Add parser keyword note to help and $nu.scope (#4978)

crates/nu-command/src/core_commands/alias.rs

@@ -25,6 +25,15 @@ impl Command for Alias {
             .category(Category::Core)
     }
 
+    fn extra_usage(&self) -> &str {
+        r#"This command is a parser keyword. For details, check
+https://www.nushell.sh/book/thinking_in_nushell.html#parsing-and-evaluation-are-different-stages"#
+    }
+
+    fn is_parser_keyword(&self) -> bool {
+        true
+    }
+
     fn run(
         &self,
         _engine_state: &EngineState,

crates/nu-command/src/core_commands/def.rs

@@ -26,6 +26,15 @@ impl Command for Def {
             .category(Category::Core)
     }
 
+    fn extra_usage(&self) -> &str {
+        r#"This command is a parser keyword. For details, check
+https://www.nushell.sh/book/thinking_in_nushell.html#parsing-and-evaluation-are-different-stages"#
+    }
+
+    fn is_parser_keyword(&self) -> bool {
+        true
+    }
+
     fn run(
         &self,
         _engine_state: &EngineState,

crates/nu-command/src/core_commands/def_env.rs

@@ -26,6 +26,15 @@ impl Command for DefEnv {
             .category(Category::Core)
     }
 
+    fn extra_usage(&self) -> &str {
+        r#"This command is a parser keyword. For details, check
+https://www.nushell.sh/book/thinking_in_nushell.html#parsing-and-evaluation-are-different-stages"#
+    }
+
+    fn is_parser_keyword(&self) -> bool {
+        true
+    }
+
     fn run(
         &self,
         _engine_state: &EngineState,

crates/nu-command/src/core_commands/export.rs

@@ -21,6 +21,15 @@ impl Command for ExportCommand {
         "Export custom commands or environment variables from a module."
     }
 
+    fn extra_usage(&self) -> &str {
+        r#"This command is a parser keyword. For details, check
+https://www.nushell.sh/book/thinking_in_nushell.html#parsing-and-evaluation-are-different-stages"#
+    }
+
+    fn is_parser_keyword(&self) -> bool {
+        true
+    }
+
     fn run(
         &self,
         engine_state: &EngineState,

crates/nu-command/src/core_commands/export_alias.rs

@@ -25,6 +25,15 @@ impl Command for ExportAlias {
             .category(Category::Core)
     }
 
+    fn extra_usage(&self) -> &str {
+        r#"This command is a parser keyword. For details, check
+https://www.nushell.sh/book/thinking_in_nushell.html#parsing-and-evaluation-are-different-stages"#
+    }
+
+    fn is_parser_keyword(&self) -> bool {
+        true
+    }
+
     fn run(
         &self,
         _engine_state: &EngineState,

crates/nu-command/src/core_commands/export_def.rs

@@ -26,6 +26,15 @@ impl Command for ExportDef {
             .category(Category::Core)
     }
 
+    fn extra_usage(&self) -> &str {
+        r#"This command is a parser keyword. For details, check
+https://www.nushell.sh/book/thinking_in_nushell.html#parsing-and-evaluation-are-different-stages"#
+    }
+
+    fn is_parser_keyword(&self) -> bool {
+        true
+    }
+
     fn run(
         &self,
         _engine_state: &EngineState,

crates/nu-command/src/core_commands/export_def_env.rs

@@ -26,6 +26,15 @@ impl Command for ExportDefEnv {
             .category(Category::Core)
     }
 
+    fn extra_usage(&self) -> &str {
+        r#"This command is a parser keyword. For details, check
+https://www.nushell.sh/book/thinking_in_nushell.html#parsing-and-evaluation-are-different-stages"#
+    }
+
+    fn is_parser_keyword(&self) -> bool {
+        true
+    }
+
     fn run(
         &self,
         _engine_state: &EngineState,

crates/nu-command/src/core_commands/export_env.rs

@@ -29,6 +29,15 @@ impl Command for ExportEnv {
             .category(Category::Core)
     }
 
+    fn extra_usage(&self) -> &str {
+        r#"This command is a parser keyword. For details, check
+https://www.nushell.sh/book/thinking_in_nushell.html#parsing-and-evaluation-are-different-stages"#
+    }
+
+    fn is_parser_keyword(&self) -> bool {
+        true
+    }
+
     fn run(
         &self,
         _engine_state: &EngineState,

crates/nu-command/src/core_commands/export_extern.rs

@@ -21,6 +21,15 @@ impl Command for ExportExtern {
             .category(Category::Core)
     }
 
+    fn extra_usage(&self) -> &str {
+        r#"This command is a parser keyword. For details, check
+https://www.nushell.sh/book/thinking_in_nushell.html#parsing-and-evaluation-are-different-stages"#
+    }
+
+    fn is_parser_keyword(&self) -> bool {
+        true
+    }
+
     fn run(
         &self,
         _engine_state: &EngineState,

crates/nu-command/src/core_commands/extern_.rs

@@ -21,6 +21,15 @@ impl Command for Extern {
             .category(Category::Core)
     }
 
+    fn extra_usage(&self) -> &str {
+        r#"This command is a parser keyword. For details, check
+https://www.nushell.sh/book/thinking_in_nushell.html#parsing-and-evaluation-are-different-stages"#
+    }
+
+    fn is_parser_keyword(&self) -> bool {
+        true
+    }
+
     fn run(
         &self,
         _engine_state: &EngineState,

crates/nu-command/src/core_commands/for_.rs

@@ -44,6 +44,15 @@ impl Command for For {
             .category(Category::Core)
     }
 
+    fn extra_usage(&self) -> &str {
+        r#"This command is a parser keyword. For details, check
+https://www.nushell.sh/book/thinking_in_nushell.html#parsing-and-evaluation-are-different-stages"#
+    }
+
+    fn is_parser_keyword(&self) -> bool {
+        true
+    }
+
     fn run(
         &self,
         engine_state: &EngineState,

crates/nu-command/src/core_commands/help.rs

@@ -85,16 +85,19 @@ fn help(
     let find: Option<Spanned<String>> = call.get_flag(engine_state, stack, "find")?;
     let rest: Vec<Spanned<String>> = call.rest(engine_state, stack, 0)?;
 
-    let full_commands = engine_state.get_signatures_with_examples(false);
+    let commands = engine_state.get_decl_ids_sorted(false);
 
     if let Some(f) = find {
         let search_string = f.item.to_lowercase();
         let mut found_cmds_vec = Vec::new();
 
-        for (sig, _, is_plugin, is_custom) in full_commands {
+        for decl_id in commands {
             let mut cols = vec![];
             let mut vals = vec![];
 
+            let decl = engine_state.get_decl(decl_id);
+            let sig = decl.signature();
+
             let key = sig.name.clone();
             let c = sig.usage.clone();
             let e = sig.extra_usage.clone();
@@ -116,13 +119,19 @@ fn help(
 
                 cols.push("is_plugin".into());
                 vals.push(Value::Bool {
-                    val: is_plugin,
+                    val: decl.is_plugin().is_some(),
                     span: head,
                 });
 
                 cols.push("is_custom".into());
                 vals.push(Value::Bool {
-                    val: is_custom,
+                    val: decl.get_block_id().is_some(),
+                    span: head,
+                });
+
+                cols.push("is_keyword".into());
+                vals.push(Value::Bool {
+                    val: decl.is_parser_keyword(),
                     span: head,
                 });
 
@@ -149,10 +158,13 @@ fn help(
         let mut found_cmds_vec = Vec::new();
 
         if rest[0].item == "commands" {
-            for (sig, _, is_plugin, is_custom) in full_commands {
+            for decl_id in commands {
                 let mut cols = vec![];
                 let mut vals = vec![];
 
+                let decl = engine_state.get_decl(decl_id);
+                let sig = decl.signature();
+
                 let key = sig.name.clone();
                 let c = sig.usage.clone();
                 let e = sig.extra_usage.clone();
@@ -171,13 +183,19 @@ fn help(
 
                 cols.push("is_plugin".into());
                 vals.push(Value::Bool {
-                    val: is_plugin,
+                    val: decl.is_plugin().is_some(),
                     span: head,
                 });
 
                 cols.push("is_custom".into());
                 vals.push(Value::Bool {
-                    val: is_custom,
+                    val: decl.get_block_id().is_some(),
+                    span: head,
+                });
+
+                cols.push("is_keyword".into());
+                vals.push(Value::Bool {
+                    val: decl.is_parser_keyword(),
                     span: head,
                 });
 
@@ -207,7 +225,8 @@ fn help(
                 name.push_str(&r.item);
             }
 
-            let output = full_commands
+            let output = engine_state
+                .get_signatures_with_examples(false)
                 .iter()
                 .filter(|(signature, _, _, _)| signature.name == name)
                 .map(|(signature, examples, _, _)| {

crates/nu-command/src/core_commands/hide.rs

@@ -23,7 +23,15 @@ impl Command for Hide {
     }
 
     fn extra_usage(&self) -> &str {
-        "Symbols are hidden by priority: First aliases, then custom commands, then environment variables."
+        r#"Symbols are hidden by priority: First aliases, then custom commands, then environment variables.
+
+This command is a parser keyword. For details, check
+https://www.nushell.sh/book/thinking_in_nushell.html#parsing-and-evaluation-are-different-stages
+            "#
+    }
+
+    fn is_parser_keyword(&self) -> bool {
+        true
     }
 
     fn run(

crates/nu-command/src/core_commands/if_.rs

@@ -34,6 +34,15 @@ impl Command for If {
             .category(Category::Core)
     }
 
+    fn extra_usage(&self) -> &str {
+        r#"This command is a parser keyword. For details, check
+https://www.nushell.sh/book/thinking_in_nushell.html#parsing-and-evaluation-are-different-stages"#
+    }
+
+    fn is_parser_keyword(&self) -> bool {
+        true
+    }
+
     fn run(
         &self,
         engine_state: &EngineState,

crates/nu-command/src/core_commands/let_.rs

@@ -26,6 +26,15 @@ impl Command for Let {
             .category(Category::Core)
     }
 
+    fn extra_usage(&self) -> &str {
+        r#"This command is a parser keyword. For details, check
+https://www.nushell.sh/book/thinking_in_nushell.html#parsing-and-evaluation-are-different-stages"#
+    }
+
+    fn is_parser_keyword(&self) -> bool {
+        true
+    }
+
     fn run(
         &self,
         engine_state: &EngineState,

crates/nu-command/src/core_commands/module.rs

@@ -25,6 +25,15 @@ impl Command for Module {
             .category(Category::Core)
     }
 
+    fn extra_usage(&self) -> &str {
+        r#"This command is a parser keyword. For details, check
+https://www.nushell.sh/book/thinking_in_nushell.html#parsing-and-evaluation-are-different-stages"#
+    }
+
+    fn is_parser_keyword(&self) -> bool {
+        true
+    }
+
     fn run(
         &self,
         _engine_state: &EngineState,

crates/nu-command/src/core_commands/register.rs

@@ -41,6 +41,15 @@ impl Command for Register {
             .category(Category::Core)
     }
 
+    fn extra_usage(&self) -> &str {
+        r#"This command is a parser keyword. For details, check
+https://www.nushell.sh/book/thinking_in_nushell.html#parsing-and-evaluation-are-different-stages"#
+    }
+
+    fn is_parser_keyword(&self) -> bool {
+        true
+    }
+
     fn run(
         &self,
         _engine_state: &EngineState,

crates/nu-command/src/core_commands/source.rs

@@ -26,6 +26,15 @@ impl Command for Source {
         "Runs a script file in the current context."
     }
 
+    fn extra_usage(&self) -> &str {
+        r#"This command is a parser keyword. For details, check
+https://www.nushell.sh/book/thinking_in_nushell.html#parsing-and-evaluation-are-different-stages"#
+    }
+
+    fn is_parser_keyword(&self) -> bool {
+        true
+    }
+
     fn run(
         &self,
         engine_state: &EngineState,

crates/nu-command/src/core_commands/use_.rs

@@ -23,6 +23,15 @@ impl Command for Use {
             .category(Category::Core)
     }
 
+    fn extra_usage(&self) -> &str {
+        r#"This command is a parser keyword. For details, check
+https://www.nushell.sh/book/thinking_in_nushell.html#parsing-and-evaluation-are-different-stages"#
+    }
+
+    fn is_parser_keyword(&self) -> bool {
+        true
+    }
+
     fn run(
         &self,
         engine_state: &EngineState,

crates/nu-engine/src/eval.rs

@@ -1002,6 +1002,12 @@ pub fn create_scope(
                 span,
             });
 
+            cols.push("is_keyword".into());
+            vals.push(Value::Bool {
+                val: decl.is_parser_keyword(),
+                span,
+            });
+
             cols.push("is_extern".to_string());
             vals.push(Value::Bool {
                 val: decl.is_known_external(),

crates/nu-protocol/src/engine/command.rs

@@ -46,6 +46,11 @@ pub trait Command: Send + Sync + CommandClone {
         self.name().contains(' ')
     }
 
+    // Is a parser keyword (source, def, etc.)
+    fn is_parser_keyword(&self) -> bool {
+        false
+    }
+
     // Is a plugin command (returns plugin's path, encoding and type of shell
     // if the declaration is a plugin)
     fn is_plugin(&self) -> Option<(&PathBuf, &str, &Option<PathBuf>)> {