fix(random dice): gracefully handle --sides 0 using NonZeroUsize (#16001)

crates/nu-command/src/random/dice.rs

@@ -1,6 +1,7 @@
 use nu_engine::command_prelude::*;
 use nu_protocol::ListStream;
 use rand::random_range;
+use std::num::NonZeroUsize;
 
 #[derive(Clone)]
 pub struct RandomDice;
@@ -70,8 +71,16 @@ fn dice(
 ) -> Result<PipelineData, ShellError> {
     let span = call.head;
 
-    let dice: usize = call.get_flag(engine_state, stack, "dice")?.unwrap_or(1);
-    let sides: usize = call.get_flag(engine_state, stack, "sides")?.unwrap_or(6);
+    let sides: NonZeroUsize = call
+        .get_flag(engine_state, stack, "sides")?
+        .unwrap_or_else(|| NonZeroUsize::new(6).expect("default sides must be non-zero"));
+
+    let dice: NonZeroUsize = call
+        .get_flag(engine_state, stack, "dice")?
+        .unwrap_or_else(|| NonZeroUsize::new(1).expect("default dice count must be non-zero"));
+
+    let sides = sides.get();
+    let dice = dice.get();
 
     let iter = (0..dice).map(move |_| Value::int(random_range(1..sides + 1) as i64, span));
 

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

@@ -10,6 +10,10 @@ use std::{
     cmp::Ordering,
     collections::{HashMap, VecDeque},
     fmt,
+    num::{
+        NonZeroI8, NonZeroI16, NonZeroI32, NonZeroI64, NonZeroIsize, NonZeroU16, NonZeroU32,
+        NonZeroU64, NonZeroUsize,
+    },
     path::PathBuf,
     str::FromStr,
 };
@@ -270,6 +274,42 @@ impl FromValue for i64 {
     }
 }
 
+//
+// We can not use impl<T: FromValue> FromValue for NonZero<T> as NonZero requires an unstable trait
+// As a result, we use this macro to implement FromValue for each NonZero type.
+//
+
+macro_rules! impl_from_value_for_nonzero {
+    ($nonzero:ty, $base:ty) => {
+        impl FromValue for $nonzero {
+            fn from_value(v: Value) -> Result<Self, ShellError> {
+                let span = v.span();
+                let val = <$base>::from_value(v)?;
+                <$nonzero>::new(val).ok_or_else(|| ShellError::IncorrectValue {
+                    msg: "use a value other than 0".into(),
+                    val_span: span,
+                    call_span: span,
+                })
+            }
+
+            fn expected_type() -> Type {
+                Type::Int
+            }
+        }
+    };
+}
+
+impl_from_value_for_nonzero!(NonZeroU16, u16);
+impl_from_value_for_nonzero!(NonZeroU32, u32);
+impl_from_value_for_nonzero!(NonZeroU64, u64);
+impl_from_value_for_nonzero!(NonZeroUsize, usize);
+
+impl_from_value_for_nonzero!(NonZeroI8, i8);
+impl_from_value_for_nonzero!(NonZeroI16, i16);
+impl_from_value_for_nonzero!(NonZeroI32, i32);
+impl_from_value_for_nonzero!(NonZeroI64, i64);
+impl_from_value_for_nonzero!(NonZeroIsize, isize);
+
 macro_rules! impl_from_value_for_int {
     ($type:ty) => {
         impl FromValue for $type {