From cde8a629c5e73e4775d01f4252f4beff253001bd Mon Sep 17 00:00:00 2001
From: Stefan Holderbach <sholderbach@users.noreply.github.com>
Date: Wed, 18 Jun 2025 10:49:40 +0200
Subject: [PATCH] Restrict `config.show_banner` to valid options (#15985)

---
 crates/nu-cli/src/repl.rs                     |  8 +--
 crates/nu-protocol/src/config/mod.rs          |  6 +-
 crates/nu-protocol/src/config/output.rs       | 68 +++++++++++++++++++
 .../nu-utils/src/default_files/doc_config.nu  |  5 +-
 4 files changed, 79 insertions(+), 8 deletions(-)

diff --git a/crates/nu-cli/src/repl.rs b/crates/nu-cli/src/repl.rs
index a4ca2903cc..f003f15b0e 100644
--- a/crates/nu-cli/src/repl.rs
+++ b/crates/nu-cli/src/repl.rs
@@ -22,8 +22,8 @@ use nu_color_config::StyleComputer;
 use nu_engine::env_to_strings;
 use nu_engine::exit::cleanup_exit;
 use nu_parser::{lex, parse, trim_quotes_str};
-use nu_protocol::shell_error;
 use nu_protocol::shell_error::io::IoError;
+use nu_protocol::{BannerKind, shell_error};
 use nu_protocol::{
     HistoryConfig, HistoryFileFormat, PipelineData, ShellError, Span, Spanned, Value,
     config::NuCursorShape,
@@ -145,8 +145,8 @@ pub fn evaluate_repl(
 
     if load_std_lib.is_none() {
         match engine_state.get_config().show_banner {
-            Value::Bool { val: false, .. } => {}
-            Value::String { ref val, .. } if val == "short" => {
+            BannerKind::None => {}
+            BannerKind::Short => {
                 eval_source(
                     engine_state,
                     &mut unique_stack,
@@ -156,7 +156,7 @@ pub fn evaluate_repl(
                     false,
                 );
             }
-            _ => {
+            BannerKind::Full => {
                 eval_source(
                     engine_state,
                     &mut unique_stack,
diff --git a/crates/nu-protocol/src/config/mod.rs b/crates/nu-protocol/src/config/mod.rs
index 42da2b3233..4f267d2597 100644
--- a/crates/nu-protocol/src/config/mod.rs
+++ b/crates/nu-protocol/src/config/mod.rs
@@ -17,7 +17,7 @@ pub use helper::extract_value;
 pub use history::{HistoryConfig, HistoryFileFormat};
 pub use hooks::Hooks;
 pub use ls::LsConfig;
-pub use output::ErrorStyle;
+pub use output::{BannerKind, ErrorStyle};
 pub use plugin_gc::{PluginGcConfig, PluginGcConfigs};
 pub use reedline::{CursorShapeConfig, EditBindings, NuCursorShape, ParsedKeybinding, ParsedMenu};
 pub use rm::RmConfig;
@@ -61,7 +61,7 @@ pub struct Config {
     pub rm: RmConfig,
     pub shell_integration: ShellIntegrationConfig,
     pub buffer_editor: Value,
-    pub show_banner: Value,
+    pub show_banner: BannerKind,
     pub bracketed_paste: bool,
     pub render_right_prompt_on_last_line: bool,
     pub explore: HashMap<String, Value>,
@@ -84,7 +84,7 @@ pub struct Config {
 impl Default for Config {
     fn default() -> Config {
         Config {
-            show_banner: Value::bool(true, Span::unknown()),
+            show_banner: BannerKind::default(),
 
             table: TableConfig::default(),
             rm: RmConfig::default(),
diff --git a/crates/nu-protocol/src/config/output.rs b/crates/nu-protocol/src/config/output.rs
index 082856bdce..c0e2a695e8 100644
--- a/crates/nu-protocol/src/config/output.rs
+++ b/crates/nu-protocol/src/config/output.rs
@@ -25,3 +25,71 @@ impl UpdateFromValue for ErrorStyle {
         config_update_string_enum(self, value, path, errors)
     }
 }
+
+/// Option: show_banner
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
+pub enum BannerKind {
+    /// No banner on startup
+    None,
+    /// Abbreviated banner just containing the startup-time
+    Short,
+    /// The full banner including Ellie
+    #[default]
+    Full,
+}
+
+impl IntoValue for BannerKind {
+    fn into_value(self, span: Span) -> Value {
+        match self {
+            // This uses a custom implementation to reflect common config
+            // bool: true, false was used for a long time
+            // string: short was added later
+            BannerKind::None => Value::bool(false, span),
+            BannerKind::Short => Value::string("short", span),
+            BannerKind::Full => Value::bool(true, span),
+        }
+    }
+}
+
+impl UpdateFromValue for BannerKind {
+    fn update<'a>(
+        &mut self,
+        value: &'a Value,
+        path: &mut ConfigPath<'a>,
+        errors: &mut ConfigErrors,
+    ) {
+        match value {
+            Value::Bool { val, .. } => match val {
+                true => {
+                    *self = BannerKind::Full;
+                }
+                false => {
+                    *self = BannerKind::None;
+                }
+            },
+            Value::String { val, .. } => match val.as_str() {
+                "true" => {
+                    *self = BannerKind::Full;
+                }
+                "full" => {
+                    *self = BannerKind::Full;
+                }
+                "short" => {
+                    *self = BannerKind::Short;
+                }
+                "false" => {
+                    *self = BannerKind::None;
+                }
+                "none" => {
+                    *self = BannerKind::None;
+                }
+                _ => {
+                    errors.invalid_value(path, "true/'full', 'short', false/'none'", value);
+                }
+            },
+            _ => {
+                errors.invalid_value(path, "true/'full', 'short', false/'none'", value);
+            }
+        }
+    }
+}
diff --git a/crates/nu-utils/src/default_files/doc_config.nu b/crates/nu-utils/src/default_files/doc_config.nu
index 252eb4718e..46bd9edecb 100644
--- a/crates/nu-utils/src/default_files/doc_config.nu
+++ b/crates/nu-utils/src/default_files/doc_config.nu
@@ -70,7 +70,10 @@ $env.config.history.isolation = true
 # Miscellaneous Settings
 # ----------------------
 
-# show_banner (bool): Enable or disable the welcome banner at startup
+# show_banner (bool|string): Enable or disable the welcome banner at startup
+# true | "full": show the full banner
+# "short": just show the start-up time
+# false | "none": don't show a banner
 $env.config.show_banner = true
 
 # rm.always_trash (bool):