improve operation mismatch errors (#8800)

# Description

This improves the operation mismatch error in a few ways:

* We now detect if the left-hand side of the operation is at fault, and
show a simpler error/error message if it is
* Removed the unhelpful hint
* Updated the error text to make it clear what types are causing the
issue


![image](https://user-images.githubusercontent.com/547158/230666329-537a8cae-6350-4ee7-878e-777e05c4f265.png)


![image](https://user-images.githubusercontent.com/547158/230666353-93529dc2-039a-4774-a84c-a6faac94d8e2.png)


# User-Facing Changes

Error texts and spans will change

# Tests + Formatting

Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A
clippy::needless_collect` to check that you're using the standard code
style
- `cargo test --workspace` to check that all tests pass
- `cargo run -- crates/nu-utils/standard_library/tests.nu` to run the
tests for the standard library

> **Note**
> from `nushell` you can also use the `toolkit` as follows
> ```bash
> use toolkit.nu # or use an `env_change` hook to activate it
automatically
> toolkit check pr
> ```

# After Submitting

If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.

benches/benchmarks.rs

@@ -22,7 +22,7 @@ fn parser_benchmarks(c: &mut Criterion) {
     c.bench_function("parse_default_env_file", |b| {
         b.iter_batched(
             || nu_protocol::engine::StateWorkingSet::new(&engine_state),
-            |mut working_set| parse(&mut working_set, None, default_env, false, &[]),
+            |mut working_set| parse(&mut working_set, None, default_env, false),
             BatchSize::SmallInput,
         )
     });
@@ -31,7 +31,7 @@ fn parser_benchmarks(c: &mut Criterion) {
     c.bench_function("parse_default_config_file", |b| {
         b.iter_batched(
             || nu_protocol::engine::StateWorkingSet::new(&engine_state),
-            |mut working_set| parse(&mut working_set, None, default_config, false, &[]),
+            |mut working_set| parse(&mut working_set, None, default_config, false),
             BatchSize::SmallInput,
         )
     });

crates/nu-parser/src/type_check.rs

@@ -55,17 +55,25 @@ pub fn math_result_type(
 
                 (Type::Any, _) => (Type::Any, None),
                 (_, Type::Any) => (Type::Any, None),
-                (Type::Int, _) => {
+                (
-                    let ty = rhs.ty.clone();
+                    Type::Int
-                    *rhs = Expression::garbage(rhs.span);
+                    | Type::Float
+                    | Type::String
+                    | Type::Date
+                    | Type::Duration
+                    | Type::Filesize,
+                    _,
+                ) => {
+                    *op = Expression::garbage(op.span);
                     (
                         Type::Any,
-                        Some(ParseError::UnsupportedOperation(
+                        Some(ParseError::UnsupportedOperationRHS(
+                            "addition".into(),
                             op.span,
                             lhs.span,
                             lhs.ty.clone(),
                             rhs.span,
-                            ty,
+                            rhs.ty.clone(),
                         )),
                     )
                 }
@@ -73,12 +81,11 @@ pub fn math_result_type(
                     *op = Expression::garbage(op.span);
                     (
                         Type::Any,
-                        Some(ParseError::UnsupportedOperation(
+                        Some(ParseError::UnsupportedOperationLHS(
+                            "addition".into(),
                             op.span,
                             lhs.span,
                             lhs.ty.clone(),
-                            rhs.span,
-                            rhs.ty.clone(),
                         )),
                     )
                 }
@@ -102,11 +109,12 @@ pub fn math_result_type(
                 (Type::String, Type::String) => (Type::String, None),
                 (Type::Binary, Type::Binary) => (Type::Binary, None),
                 (Type::Any, _) | (_, Type::Any) => (Type::Any, None),
-                _ => {
+                (Type::Table(_) | Type::String | Type::Binary, _) => {
                     *op = Expression::garbage(op.span);
                     (
                         Type::Any,
-                        Some(ParseError::UnsupportedOperation(
+                        Some(ParseError::UnsupportedOperationRHS(
+                            "append".into(),
                             op.span,
                             lhs.span,
                             lhs.ty.clone(),
@@ -115,6 +123,18 @@ pub fn math_result_type(
                         )),
                     )
                 }
+                _ => {
+                    *op = Expression::garbage(op.span);
+                    (
+                        Type::Any,
+                        Some(ParseError::UnsupportedOperationLHS(
+                            "append".into(),
+                            op.span,
+                            lhs.span,
+                            lhs.ty.clone(),
+                        )),
+                    )
+                }
             },
             Operator::Math(Math::Minus) => match (&lhs.ty, &rhs.ty) {
                 (Type::Int, Type::Int) => (Type::Int, None),
@@ -131,11 +151,12 @@ pub fn math_result_type(
 
                 (Type::Any, _) => (Type::Any, None),
                 (_, Type::Any) => (Type::Any, None),
-                _ => {
+                (Type::Int | Type::Float | Type::Date | Type::Duration | Type::Filesize, _) => {
                     *op = Expression::garbage(op.span);
                     (
                         Type::Any,
-                        Some(ParseError::UnsupportedOperation(
+                        Some(ParseError::UnsupportedOperationRHS(
+                            "subtraction".into(),
                             op.span,
                             lhs.span,
                             lhs.ty.clone(),
@@ -144,6 +165,18 @@ pub fn math_result_type(
                         )),
                     )
                 }
+                _ => {
+                    *op = Expression::garbage(op.span);
+                    (
+                        Type::Any,
+                        Some(ParseError::UnsupportedOperationLHS(
+                            "subtraction".into(),
+                            op.span,
+                            lhs.span,
+                            lhs.ty.clone(),
+                        )),
+                    )
+                }
             },
             Operator::Math(Math::Multiply) => match (&lhs.ty, &rhs.ty) {
                 (Type::Int, Type::Int) => (Type::Int, None),
@@ -168,11 +201,18 @@ pub fn math_result_type(
 
                 (Type::Any, _) => (Type::Any, None),
                 (_, Type::Any) => (Type::Any, None),
-                _ => {
+                (Type::Int, _)
+                | (Type::Float, _)
+                | (Type::String, _)
+                | (Type::Date, _)
+                | (Type::Duration, _)
+                | (Type::Filesize, _)
+                | (Type::List(_), _) => {
                     *op = Expression::garbage(op.span);
                     (
                         Type::Any,
-                        Some(ParseError::UnsupportedOperation(
+                        Some(ParseError::UnsupportedOperationRHS(
+                            "multiplication".into(),
                             op.span,
                             lhs.span,
                             lhs.ty.clone(),
@@ -181,6 +221,18 @@ pub fn math_result_type(
                         )),
                     )
                 }
+                _ => {
+                    *op = Expression::garbage(op.span);
+                    (
+                        Type::Any,
+                        Some(ParseError::UnsupportedOperationLHS(
+                            "multiplication".into(),
+                            op.span,
+                            lhs.span,
+                            lhs.ty.clone(),
+                        )),
+                    )
+                }
             },
             Operator::Math(Math::Pow) => match (&lhs.ty, &rhs.ty) {
                 (Type::Int, Type::Int) => (Type::Int, None),
@@ -193,11 +245,12 @@ pub fn math_result_type(
 
                 (Type::Any, _) => (Type::Any, None),
                 (_, Type::Any) => (Type::Any, None),
-                _ => {
+                (Type::Int | Type::Float, _) => {
                     *op = Expression::garbage(op.span);
                     (
                         Type::Any,
-                        Some(ParseError::UnsupportedOperation(
+                        Some(ParseError::UnsupportedOperationRHS(
+                            "exponentiation".into(),
                             op.span,
                             lhs.span,
                             lhs.ty.clone(),
@@ -206,6 +259,18 @@ pub fn math_result_type(
                         )),
                     )
                 }
+                _ => {
+                    *op = Expression::garbage(op.span);
+                    (
+                        Type::Any,
+                        Some(ParseError::UnsupportedOperationLHS(
+                            "exponentiation".into(),
+                            op.span,
+                            lhs.span,
+                            lhs.ty.clone(),
+                        )),
+                    )
+                }
             },
             Operator::Math(Math::Divide) | Operator::Math(Math::Modulo) => match (&lhs.ty, &rhs.ty)
             {
@@ -225,11 +290,12 @@ pub fn math_result_type(
 
                 (Type::Any, _) => (Type::Any, None),
                 (_, Type::Any) => (Type::Any, None),
-                _ => {
+                (Type::Int | Type::Float | Type::Filesize | Type::Duration, _) => {
                     *op = Expression::garbage(op.span);
                     (
                         Type::Any,
-                        Some(ParseError::UnsupportedOperation(
+                        Some(ParseError::UnsupportedOperationRHS(
+                            "division".into(),
                             op.span,
                             lhs.span,
                             lhs.ty.clone(),
@@ -238,6 +304,18 @@ pub fn math_result_type(
                         )),
                     )
                 }
+                _ => {
+                    *op = Expression::garbage(op.span);
+                    (
+                        Type::Any,
+                        Some(ParseError::UnsupportedOperationLHS(
+                            "division".into(),
+                            op.span,
+                            lhs.span,
+                            lhs.ty.clone(),
+                        )),
+                    )
+                }
             },
             Operator::Math(Math::FloorDivision) => match (&lhs.ty, &rhs.ty) {
                 (Type::Int, Type::Int) => (Type::Int, None),
@@ -253,11 +331,12 @@ pub fn math_result_type(
 
                 (Type::Any, _) => (Type::Any, None),
                 (_, Type::Any) => (Type::Any, None),
-                _ => {
+                (Type::Int | Type::Float | Type::Filesize | Type::Duration, _) => {
                     *op = Expression::garbage(op.span);
                     (
                         Type::Any,
-                        Some(ParseError::UnsupportedOperation(
+                        Some(ParseError::UnsupportedOperationRHS(
+                            "floor division".into(),
                             op.span,
                             lhs.span,
                             lhs.ty.clone(),
@@ -266,6 +345,18 @@ pub fn math_result_type(
                         )),
                     )
                 }
+                _ => {
+                    *op = Expression::garbage(op.span);
+                    (
+                        Type::Any,
+                        Some(ParseError::UnsupportedOperationLHS(
+                            "floor division".into(),
+                            op.span,
+                            lhs.span,
+                            lhs.ty.clone(),
+                        )),
+                    )
+                }
             },
             Operator::Boolean(Boolean::And)
             | Operator::Boolean(Boolean::Or)
@@ -284,11 +375,12 @@ pub fn math_result_type(
                     // FIX ME. This is added because there is no type output for custom function
                     // definitions. As soon as that syntax is added this should be removed
                     (a, b) if a == b => (Type::Bool, None),
-                    _ => {
+                    (Type::Bool, _) => {
                         *op = Expression::garbage(op.span);
                         (
                             Type::Any,
-                            Some(ParseError::UnsupportedOperation(
+                            Some(ParseError::UnsupportedOperationRHS(
+                                "boolean operation".into(),
                                 op.span,
                                 lhs.span,
                                 lhs.ty.clone(),
@@ -297,6 +389,18 @@ pub fn math_result_type(
                             )),
                         )
                     }
+                    _ => {
+                        *op = Expression::garbage(op.span);
+                        (
+                            Type::Any,
+                            Some(ParseError::UnsupportedOperationLHS(
+                                "boolean operation".into(),
+                                op.span,
+                                lhs.span,
+                                lhs.ty.clone(),
+                            )),
+                        )
+                    }
                 }
             }
             Operator::Comparison(Comparison::LessThan) => match (&lhs.ty, &rhs.ty) {
@@ -315,11 +419,12 @@ pub fn math_result_type(
 
                 (Type::Any, _) => (Type::Bool, None),
                 (_, Type::Any) => (Type::Bool, None),
-                _ => {
+                (Type::Int | Type::Float | Type::Duration | Type::Filesize, _) => {
                     *op = Expression::garbage(op.span);
                     (
                         Type::Any,
-                        Some(ParseError::UnsupportedOperation(
+                        Some(ParseError::UnsupportedOperationRHS(
+                            "less-than comparison".into(),
                             op.span,
                             lhs.span,
                             lhs.ty.clone(),
@@ -328,6 +433,18 @@ pub fn math_result_type(
                         )),
                     )
                 }
+                _ => {
+                    *op = Expression::garbage(op.span);
+                    (
+                        Type::Any,
+                        Some(ParseError::UnsupportedOperationLHS(
+                            "less-than comparison".into(),
+                            op.span,
+                            lhs.span,
+                            lhs.ty.clone(),
+                        )),
+                    )
+                }
             },
             Operator::Comparison(Comparison::LessThanOrEqual) => match (&lhs.ty, &rhs.ty) {
                 (Type::Int, Type::Int) => (Type::Bool, None),
@@ -345,11 +462,12 @@ pub fn math_result_type(
 
                 (Type::Any, _) => (Type::Bool, None),
                 (_, Type::Any) => (Type::Bool, None),
-                _ => {
+                (Type::Int | Type::Float | Type::Duration | Type::Filesize, _) => {
                     *op = Expression::garbage(op.span);
                     (
                         Type::Any,
-                        Some(ParseError::UnsupportedOperation(
+                        Some(ParseError::UnsupportedOperationRHS(
+                            "less-than or equal comparison".into(),
                             op.span,
                             lhs.span,
                             lhs.ty.clone(),
@@ -358,6 +476,18 @@ pub fn math_result_type(
                         )),
                     )
                 }
+                _ => {
+                    *op = Expression::garbage(op.span);
+                    (
+                        Type::Any,
+                        Some(ParseError::UnsupportedOperationLHS(
+                            "less-than or equal comparison".into(),
+                            op.span,
+                            lhs.span,
+                            lhs.ty.clone(),
+                        )),
+                    )
+                }
             },
             Operator::Comparison(Comparison::GreaterThan) => match (&lhs.ty, &rhs.ty) {
                 (Type::Int, Type::Int) => (Type::Bool, None),
@@ -375,11 +505,12 @@ pub fn math_result_type(
 
                 (Type::Nothing, _) => (Type::Nothing, None),
                 (_, Type::Nothing) => (Type::Nothing, None),
-                _ => {
+                (Type::Int | Type::Float | Type::Duration | Type::Filesize, _) => {
                     *op = Expression::garbage(op.span);
                     (
                         Type::Any,
-                        Some(ParseError::UnsupportedOperation(
+                        Some(ParseError::UnsupportedOperationRHS(
+                            "greater-than comparison".into(),
                             op.span,
                             lhs.span,
                             lhs.ty.clone(),
@@ -388,6 +519,18 @@ pub fn math_result_type(
                         )),
                     )
                 }
+                _ => {
+                    *op = Expression::garbage(op.span);
+                    (
+                        Type::Any,
+                        Some(ParseError::UnsupportedOperationLHS(
+                            "greater-than comparison".into(),
+                            op.span,
+                            lhs.span,
+                            lhs.ty.clone(),
+                        )),
+                    )
+                }
             },
             Operator::Comparison(Comparison::GreaterThanOrEqual) => match (&lhs.ty, &rhs.ty) {
                 (Type::Int, Type::Int) => (Type::Bool, None),
@@ -405,11 +548,12 @@ pub fn math_result_type(
 
                 (Type::Nothing, _) => (Type::Nothing, None),
                 (_, Type::Nothing) => (Type::Nothing, None),
-                _ => {
+                (Type::Int | Type::Float | Type::Duration | Type::Filesize, _) => {
                     *op = Expression::garbage(op.span);
                     (
                         Type::Any,
-                        Some(ParseError::UnsupportedOperation(
+                        Some(ParseError::UnsupportedOperationRHS(
+                            "greater-than or equal comparison".into(),
                             op.span,
                             lhs.span,
                             lhs.ty.clone(),
@@ -418,6 +562,18 @@ pub fn math_result_type(
                         )),
                     )
                 }
+                _ => {
+                    *op = Expression::garbage(op.span);
+                    (
+                        Type::Any,
+                        Some(ParseError::UnsupportedOperationLHS(
+                            "greater-than or equal comparison".into(),
+                            op.span,
+                            lhs.span,
+                            lhs.ty.clone(),
+                        )),
+                    )
+                }
             },
             Operator::Comparison(Comparison::Equal) => match (&lhs.ty, &rhs.ty) {
                 (Type::Custom(a), Type::Custom(b)) if a == b => (Type::Custom(a.to_string()), None),
@@ -439,11 +595,12 @@ pub fn math_result_type(
                 (Type::Custom(a), Type::Custom(b)) if a == b => (Type::Custom(a.to_string()), None),
                 (Type::Custom(a), _) => (Type::Custom(a.to_string()), None),
 
-                _ => {
+                (Type::String, _) => {
                     *op = Expression::garbage(op.span);
                     (
                         Type::Any,
-                        Some(ParseError::UnsupportedOperation(
+                        Some(ParseError::UnsupportedOperationRHS(
+                            "regex matching".into(),
                             op.span,
                             lhs.span,
                             lhs.ty.clone(),
@@ -452,6 +609,18 @@ pub fn math_result_type(
                         )),
                     )
                 }
+                _ => {
+                    *op = Expression::garbage(op.span);
+                    (
+                        Type::Any,
+                        Some(ParseError::UnsupportedOperationLHS(
+                            "regex matching".into(),
+                            op.span,
+                            lhs.span,
+                            lhs.ty.clone(),
+                        )),
+                    )
+                }
             },
             Operator::Comparison(Comparison::NotRegexMatch) => match (&lhs.ty, &rhs.ty) {
                 (Type::String, Type::String) => (Type::Bool, None),
@@ -461,11 +630,12 @@ pub fn math_result_type(
                 (Type::Custom(a), Type::Custom(b)) if a == b => (Type::Custom(a.to_string()), None),
                 (Type::Custom(a), _) => (Type::Custom(a.to_string()), None),
 
-                _ => {
+                (Type::String, _) => {
                     *op = Expression::garbage(op.span);
                     (
                         Type::Any,
-                        Some(ParseError::UnsupportedOperation(
+                        Some(ParseError::UnsupportedOperationRHS(
+                            "regex matching".into(),
                             op.span,
                             lhs.span,
                             lhs.ty.clone(),
@@ -474,6 +644,18 @@ pub fn math_result_type(
                         )),
                     )
                 }
+                _ => {
+                    *op = Expression::garbage(op.span);
+                    (
+                        Type::Any,
+                        Some(ParseError::UnsupportedOperationLHS(
+                            "regex matching".into(),
+                            op.span,
+                            lhs.span,
+                            lhs.ty.clone(),
+                        )),
+                    )
+                }
             },
             Operator::Comparison(Comparison::StartsWith) => match (&lhs.ty, &rhs.ty) {
                 (Type::String, Type::String) => (Type::Bool, None),
@@ -483,11 +665,12 @@ pub fn math_result_type(
                 (Type::Custom(a), Type::Custom(b)) if a == b => (Type::Custom(a.to_string()), None),
                 (Type::Custom(a), _) => (Type::Custom(a.to_string()), None),
 
-                _ => {
+                (Type::String, _) => {
                     *op = Expression::garbage(op.span);
                     (
                         Type::Any,
-                        Some(ParseError::UnsupportedOperation(
+                        Some(ParseError::UnsupportedOperationRHS(
+                            "starts-with comparison".into(),
                             op.span,
                             lhs.span,
                             lhs.ty.clone(),
@@ -496,6 +679,18 @@ pub fn math_result_type(
                         )),
                     )
                 }
+                _ => {
+                    *op = Expression::garbage(op.span);
+                    (
+                        Type::Any,
+                        Some(ParseError::UnsupportedOperationLHS(
+                            "starts-with comparison".into(),
+                            op.span,
+                            lhs.span,
+                            lhs.ty.clone(),
+                        )),
+                    )
+                }
             },
             Operator::Comparison(Comparison::EndsWith) => match (&lhs.ty, &rhs.ty) {
                 (Type::String, Type::String) => (Type::Bool, None),
@@ -505,11 +700,12 @@ pub fn math_result_type(
                 (Type::Custom(a), Type::Custom(b)) if a == b => (Type::Custom(a.to_string()), None),
                 (Type::Custom(a), _) => (Type::Custom(a.to_string()), None),
 
-                _ => {
+                (Type::String, _) => {
                     *op = Expression::garbage(op.span);
                     (
                         Type::Any,
-                        Some(ParseError::UnsupportedOperation(
+                        Some(ParseError::UnsupportedOperationRHS(
+                            "ends-with comparison".into(),
                             op.span,
                             lhs.span,
                             lhs.ty.clone(),
@@ -518,6 +714,18 @@ pub fn math_result_type(
                         )),
                     )
                 }
+                _ => {
+                    *op = Expression::garbage(op.span);
+                    (
+                        Type::Any,
+                        Some(ParseError::UnsupportedOperationLHS(
+                            "ends-with comparison".into(),
+                            op.span,
+                            lhs.span,
+                            lhs.ty.clone(),
+                        )),
+                    )
+                }
             },
             Operator::Comparison(Comparison::In) => match (&lhs.ty, &rhs.ty) {
                 (t, Type::List(u)) if type_compatible(t, u) => (Type::Bool, None),
@@ -530,11 +738,12 @@ pub fn math_result_type(
 
                 (Type::Any, _) => (Type::Bool, None),
                 (_, Type::Any) => (Type::Bool, None),
-                _ => {
+                (Type::Int | Type::Float | Type::String, _) => {
                     *op = Expression::garbage(op.span);
                     (
                         Type::Any,
-                        Some(ParseError::UnsupportedOperation(
+                        Some(ParseError::UnsupportedOperationRHS(
+                            "subset comparison".into(),
                             op.span,
                             lhs.span,
                             lhs.ty.clone(),
@@ -543,6 +752,18 @@ pub fn math_result_type(
                         )),
                     )
                 }
+                _ => {
+                    *op = Expression::garbage(op.span);
+                    (
+                        Type::Any,
+                        Some(ParseError::UnsupportedOperationLHS(
+                            "subset comparison".into(),
+                            op.span,
+                            lhs.span,
+                            lhs.ty.clone(),
+                        )),
+                    )
+                }
             },
             Operator::Comparison(Comparison::NotIn) => match (&lhs.ty, &rhs.ty) {
                 (t, Type::List(u)) if type_compatible(t, u) => (Type::Bool, None),
@@ -555,11 +776,12 @@ pub fn math_result_type(
 
                 (Type::Any, _) => (Type::Bool, None),
                 (_, Type::Any) => (Type::Bool, None),
-                _ => {
+                (Type::Int | Type::Float | Type::String, _) => {
                     *op = Expression::garbage(op.span);
                     (
                         Type::Any,
-                        Some(ParseError::UnsupportedOperation(
+                        Some(ParseError::UnsupportedOperationRHS(
+                            "subset comparison".into(),
                             op.span,
                             lhs.span,
                             lhs.ty.clone(),
@@ -568,6 +790,18 @@ pub fn math_result_type(
                         )),
                     )
                 }
+                _ => {
+                    *op = Expression::garbage(op.span);
+                    (
+                        Type::Any,
+                        Some(ParseError::UnsupportedOperationLHS(
+                            "subset comparison".into(),
+                            op.span,
+                            lhs.span,
+                            lhs.ty.clone(),
+                        )),
+                    )
+                }
             },
             Operator::Bits(Bits::ShiftLeft)
             | Operator::Bits(Bits::ShiftRight)
@@ -578,11 +812,12 @@ pub fn math_result_type(
 
                 (Type::Any, _) => (Type::Any, None),
                 (_, Type::Any) => (Type::Any, None),
-                _ => {
+                (Type::Int, _) => {
                     *op = Expression::garbage(op.span);
                     (
                         Type::Any,
-                        Some(ParseError::UnsupportedOperation(
+                        Some(ParseError::UnsupportedOperationRHS(
+                            "bit operations".into(),
                             op.span,
                             lhs.span,
                             lhs.ty.clone(),
@@ -591,6 +826,18 @@ pub fn math_result_type(
                         )),
                     )
                 }
+                _ => {
+                    *op = Expression::garbage(op.span);
+                    (
+                        Type::Any,
+                        Some(ParseError::UnsupportedOperationLHS(
+                            "bit operations".into(),
+                            op.span,
+                            lhs.span,
+                            lhs.ty.clone(),
+                        )),
+                    )
+                }
             },
             Operator::Assignment(_) => match (&lhs.ty, &rhs.ty) {
                 (x, y) if x == y => (Type::Nothing, None),

crates/nu-protocol/src/parse_error.rs

@@ -74,16 +74,23 @@ pub enum ParseError {
     )]
     ShellOutErrRedirect(#[label("use 'out+err>' instead of '2>&1' in Nushell")] Span),
 
-    #[error("Types mismatched for operation.")]
+    #[error("{0} is not supported on values of type {3}")]
-    #[diagnostic(
+    #[diagnostic(code(nu::parser::unsupported_operation))]
-        code(nu::parser::unsupported_operation),
+    UnsupportedOperationLHS(
-        help("Change {2} or {4} to be the right types and try again.")
+        String,
-    )]
+        #[label = "doesn't support this value"] Span,
-    UnsupportedOperation(
+        #[label("{3}")] Span,
-        #[label = "doesn't support these values."] Span,
-        #[label("{2}")] Span,
         Type,
-        #[label("{4}")] Span,
+    ),
+
+    #[error("{0} is not supported between {3} and {5}.")]
+    #[diagnostic(code(nu::parser::unsupported_operation))]
+    UnsupportedOperationRHS(
+        String,
+        #[label = "doesn't support these values"] Span,
+        #[label("{3}")] Span,
+        Type,
+        #[label("{5}")] Span,
         Type,
     ),
 
@@ -437,7 +444,8 @@ impl ParseError {
             ParseError::Unbalanced(_, _, s) => *s,
             ParseError::Expected(_, s) => *s,
             ParseError::Mismatch(_, _, s) => *s,
-            ParseError::UnsupportedOperation(_, _, _, s, _) => *s,
+            ParseError::UnsupportedOperationLHS(_, _, s, _) => *s,
+            ParseError::UnsupportedOperationRHS(_, _, _, _, s, _) => *s,
             ParseError::ExpectedKeyword(_, s) => *s,
             ParseError::UnexpectedKeyword(_, s) => *s,
             ParseError::CantAliasKeyword(_, s) => *s,

src/tests/test_ranges.rs

@@ -17,7 +17,7 @@ fn int_in_exclusive_range() -> TestResult {
 
 #[test]
 fn non_number_in_range() -> TestResult {
-    fail_test(r#"'a' in 1..3"#, "mismatched for operation")
+    fail_test(r#"'a' in 1..3"#, "subset comparison is not supported")
 }
 
 #[test]

src/tests/test_regex.rs

@@ -73,10 +73,10 @@ fn invalid_not_regex_fails() -> TestResult {
 
 #[test]
 fn regex_on_int_fails() -> TestResult {
-    fail_test(r#"33 =~ foo"#, "Types mismatched")
+    fail_test(r#"33 =~ foo"#, "is not supported")
 }
 
 #[test]
 fn not_regex_on_int_fails() -> TestResult {
-    fail_test(r#"33 !~ foo"#, "Types mismatched")
+    fail_test(r#"33 !~ foo"#, "is not supported")
 }

src/tests/test_strings.rs

@@ -20,7 +20,7 @@ fn string_in_string() -> TestResult {
 
 #[test]
 fn non_string_in_string() -> TestResult {
-    fail_test(r#"42 in 'abc'"#, "mismatched for operation")
+    fail_test(r#"42 in 'abc'"#, "is not supported")
 }
 
 #[test]

src/tests/test_type_check.rs

@@ -12,7 +12,7 @@ fn type_in_list_of_this_type() -> TestResult {
 
 #[test]
 fn type_in_list_of_non_this_type() -> TestResult {
-    fail_test(r#"'hello' in [41 42 43]"#, "mismatched for operation")
+    fail_test(r#"'hello' in [41 42 43]"#, "is not supported")
 }
 
 #[test]