Enhance vector variable expansion to properly handle command names

To eliminate false positives in rust-analyzer. Also add compile_fail
tests to ensure invalid syntax is still rejected.

Author: tao-guo

macros/src/lexer.rs

@@ -417,8 +417,22 @@ impl Lexer {
                     if g.delimiter() == Delimiter::Brace {
                         self.extend_last_arg(quote!(#var.as_os_str()));
                     } else {
+                        // For vector variables $[var], we need to check if there's content
+                        // immediately before (without space), which would be invalid like: xxx$[var]
+                        // But if last_arg_str is just the command name, it should be flushed first
                         if !self.last_arg_str.is_empty() {
-                            abort!(span, "vector variable can only be used alone");
+                            // Check if this is the first argument (command name)
+                            if self.args.is_empty() {
+                                // Flush the command name as the first argument
+                                self.args.push(ParseArg::ArgStr(self.last_arg_str.clone()));
+                                self.last_arg_str = TokenStream::new();
+                            } else {
+                                // This is an error: something like xxx$[var] without space
+                                abort!(
+                                    span,
+                                    "vector variable cannot have content immediately before it"
+                                );
+                            }
                         }
                         self.args.push(ParseArg::ArgVec(quote!(#var)));
                     }

macros/src/lib.rs

@@ -56,6 +56,22 @@
 //! run_fun!(echo "${msg 0}");
 //! ```
 //!
+//! ### Invalid vector variable syntax
+//!
+//! Vector variables cannot have text immediately before them:
+//! ```compile_fail
+//! # use cmd_lib::*;
+//! let opts = ["-a", "-f"];
+//! run_cmd!(ls xxx$[opts]);
+//! ```
+//!
+//! ```compile_fail
+//! # use cmd_lib::*;
+//! let msg = "hello";
+//! let opts = ["-a", "-f"];
+//! run_cmd!(ls $msg$[opts]);
+//! ```
+//!
 //! ### Invalid redirect syntax
 //!
 //! Invalid redirect operator spacing:

tests/test_macros.rs

@@ -372,3 +372,9 @@ fn test_empty_arg() {
 fn test_env_var_with_equal_sign() {
     assert!(run_cmd!(A="-c B=c" echo).is_ok());
 }
+
+#[test]
+fn test_vector_variable() {
+    let opts = ["-n", "hello"];
+    assert!(run_cmd!(echo $[opts]).is_ok())
+}