5 /// Test that we lint if we use a binding with a single leading underscore
6 fn prefix_underscore(_foo: u32) -> u32 {
7 _foo + 1 //~ ERROR used binding which is prefixed with an underscore
10 /// Test that we lint even if the use is within a macro expansion
11 fn in_macro(_foo: u32) {
12 println!("{}", _foo); //~ ERROR used binding which is prefixed with an underscore
15 // Struct for testing use of fields prefixed with an underscore
16 struct StructFieldTest {
17 _underscore_field: u32,
20 /// Test that we lint the use of a struct field which is prefixed with an underscore
21 fn in_struct_field() {
22 let mut s = StructFieldTest { _underscore_field: 0 };
23 s._underscore_field += 1; //~ Error used binding which is prefixed with an underscore
26 /// Test that we do not lint if the underscore is not a prefix
27 fn non_prefix_underscore(some_foo: u32) -> u32 {
31 /// Test that we do not lint if we do not use the binding (simple case)
32 fn unused_underscore_simple(_foo: u32) -> u32 {
36 /// Test that we do not lint if we do not use the binding (complex case). This checks for
37 /// compatibility with the built-in `unused_variables` lint.
38 fn unused_underscore_complex(mut _foo: u32) -> u32 {
44 ///Test that we do not lint for multiple underscores
45 fn multiple_underscores(__foo: u32) -> u32 {
49 // Non-variable bindings with preceding underscore
57 /// Test that we do not lint for non-variable bindings
61 let _e = match _EnumTest::_Value(_StructTest) {
62 _EnumTest::_Empty => 0,
63 _EnumTest::_Value(_st) => 1,
71 // tests of unused_underscore lint
72 let _ = prefix_underscore(foo);
75 // possible false positives
76 let _ = non_prefix_underscore(foo);
77 let _ = unused_underscore_simple(foo);
78 let _ = unused_underscore_complex(foo);
79 let _ = multiple_underscores(foo);