bendns' repos / rust-analyzer
Unnamed repository; edit this file 'description' to name the repository.
Diffstat (limited to 'crates/ide-diagnostics/src/handlers/unused_variables.rs')
-rw-r--r--crates/ide-diagnostics/src/handlers/unused_variables.rs111
1 files changed, 111 insertions, 0 deletions
diff --git a/crates/ide-diagnostics/src/handlers/unused_variables.rs b/crates/ide-diagnostics/src/handlers/unused_variables.rs
new file mode 100644
index 0000000000..28ccf474b4
--- /dev/null
+++ b/crates/ide-diagnostics/src/handlers/unused_variables.rs
@@ -0,0 +1,111 @@
+use crate::{Diagnostic, DiagnosticCode, DiagnosticsContext};
+
+// Diagnostic: unused-variables
+//
+// This diagnostic is triggered when a local variable is not used.
+pub(crate) fn unused_variables(
+ ctx: &DiagnosticsContext<'_>,
+ d: &hir::UnusedVariable,
+) -> Diagnostic {
+ let ast = d.local.primary_source(ctx.sema.db).syntax_ptr();
+ Diagnostic::new_with_syntax_node_ptr(
+ ctx,
+ DiagnosticCode::RustcLint("unused_variables"),
+ "unused variable",
+ ast,
+ )
+ .experimental()
+}
+
+#[cfg(test)]
+mod tests {
+ use crate::tests::check_diagnostics;
+
+ #[test]
+ fn unused_variables_simple() {
+ check_diagnostics(
+ r#"
+//- minicore: fn
+struct Foo { f1: i32, f2: i64 }
+
+fn f(kkk: i32) {}
+ //^^^ warn: unused variable
+fn main() {
+ let a = 2;
+ //^ warn: unused variable
+ let b = 5;
+ // note: `unused variable` implies `unused mut`, so we should not emit both at the same time.
+ let mut c = f(b);
+ //^^^^^ warn: unused variable
+ let (d, e) = (3, 5);
+ //^ warn: unused variable
+ let _ = e;
+ let f1 = 2;
+ let f2 = 5;
+ let f = Foo { f1, f2 };
+ match f {
+ Foo { f1, f2 } => {
+ //^^ warn: unused variable
+ _ = f2;
+ }
+ }
+ let g = false;
+ if g {}
+ let h: fn() -> i32 = || 2;
+ let i = h();
+ //^ warn: unused variable
+}
+"#,
+ );
+ }
+
+ #[test]
+ fn unused_self() {
+ check_diagnostics(
+ r#"
+struct S {
+}
+impl S {
+ fn owned_self(self, u: i32) {}
+ //^ warn: unused variable
+ fn ref_self(&self, u: i32) {}
+ //^ warn: unused variable
+ fn ref_mut_self(&mut self, u: i32) {}
+ //^ warn: unused variable
+ fn owned_mut_self(mut self) {}
+ //^^^^^^^^ 💡 warn: variable does not need to be mutable
+
+}
+"#,
+ );
+ }
+
+ #[test]
+ fn allow_unused_variables_for_identifiers_starting_with_underline() {
+ check_diagnostics(
+ r#"
+fn main() {
+ let _x = 2;
+}
+"#,
+ );
+ }
+
+ #[test]
+ fn respect_lint_attributes_for_unused_variables() {
+ check_diagnostics(
+ r#"
+fn main() {
+ #[allow(unused_variables)]
+ let x = 2;
+}
+
+#[deny(unused)]
+fn main2() {
+ let x = 2;
+ //^ error: unused variable
+}
+"#,
+ );
+ }
+}