^
| |
| expression has type `&i32`
warning: references are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:46:8
|
LL | if ptr::from_ref(&8).cast_mut().is_null() {}
| ^^^^^^^^^^^^^^--^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `&i32`
warning: references are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:48:8
|
LL | if (ptr::from_ref(&8).cast_mut() as *mut i32).is_null() {}
| ^^^^^^^^^^^^^^^--^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `&i32`
warning: references are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:50:8
|
LL | if (&8 as *const i32) == std::ptr::null() {}
| ^--^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `&i32`
warning: references are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:53:8
|
LL | if (ref_num as *const i32) == std::ptr::null() {}
| ^-------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `&i32`
warning: references are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:55:8
|
LL | if (b"\0" as *const u8).is_null() {}
| ^-----^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `&[u8; 1]`
warning: references are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:57:8
|
LL | if ("aa" as *const str).is_null() {}
| ^----^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `&str`
warning: references are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:59:8
|
LL | if (&[1, 2] as *const i32).is_null() {}
| ^-------^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `&[i32; 2]`
warning: references are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:61:8
|
LL | if (&mut [1, 2] as *mut i32) == std::ptr::null_mut() {}
| ^-----------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `&mut [i32; 2]`
warning: references are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:63:8
|
LL | if (static_i32() as *const i32).is_null() {}
| ^------------^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `&i32`
warning: references are not nullable, so checking them for null will always return false
--> $DIR/ptr_null_checks.rs:65:8
|
LL | if (&*{ static_i32() } as *const i32).is_null() {}
| ^------------------^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expression has type `&i32`
warning: 25 warnings emitted