119 lines
2.9 KiB
Rust
119 lines
2.9 KiB
Rust
// edition:2018
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// aux-build:proc_macro_derive.rs
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#![feature(rustc_private)]
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#![warn(clippy::all)]
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#![allow(clippy::blacklisted_name, clippy::eq_op)]
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#![warn(clippy::used_underscore_binding)]
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#[macro_use]
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extern crate proc_macro_derive;
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// This should not trigger the lint. There's underscore binding inside the external derive that
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// would trigger the `used_underscore_binding` lint.
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#[derive(DeriveSomething)]
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struct Baz;
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macro_rules! test_macro {
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() => {{
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let _foo = 42;
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_foo + 1
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}};
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}
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/// Tests that we lint if we use a binding with a single leading underscore
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fn prefix_underscore(_foo: u32) -> u32 {
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_foo + 1
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}
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/// Tests that we lint if we use a `_`-variable defined outside within a macro expansion
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fn in_macro_or_desugar(_foo: u32) {
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println!("{}", _foo);
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assert_eq!(_foo, _foo);
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test_macro!() + 1;
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}
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// Struct for testing use of fields prefixed with an underscore
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struct StructFieldTest {
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_underscore_field: u32,
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}
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/// Tests that we lint the use of a struct field which is prefixed with an underscore
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fn in_struct_field() {
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let mut s = StructFieldTest { _underscore_field: 0 };
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s._underscore_field += 1;
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}
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/// Tests that we do not lint if the underscore is not a prefix
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fn non_prefix_underscore(some_foo: u32) -> u32 {
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some_foo + 1
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}
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/// Tests that we do not lint if we do not use the binding (simple case)
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fn unused_underscore_simple(_foo: u32) -> u32 {
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1
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}
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/// Tests that we do not lint if we do not use the binding (complex case). This checks for
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/// compatibility with the built-in `unused_variables` lint.
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fn unused_underscore_complex(mut _foo: u32) -> u32 {
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_foo += 1;
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_foo = 2;
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1
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}
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/// Test that we do not lint for multiple underscores
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fn multiple_underscores(__foo: u32) -> u32 {
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__foo + 1
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}
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// Non-variable bindings with preceding underscore
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fn _fn_test() {}
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struct _StructTest;
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enum _EnumTest {
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_Empty,
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_Value(_StructTest),
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}
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/// Tests that we do not lint for non-variable bindings
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fn non_variables() {
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_fn_test();
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let _s = _StructTest;
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let _e = match _EnumTest::_Value(_StructTest) {
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_EnumTest::_Empty => 0,
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_EnumTest::_Value(_st) => 1,
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};
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let f = _fn_test;
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f();
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}
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// Tests that we do not lint if the binding comes from await desugaring,
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// but we do lint the awaited expression. See issue 5360.
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async fn await_desugaring() {
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async fn foo() {}
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fn uses_i(_i: i32) {}
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foo().await;
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({
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let _i = 5;
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uses_i(_i);
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foo()
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})
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.await
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}
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fn main() {
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let foo = 0u32;
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// tests of unused_underscore lint
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let _ = prefix_underscore(foo);
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in_macro_or_desugar(foo);
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in_struct_field();
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// possible false positives
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let _ = non_prefix_underscore(foo);
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let _ = unused_underscore_simple(foo);
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let _ = unused_underscore_complex(foo);
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let _ = multiple_underscores(foo);
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non_variables();
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await_desugaring();
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}
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