Better handle method/function calls

[rust.git] / clippy_lints / src / transmuting_null.rs

diff --git a/clippy_lints/src/transmuting_null.rs b/clippy_lints/src/transmuting_null.rs
index 5bbaeedad5f0db8963a47758d0acd618b7229f7a..7939dfedc3a2b4fb6d39555f29a3596828895861 100644 (file)
--- a/clippy_lints/src/transmuting_null.rs
+++ b/clippy_lints/src/transmuting_null.rs
@@ -1,6 +1,6 @@
 use clippy_utils::consts::{constant_context, Constant};
 use clippy_utils::diagnostics::span_lint;
-use clippy_utils::{is_expr_diagnostic_item, is_expr_path_def_path, paths};
+use clippy_utils::is_expr_diagnostic_item;
 use if_chain::if_chain;
 use rustc_ast::LitKind;
 use rustc_hir::{Expr, ExprKind};
@@ -10,18 +10,22 @@
 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"
@@ -39,15 +43,15 @@ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
 
         if_chain! {
             if let ExprKind::Call(func, [arg]) = expr.kind;
-            if is_expr_path_def_path(cx, func, &paths::TRANSMUTE);
+            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) = arg.kind;
-                    let x = const_eval_context.expr(arg);
-                    if let Some(Constant::RawPtr(0)) = x;
+                    if let Some(Constant::RawPtr(x)) = const_eval_context.expr(arg);
+                    if x == 0;
                     then {
                         span_lint(cx, TRANSMUTING_NULL, expr.span, LINT_MSG)
                     }