-use crate::consts::{constant_context, Constant};
+use clippy_utils::consts::{constant_context, Constant};
use clippy_utils::diagnostics::span_lint;
-use clippy_utils::{match_qpath, paths};
+use clippy_utils::is_expr_diagnostic_item;
use if_chain::if_chain;
use rustc_ast::LitKind;
use rustc_hir::{Expr, ExprKind};
use rustc_lint::{LateContext, LateLintPass, LintContext};
use rustc_middle::lint::in_external_macro;
use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::symbol::sym;
declare_clippy_lint! {
- /// **What it does:** Checks for transmute calls which would receive a null pointer.
+ /// ### What it does
+ /// Checks for transmute calls which would receive a null pointer.
///
- /// **Why is this bad?** Transmuting a null pointer is undefined behavior.
+ /// ### Why is this bad?
+ /// Transmuting a null pointer is undefined behavior.
///
- /// **Known problems:** Not all cases can be detected at the moment of this writing.
+ /// ### Known problems
+ /// Not all cases can be detected at the moment of this writing.
/// For example, variables which hold a null pointer and are then fed to a `transmute`
/// call, aren't detectable yet.
///
- /// **Example:**
+ /// ### Example
/// ```rust
/// let null_ref: &u64 = unsafe { std::mem::transmute(0 as *const u64) };
/// ```
+ #[clippy::version = "1.35.0"]
pub TRANSMUTING_NULL,
correctness,
"transmutes from a null pointer to a reference, which is undefined behavior"
}
if_chain! {
- if let ExprKind::Call(func, args) = expr.kind;
- if let ExprKind::Path(ref path) = func.kind;
- if match_qpath(path, &paths::STD_MEM_TRANSMUTE);
- if args.len() == 1;
+ if let ExprKind::Call(func, [arg]) = expr.kind;
+ if is_expr_diagnostic_item(cx, func, sym::transmute);
then {
-
// Catching transmute over constants that resolve to `null`.
let mut const_eval_context = constant_context(cx, cx.typeck_results());
if_chain! {
- if let ExprKind::Path(ref _qpath) = args[0].kind;
- let x = const_eval_context.expr(&args[0]);
- if let Some(Constant::RawPtr(0)) = x;
+ if let ExprKind::Path(ref _qpath) = arg.kind;
+ if let Some(Constant::RawPtr(x)) = const_eval_context.expr(arg);
+ if x == 0;
then {
span_lint(cx, TRANSMUTING_NULL, expr.span, LINT_MSG)
}
// Catching:
// `std::mem::transmute(0 as *const i32)`
if_chain! {
- if let ExprKind::Cast(inner_expr, _cast_ty) = args[0].kind;
+ if let ExprKind::Cast(inner_expr, _cast_ty) = arg.kind;
if let ExprKind::Lit(ref lit) = inner_expr.kind;
if let LitKind::Int(0, _) = lit.node;
then {
// Catching:
// `std::mem::transmute(std::ptr::null::<i32>())`
if_chain! {
- if let ExprKind::Call(func1, args1) = args[0].kind;
- if let ExprKind::Path(ref path1) = func1.kind;
- if match_qpath(path1, &paths::STD_PTR_NULL);
- if args1.is_empty();
+ if let ExprKind::Call(func1, []) = arg.kind;
+ if is_expr_diagnostic_item(cx, func1, sym::ptr_null);
then {
span_lint(cx, TRANSMUTING_NULL, expr.span, LINT_MSG)
}