Don't lint unit args if expression kind is path

Author: mdm

clippy_lints/src/types.rs

@@ -955,16 +955,10 @@ impl<'tcx> LateLintPass<'tcx> for UnitArg {
                     .iter()
                     .filter(|arg| {
                         if is_unit(cx.typeck_results().expr_ty(arg)) && !is_unit_literal(arg) {
-                            match &arg.kind {
-                                ExprKind::Block(..)
-                                | ExprKind::Call(..)
-                                | ExprKind::If(..)
-                                | ExprKind::MethodCall(..) => true,
-                                ExprKind::Match(..) => {
-                                    !matches!(&arg.kind, ExprKind::Match(.., MatchSource::TryDesugar))
-                                },
-                                _ => false,
-                            }
+                            !matches!(
+                                &arg.kind,
+                                ExprKind::Match(.., MatchSource::TryDesugar) | ExprKind::Path(..)
+                            )
                         } else {
                             false
                         }

tests/ui/unit_arg.rs

@@ -27,6 +27,10 @@ impl Bar {
     }
 }
 
+fn baz<T: Debug>(t: T) {
+    foo(t);
+}
+
 fn bad() {
     foo({
         1;
@@ -73,6 +77,7 @@ fn ok() {
     question_mark();
     let named_unit_arg = ();
     foo(named_unit_arg);
+    baz(());
 }
 
 fn question_mark() -> Result<(), ()> {

tests/ui/unit_arg.stderr

@@ -1,5 +1,5 @@
 error: passing a unit value to a function
-  --> $DIR/unit_arg.rs:31:5
+  --> $DIR/unit_arg.rs:35:5
    |
 LL | /     foo({
 LL | |         1;
@@ -20,7 +20,7 @@ LL |     foo(());
    |
 
 error: passing a unit value to a function
-  --> $DIR/unit_arg.rs:34:5
+  --> $DIR/unit_arg.rs:38:5
    |
 LL |     foo(foo(1));
    |     ^^^^^^^^^^^
@@ -32,7 +32,7 @@ LL |     foo(());
    |
 
 error: passing a unit value to a function
-  --> $DIR/unit_arg.rs:35:5
+  --> $DIR/unit_arg.rs:39:5
    |
 LL | /     foo({
 LL | |         foo(1);
@@ -54,7 +54,7 @@ LL |     foo(());
    |
 
 error: passing a unit value to a function
-  --> $DIR/unit_arg.rs:40:5
+  --> $DIR/unit_arg.rs:44:5
    |
 LL | /     b.bar({
 LL | |         1;
@@ -74,7 +74,7 @@ LL |     b.bar(());
    |
 
 error: passing unit values to a function
-  --> $DIR/unit_arg.rs:43:5
+  --> $DIR/unit_arg.rs:47:5
    |
 LL |     taking_multiple_units(foo(0), foo(1));
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -87,7 +87,7 @@ LL |     taking_multiple_units((), ());
    |
 
 error: passing unit values to a function
-  --> $DIR/unit_arg.rs:44:5
+  --> $DIR/unit_arg.rs:48:5
    |
 LL | /     taking_multiple_units(foo(0), {
 LL | |         foo(1);
@@ -110,7 +110,7 @@ LL |     taking_multiple_units((), ());
    |
 
 error: passing unit values to a function
-  --> $DIR/unit_arg.rs:48:5
+  --> $DIR/unit_arg.rs:52:5
    |
 LL | /     taking_multiple_units(
 LL | |         {
@@ -140,7 +140,7 @@ LL |         foo(2);
  ...
 
 error: passing a unit value to a function
-  --> $DIR/unit_arg.rs:59:13
+  --> $DIR/unit_arg.rs:63:13
    |
 LL |     None.or(Some(foo(2)));
    |             ^^^^^^^^^^^^
@@ -154,7 +154,7 @@ LL |     });
    |
 
 error: passing a unit value to a function
-  --> $DIR/unit_arg.rs:62:5
+  --> $DIR/unit_arg.rs:66:5
    |
 LL |     foo(foo(()));
    |     ^^^^^^^^^^^^
@@ -166,7 +166,7 @@ LL |     foo(());
    |
 
 error: passing a unit value to a function
-  --> $DIR/unit_arg.rs:97:5
+  --> $DIR/unit_arg.rs:102:5
    |
 LL |     Some(foo(1))
    |     ^^^^^^^^^^^^