diff --git a/compiler/rustc_lint/messages.ftl b/compiler/rustc_lint/messages.ftl index c4a7f717840..61f68db2cc0 100644 --- a/compiler/rustc_lint/messages.ftl +++ b/compiler/rustc_lint/messages.ftl @@ -457,6 +457,8 @@ lint_ptr_null_checks_fn_ptr = function pointers are not nullable, so checking th .help = wrap the function pointer inside an `Option` and use `Option::is_none` to check for null pointer value .label = expression has type `{$orig_ty}` +lint_ptr_null_checks_fn_ret = returned pointer of `{$fn_name}` call is never null, so checking it for null will always return false + lint_ptr_null_checks_ref = references are not nullable, so checking them for null will always return false .label = expression has type `{$orig_ty}` diff --git a/compiler/rustc_lint/src/lints.rs b/compiler/rustc_lint/src/lints.rs index 70311a5c576..049a7c3f7fa 100644 --- a/compiler/rustc_lint/src/lints.rs +++ b/compiler/rustc_lint/src/lints.rs @@ -634,6 +634,8 @@ pub enum PtrNullChecksDiag<'a> { #[label] label: Span, }, + #[diag(lint_ptr_null_checks_fn_ret)] + FnRet { fn_name: Ident }, } // for_loops_over_fallibles.rs diff --git a/compiler/rustc_lint/src/ptr_nulls.rs b/compiler/rustc_lint/src/ptr_nulls.rs index 52d8099091a..0de72d8d3db 100644 --- a/compiler/rustc_lint/src/ptr_nulls.rs +++ b/compiler/rustc_lint/src/ptr_nulls.rs @@ -31,12 +31,30 @@ declare_lint! { 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>> { +/// This function checks if the expression is from a series of consecutive casts, +/// ie. `(my_fn as *const _ as *mut _).cast_mut()` and whether the original expression is either +/// a fn ptr, a reference, or a function call whose definition is +/// annotated with `#![rustc_never_returns_null_ptr]`. +/// If this situation is present, the function returns the appropriate diagnostic. +fn incorrect_check<'a, 'tcx: 'a>( + cx: &'a LateContext<'tcx>, + mut e: &'a Expr<'a>, +) -> Option> { let mut had_at_least_one_cast = false; loop { e = e.peel_blocks(); + if let ExprKind::MethodCall(_, _expr, [], _) = e.kind + && let Some(def_id) = cx.typeck_results().type_dependent_def_id(e.hir_id) + && cx.tcx.has_attr(def_id, sym::rustc_never_returns_null_ptr) + && let Some(fn_name) = cx.tcx.opt_item_ident(def_id) { + return Some(PtrNullChecksDiag::FnRet { fn_name }); + } else if let ExprKind::Call(path, _args) = e.kind + && let ExprKind::Path(ref qpath) = path.kind + && let Some(def_id) = cx.qpath_res(qpath, path.hir_id).opt_def_id() + && cx.tcx.has_attr(def_id, sym::rustc_never_returns_null_ptr) + && let Some(fn_name) = cx.tcx.opt_item_ident(def_id) { + return Some(PtrNullChecksDiag::FnRet { fn_name }); + } e = if let ExprKind::Cast(expr, t) = e.kind && let TyKind::Ptr(_) = t.kind { had_at_least_one_cast = true; @@ -46,33 +64,21 @@ fn ptr_cast_chain<'a>(cx: &'a LateContext<'_>, mut e: &'a Expr<'a>) -> Option<&' && 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() - && cx.tcx.has_attr(def_id, sym::rustc_never_returns_null_ptr) { - had_at_least_one_cast = true; - arg } else if had_at_least_one_cast { - return Some(e); + let orig_ty = cx.typeck_results().expr_ty(e); + return if orig_ty.is_fn() { + Some(PtrNullChecksDiag::FnPtr { orig_ty, label: e.span }) + } else if orig_ty.is_ref() { + Some(PtrNullChecksDiag::Ref { orig_ty, label: e.span }) + } else { + None + }; } else { 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 { 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 { diff --git a/tests/ui/lint/ptr_null_checks.rs b/tests/ui/lint/ptr_null_checks.rs index e677ea3094d..3028084e962 100644 --- a/tests/ui/lint/ptr_null_checks.rs +++ b/tests/ui/lint/ptr_null_checks.rs @@ -38,15 +38,15 @@ fn main() { 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 + //~^ WARN call is never null if (&8 as *const i32).is_null() {} //~^ WARN references are not nullable if ptr::from_ref(&8).is_null() {} - //~^ WARN references are not nullable + //~^ WARN call is never null if ptr::from_ref(&8).cast_mut().is_null() {} - //~^ WARN references are not nullable + //~^ WARN call is never null if (ptr::from_ref(&8).cast_mut() as *mut i32).is_null() {} - //~^ WARN references are not nullable + //~^ WARN call is never null if (&8 as *const i32) == std::ptr::null() {} //~^ WARN references are not nullable let ref_num = &8; @@ -65,6 +65,12 @@ fn main() { if (&*{ static_i32() } as *const i32).is_null() {} //~^ WARN references are not nullable + // ---------------- Functions ------------------- + if ptr::NonNull::new(&mut 8).unwrap().as_ptr().is_null() {} + //~^ WARN call is never null + if ptr::NonNull::::dangling().as_ptr().is_null() {} + //~^ WARN call is never null + // ---------------------------------------------- const ZPTR: *const () = 0 as *const _; const NOT_ZPTR: *const () = 1 as *const _; diff --git a/tests/ui/lint/ptr_null_checks.stderr b/tests/ui/lint/ptr_null_checks.stderr index 3cee1804b62..0edc1b86536 100644 --- a/tests/ui/lint/ptr_null_checks.stderr +++ b/tests/ui/lint/ptr_null_checks.stderr @@ -117,13 +117,11 @@ 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 +warning: returned pointer of `from_mut` call is never null, so checking it 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 @@ -133,29 +131,23 @@ 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 +warning: returned pointer of `from_ref` call is never null, so checking it 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 +warning: returned pointer of `from_ref` call is never null, so checking it 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 +warning: returned pointer of `from_ref` call is never null, so checking it 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 @@ -221,5 +213,17 @@ LL | if (&*{ static_i32() } as *const i32).is_null() {} | | | expression has type `&i32` -warning: 25 warnings emitted +warning: returned pointer of `as_ptr` call is never null, so checking it for null will always return false + --> $DIR/ptr_null_checks.rs:69:8 + | +LL | if ptr::NonNull::new(&mut 8).unwrap().as_ptr().is_null() {} + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +warning: returned pointer of `as_ptr` call is never null, so checking it for null will always return false + --> $DIR/ptr_null_checks.rs:71:8 + | +LL | if ptr::NonNull::::dangling().as_ptr().is_null() {} + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +warning: 27 warnings emitted