diff --git a/compiler/rustc_lint/src/ptr_nulls.rs b/compiler/rustc_lint/src/ptr_nulls.rs index b2138c42224..64b86fec46b 100644 --- a/compiler/rustc_lint/src/ptr_nulls.rs +++ b/compiler/rustc_lint/src/ptr_nulls.rs @@ -31,25 +31,45 @@ declare_lint! { declare_lint_pass!(PtrNullChecks => [USELESS_PTR_NULL_CHECKS]); -fn incorrect_check<'a>(cx: &LateContext<'a>, expr: &Expr<'_>) -> Option> { - let mut expr = expr.peel_blocks(); +/// 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; - 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; - } - if !had_at_least_one_cast { - None - } else { - let orig_ty = cx.typeck_results().expr_ty(expr); - if orig_ty.is_fn() { - Some(PtrNullChecksDiag::FnPtr) - } else if orig_ty.is_ref() { - Some(PtrNullChecksDiag::Ref { orig_ty, label: expr.span }) + 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 { - None - } + return None; + }; + } +} + +fn incorrect_check<'a>(cx: &LateContext<'a>, expr: &Expr<'_>) -> Option> { + let expr = ptr_cast_chain(cx, expr)?; + + let orig_ty = cx.typeck_results().expr_ty(expr); + if orig_ty.is_fn() { + Some(PtrNullChecksDiag::FnPtr) + } else if orig_ty.is_ref() { + Some(PtrNullChecksDiag::Ref { orig_ty, label: expr.span }) + } else { + None } } diff --git a/tests/ui/consts/ptr_is_null.rs b/tests/ui/consts/ptr_is_null.rs index 8babb68585d..43b9767db16 100644 --- a/tests/ui/consts/ptr_is_null.rs +++ b/tests/ui/consts/ptr_is_null.rs @@ -2,6 +2,7 @@ // check-pass #![feature(const_ptr_is_null)] +#![allow(useless_ptr_null_checks)] const FOO: &usize = &42; diff --git a/tests/ui/lint/ptr_null_checks.rs b/tests/ui/lint/ptr_null_checks.rs index 600ca32ca89..e677ea3094d 100644 --- a/tests/ui/lint/ptr_null_checks.rs +++ b/tests/ui/lint/ptr_null_checks.rs @@ -1,5 +1,9 @@ // check-pass +#![feature(ptr_from_ref)] + +use std::ptr; + extern "C" fn c_fn() {} fn static_i32() -> &'static i32 { &1 } @@ -21,6 +25,10 @@ fn main() { //~^ 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() {} @@ -29,8 +37,16 @@ fn main() { // ---------------- 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; diff --git a/tests/ui/lint/ptr_null_checks.stderr b/tests/ui/lint/ptr_null_checks.stderr index 10efa8685be..525d96c4919 100644 --- a/tests/ui/lint/ptr_null_checks.stderr +++ b/tests/ui/lint/ptr_null_checks.stderr @@ -1,5 +1,5 @@ warning: function pointers are not nullable, so checking them for null will always return false - --> $DIR/ptr_null_checks.rs:10:8 + --> $DIR/ptr_null_checks.rs:14:8 | LL | if (fn_ptr as *mut ()).is_null() {} | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ @@ -8,7 +8,7 @@ LL | if (fn_ptr as *mut ()).is_null() {} = 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:12:8 + --> $DIR/ptr_null_checks.rs:16:8 | LL | if (fn_ptr as *const u8).is_null() {} | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ @@ -16,7 +16,7 @@ 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/ptr_null_checks.rs:14:8 + --> $DIR/ptr_null_checks.rs:18:8 | LL | if (fn_ptr as *const ()) == std::ptr::null() {} | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ @@ -24,7 +24,7 @@ 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/ptr_null_checks.rs:16:8 + --> $DIR/ptr_null_checks.rs:20:8 | LL | if (fn_ptr as *mut ()) == std::ptr::null_mut() {} | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ @@ -32,7 +32,7 @@ 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/ptr_null_checks.rs:18:8 + --> $DIR/ptr_null_checks.rs:22:8 | LL | if (fn_ptr as *const ()) == (0 as *const ()) {} | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ @@ -40,7 +40,7 @@ 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/ptr_null_checks.rs:20:8 + --> $DIR/ptr_null_checks.rs:24:8 | LL | if <*const _>::is_null(fn_ptr as *const ()) {} | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ @@ -48,7 +48,7 @@ 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/ptr_null_checks.rs:22:8 + --> $DIR/ptr_null_checks.rs:26:8 | LL | if (fn_ptr as *mut fn() as *const fn() as *const ()).is_null() {} | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ @@ -56,7 +56,23 @@ 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/ptr_null_checks.rs:24:8 + --> $DIR/ptr_null_checks.rs:28:8 + | +LL | if (fn_ptr as *mut fn() as *const fn()).cast_mut().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/ptr_null_checks.rs:30:8 + | +LL | if ((fn_ptr as *mut fn()).cast() as *const fn()).cast_mut().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/ptr_null_checks.rs:32:8 | LL | if (fn_ptr as fn() as *const ()).is_null() {} | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ @@ -64,7 +80,7 @@ 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: function pointers are not nullable, so checking them for null will always return false - --> $DIR/ptr_null_checks.rs:26:8 + --> $DIR/ptr_null_checks.rs:34:8 | LL | if (c_fn as *const fn()).is_null() {} | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ @@ -72,7 +88,7 @@ LL | if (c_fn as *const fn()).is_null() {} = 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:30:8 + --> $DIR/ptr_null_checks.rs:38:8 | LL | if (&mut 8 as *mut i32).is_null() {} | ^------^^^^^^^^^^^^^^^^^^^^^^^ @@ -80,7 +96,15 @@ 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:32:8 + --> $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() {} | ^--^^^^^^^^^^^^^^^^^^^^^^^^^ @@ -88,7 +112,31 @@ 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:34:8 + --> $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() {} | ^--^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ @@ -96,7 +144,7 @@ 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:37:8 + --> $DIR/ptr_null_checks.rs:53:8 | LL | if (ref_num as *const i32) == std::ptr::null() {} | ^-------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ @@ -104,7 +152,7 @@ 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:39:8 + --> $DIR/ptr_null_checks.rs:55:8 | LL | if (b"\0" as *const u8).is_null() {} | ^-----^^^^^^^^^^^^^^^^^^^^^^^^ @@ -112,7 +160,7 @@ 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:41:8 + --> $DIR/ptr_null_checks.rs:57:8 | LL | if ("aa" as *const str).is_null() {} | ^----^^^^^^^^^^^^^^^^^^^^^^^^^ @@ -120,7 +168,7 @@ 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:43:8 + --> $DIR/ptr_null_checks.rs:59:8 | LL | if (&[1, 2] as *const i32).is_null() {} | ^-------^^^^^^^^^^^^^^^^^^^^^^^^^ @@ -128,7 +176,7 @@ 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:45:8 + --> $DIR/ptr_null_checks.rs:61:8 | LL | if (&mut [1, 2] as *mut i32) == std::ptr::null_mut() {} | ^-----------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ @@ -136,7 +184,7 @@ 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:47:8 + --> $DIR/ptr_null_checks.rs:63:8 | LL | if (static_i32() as *const i32).is_null() {} | ^------------^^^^^^^^^^^^^^^^^^^^^^^^^ @@ -144,12 +192,12 @@ 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:49:8 + --> $DIR/ptr_null_checks.rs:65:8 | LL | if (&*{ static_i32() } as *const i32).is_null() {} | ^------------------^^^^^^^^^^^^^^^^^^^^^^^^^ | | | expression has type `&i32` -warning: 19 warnings emitted +warning: 25 warnings emitted