do the same for Calls

Author: ada4a

clippy_lints/src/no_effect.rs

@@ -382,6 +382,11 @@ fn reduce_expression<'a>(
             }
         },
         ExprKind::Call(callee, args) => {
+            if args.iter().any(|a| !expr_type_is_certain(cx, a)) {
+                // there's a risk that if we take the args out of the context of the
+                // call/constructor, their types might become ambiguous
+                *applicability = Applicability::MaybeIncorrect;
+            }
             if let ExprKind::Path(ref qpath) = callee.kind {
                 if cx.typeck_results().type_dependent_def(expr.hir_id).is_some() {
                     // type-dependent function call like `impl FnOnce for X`

tests/ui/unnecessary_operation_unfixable.rs

@@ -8,6 +8,21 @@ fn issue15381() {
         slots: Vec<u32>,
     }
 
+    // the repro
     DescriptorSet { slots: Vec::new() };
     //~^ unnecessary_operation
+
+    // other cases
+    enum E {
+        Foo { f: Vec<u32> },
+        Bar(Vec<u32>),
+    }
+    E::Foo { f: Vec::new() };
+    //~^ unnecessary_operation
+    E::Bar(Vec::new());
+    //~^ unnecessary_operation
+
+    struct Tuple(Vec<u32>);
+    Tuple(Vec::new());
+    //~^ unnecessary_operation
 }

tests/ui/unnecessary_operation_unfixable.stderr

@@ -1,11 +1,29 @@
 error: unnecessary operation
-  --> tests/ui/unnecessary_operation_unfixable.rs:11:5
+  --> tests/ui/unnecessary_operation_unfixable.rs:12:5
    |
 LL |     DescriptorSet { slots: Vec::new() };
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: statement can be reduced to: `Vec::new();`
    |
    = note: `-D clippy::unnecessary-operation` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::unnecessary_operation)]`
 
-error: aborting due to 1 previous error
+error: unnecessary operation
+  --> tests/ui/unnecessary_operation_unfixable.rs:20:5
+   |
+LL |     E::Foo { f: Vec::new() };
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^ help: statement can be reduced to: `Vec::new();`
+
+error: unnecessary operation
+  --> tests/ui/unnecessary_operation_unfixable.rs:22:5
+   |
+LL |     E::Bar(Vec::new());
+   |     ^^^^^^^^^^^^^^^^^^^ help: statement can be reduced to: `Vec::new();`
+
+error: unnecessary operation
+  --> tests/ui/unnecessary_operation_unfixable.rs:26:5
+   |
+LL |     Tuple(Vec::new());
+   |     ^^^^^^^^^^^^^^^^^^ help: statement can be reduced to: `Vec::new();`
+
+error: aborting due to 4 previous errors