Auto merge of #5329 - matthiaskrgr:int_arith_on_ref_5328, r=flip1995

integer_arithmetic: detect integer arithmetic on references.

changelog: integer_arithmetic fix false negatives with references on integers

Fixes #5328

11 files changed, 355 insertions, 184 deletions

diff --git a/clippy_dev/src/stderr_length_check.rs b/clippy_dev/src/stderr_length_check.rs
index 041ee691137..c511733f7bf 100644
--- a/clippy_dev/src/stderr_length_check.rs
+++ b/clippy_dev/src/stderr_length_check.rs
@@ -4,6 +4,8 @@ use std::path::{Path, PathBuf};
 
 use walkdir::WalkDir;
 
+use clippy_dev::clippy_project_root;
+
 // The maximum length allowed for stderr files.
 //
 // We limit this because small files are easier to deal with than bigger files.
@@ -14,22 +16,24 @@ pub fn check() {
 
     if !exceeding_files.is_empty() {
         eprintln!("Error: stderr files exceeding limit of {} lines:", LENGTH_LIMIT);
-        for path in exceeding_files {
-            println!("{}", path.display());
+        for (path, count) in exceeding_files {
+            println!("{}: {}", path.display(), count);
         }
         std::process::exit(1);
     }
 }
 
-fn exceeding_stderr_files() -> Vec<PathBuf> {
+fn exceeding_stderr_files() -> Vec<(PathBuf, usize)> {
     // We use `WalkDir` instead of `fs::read_dir` here in order to recurse into subdirectories.
-    WalkDir::new("../tests/ui")
+    WalkDir::new(clippy_project_root().join("tests/ui"))
         .into_iter()
         .filter_map(Result::ok)
+        .filter(|f| !f.file_type().is_dir())
         .filter_map(|e| {
             let p = e.into_path();
-            if p.extension() == Some(OsStr::new("stderr")) && count_linenumbers(&p) > LENGTH_LIMIT {
-                Some(p)
+            let count = count_linenumbers(&p);
+            if p.extension() == Some(OsStr::new("stderr")) && count > LENGTH_LIMIT {
+                Some((p, count))
             } else {
                 None
             }
diff --git a/clippy_lints/src/arithmetic.rs b/clippy_lints/src/arithmetic.rs
index fd252b9ee10..a138c9d3545 100644
--- a/clippy_lints/src/arithmetic.rs
+++ b/clippy_lints/src/arithmetic.rs
@@ -81,11 +81,12 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Arithmetic {
                     | hir::BinOpKind::Gt => return,
                     _ => (),
                 }
+
                 let (l_ty, r_ty) = (cx.tables.expr_ty(l), cx.tables.expr_ty(r));
-                if l_ty.is_integral() && r_ty.is_integral() {
+                if l_ty.peel_refs().is_integral() && r_ty.peel_refs().is_integral() {
                     span_lint(cx, INTEGER_ARITHMETIC, expr.span, "integer arithmetic detected");
                     self.expr_span = Some(expr.span);
-                } else if l_ty.is_floating_point() && r_ty.is_floating_point() {
+                } else if l_ty.peel_refs().is_floating_point() && r_ty.peel_refs().is_floating_point() {
                     span_lint(cx, FLOAT_ARITHMETIC, expr.span, "floating-point arithmetic detected");
                     self.expr_span = Some(expr.span);
                 }
diff --git a/tests/ui/arithmetic.stderr b/tests/ui/arithmetic.stderr
deleted file mode 100644
index d999b69d7cb..00000000000
--- a/tests/ui/arithmetic.stderr
+++ /dev/null
@@ -1,127 +0,0 @@
-error: integer arithmetic detected
-  --> $DIR/arithmetic.rs:13:5
-   |
-LL |     1 + i;
-   |     ^^^^^
-   |
-   = note: `-D clippy::integer-arithmetic` implied by `-D warnings`
-
-error: integer arithmetic detected
-  --> $DIR/arithmetic.rs:14:5
-   |
-LL |     i * 2;
-   |     ^^^^^
-
-error: integer arithmetic detected
-  --> $DIR/arithmetic.rs:15:5
-   |
-LL | /     1 %
-LL | |     i / 2; // no error, this is part of the expression in the preceding line
-   | |_________^
-
-error: integer arithmetic detected
-  --> $DIR/arithmetic.rs:17:5
-   |
-LL |     i - 2 + 2 - i;
-   |     ^^^^^^^^^^^^^
-
-error: integer arithmetic detected
-  --> $DIR/arithmetic.rs:18:5
-   |
-LL |     -i;
-   |     ^^
-
-error: integer arithmetic detected
-  --> $DIR/arithmetic.rs:30:5
-   |
-LL |     i += 1;
-   |     ^^^^^^
-
-error: integer arithmetic detected
-  --> $DIR/arithmetic.rs:31:5
-   |
-LL |     i -= 1;
-   |     ^^^^^^
-
-error: integer arithmetic detected
-  --> $DIR/arithmetic.rs:32:5
-   |
-LL |     i *= 2;
-   |     ^^^^^^
-
-error: integer arithmetic detected
-  --> $DIR/arithmetic.rs:33:5
-   |
-LL |     i /= 2;
-   |     ^^^^^^
-
-error: integer arithmetic detected
-  --> $DIR/arithmetic.rs:34:5
-   |
-LL |     i %= 2;
-   |     ^^^^^^
-
-error: floating-point arithmetic detected
-  --> $DIR/arithmetic.rs:45:5
-   |
-LL |     f * 2.0;
-   |     ^^^^^^^
-   |
-   = note: `-D clippy::float-arithmetic` implied by `-D warnings`
-
-error: floating-point arithmetic detected
-  --> $DIR/arithmetic.rs:47:5
-   |
-LL |     1.0 + f;
-   |     ^^^^^^^
-
-error: floating-point arithmetic detected
-  --> $DIR/arithmetic.rs:48:5
-   |
-LL |     f * 2.0;
-   |     ^^^^^^^
-
-error: floating-point arithmetic detected
-  --> $DIR/arithmetic.rs:49:5
-   |
-LL |     f / 2.0;
-   |     ^^^^^^^
-
-error: floating-point arithmetic detected
-  --> $DIR/arithmetic.rs:50:5
-   |
-LL |     f - 2.0 * 4.2;
-   |     ^^^^^^^^^^^^^
-
-error: floating-point arithmetic detected
-  --> $DIR/arithmetic.rs:51:5
-   |
-LL |     -f;
-   |     ^^
-
-error: floating-point arithmetic detected
-  --> $DIR/arithmetic.rs:53:5
-   |
-LL |     f += 1.0;
-   |     ^^^^^^^^
-
-error: floating-point arithmetic detected
-  --> $DIR/arithmetic.rs:54:5
-   |
-LL |     f -= 1.0;
-   |     ^^^^^^^^
-
-error: floating-point arithmetic detected
-  --> $DIR/arithmetic.rs:55:5
-   |
-LL |     f *= 2.0;
-   |     ^^^^^^^^
-
-error: floating-point arithmetic detected
-  --> $DIR/arithmetic.rs:56:5
-   |
-LL |     f /= 2.0;
-   |     ^^^^^^^^
-
-error: aborting due to 20 previous errors
-
diff --git a/tests/ui/checked_unwrap/complex_conditionals.rs b/tests/ui/checked_unwrap/complex_conditionals.rs
index fbeee1b572a..c986c992a07 100644
--- a/tests/ui/checked_unwrap/complex_conditionals.rs
+++ b/tests/ui/checked_unwrap/complex_conditionals.rs
@@ -51,15 +51,4 @@ fn test_complex_conditions() {
     }
 }
 
-fn test_nested() {
-    fn nested() {
-        let x = Some(());
-        if x.is_some() {
-            x.unwrap(); // unnecessary
-        } else {
-            x.unwrap(); // will panic
-        }
-    }
-}
-
 fn main() {}
diff --git a/tests/ui/checked_unwrap/complex_conditionals.stderr b/tests/ui/checked_unwrap/complex_conditionals.stderr
index 4e53bd769e2..dc666bab460 100644
--- a/tests/ui/checked_unwrap/complex_conditionals.stderr
+++ b/tests/ui/checked_unwrap/complex_conditionals.stderr
@@ -188,22 +188,5 @@ LL |     if x.is_ok() || !(y.is_ok() && z.is_err()) {
 LL |         z.unwrap_err(); // unnecessary
    |         ^^^^^^^^^^^^^^
 
-error: You checked before that `unwrap()` cannot fail. Instead of checking and unwrapping, it's better to use `if let` or `match`.
-  --> $DIR/complex_conditionals.rs:58:13
-   |
-LL |         if x.is_some() {
-   |            ----------- the check is happening here
-LL |             x.unwrap(); // unnecessary
-   |             ^^^^^^^^^^
-
-error: This call to `unwrap()` will always panic.
-  --> $DIR/complex_conditionals.rs:60:13
-   |
-LL |         if x.is_some() {
-   |            ----------- because of this check
-...
-LL |             x.unwrap(); // will panic
-   |             ^^^^^^^^^^
-
-error: aborting due to 22 previous errors
+error: aborting due to 20 previous errors
 
diff --git a/tests/ui/checked_unwrap/complex_conditionals_nested.rs b/tests/ui/checked_unwrap/complex_conditionals_nested.rs
new file mode 100644
index 00000000000..2307996a48f
--- /dev/null
+++ b/tests/ui/checked_unwrap/complex_conditionals_nested.rs
@@ -0,0 +1,15 @@
+#![deny(clippy::panicking_unwrap, clippy::unnecessary_unwrap)]
+#![allow(clippy::if_same_then_else)]
+
+fn test_nested() {
+    fn nested() {
+        let x = Some(());
+        if x.is_some() {
+            x.unwrap(); // unnecessary
+        } else {
+            x.unwrap(); // will panic
+        }
+    }
+}
+
+fn main() {}
diff --git a/tests/ui/checked_unwrap/complex_conditionals_nested.stderr b/tests/ui/checked_unwrap/complex_conditionals_nested.stderr
new file mode 100644
index 00000000000..e4d085470c3
--- /dev/null
+++ b/tests/ui/checked_unwrap/complex_conditionals_nested.stderr
@@ -0,0 +1,31 @@
+error: You checked before that `unwrap()` cannot fail. Instead of checking and unwrapping, it's better to use `if let` or `match`.
+  --> $DIR/complex_conditionals_nested.rs:8:13
+   |
+LL |         if x.is_some() {
+   |            ----------- the check is happening here
+LL |             x.unwrap(); // unnecessary
+   |             ^^^^^^^^^^
+   |
+note: the lint level is defined here
+  --> $DIR/complex_conditionals_nested.rs:1:35
+   |
+LL | #![deny(clippy::panicking_unwrap, clippy::unnecessary_unwrap)]
+   |                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: This call to `unwrap()` will always panic.
+  --> $DIR/complex_conditionals_nested.rs:10:13
+   |
+LL |         if x.is_some() {
+   |            ----------- because of this check
+...
+LL |             x.unwrap(); // will panic
+   |             ^^^^^^^^^^
+   |
+note: the lint level is defined here
+  --> $DIR/complex_conditionals_nested.rs:1:9
+   |
+LL | #![deny(clippy::panicking_unwrap, clippy::unnecessary_unwrap)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors
+
diff --git a/tests/ui/float_arithmetic.rs b/tests/ui/float_arithmetic.rs
new file mode 100644
index 00000000000..5ad320c6209
--- /dev/null
+++ b/tests/ui/float_arithmetic.rs
@@ -0,0 +1,53 @@
+#![warn(clippy::integer_arithmetic, clippy::float_arithmetic)]
+#![allow(
+    unused,
+    clippy::shadow_reuse,
+    clippy::shadow_unrelated,
+    clippy::no_effect,
+    clippy::unnecessary_operation,
+    clippy::op_ref,
+    clippy::trivially_copy_pass_by_ref
+)]
+
+#[rustfmt::skip]
+fn main() {
+    let mut f = 1.0f32;
+
+    f * 2.0;
+
+    1.0 + f;
+    f * 2.0;
+    f / 2.0;
+    f - 2.0 * 4.2;
+    -f;
+
+    f += 1.0;
+    f -= 1.0;
+    f *= 2.0;
+    f /= 2.0;
+}
+
+// also warn about floating point arith with references involved
+
+pub fn float_arith_ref() {
+    3.1_f32 + &1.2_f32;
+    &3.4_f32 + 1.5_f32;
+    &3.5_f32 + &1.3_f32;
+}
+
+pub fn float_foo(f: &f32) -> f32 {
+    let a = 5.1;
+    a + f
+}
+
+pub fn float_bar(f1: &f32, f2: &f32) -> f32 {
+    f1 + f2
+}
+
+pub fn float_baz(f1: f32, f2: &f32) -> f32 {
+    f1 + f2
+}
+
+pub fn float_qux(f1: f32, f2: f32) -> f32 {
+    (&f1 + &f2)
+}
diff --git a/tests/ui/float_arithmetic.stderr b/tests/ui/float_arithmetic.stderr
new file mode 100644
index 00000000000..809392529fd
--- /dev/null
+++ b/tests/ui/float_arithmetic.stderr
@@ -0,0 +1,106 @@
+error: floating-point arithmetic detected
+  --> $DIR/float_arithmetic.rs:16:5
+   |
+LL |     f * 2.0;
+   |     ^^^^^^^
+   |
+   = note: `-D clippy::float-arithmetic` implied by `-D warnings`
+
+error: floating-point arithmetic detected
+  --> $DIR/float_arithmetic.rs:18:5
+   |
+LL |     1.0 + f;
+   |     ^^^^^^^
+
+error: floating-point arithmetic detected
+  --> $DIR/float_arithmetic.rs:19:5
+   |
+LL |     f * 2.0;
+   |     ^^^^^^^
+
+error: floating-point arithmetic detected
+  --> $DIR/float_arithmetic.rs:20:5
+   |
+LL |     f / 2.0;
+   |     ^^^^^^^
+
+error: floating-point arithmetic detected
+  --> $DIR/float_arithmetic.rs:21:5
+   |
+LL |     f - 2.0 * 4.2;
+   |     ^^^^^^^^^^^^^
+
+error: floating-point arithmetic detected
+  --> $DIR/float_arithmetic.rs:22:5
+   |
+LL |     -f;
+   |     ^^
+
+error: floating-point arithmetic detected
+  --> $DIR/float_arithmetic.rs:24:5
+   |
+LL |     f += 1.0;
+   |     ^^^^^^^^
+
+error: floating-point arithmetic detected
+  --> $DIR/float_arithmetic.rs:25:5
+   |
+LL |     f -= 1.0;
+   |     ^^^^^^^^
+
+error: floating-point arithmetic detected
+  --> $DIR/float_arithmetic.rs:26:5
+   |
+LL |     f *= 2.0;
+   |     ^^^^^^^^
+
+error: floating-point arithmetic detected
+  --> $DIR/float_arithmetic.rs:27:5
+   |
+LL |     f /= 2.0;
+   |     ^^^^^^^^
+
+error: floating-point arithmetic detected
+  --> $DIR/float_arithmetic.rs:33:5
+   |
+LL |     3.1_f32 + &1.2_f32;
+   |     ^^^^^^^^^^^^^^^^^^
+
+error: floating-point arithmetic detected
+  --> $DIR/float_arithmetic.rs:34:5
+   |
+LL |     &3.4_f32 + 1.5_f32;
+   |     ^^^^^^^^^^^^^^^^^^
+
+error: floating-point arithmetic detected
+  --> $DIR/float_arithmetic.rs:35:5
+   |
+LL |     &3.5_f32 + &1.3_f32;
+   |     ^^^^^^^^^^^^^^^^^^^
+
+error: floating-point arithmetic detected
+  --> $DIR/float_arithmetic.rs:40:5
+   |
+LL |     a + f
+   |     ^^^^^
+
+error: floating-point arithmetic detected
+  --> $DIR/float_arithmetic.rs:44:5
+   |
+LL |     f1 + f2
+   |     ^^^^^^^
+
+error: floating-point arithmetic detected
+  --> $DIR/float_arithmetic.rs:48:5
+   |
+LL |     f1 + f2
+   |     ^^^^^^^
+
+error: floating-point arithmetic detected
+  --> $DIR/float_arithmetic.rs:52:5
+   |
+LL |     (&f1 + &f2)
+   |     ^^^^^^^^^^^
+
+error: aborting due to 17 previous errors
+
diff --git a/tests/ui/arithmetic.rs b/tests/ui/integer_arithmetic.rs
index dc11cbd98de..31a07e7c35b 100644
--- a/tests/ui/arithmetic.rs
+++ b/tests/ui/integer_arithmetic.rs
@@ -4,7 +4,9 @@
     clippy::shadow_reuse,
     clippy::shadow_unrelated,
     clippy::no_effect,
-    clippy::unnecessary_operation
+    clippy::unnecessary_operation,
+    clippy::op_ref,
+    clippy::trivially_copy_pass_by_ref
 )]
 
 #[rustfmt::skip]
@@ -40,25 +42,6 @@ fn main() {
     i &= 1;
     i ^= i;
 
-    let mut f = 1.0f32;
-
-    f * 2.0;
-
-    1.0 + f;
-    f * 2.0;
-    f / 2.0;
-    f - 2.0 * 4.2;
-    -f;
-
-    f += 1.0;
-    f -= 1.0;
-    f *= 2.0;
-    f /= 2.0;
-
-    // no error, overflows are checked by `overflowing_literals`
-    -1.;
-    -(-1.);
-
     // No errors for the following items because they are constant expressions
     enum Foo {
         Bar = -2,
@@ -90,4 +73,30 @@ fn main() {
             1 + 1
         };
     }
+
+
+}
+
+// warn on references as well! (#5328)
+pub fn int_arith_ref() {
+    3 + &1;
+    &3 + 1;
+    &3 + &1;
+}
+
+pub fn foo(x: &i32) -> i32 {
+    let a = 5;
+    a + x
+}
+
+pub fn bar(x: &i32, y: &i32) -> i32 {
+    x + y
+}
+
+pub fn baz(x: i32, y: &i32) -> i32 {
+    x + y
+}
+
+pub fn qux(x: i32, y: i32) -> i32 {
+    (&x + &y)
 }
diff --git a/tests/ui/integer_arithmetic.stderr b/tests/ui/integer_arithmetic.stderr
new file mode 100644
index 00000000000..0b8d0b767bf
--- /dev/null
+++ b/tests/ui/integer_arithmetic.stderr
@@ -0,0 +1,107 @@
+error: integer arithmetic detected
+  --> $DIR/integer_arithmetic.rs:15:5
+   |
+LL |     1 + i;
+   |     ^^^^^
+   |
+   = note: `-D clippy::integer-arithmetic` implied by `-D warnings`
+
+error: integer arithmetic detected
+  --> $DIR/integer_arithmetic.rs:16:5
+   |
+LL |     i * 2;
+   |     ^^^^^
+
+error: integer arithmetic detected
+  --> $DIR/integer_arithmetic.rs:17:5
+   |
+LL | /     1 %
+LL | |     i / 2; // no error, this is part of the expression in the preceding line
+   | |_________^
+
+error: integer arithmetic detected
+  --> $DIR/integer_arithmetic.rs:19:5
+   |
+LL |     i - 2 + 2 - i;
+   |     ^^^^^^^^^^^^^
+
+error: integer arithmetic detected
+  --> $DIR/integer_arithmetic.rs:20:5
+   |
+LL |     -i;
+   |     ^^
+
+error: integer arithmetic detected
+  --> $DIR/integer_arithmetic.rs:32:5
+   |
+LL |     i += 1;
+   |     ^^^^^^
+
+error: integer arithmetic detected
+  --> $DIR/integer_arithmetic.rs:33:5
+   |
+LL |     i -= 1;
+   |     ^^^^^^
+
+error: integer arithmetic detected
+  --> $DIR/integer_arithmetic.rs:34:5
+   |
+LL |     i *= 2;
+   |     ^^^^^^
+
+error: integer arithmetic detected
+  --> $DIR/integer_arithmetic.rs:35:5
+   |
+LL |     i /= 2;
+   |     ^^^^^^
+
+error: integer arithmetic detected
+  --> $DIR/integer_arithmetic.rs:36:5
+   |
+LL |     i %= 2;
+   |     ^^^^^^
+
+error: integer arithmetic detected
+  --> $DIR/integer_arithmetic.rs:82:5
+   |
+LL |     3 + &1;
+   |     ^^^^^^
+
+error: integer arithmetic detected
+  --> $DIR/integer_arithmetic.rs:83:5
+   |
+LL |     &3 + 1;
+   |     ^^^^^^
+
+error: integer arithmetic detected
+  --> $DIR/integer_arithmetic.rs:84:5
+   |
+LL |     &3 + &1;
+   |     ^^^^^^^
+
+error: integer arithmetic detected
+  --> $DIR/integer_arithmetic.rs:89:5
+   |
+LL |     a + x
+   |     ^^^^^
+
+error: integer arithmetic detected
+  --> $DIR/integer_arithmetic.rs:93:5
+   |
+LL |     x + y
+   |     ^^^^^
+
+error: integer arithmetic detected
+  --> $DIR/integer_arithmetic.rs:97:5
+   |
+LL |     x + y
+   |     ^^^^^
+
+error: integer arithmetic detected
+  --> $DIR/integer_arithmetic.rs:101:5
+   |
+LL |     (&x + &y)
+   |     ^^^^^^^^^
+
+error: aborting due to 17 previous errors
+