Auto merge of #14750 - epage:normalize, r=weihanglo

fix(util): Respect all `..`s in `normalize_path`

### What does this PR try to resolve?

The fact that `normalize_path` was only designed for absolute paths bit us when working out #14497 and so I decided to make sure it worked.  The other alternative I considered was having it assert that the path was absolute.

Since I did try out the assert and Cargo tests hit it, this likely fixes something but I haven't dug through to be able to say what.

### How should we test and review this PR?

### Additional information

Author: bors

crates/cargo-util/src/paths.rs

@@ -94,11 +94,18 @@ pub fn normalize_path(path: &Path) -> PathBuf {
         match component {
             Component::Prefix(..) => unreachable!(),
             Component::RootDir => {
-                ret.push(component.as_os_str());
+                ret.push(Component::RootDir);
             }
             Component::CurDir => {}
             Component::ParentDir => {
-                ret.pop();
+                if ret.ends_with(Component::ParentDir) {
+                    ret.push(Component::ParentDir);
+                } else {
+                    let popped = ret.pop();
+                    if !popped && !ret.has_root() {
+                        ret.push(Component::ParentDir);
+                    }
+                }
             }
             Component::Normal(c) => {
                 ret.push(c);
@@ -856,9 +863,43 @@ fn exclude_from_time_machine(path: &Path) {
 #[cfg(test)]
 mod tests {
     use super::join_paths;
+    use super::normalize_path;
     use super::write;
     use super::write_atomic;
 
+    #[test]
+    fn test_normalize_path() {
+        let cases = &[
+            ("", ""),
+            (".", ""),
+            (".////./.", ""),
+            ("/", "/"),
+            ("/..", "/"),
+            ("/foo/bar", "/foo/bar"),
+            ("/foo/bar/", "/foo/bar"),
+            ("/foo/bar/./././///", "/foo/bar"),
+            ("/foo/bar/..", "/foo"),
+            ("/foo/bar/../..", "/"),
+            ("/foo/bar/../../..", "/"),
+            ("foo/bar", "foo/bar"),
+            ("foo/bar/", "foo/bar"),
+            ("foo/bar/./././///", "foo/bar"),
+            ("foo/bar/..", "foo"),
+            ("foo/bar/../..", ""),
+            ("foo/bar/../../..", ".."),
+            ("../../foo/bar", "../../foo/bar"),
+            ("../../foo/bar/", "../../foo/bar"),
+            ("../../foo/bar/./././///", "../../foo/bar"),
+            ("../../foo/bar/..", "../../foo"),
+            ("../../foo/bar/../..", "../.."),
+            ("../../foo/bar/../../..", "../../.."),
+        ];
+        for (input, expected) in cases {
+            let actual = normalize_path(std::path::Path::new(input));
+            assert_eq!(actual, std::path::Path::new(expected), "input: {input}");
+        }
+    }
+
     #[test]
     fn write_works() {
         let original_contents = "[dependencies]\nfoo = 0.1.0";