Fixing confusion between mod and remainder

compiler/rustc_hir_typeck/src/op.rs

@@ -335,7 +335,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                 format!("cannot divide `{lhs_ty}` by `{rhs_ty}`")
                             }
                             hir::BinOpKind::Rem => {
-                                format!("cannot mod `{lhs_ty}` by `{rhs_ty}`")
+                                format!(
+                                    "cannot calculate the remainder of `{lhs_ty}` divided by `{rhs_ty}`"
+                                )
                             }
                             hir::BinOpKind::BitAnd => {
                                 format!("no implementation for `{lhs_ty} & {rhs_ty}`")

library/core/src/ops/arith.rs

@@ -545,7 +545,7 @@ div_impl_float! { f32 f64 }
 #[lang = "rem"]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_on_unimplemented(
-    message = "cannot mod `{Self}` by `{Rhs}`",
+    message = "cannot calculate the remainder of `{Self}` divided by `{Rhs}`",
     label = "no implementation for `{Self} % {Rhs}`"
 )]
 #[doc(alias = "%")]
@@ -981,7 +981,7 @@ div_assign_impl! { usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f32 f64 }
 #[lang = "rem_assign"]
 #[stable(feature = "op_assign_traits", since = "1.8.0")]
 #[rustc_on_unimplemented(
-    message = "cannot mod-assign `{Self}` by `{Rhs}``",
+    message = "cannot calculate and assign the remainder of `{Self}` divided by `{Rhs}`",
     label = "no implementation for `{Self} %= {Rhs}`"
 )]
 #[doc(alias = "%")]

tests/ui/binop/binary-op-on-double-ref.fixed

@@ -3,7 +3,7 @@ fn main() {
     let v = vec![1, 2, 3, 4, 5, 6, 7, 8, 9];
     let vr = v.iter().filter(|x| {
         *x % 2 == 0
-        //~^ ERROR cannot mod `&&{integer}` by `{integer}`
+        //~^ ERROR cannot calculate the remainder of `&&{integer}` divided by `{integer}`
     });
     println!("{:?}", vr);
 }

tests/ui/binop/binary-op-on-double-ref.rs

@@ -3,7 +3,7 @@ fn main() {
     let v = vec![1, 2, 3, 4, 5, 6, 7, 8, 9];
     let vr = v.iter().filter(|x| {
         x % 2 == 0
-        //~^ ERROR cannot mod `&&{integer}` by `{integer}`
+        //~^ ERROR cannot calculate the remainder of `&&{integer}` divided by `{integer}`
     });
     println!("{:?}", vr);
 }

tests/ui/binop/binary-op-on-double-ref.stderr

@@ -1,4 +1,4 @@
-error[E0369]: cannot mod `&&{integer}` by `{integer}`
+error[E0369]: cannot calculate the remainder of `&&{integer}` divided by `{integer}`
   --> $DIR/binary-op-on-double-ref.rs:5:11
    |
 LL |         x % 2 == 0

tests/ui/binop/issue-28837.rs

@@ -11,7 +11,7 @@ fn main() {
 
     a / a; //~ ERROR cannot divide `A` by `A`
 
-    a % a; //~ ERROR cannot mod `A` by `A`
+    a % a; //~ ERROR cannot calculate the remainder of `A` divided by `A`
 
     a & a; //~ ERROR no implementation for `A & A`
 

tests/ui/binop/issue-28837.stderr

@@ -62,7 +62,7 @@ LL | struct A;
 note: the trait `Div` must be implemented
   --> $SRC_DIR/core/src/ops/arith.rs:LL:COL
 
-error[E0369]: cannot mod `A` by `A`
+error[E0369]: cannot calculate the remainder of `A` divided by `A`
   --> $DIR/issue-28837.rs:14:7
    |
 LL |     a % a;