Exclude generated code

clippy_lints/src/default_trait_access.rs

@@ -1,7 +1,8 @@
 use rustc::hir::*;
 use rustc::lint::*;
+use rustc::ty::TypeVariants;
 
-use crate::utils::{match_def_path, opt_def_id, paths, span_lint_and_sugg};
+use crate::utils::{any_parent_is_automatically_derived, match_def_path, opt_def_id, paths, span_lint_and_sugg};
 
 
 /// **What it does:** Checks for literal calls to `Default::default()`.
@@ -38,6 +39,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for DefaultTraitAccess {
     fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
         if_chain! {
             if let ExprCall(ref path, ..) = expr.node;
+            if !any_parent_is_automatically_derived(cx.tcx, expr.id);
             if let ExprPath(ref qpath) = path.node;
             if let Some(def_id) = opt_def_id(cx.tables.qpath_def(qpath, path.hir_id));
             if match_def_path(cx.tcx, def_id, &paths::DEFAULT_TRAIT_METHOD);
@@ -46,14 +48,17 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for DefaultTraitAccess {
                     QPath::Resolved(..) => {
                         // TODO: Work out a way to put "whatever the imported way of referencing
                         // this type in this file" rather than a fully-qualified type.
-                        let replacement = format!("{}::default()", cx.tables.expr_ty(expr));
-                        span_lint_and_sugg(
-                            cx,
-                            DEFAULT_TRAIT_ACCESS,
-                            expr.span,
-                            &format!("Calling {} is more clear than this expression", replacement),
-                            "try",
-                            replacement);
+                        let expr_ty = cx.tables.expr_ty(expr);
+                        if let TypeVariants::TyAdt(..) = expr_ty.sty {
+                            let replacement = format!("{}::default()", expr_ty);
+                            span_lint_and_sugg(
+                                cx,
+                                DEFAULT_TRAIT_ACCESS,
+                                expr.span,
+                                &format!("Calling {} is more clear than this expression", replacement),
+                                "try",
+                                replacement);
+                         }
                     },
                     QPath::TypeRelative(..) => {},
                 }

clippy_lints/src/utils/mod.rs

@@ -1128,3 +1128,17 @@ pub fn without_block_comments(lines: Vec<&str>) -> Vec<&str> {
 
     without
 }
+
+pub fn any_parent_is_automatically_derived(tcx: TyCtxt, node: NodeId) -> bool {
+    let map = &tcx.hir;
+    let mut prev_enclosing_node = None;
+    let mut enclosing_node = node;
+    while Some(enclosing_node) != prev_enclosing_node {
+        if is_automatically_derived(map.attrs(enclosing_node)) {
+            return true;
+        }
+        prev_enclosing_node = Some(enclosing_node);
+        enclosing_node = map.get_parent(enclosing_node);
+    }
+    false
+}

tests/ui/default_trait_access.rs

@@ -23,7 +23,45 @@ fn main() {
 
     let s9: String = DefaultFactory::make_t_nicely();
 
-    println!("[{}] [{}] [{}] [{}] [{}] [{}] [{}] [{}] [{}]", s1, s2, s3, s4, s5, s6, s7, s8, s9);
+    let s10 = DerivedDefault::default();
+
+    let s11: GenericDerivedDefault<String> = Default::default();
+
+    let s12 = GenericDerivedDefault::<String>::default();
+
+    let s13 = TupleDerivedDefault::default();
+
+    let s14: TupleDerivedDefault = Default::default();
+
+    let s15: ArrayDerivedDefault = Default::default();
+
+    let s16 = ArrayDerivedDefault::default();
+
+    let s17: TupleStructDerivedDefault = Default::default();
+
+    let s18 = TupleStructDerivedDefault::default();
+
+    println!(
+        "[{}] [{}] [{}] [{}] [{}] [{}] [{}] [{}] [{}] [{:?}] [{:?}] [{:?}] [{:?}] [{:?}] [{:?}] [{:?}] [{:?}] [{:?}]",
+        s1,
+        s2,
+        s3,
+        s4,
+        s5,
+        s6,
+        s7,
+        s8,
+        s9,
+        s10,
+        s11,
+        s12,
+        s13,
+        s14,
+        s15,
+        s16,
+        s17,
+        s18,
+    );
 }
 
 struct DefaultFactory;
@@ -37,3 +75,26 @@ impl DefaultFactory {
         T::default()
     }
 }
+
+#[derive(Debug, Default)]
+struct DerivedDefault {
+    pub s: String,
+}
+
+#[derive(Debug, Default)]
+struct GenericDerivedDefault<T: Default + std::fmt::Debug> {
+    pub s: T,
+}
+
+#[derive(Debug, Default)]
+struct TupleDerivedDefault {
+    pub s: (String, String),
+}
+
+#[derive(Debug, Default)]
+struct ArrayDerivedDefault {
+    pub s: [String; 10],
+}
+
+#[derive(Debug, Default)]
+struct TupleStructDerivedDefault(String);

tests/ui/default_trait_access.stderr

@@ -24,11 +24,29 @@ error: Calling std::string::String::default() is more clear than this expression
 18 |     let s6: String = default::Default::default();
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `std::string::String::default()`
 
-error: Calling T::default() is more clear than this expression
-  --> $DIR/default_trait_access.rs:33:9
+error: Calling GenericDerivedDefault<std::string::String>::default() is more clear than this expression
+  --> $DIR/default_trait_access.rs:28:46
    |
-33 |         Default::default()
-   |         ^^^^^^^^^^^^^^^^^^ help: try: `T::default()`
+28 |     let s11: GenericDerivedDefault<String> = Default::default();
+   |                                              ^^^^^^^^^^^^^^^^^^ help: try: `GenericDerivedDefault<std::string::String>::default()`
 
-error: aborting due to 5 previous errors
+error: Calling TupleDerivedDefault::default() is more clear than this expression
+  --> $DIR/default_trait_access.rs:34:36
+   |
+34 |     let s14: TupleDerivedDefault = Default::default();
+   |                                    ^^^^^^^^^^^^^^^^^^ help: try: `TupleDerivedDefault::default()`
+
+error: Calling ArrayDerivedDefault::default() is more clear than this expression
+  --> $DIR/default_trait_access.rs:36:36
+   |
+36 |     let s15: ArrayDerivedDefault = Default::default();
+   |                                    ^^^^^^^^^^^^^^^^^^ help: try: `ArrayDerivedDefault::default()`
+
+error: Calling TupleStructDerivedDefault::default() is more clear than this expression
+  --> $DIR/default_trait_access.rs:40:42
+   |
+40 |     let s17: TupleStructDerivedDefault = Default::default();
+   |                                          ^^^^^^^^^^^^^^^^^^ help: try: `TupleStructDerivedDefault::default()`
+
+error: aborting due to 8 previous errors