Lint mem_replace_with_default within internal macros

Author: krishna-veerareddy

README.md

@@ -6,7 +6,7 @@
 
 A collection of lints to catch common mistakes and improve your [Rust](https://github.com/rust-lang/rust) code.
 
-[There are 340 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
+[There are 341 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
 
 We have a bunch of lint categories to allow you to choose how much Clippy is supposed to ~~annoy~~ help you:
 

clippy_lints/src/mem_replace.rs

@@ -1,5 +1,5 @@
 use crate::utils::{
-    in_macro, match_def_path, match_qpath, paths, snippet_with_applicability, span_help_and_lint, span_lint_and_sugg,
+    match_def_path, match_qpath, paths, snippet_with_applicability, span_help_and_lint, span_lint_and_sugg,
 };
 use if_chain::if_chain;
 use rustc::declare_lint_pass;
@@ -166,7 +166,7 @@ fn check_replace_with_uninit(cx: &LateContext<'_, '_>, src: &Expr, expr_span: Sp
 fn check_replace_with_default(cx: &LateContext<'_, '_>, src: &Expr, dest: &Expr, expr_span: Span) {
     if let ExprKind::Call(ref repl_func, _) = src.kind {
         if_chain! {
-            if !in_macro(expr_span) && !in_external_macro(cx.tcx.sess, expr_span);
+            if !in_external_macro(cx.tcx.sess, expr_span);
             if let ExprKind::Path(ref repl_func_qpath) = repl_func.kind;
             if let Some(repl_def_id) = cx.tables.qpath_res(repl_func_qpath, repl_func.hir_id).opt_def_id();
             if match_def_path(cx, repl_def_id, &paths::DEFAULT_TRAIT_METHOD);

src/lintlist/mod.rs

@@ -6,7 +6,7 @@ pub use lint::Lint;
 pub use lint::LINT_LEVELS;
 
 // begin lint list, do not remove this comment, it’s used in `update_lints`
-pub const ALL_LINTS: [Lint; 340] = [
+pub const ALL_LINTS: [Lint; 341] = [
     Lint {
         name: "absurd_extreme_comparisons",
         group: "correctness",

tests/ui/mem_replace.fixed

@@ -8,6 +8,7 @@
 // except according to those terms.
 
 // run-rustfix
+// rustfix-only-machine-applicable
 // aux-build:macro_rules.rs
 #![allow(unused_imports)]
 #![warn(
@@ -24,7 +25,7 @@ use std::mem;
 
 macro_rules! take {
     ($s:expr) => {
-        std::mem::replace($s, Default::default())
+        std::mem::take(s)
     };
 }
 
@@ -41,9 +42,9 @@ fn replace_with_default() {
     let s = &mut String::from("foo");
     let _ = std::mem::take(s);
     let _ = std::mem::take(s);
-
-    // dont lint within macros
     take!(s);
+
+    // dont lint within external macros
     take_external!(s);
 }
 

tests/ui/mem_replace.rs

@@ -8,6 +8,7 @@
 // except according to those terms.
 
 // run-rustfix
+// rustfix-only-machine-applicable
 // aux-build:macro_rules.rs
 #![allow(unused_imports)]
 #![warn(
@@ -41,9 +42,9 @@ fn replace_with_default() {
     let s = &mut String::from("foo");
     let _ = std::mem::replace(s, String::default());
     let _ = std::mem::replace(s, Default::default());
-
-    // dont lint within macros
     take!(s);
+
+    // dont lint within external macros
     take_external!(s);
 }
 

tests/ui/mem_replace.stderr

@@ -1,36 +1,45 @@
 error: replacing an `Option` with `None`
-  --> $DIR/mem_replace.rs:33:13
+  --> $DIR/mem_replace.rs:34:13
    |
 LL |     let _ = mem::replace(&mut an_option, None);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider `Option::take()` instead: `an_option.take()`
    |
    = note: `-D clippy::mem-replace-option-with-none` implied by `-D warnings`
 
 error: replacing an `Option` with `None`
-  --> $DIR/mem_replace.rs:35:13
+  --> $DIR/mem_replace.rs:36:13
    |
 LL |     let _ = mem::replace(an_option, None);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider `Option::take()` instead: `an_option.take()`
 
 error: replacing a value of type `T` with `T::default()` is better expressed using `std::mem::take`
-  --> $DIR/mem_replace.rs:40:13
+  --> $DIR/mem_replace.rs:41:13
    |
 LL |     let _ = std::mem::replace(&mut s, String::default());
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::mem::take(&mut s)`
    |
    = note: `-D clippy::mem-replace-with-default` implied by `-D warnings`
 
 error: replacing a value of type `T` with `T::default()` is better expressed using `std::mem::take`
-  --> $DIR/mem_replace.rs:42:13
+  --> $DIR/mem_replace.rs:43:13
    |
 LL |     let _ = std::mem::replace(s, String::default());
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::mem::take(s)`
 
 error: replacing a value of type `T` with `T::default()` is better expressed using `std::mem::take`
-  --> $DIR/mem_replace.rs:43:13
+  --> $DIR/mem_replace.rs:44:13
    |
 LL |     let _ = std::mem::replace(s, Default::default());
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::mem::take(s)`
 
-error: aborting due to 5 previous errors
+error: replacing a value of type `T` with `T::default()` is better expressed using `std::mem::take`
+  --> $DIR/mem_replace.rs:28:9
+   |
+LL |         std::mem::replace($s, Default::default())
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::mem::take(s)`
+...
+LL |     take!(s);
+   |     --------- in this macro invocation
+
+error: aborting due to 6 previous errors