Don't lint default_trait_access in proc-macro expansions

Author: Jarcho

clippy_lints/src/default.rs

@@ -1,7 +1,9 @@
 use clippy_utils::diagnostics::{span_lint_and_note, span_lint_and_sugg};
 use clippy_utils::source::snippet_with_macro_callsite;
 use clippy_utils::ty::{has_drop, is_copy};
-use clippy_utils::{any_parent_is_automatically_derived, contains_name, get_parent_expr, match_def_path, paths};
+use clippy_utils::{
+    any_parent_is_automatically_derived, contains_name, get_parent_expr, is_from_proc_macro, match_def_path, paths,
+};
 use if_chain::if_chain;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::Applicability;
@@ -94,6 +96,7 @@ impl<'tcx> LateLintPass<'tcx> for Default {
             if let QPath::Resolved(None, _path) = qpath;
             let expr_ty = cx.typeck_results().expr_ty(expr);
             if let ty::Adt(def, ..) = expr_ty.kind();
+            if !is_from_proc_macro(cx, expr);
             then {
                 // TODO: Work out a way to put "whatever the imported way of referencing
                 // this type in this file" rather than a fully-qualified type.

tests/ui/default_trait_access.fixed

@@ -1,8 +1,12 @@
 // run-rustfix
+// aux-build: proc_macro_with_span.rs
 
 #![allow(unused_imports, dead_code)]
 #![deny(clippy::default_trait_access)]
 
+extern crate proc_macro_with_span;
+
+use proc_macro_with_span::with_span;
 use std::default;
 use std::default::Default as D2;
 use std::string;
@@ -51,6 +55,8 @@ fn main() {
         ..Default::default()
     };
 
+    let _s21: String = with_span!(s Default::default());
+
     println!(
         "[{}] [{}] [{}] [{}] [{}] [{}] [{}] [{}] [{}] [{:?}] [{:?}] [{:?}] [{:?}] [{:?}] [{:?}] [{:?}] [{:?}] [{:?}] [{:?}] [{:?}]",
         s1, s2, s3, s4, s5, s6, s7, s8, s9, s10, s11, s12, s13, s14, s15, s16, s17, s18, s19, s20,

tests/ui/default_trait_access.rs

@@ -1,8 +1,12 @@
 // run-rustfix
+// aux-build: proc_macro_with_span.rs
 
 #![allow(unused_imports, dead_code)]
 #![deny(clippy::default_trait_access)]
 
+extern crate proc_macro_with_span;
+
+use proc_macro_with_span::with_span;
 use std::default;
 use std::default::Default as D2;
 use std::string;
@@ -51,6 +55,8 @@ fn main() {
         ..Default::default()
     };
 
+    let _s21: String = with_span!(s Default::default());
+
     println!(
         "[{}] [{}] [{}] [{}] [{}] [{}] [{}] [{}] [{}] [{:?}] [{:?}] [{:?}] [{:?}] [{:?}] [{:?}] [{:?}] [{:?}] [{:?}] [{:?}] [{:?}]",
         s1, s2, s3, s4, s5, s6, s7, s8, s9, s10, s11, s12, s13, s14, s15, s16, s17, s18, s19, s20,

tests/ui/default_trait_access.stderr

@@ -1,53 +1,53 @@
 error: calling `std::string::String::default()` is more clear than this expression
-  --> $DIR/default_trait_access.rs:11:22
+  --> $DIR/default_trait_access.rs:15:22
    |
 LL |     let s1: String = Default::default();
    |                      ^^^^^^^^^^^^^^^^^^ help: try: `std::string::String::default()`
    |
 note: the lint level is defined here
-  --> $DIR/default_trait_access.rs:4:9
+  --> $DIR/default_trait_access.rs:5:9
    |
 LL | #![deny(clippy::default_trait_access)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: calling `std::string::String::default()` is more clear than this expression
-  --> $DIR/default_trait_access.rs:15:22
+  --> $DIR/default_trait_access.rs:19:22
    |
 LL |     let s3: String = D2::default();
    |                      ^^^^^^^^^^^^^ help: try: `std::string::String::default()`
 
 error: calling `std::string::String::default()` is more clear than this expression
-  --> $DIR/default_trait_access.rs:17:22
+  --> $DIR/default_trait_access.rs:21:22
    |
 LL |     let s4: String = std::default::Default::default();
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `std::string::String::default()`
 
 error: calling `std::string::String::default()` is more clear than this expression
-  --> $DIR/default_trait_access.rs:21:22
+  --> $DIR/default_trait_access.rs:25:22
    |
 LL |     let s6: String = default::Default::default();
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `std::string::String::default()`
 
 error: calling `GenericDerivedDefault::default()` is more clear than this expression
-  --> $DIR/default_trait_access.rs:31:46
+  --> $DIR/default_trait_access.rs:35:46
    |
 LL |     let s11: GenericDerivedDefault<String> = Default::default();
    |                                              ^^^^^^^^^^^^^^^^^^ help: try: `GenericDerivedDefault::default()`
 
 error: calling `TupleDerivedDefault::default()` is more clear than this expression
-  --> $DIR/default_trait_access.rs:37:36
+  --> $DIR/default_trait_access.rs:41:36
    |
 LL |     let s14: TupleDerivedDefault = Default::default();
    |                                    ^^^^^^^^^^^^^^^^^^ help: try: `TupleDerivedDefault::default()`
 
 error: calling `ArrayDerivedDefault::default()` is more clear than this expression
-  --> $DIR/default_trait_access.rs:39:36
+  --> $DIR/default_trait_access.rs:43:36
    |
 LL |     let s15: ArrayDerivedDefault = Default::default();
    |                                    ^^^^^^^^^^^^^^^^^^ help: try: `ArrayDerivedDefault::default()`
 
 error: calling `TupleStructDerivedDefault::default()` is more clear than this expression
-  --> $DIR/default_trait_access.rs:43:42
+  --> $DIR/default_trait_access.rs:47:42
    |
 LL |     let s17: TupleStructDerivedDefault = Default::default();
    |                                          ^^^^^^^^^^^^^^^^^^ help: try: `TupleStructDerivedDefault::default()`