Handle Windows drive paths in auto-cd (#6051)

* Handle Windows drive paths in auto-cd

* Limit `use regex` to Windows

* Use lazy_static for Windows drive path regex

* try fixing Clippy on *nix

Cargo.lock

@@ -2607,6 +2607,7 @@ dependencies = [
  "crossterm",
  "fuzzy-matcher",
  "is_executable",
+ "lazy_static",
  "log",
  "miette 5.1.0",
  "nu-ansi-term",
@@ -2619,6 +2620,7 @@ dependencies = [
  "nu-test-support",
  "nu-utils",
  "reedline",
+ "regex",
  "sysinfo",
  "thiserror",
 ]

crates/nu-cli/Cargo.toml

@@ -24,9 +24,11 @@ miette = { version = "5.1.0", features = ["fancy"] }
 thiserror = "1.0.31"
 fuzzy-matcher = "0.3.7"
 
-log = "0.4"
-is_executable = "1.0.1"
 chrono = "0.4.19"
+is_executable = "1.0.1"
+lazy_static = "1.4.0"
+log = "0.4"
+regex = "1.5.4"
 sysinfo = "0.24.1"
 
 [features]

crates/nu-cli/src/repl.rs

@@ -5,6 +5,7 @@ use crate::{
     util::{eval_source, get_guaranteed_cwd, report_error, report_error_new},
     NuHighlighter, NuValidator, NushellPrompt,
 };
+use lazy_static::lazy_static;
 use log::{info, trace};
 use miette::{IntoDiagnostic, Result};
 use nu_color_config::get_color_config;
@@ -16,6 +17,7 @@ use nu_protocol::{
     BlockId, HistoryFileFormat, PipelineData, PositionalArg, ShellError, Span, Type, Value, VarId,
 };
 use reedline::{DefaultHinter, Emacs, SqliteBackedHistory, Vi};
+use regex::Regex;
 use std::io::{self, Write};
 use std::{sync::atomic::Ordering, time::Instant};
 use sysinfo::SystemExt;
@@ -335,13 +337,7 @@ pub fn evaluate_repl(
 
                 let orig = s.clone();
 
-                if (orig.starts_with('.')
+                if looks_like_path(&orig) && path.is_dir() && tokens.0.len() == 1 {
-                    || orig.starts_with('~')
-                    || orig.starts_with('/')
-                    || orig.starts_with('\\'))
-                    && path.is_dir()
-                    && tokens.0.len() == 1
-                {
                     // We have an auto-cd
                     let (path, span) = {
                         if !path.exists() {
@@ -756,3 +752,34 @@ fn run_ansi_sequence(seq: &str) -> Result<(), ShellError> {
         )
     })
 }
+
+lazy_static! {
+    // Absolute paths with a drive letter, like 'C:', 'D:\', 'E:\foo'
+    static ref DRIVE_PATH_REGEX: Regex =
+        Regex::new(r"^[a-zA-Z]:[/\\]?").expect("Internal error: regex creation");
+}
+
+// A best-effort "does this string look kinda like a path?" function to determine whether to auto-cd
+fn looks_like_path(orig: &str) -> bool {
+    #[cfg(windows)]
+    {
+        if DRIVE_PATH_REGEX.is_match(orig) {
+            return true;
+        }
+    }
+
+    orig.starts_with('.')
+        || orig.starts_with('~')
+        || orig.starts_with('/')
+        || orig.starts_with('\\')
+}
+
+#[test]
+fn looks_like_path_windows_drive_path_works() {
+    let on_windows = cfg!(windows);
+    assert_eq!(looks_like_path("C:"), on_windows);
+    assert_eq!(looks_like_path("D:\\"), on_windows);
+    assert_eq!(looks_like_path("E:/"), on_windows);
+    assert_eq!(looks_like_path("F:\\some_dir"), on_windows);
+    assert_eq!(looks_like_path("G:/some_dir"), on_windows);
+}