From 34da26d039b85581332e58893cd539951a888c4f Mon Sep 17 00:00:00 2001
From: Himadri Bhattacharjee <107522312+lavafroth@users.noreply.github.com>
Date: Fri, 5 Jul 2024 19:31:27 +0530
Subject: [PATCH] fix: exotic types return float on division, self on modulo
 (#13301)

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Related to #13298

# Description
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Exotic types like `Duration` and `Filesize` return a float on division
by the same type, i.e., the unit is gone since division results in a
scalar. When using the modulo operator, the output type has the same
unit.

# User-Facing Changes
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helps us keep track of breaking changes. -->

Division results in a float like the following:

```sh
~/Public/nushell> 512sec / 3sec
170.66666666666666
```

Modulo results in an output with the same unit:

```sh
~/Public/nushell> 512sec mod 3sec
2sec
```

Type checking isn't confused with output types:

```sh
~/Public/nushell> (512sec mod 3sec) / 0.5sec
4
```

# Tests + Formatting
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Existing tests are passing.

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---
 crates/nu-parser/src/type_check.rs | 52 ++++++++++++++++++++++++++++--
 1 file changed, 50 insertions(+), 2 deletions(-)

diff --git a/crates/nu-parser/src/type_check.rs b/crates/nu-parser/src/type_check.rs
index 872bb6a94c..6999a0469b 100644
--- a/crates/nu-parser/src/type_check.rs
+++ b/crates/nu-parser/src/type_check.rs
@@ -278,8 +278,7 @@ pub fn math_result_type(
                     )
                 }
             },
-            Operator::Math(Math::Divide) | Operator::Math(Math::Modulo) => match (&lhs.ty, &rhs.ty)
-            {
+            Operator::Math(Math::Divide) => match (&lhs.ty, &rhs.ty) {
                 (Type::Int, Type::Int) => (Type::Int, None),
                 (Type::Float, Type::Int) => (Type::Float, None),
                 (Type::Int, Type::Float) => (Type::Float, None),
@@ -292,6 +291,55 @@ pub fn math_result_type(
                 (Type::Filesize, Type::Filesize) => (Type::Float, None),
                 (Type::Filesize, Type::Int) => (Type::Filesize, None),
                 (Type::Filesize, Type::Float) => (Type::Filesize, None),
+                (Type::Duration, Type::Duration) => (Type::Float, None),
+                (Type::Duration, Type::Int) => (Type::Duration, None),
+                (Type::Duration, Type::Float) => (Type::Duration, None),
+
+                (Type::Custom(a), Type::Custom(b)) if a == b => (Type::Custom(a.clone()), None),
+                (Type::Custom(a), _) => (Type::Custom(a.clone()), None),
+
+                (Type::Any, _) => (Type::Any, None),
+                (_, Type::Any) => (Type::Any, None),
+                (Type::Int | Type::Float | Type::Filesize | Type::Duration, _) => {
+                    *op = Expression::garbage(working_set, op.span);
+                    (
+                        Type::Any,
+                        Some(ParseError::UnsupportedOperationRHS(
+                            "division".into(),
+                            op.span,
+                            lhs.span,
+                            lhs.ty.clone(),
+                            rhs.span,
+                            rhs.ty.clone(),
+                        )),
+                    )
+                }
+                _ => {
+                    *op = Expression::garbage(working_set, op.span);
+                    (
+                        Type::Any,
+                        Some(ParseError::UnsupportedOperationLHS(
+                            "division".into(),
+                            op.span,
+                            lhs.span,
+                            lhs.ty.clone(),
+                        )),
+                    )
+                }
+            },
+            Operator::Math(Math::Modulo) => match (&lhs.ty, &rhs.ty) {
+                (Type::Int, Type::Int) => (Type::Int, None),
+                (Type::Float, Type::Int) => (Type::Float, None),
+                (Type::Int, Type::Float) => (Type::Float, None),
+                (Type::Float, Type::Float) => (Type::Float, None),
+                (Type::Number, Type::Number) => (Type::Number, None),
+                (Type::Number, Type::Int) => (Type::Number, None),
+                (Type::Int, Type::Number) => (Type::Number, None),
+                (Type::Number, Type::Float) => (Type::Number, None),
+                (Type::Float, Type::Number) => (Type::Number, None),
+                (Type::Filesize, Type::Filesize) => (Type::Filesize, None),
+                (Type::Filesize, Type::Int) => (Type::Filesize, None),
+                (Type::Filesize, Type::Float) => (Type::Filesize, None),
                 (Type::Duration, Type::Duration) => (Type::Duration, None),
                 (Type::Duration, Type::Int) => (Type::Duration, None),
                 (Type::Duration, Type::Float) => (Type::Duration, None),