From 725e9621d0ea1f07ad75d5f26193dfba72ee73b2 Mon Sep 17 00:00:00 2001
From: Michael Wright <mikerite@lavabit.com>
Date: Tue, 12 Jun 2018 08:25:10 +0200
Subject: [PATCH] duration_subsec: Add check for `subsec_micros`

---
 clippy_lints/src/duration_subsec.rs | 17 ++++++++-------
 tests/ui/duration_subsec.rs         | 11 +++++-----
 tests/ui/duration_subsec.stderr     | 32 +++++++++++++++++------------
 3 files changed, 33 insertions(+), 27 deletions(-)

diff --git a/clippy_lints/src/duration_subsec.rs b/clippy_lints/src/duration_subsec.rs
index fced237b6..5f34803c8 100644
--- a/clippy_lints/src/duration_subsec.rs
+++ b/clippy_lints/src/duration_subsec.rs
@@ -6,11 +6,11 @@ use crate::consts::{constant, Constant};
 use crate::utils::paths;
 use crate::utils::{match_type, snippet, span_lint_and_sugg, walk_ptrs_ty};
 
-/// **What it does:** Checks for calculation of subsecond microseconds or milliseconds from
-/// `Duration::subsec_nanos()`.
+/// **What it does:** Checks for calculation of subsecond microseconds or milliseconds
+/// from other `Duration` methods.
 ///
 /// **Why is this bad?** It's more concise to call `Duration::subsec_micros()` or
-/// `Duration::subsec_millis()`.
+/// `Duration::subsec_millis()` than to calculate them.
 ///
 /// **Known problems:** None.
 ///
@@ -23,7 +23,7 @@ use crate::utils::{match_type, snippet, span_lint_and_sugg, walk_ptrs_ty};
 declare_clippy_lint! {
     pub DURATION_SUBSEC,
     complexity,
-    "checks for `dur.subsec_nanos() / 1_000` or `dur.subsec_nanos() / 1_000_000`"
+    "checks for calculation of subsecond microseconds or milliseconds"
 }
 
 #[derive(Copy, Clone)]
@@ -40,16 +40,15 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for DurationSubsec {
         if_chain! {
             if let ExprBinary(Spanned { node: BiDiv, .. }, ref left, ref right) = expr.node;
             if let ExprMethodCall(ref method_path, _ , ref args) = left.node;
-            if method_path.name == "subsec_nanos";
             if match_type(cx, walk_ptrs_ty(cx.tables.expr_ty(&args[0])), &paths::DURATION);
             if let Some((Constant::Int(divisor), _)) = constant(cx, cx.tables, right);
             then {
-                let suggested_fn = match divisor {
-                    1_000 => "subsec_micros",
-                    1_000_000 => "subsec_millis",
+                let suggested_fn = match (method_path.name.as_str().as_ref(), divisor) {
+                    ("subsec_micros", 1_000) => "subsec_millis",
+                    ("subsec_nanos", 1_000) => "subsec_micros",
+                    ("subsec_nanos", 1_000_000) => "subsec_millis",
                     _ => return,
                 };
-
                 span_lint_and_sugg(
                     cx,
                     DURATION_SUBSEC,
diff --git a/tests/ui/duration_subsec.rs b/tests/ui/duration_subsec.rs
index 5b87d6964..8c75c5f2f 100644
--- a/tests/ui/duration_subsec.rs
+++ b/tests/ui/duration_subsec.rs
@@ -5,14 +5,16 @@ use std::time::Duration;
 fn main() {
     let dur = Duration::new(5, 0);
 
+    let bad_millis_1 = dur.subsec_micros() / 1_000;
+    let bad_millis_2 = dur.subsec_nanos() / 1_000_000;
+    let good_millis = dur.subsec_millis();
+    assert_eq!(bad_millis_1, good_millis);
+    assert_eq!(bad_millis_2, good_millis);
+
     let bad_micros = dur.subsec_nanos() / 1_000;
     let good_micros = dur.subsec_micros();
     assert_eq!(bad_micros, good_micros);
 
-    let bad_millis = dur.subsec_nanos() / 1_000_000;
-    let good_millis = dur.subsec_millis();
-    assert_eq!(bad_millis, good_millis);
-
     // Handle refs
     let _ = (&dur).subsec_nanos() / 1_000;
 
@@ -22,5 +24,4 @@ fn main() {
 
     // Other literals aren't linted
     let _ = dur.subsec_nanos() / 699;
-
 }
diff --git a/tests/ui/duration_subsec.stderr b/tests/ui/duration_subsec.stderr
index f77aa2172..a1aacec3a 100644
--- a/tests/ui/duration_subsec.stderr
+++ b/tests/ui/duration_subsec.stderr
@@ -1,28 +1,34 @@
-error: Calling `subsec_micros()` is more concise than this calculation
- --> $DIR/duration_subsec.rs:8:22
+error: Calling `subsec_millis()` is more concise than this calculation
+ --> $DIR/duration_subsec.rs:8:24
   |
-8 |     let bad_micros = dur.subsec_nanos() / 1_000;
-  |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `dur.subsec_micros()`
+8 |     let bad_millis_1 = dur.subsec_micros() / 1_000;
+  |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `dur.subsec_millis()`
   |
   = note: `-D duration-subsec` implied by `-D warnings`
 
 error: Calling `subsec_millis()` is more concise than this calculation
-  --> $DIR/duration_subsec.rs:12:22
-   |
-12 |     let bad_millis = dur.subsec_nanos() / 1_000_000;
-   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `dur.subsec_millis()`
+ --> $DIR/duration_subsec.rs:9:24
+  |
+9 |     let bad_millis_2 = dur.subsec_nanos() / 1_000_000;
+  |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `dur.subsec_millis()`
 
 error: Calling `subsec_micros()` is more concise than this calculation
-  --> $DIR/duration_subsec.rs:17:13
+  --> $DIR/duration_subsec.rs:14:22
    |
-17 |     let _ = (&dur).subsec_nanos() / 1_000;
+14 |     let bad_micros = dur.subsec_nanos() / 1_000;
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `dur.subsec_micros()`
+
+error: Calling `subsec_micros()` is more concise than this calculation
+  --> $DIR/duration_subsec.rs:19:13
+   |
+19 |     let _ = (&dur).subsec_nanos() / 1_000;
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `(&dur).subsec_micros()`
 
 error: Calling `subsec_micros()` is more concise than this calculation
-  --> $DIR/duration_subsec.rs:21:13
+  --> $DIR/duration_subsec.rs:23:13
    |
-21 |     let _ = dur.subsec_nanos() / NANOS_IN_MICRO;
+23 |     let _ = dur.subsec_nanos() / NANOS_IN_MICRO;
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `dur.subsec_micros()`
 
-error: aborting due to 4 previous errors
+error: aborting due to 5 previous errors