Allow duration to be added to date (#14295)

# Description

Fixes #14294 - Turned out to be a whole lot easier than I expected, but
please double-check me on this, since it's an area I haven't been in
before.

# User-Facing Changes

Allow date to be added to a duration type.

# Tests + Formatting

Tests added:

* Duration + Date is allowed
* Duration - Date is not allowed

crates/nu-parser/src/type_check.rs

@@ -88,6 +88,7 @@ pub fn math_result_type(
                 (Type::Float, Type::Number) => (Type::Number, None),
                 (Type::String, Type::String) => (Type::String, None),
                 (Type::Date, Type::Duration) => (Type::Date, None),
+                (Type::Duration, Type::Date) => (Type::Date, None),
                 (Type::Duration, Type::Duration) => (Type::Duration, None),
                 (Type::Filesize, Type::Filesize) => (Type::Filesize, None),
 

crates/nu-protocol/src/value/mod.rs

@@ -2444,6 +2444,17 @@ impl Value {
                 Ok(Value::string(lhs.to_string() + rhs, span))
             }
 
+            (Value::Duration { val: lhs, .. }, Value::Date { val: rhs, .. }) => {
+                if let Some(val) = rhs.checked_add_signed(chrono::Duration::nanoseconds(*lhs)) {
+                    Ok(Value::date(val, span))
+                } else {
+                    Err(ShellError::OperatorOverflow {
+                        msg: "addition operation overflowed".into(),
+                        span,
+                        help: None,
+                    })
+                }
+            }
             (Value::Date { val: lhs, .. }, Value::Duration { val: rhs, .. }) => {
                 if let Some(val) = lhs.checked_add_signed(chrono::Duration::nanoseconds(*rhs)) {
                     Ok(Value::date(val, span))

tests/repl/test_type_check.rs

@@ -37,6 +37,11 @@ fn date_minus_duration() -> TestResult {
     run_test(input, expected)
 }
 
+#[test]
+fn duration_minus_date_not_supported() -> TestResult {
+    fail_test("2day - 2023-04-22", "doesn't support these values")
+}
+
 #[test]
 fn date_plus_duration() -> TestResult {
     let input = "2023-04-18 + 2day | format date %Y-%m-%d";
@@ -44,6 +49,13 @@ fn date_plus_duration() -> TestResult {
     run_test(input, expected)
 }
 
+#[test]
+fn duration_plus_date() -> TestResult {
+    let input = "2024-11-10T00:00:00-00:00 + 4hr | format date";
+    let expected = "Sun, 10 Nov 2024 04:00:00 +0000";
+    run_test(input, expected)
+}
+
 #[test]
 fn block_not_first_class_def() -> TestResult {
     fail_test(