ignore usage in same expr temporary_cstring_as_ptr

Fixes: rust-lang#5838
wiomoc · Aug 16, 2020 · dc74fd0 · dc74fd0
1 parent 3bd9889
commit dc74fd0
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Showing 3 changed files with 19 additions and 7 deletions.
diff --git a/clippy_lints/src/methods/mod.rs b/clippy_lints/src/methods/mod.rs
@@ -2165,6 +2165,13 @@ fn lint_cstring_as_ptr(cx: &LateContext<'_>, expr: &hir::Expr<'_>, source: &hir:
         if cx.tcx.is_diagnostic_item(sym!(result_type), def.did);
         if match_type(cx, substs.type_at(0), &paths::CSTRING);
         then {
+            // Ignore, if ptr is used in a call in the same expression #5838
+            if let Some((_, hir::Node::Expr(parent_expr))) = cx.tcx.hir().parent_iter(expr.hir_id).next() {
+                if let hir::ExprKind::Call(_, _) = parent_expr.kind {
+                    return;
+                }
+            }
+
             span_lint_and_then(
                 cx,
                 TEMPORARY_CSTRING_AS_PTR,

diff --git a/tests/ui/cstring.rs b/tests/ui/cstring.rs
@@ -17,8 +17,13 @@ mod issue4375 {
         fn foo(data: *const c_char);
     }
 
-    pub fn bar(v: &[u8]) {
+    pub fn bar_ok(v: &[u8]) {
         let cstr = CString::new(v);
         unsafe { foo(cstr.unwrap().as_ptr()) }
     }
+
+    pub fn bar_bad(v: &[u8]) {
+        let c_str = CString::new(v).unwrap().as_ptr();
+        unsafe { foo(c_str) }
+    }
 }
diff --git a/tests/ui/cstring.stderr b/tests/ui/cstring.stderr
@@ -30,17 +30,17 @@ LL |     CString::new("foo").expect("dummy").as_ptr();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: you are getting the inner pointer of a temporary `CString`
-  --> $DIR/cstring.rs:22:22
+  --> $DIR/cstring.rs:26:21
    |
-LL |         unsafe { foo(cstr.unwrap().as_ptr()) }
-   |                      ^^^^^^^^^^^^^^^^^^^^^^
+LL |         let c_str = CString::new(v).unwrap().as_ptr();
+   |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: that pointer will be invalid outside this expression
 help: assign the `CString` to a variable to extend its lifetime
-  --> $DIR/cstring.rs:22:22
+  --> $DIR/cstring.rs:26:21
    |
-LL |         unsafe { foo(cstr.unwrap().as_ptr()) }
-   |                      ^^^^^^^^^^^^^
+LL |         let c_str = CString::new(v).unwrap().as_ptr();
+   |                     ^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to 3 previous errors