build: add deny(unreachable_pub)

Signed-off-by: Charlotte Meyer <dev@buffet.sh>

crates/oyster_builtin_proc/src/lib.rs

@@ -1,3 +1,5 @@
+#![deny(unreachable_pub)]
+
 use darling::FromMeta;
 use proc_macro::TokenStream;
 use proc_macro2::Span;

crates/oyster_lineedit/src/lib.rs

@@ -1,3 +1,5 @@
+#![deny(unreachable_pub)]
+
 use std::io::{self, Write};
 
 pub fn readline(prompt: &str) -> Result<String, io::Error> {

crates/oyster_parser/src/lib.rs

@@ -1,3 +1,5 @@
+#![deny(unreachable_pub)]
+
 //! Parser for the oyster shell, the grammar is outlined below, `extras` are allowed everywhere,
 //! *except* inside `word`.
 //! `_` means that the rule does not produce an explicit node.

crates/oyster_runtime/src/lib.rs

@@ -1,3 +1,5 @@
+#![deny(unreachable_pub)]
+
 //! The runtime for executing oyster programs.
 //! Panics when an invalid ast gets passed.