1 files changed, 77 insertions, 0 deletions
diff --git a/src/tools/clippy/clippy_lints/src/disallowed_names.rs b/src/tools/clippy/clippy_lints/src/disallowed_names.rs
new file mode 100644
index 000000000..6e6615f08
--- /dev/null
+++ b/src/tools/clippy/clippy_lints/src/disallowed_names.rs
@@ -0,0 +1,77 @@
+use clippy_utils::{diagnostics::span_lint, is_test_module_or_function};
+use rustc_data_structures::fx::FxHashSet;
+use rustc_hir::{Item, Pat, PatKind};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_tool_lint, impl_lint_pass};
+
+declare_clippy_lint! {
+    /// ### What it does
+    /// Checks for usage of disallowed names for variables, such
+    /// as `foo`.
+    ///
+    /// ### Why is this bad?
+    /// These names are usually placeholder names and should be
+    /// avoided.
+    ///
+    /// ### Example
+    /// ```rust
+    /// let foo = 3.14;
+    /// ```
+    #[clippy::version = "pre 1.29.0"]
+    pub DISALLOWED_NAMES,
+    style,
+    "usage of a disallowed/placeholder name"
+}
+
+#[derive(Clone, Debug)]
+pub struct DisallowedNames {
+    disallow: FxHashSet<String>,
+    test_modules_deep: u32,
+}
+
+impl DisallowedNames {
+    pub fn new(disallow: FxHashSet<String>) -> Self {
+        Self {
+            disallow,
+            test_modules_deep: 0,
+        }
+    }
+
+    fn in_test_module(&self) -> bool {
+        self.test_modules_deep != 0
+    }
+}
+
+impl_lint_pass!(DisallowedNames => [DISALLOWED_NAMES]);
+
+impl<'tcx> LateLintPass<'tcx> for DisallowedNames {
+    fn check_item(&mut self, cx: &LateContext<'_>, item: &Item<'_>) {
+        if is_test_module_or_function(cx.tcx, item) {
+            self.test_modules_deep = self.test_modules_deep.saturating_add(1);
+        }
+    }
+
+    fn check_pat(&mut self, cx: &LateContext<'tcx>, pat: &'tcx Pat<'_>) {
+        // Check whether we are under the `test` attribute.
+        if self.in_test_module() {
+            return;
+        }
+
+        if let PatKind::Binding(.., ident, _) = pat.kind {
+            if self.disallow.contains(&ident.name.to_string()) {
+                span_lint(
+                    cx,
+                    DISALLOWED_NAMES,
+                    ident.span,
+                    &format!("use of a disallowed/placeholder name `{}`", ident.name),
+                );
+            }
+        }
+    }
+
+    fn check_item_post(&mut self, cx: &LateContext<'_>, item: &Item<'_>) {
+        if is_test_module_or_function(cx.tcx, item) {
+            self.test_modules_deep = self.test_modules_deep.saturating_sub(1);
+        }
+    }
+}