Don't warn about modulo arithmetic when comparing to zero

Add lint configuration for `modulo_arithmetic`

Collect meta-data

tests/ui-toml/modulo_arithmetic/clippy.toml

@@ -0,0 +1 @@
+allow-comparison-to-zero = false

tests/ui-toml/modulo_arithmetic/modulo_arithmetic.rs

@@ -0,0 +1,10 @@
+#![warn(clippy::modulo_arithmetic)]
+
+fn main() {
+    let a = -1;
+    let b = 2;
+    let c = a % b == 0;
+    let c = a % b != 0;
+    let c = 0 == a % b;
+    let c = 0 != a % b;
+}

tests/ui-toml/modulo_arithmetic/modulo_arithmetic.stderr

@@ -0,0 +1,40 @@
+error: you are using modulo operator on types that might have different signs
+  --> $DIR/modulo_arithmetic.rs:6:13
+   |
+LL |     let c = a % b == 0;
+   |             ^^^^^
+   |
+   = note: double check for expected result especially when interoperating with different languages
+   = note: or consider using `rem_euclid` or similar function
+   = note: `-D clippy::modulo-arithmetic` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(clippy::modulo_arithmetic)]`
+
+error: you are using modulo operator on types that might have different signs
+  --> $DIR/modulo_arithmetic.rs:7:13
+   |
+LL |     let c = a % b != 0;
+   |             ^^^^^
+   |
+   = note: double check for expected result especially when interoperating with different languages
+   = note: or consider using `rem_euclid` or similar function
+
+error: you are using modulo operator on types that might have different signs
+  --> $DIR/modulo_arithmetic.rs:8:18
+   |
+LL |     let c = 0 == a % b;
+   |                  ^^^^^
+   |
+   = note: double check for expected result especially when interoperating with different languages
+   = note: or consider using `rem_euclid` or similar function
+
+error: you are using modulo operator on types that might have different signs
+  --> $DIR/modulo_arithmetic.rs:9:18
+   |
+LL |     let c = 0 != a % b;
+   |                  ^^^^^
+   |
+   = note: double check for expected result especially when interoperating with different languages
+   = note: or consider using `rem_euclid` or similar function
+
+error: aborting due to 4 previous errors
+

tests/ui-toml/toml_unknown_key/conf_unknown_key.stderr

@@ -3,6 +3,7 @@ error: error reading Clippy's configuration file: unknown field `foobar`, expect
            absolute-paths-max-segments
            accept-comment-above-attributes
            accept-comment-above-statement
+           allow-comparison-to-zero
            allow-dbg-in-tests
            allow-expect-in-tests
            allow-mixed-uninlined-format-args
@@ -80,6 +81,7 @@ error: error reading Clippy's configuration file: unknown field `barfoo`, expect
            absolute-paths-max-segments
            accept-comment-above-attributes
            accept-comment-above-statement
+           allow-comparison-to-zero
            allow-dbg-in-tests
            allow-expect-in-tests
            allow-mixed-uninlined-format-args
@@ -157,6 +159,7 @@ error: error reading Clippy's configuration file: unknown field `allow_mixed_uni
            absolute-paths-max-segments
            accept-comment-above-attributes
            accept-comment-above-statement
+           allow-comparison-to-zero
            allow-dbg-in-tests
            allow-expect-in-tests
            allow-mixed-uninlined-format-args

tests/ui/modulo_arithmetic_integral.rs

@@ -114,4 +114,12 @@ fn main() {
     a_usize % b_usize;
     let mut a_usize: usize = 1;
     a_usize %= 2;
+
+    // No lint when comparing to zero
+    let a = -1;
+    let mut b = 2;
+    let c = a % b == 0;
+    let c = 0 == a % b;
+    let c = a % b != 0;
+    let c = 0 != a % b;
 }