diff --git a/library/std/src/path.rs b/library/std/src/path.rs
index ed0987064e8f7..8a2450fcb887c 100644
--- a/library/std/src/path.rs
+++ b/library/std/src/path.rs
@@ -315,7 +315,7 @@ fn has_physical_root(s: &[u8], prefix: Option<Prefix<'_>>) -> bool {
 }
 
 // basic workhorse for splitting stem and extension
-fn split_file_at_dot(file: &OsStr) -> (Option<&OsStr>, Option<&OsStr>) {
+fn rsplit_file_at_dot(file: &OsStr) -> (Option<&OsStr>, Option<&OsStr>) {
     if os_str_as_u8_slice(file) == b".." {
         return (Some(file), None);
     }
@@ -334,6 +334,25 @@ fn split_file_at_dot(file: &OsStr) -> (Option<&OsStr>, Option<&OsStr>) {
     }
 }
 
+fn split_file_at_dot(file: &OsStr) -> (&OsStr, Option<&OsStr>) {
+    let slice = os_str_as_u8_slice(file);
+    if slice == b".." {
+        return (file, None);
+    }
+
+    // The unsafety here stems from converting between &OsStr and &[u8]
+    // and back. This is safe to do because (1) we only look at ASCII
+    // contents of the encoding and (2) new &OsStr values are produced
+    // only from ASCII-bounded slices of existing &OsStr values.
+    let i = match slice[1..].iter().position(|b| *b == b'.') {
+        Some(i) => i + 1,
+        None => return (file, None),
+    };
+    let before = &slice[..i];
+    let after = &slice[i + 1..];
+    unsafe { (u8_slice_as_os_str(before), Some(u8_slice_as_os_str(after))) }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // The core iterators
 ////////////////////////////////////////////////////////////////////////////////
@@ -2156,9 +2175,49 @@ impl Path {
     /// assert_eq!("foo", Path::new("foo.rs").file_stem().unwrap());
     /// assert_eq!("foo.tar", Path::new("foo.tar.gz").file_stem().unwrap());
     /// ```
+    ///
+    /// # See Also
+    /// This method is similar to [`Path::file_prefix`], which extracts the portion of the file name
+    /// before the *first* `.`
+    ///
+    /// [`Path::file_prefix`]: Path::file_prefix
+    ///
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn file_stem(&self) -> Option<&OsStr> {
-        self.file_name().map(split_file_at_dot).and_then(|(before, after)| before.or(after))
+        self.file_name().map(rsplit_file_at_dot).and_then(|(before, after)| before.or(after))
+    }
+
+    /// Extracts the prefix of [`self.file_name`].
+    ///
+    /// The prefix is:
+    ///
+    /// * [`None`], if there is no file name;
+    /// * The entire file name if there is no embedded `.`;
+    /// * The portion of the file name before the first non-beginning `.`;
+    /// * The entire file name if the file name begins with `.` and has no other `.`s within;
+    /// * The portion of the file name before the second `.` if the file name begins with `.`
+    ///
+    /// [`self.file_name`]: Path::file_name
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # #![feature(path_file_prefix)]
+    /// use std::path::Path;
+    ///
+    /// assert_eq!("foo", Path::new("foo.rs").file_prefix().unwrap());
+    /// assert_eq!("foo", Path::new("foo.tar.gz").file_prefix().unwrap());
+    /// ```
+    ///
+    /// # See Also
+    /// This method is similar to [`Path::file_stem`], which extracts the portion of the file name
+    /// before the *last* `.`
+    ///
+    /// [`Path::file_stem`]: Path::file_stem
+    ///
+    #[unstable(feature = "path_file_prefix", issue = "86319")]
+    pub fn file_prefix(&self) -> Option<&OsStr> {
+        self.file_name().map(split_file_at_dot).and_then(|(before, _after)| Some(before))
     }
 
     /// Extracts the extension of [`self.file_name`], if possible.
@@ -2182,7 +2241,7 @@ impl Path {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn extension(&self) -> Option<&OsStr> {
-        self.file_name().map(split_file_at_dot).and_then(|(before, after)| before.and(after))
+        self.file_name().map(rsplit_file_at_dot).and_then(|(before, after)| before.and(after))
     }
 
     /// Creates an owned [`PathBuf`] with `path` adjoined to `self`.
diff --git a/library/std/src/path/tests.rs b/library/std/src/path/tests.rs
index 896d6c2a64c60..e8b960e6d7370 100644
--- a/library/std/src/path/tests.rs
+++ b/library/std/src/path/tests.rs
@@ -3,7 +3,7 @@ use super::*;
 use crate::rc::Rc;
 use crate::sync::Arc;
 
-macro_rules! t(
+macro_rules! t (
     ($path:expr, iter: $iter:expr) => (
         {
             let path = Path::new($path);
@@ -73,15 +73,33 @@ macro_rules! t(
         }
     );
 
+    ($path:expr, file_prefix: $file_prefix:expr, extension: $extension:expr) => (
+        {
+            let path = Path::new($path);
+
+            let prefix = path.file_prefix().map(|p| p.to_str().unwrap());
+            let exp_prefix: Option<&str> = $file_prefix;
+            assert!(prefix == exp_prefix, "file_prefix: Expected {:?}, found {:?}",
+                    exp_prefix, prefix);
+
+            let ext = path.extension().map(|p| p.to_str().unwrap());
+            let exp_ext: Option<&str> = $extension;
+            assert!(ext == exp_ext, "extension: Expected {:?}, found {:?}",
+                    exp_ext, ext);
+        }
+    );
+
     ($path:expr, iter: $iter:expr,
                  has_root: $has_root:expr, is_absolute: $is_absolute:expr,
                  parent: $parent:expr, file_name: $file:expr,
-                 file_stem: $file_stem:expr, extension: $extension:expr) => (
+                 file_stem: $file_stem:expr, extension: $extension:expr,
+                 file_prefix: $file_prefix:expr) => (
         {
             t!($path, iter: $iter);
             t!($path, has_root: $has_root, is_absolute: $is_absolute);
             t!($path, parent: $parent, file_name: $file);
             t!($path, file_stem: $file_stem, extension: $extension);
+            t!($path, file_prefix: $file_prefix, extension: $extension);
         }
     );
 );
@@ -116,7 +134,8 @@ pub fn test_decompositions_unix() {
     parent: None,
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("foo",
@@ -126,7 +145,8 @@ pub fn test_decompositions_unix() {
     parent: Some(""),
     file_name: Some("foo"),
     file_stem: Some("foo"),
-    extension: None
+    extension: None,
+    file_prefix: Some("foo")
     );
 
     t!("/",
@@ -136,7 +156,8 @@ pub fn test_decompositions_unix() {
     parent: None,
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("/foo",
@@ -146,7 +167,8 @@ pub fn test_decompositions_unix() {
     parent: Some("/"),
     file_name: Some("foo"),
     file_stem: Some("foo"),
-    extension: None
+    extension: None,
+    file_prefix: Some("foo")
     );
 
     t!("foo/",
@@ -156,7 +178,8 @@ pub fn test_decompositions_unix() {
     parent: Some(""),
     file_name: Some("foo"),
     file_stem: Some("foo"),
-    extension: None
+    extension: None,
+    file_prefix: Some("foo")
     );
 
     t!("/foo/",
@@ -166,7 +189,8 @@ pub fn test_decompositions_unix() {
     parent: Some("/"),
     file_name: Some("foo"),
     file_stem: Some("foo"),
-    extension: None
+    extension: None,
+    file_prefix: Some("foo")
     );
 
     t!("foo/bar",
@@ -176,7 +200,8 @@ pub fn test_decompositions_unix() {
     parent: Some("foo"),
     file_name: Some("bar"),
     file_stem: Some("bar"),
-    extension: None
+    extension: None,
+    file_prefix: Some("bar")
     );
 
     t!("/foo/bar",
@@ -186,7 +211,8 @@ pub fn test_decompositions_unix() {
     parent: Some("/foo"),
     file_name: Some("bar"),
     file_stem: Some("bar"),
-    extension: None
+    extension: None,
+    file_prefix: Some("bar")
     );
 
     t!("///foo///",
@@ -196,7 +222,8 @@ pub fn test_decompositions_unix() {
     parent: Some("/"),
     file_name: Some("foo"),
     file_stem: Some("foo"),
-    extension: None
+    extension: None,
+    file_prefix: Some("foo")
     );
 
     t!("///foo///bar",
@@ -206,7 +233,8 @@ pub fn test_decompositions_unix() {
     parent: Some("///foo"),
     file_name: Some("bar"),
     file_stem: Some("bar"),
-    extension: None
+    extension: None,
+    file_prefix: Some("bar")
     );
 
     t!("./.",
@@ -216,7 +244,8 @@ pub fn test_decompositions_unix() {
     parent: Some(""),
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("/..",
@@ -226,7 +255,8 @@ pub fn test_decompositions_unix() {
     parent: Some("/"),
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("../",
@@ -236,7 +266,8 @@ pub fn test_decompositions_unix() {
     parent: Some(""),
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("foo/.",
@@ -246,7 +277,8 @@ pub fn test_decompositions_unix() {
     parent: Some(""),
     file_name: Some("foo"),
     file_stem: Some("foo"),
-    extension: None
+    extension: None,
+    file_prefix: Some("foo")
     );
 
     t!("foo/..",
@@ -256,7 +288,8 @@ pub fn test_decompositions_unix() {
     parent: Some("foo"),
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("foo/./",
@@ -266,7 +299,8 @@ pub fn test_decompositions_unix() {
     parent: Some(""),
     file_name: Some("foo"),
     file_stem: Some("foo"),
-    extension: None
+    extension: None,
+    file_prefix: Some("foo")
     );
 
     t!("foo/./bar",
@@ -276,7 +310,8 @@ pub fn test_decompositions_unix() {
     parent: Some("foo"),
     file_name: Some("bar"),
     file_stem: Some("bar"),
-    extension: None
+    extension: None,
+    file_prefix: Some("bar")
     );
 
     t!("foo/../",
@@ -286,7 +321,8 @@ pub fn test_decompositions_unix() {
     parent: Some("foo"),
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("foo/../bar",
@@ -296,7 +332,8 @@ pub fn test_decompositions_unix() {
     parent: Some("foo/.."),
     file_name: Some("bar"),
     file_stem: Some("bar"),
-    extension: None
+    extension: None,
+    file_prefix: Some("bar")
     );
 
     t!("./a",
@@ -306,7 +343,8 @@ pub fn test_decompositions_unix() {
     parent: Some("."),
     file_name: Some("a"),
     file_stem: Some("a"),
-    extension: None
+    extension: None,
+    file_prefix: Some("a")
     );
 
     t!(".",
@@ -316,7 +354,8 @@ pub fn test_decompositions_unix() {
     parent: Some(""),
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("./",
@@ -326,7 +365,8 @@ pub fn test_decompositions_unix() {
     parent: Some(""),
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("a/b",
@@ -336,7 +376,8 @@ pub fn test_decompositions_unix() {
     parent: Some("a"),
     file_name: Some("b"),
     file_stem: Some("b"),
-    extension: None
+    extension: None,
+    file_prefix: Some("b")
     );
 
     t!("a//b",
@@ -346,7 +387,8 @@ pub fn test_decompositions_unix() {
     parent: Some("a"),
     file_name: Some("b"),
     file_stem: Some("b"),
-    extension: None
+    extension: None,
+    file_prefix: Some("b")
     );
 
     t!("a/./b",
@@ -356,7 +398,8 @@ pub fn test_decompositions_unix() {
     parent: Some("a"),
     file_name: Some("b"),
     file_stem: Some("b"),
-    extension: None
+    extension: None,
+    file_prefix: Some("b")
     );
 
     t!("a/b/c",
@@ -366,7 +409,8 @@ pub fn test_decompositions_unix() {
     parent: Some("a/b"),
     file_name: Some("c"),
     file_stem: Some("c"),
-    extension: None
+    extension: None,
+    file_prefix: Some("c")
     );
 
     t!(".foo",
@@ -376,7 +420,41 @@ pub fn test_decompositions_unix() {
     parent: Some(""),
     file_name: Some(".foo"),
     file_stem: Some(".foo"),
-    extension: None
+    extension: None,
+    file_prefix: Some(".foo")
+    );
+
+    t!("a/.foo",
+    iter: ["a", ".foo"],
+    has_root: false,
+    is_absolute: false,
+    parent: Some("a"),
+    file_name: Some(".foo"),
+    file_stem: Some(".foo"),
+    extension: None,
+    file_prefix: Some(".foo")
+    );
+
+    t!("a/.rustfmt.toml",
+    iter: ["a", ".rustfmt.toml"],
+    has_root: false,
+    is_absolute: false,
+    parent: Some("a"),
+    file_name: Some(".rustfmt.toml"),
+    file_stem: Some(".rustfmt"),
+    extension: Some("toml"),
+    file_prefix: Some(".rustfmt")
+    );
+
+    t!("a/.x.y.z",
+    iter: ["a", ".x.y.z"],
+    has_root: false,
+    is_absolute: false,
+    parent: Some("a"),
+    file_name: Some(".x.y.z"),
+    file_stem: Some(".x.y"),
+    extension: Some("z"),
+    file_prefix: Some(".x")
     );
 }
 
@@ -390,7 +468,8 @@ pub fn test_decompositions_windows() {
     parent: None,
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("foo",
@@ -400,7 +479,8 @@ pub fn test_decompositions_windows() {
     parent: Some(""),
     file_name: Some("foo"),
     file_stem: Some("foo"),
-    extension: None
+    extension: None,
+    file_prefix: Some("foo")
     );
 
     t!("/",
@@ -410,7 +490,8 @@ pub fn test_decompositions_windows() {
     parent: None,
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("\\",
@@ -420,7 +501,8 @@ pub fn test_decompositions_windows() {
     parent: None,
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("c:",
@@ -430,7 +512,8 @@ pub fn test_decompositions_windows() {
     parent: None,
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("c:\\",
@@ -440,7 +523,8 @@ pub fn test_decompositions_windows() {
     parent: None,
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("c:/",
@@ -450,7 +534,8 @@ pub fn test_decompositions_windows() {
     parent: None,
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("/foo",
@@ -460,7 +545,8 @@ pub fn test_decompositions_windows() {
     parent: Some("/"),
     file_name: Some("foo"),
     file_stem: Some("foo"),
-    extension: None
+    extension: None,
+    file_prefix: Some("foo")
     );
 
     t!("foo/",
@@ -470,7 +556,8 @@ pub fn test_decompositions_windows() {
     parent: Some(""),
     file_name: Some("foo"),
     file_stem: Some("foo"),
-    extension: None
+    extension: None,
+    file_prefix: Some("foo")
     );
 
     t!("/foo/",
@@ -480,7 +567,8 @@ pub fn test_decompositions_windows() {
     parent: Some("/"),
     file_name: Some("foo"),
     file_stem: Some("foo"),
-    extension: None
+    extension: None,
+    file_prefix: Some("foo")
     );
 
     t!("foo/bar",
@@ -490,7 +578,8 @@ pub fn test_decompositions_windows() {
     parent: Some("foo"),
     file_name: Some("bar"),
     file_stem: Some("bar"),
-    extension: None
+    extension: None,
+    file_prefix: Some("bar")
     );
 
     t!("/foo/bar",
@@ -500,7 +589,8 @@ pub fn test_decompositions_windows() {
     parent: Some("/foo"),
     file_name: Some("bar"),
     file_stem: Some("bar"),
-    extension: None
+    extension: None,
+    file_prefix: Some("bar")
     );
 
     t!("///foo///",
@@ -510,7 +600,8 @@ pub fn test_decompositions_windows() {
     parent: Some("/"),
     file_name: Some("foo"),
     file_stem: Some("foo"),
-    extension: None
+    extension: None,
+    file_prefix: Some("foo")
     );
 
     t!("///foo///bar",
@@ -520,7 +611,8 @@ pub fn test_decompositions_windows() {
     parent: Some("///foo"),
     file_name: Some("bar"),
     file_stem: Some("bar"),
-    extension: None
+    extension: None,
+    file_prefix: Some("bar")
     );
 
     t!("./.",
@@ -530,7 +622,8 @@ pub fn test_decompositions_windows() {
     parent: Some(""),
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("/..",
@@ -540,7 +633,8 @@ pub fn test_decompositions_windows() {
     parent: Some("/"),
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("../",
@@ -550,7 +644,8 @@ pub fn test_decompositions_windows() {
     parent: Some(""),
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("foo/.",
@@ -560,7 +655,8 @@ pub fn test_decompositions_windows() {
     parent: Some(""),
     file_name: Some("foo"),
     file_stem: Some("foo"),
-    extension: None
+    extension: None,
+    file_prefix: Some("foo")
     );
 
     t!("foo/..",
@@ -570,7 +666,8 @@ pub fn test_decompositions_windows() {
     parent: Some("foo"),
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("foo/./",
@@ -580,7 +677,8 @@ pub fn test_decompositions_windows() {
     parent: Some(""),
     file_name: Some("foo"),
     file_stem: Some("foo"),
-    extension: None
+    extension: None,
+    file_prefix: Some("foo")
     );
 
     t!("foo/./bar",
@@ -590,7 +688,8 @@ pub fn test_decompositions_windows() {
     parent: Some("foo"),
     file_name: Some("bar"),
     file_stem: Some("bar"),
-    extension: None
+    extension: None,
+    file_prefix: Some("bar")
     );
 
     t!("foo/../",
@@ -600,7 +699,8 @@ pub fn test_decompositions_windows() {
     parent: Some("foo"),
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("foo/../bar",
@@ -610,7 +710,8 @@ pub fn test_decompositions_windows() {
     parent: Some("foo/.."),
     file_name: Some("bar"),
     file_stem: Some("bar"),
-    extension: None
+    extension: None,
+    file_prefix: Some("bar")
     );
 
     t!("./a",
@@ -620,7 +721,8 @@ pub fn test_decompositions_windows() {
     parent: Some("."),
     file_name: Some("a"),
     file_stem: Some("a"),
-    extension: None
+    extension: None,
+    file_prefix: Some("a")
     );
 
     t!(".",
@@ -630,7 +732,8 @@ pub fn test_decompositions_windows() {
     parent: Some(""),
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("./",
@@ -640,7 +743,8 @@ pub fn test_decompositions_windows() {
     parent: Some(""),
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("a/b",
@@ -650,7 +754,8 @@ pub fn test_decompositions_windows() {
     parent: Some("a"),
     file_name: Some("b"),
     file_stem: Some("b"),
-    extension: None
+    extension: None,
+    file_prefix: Some("b")
     );
 
     t!("a//b",
@@ -660,7 +765,8 @@ pub fn test_decompositions_windows() {
     parent: Some("a"),
     file_name: Some("b"),
     file_stem: Some("b"),
-    extension: None
+    extension: None,
+    file_prefix: Some("b")
     );
 
     t!("a/./b",
@@ -670,7 +776,8 @@ pub fn test_decompositions_windows() {
     parent: Some("a"),
     file_name: Some("b"),
     file_stem: Some("b"),
-    extension: None
+    extension: None,
+    file_prefix: Some("b")
     );
 
     t!("a/b/c",
@@ -680,7 +787,9 @@ pub fn test_decompositions_windows() {
        parent: Some("a/b"),
        file_name: Some("c"),
        file_stem: Some("c"),
-       extension: None);
+       extension: None,
+       file_prefix: Some("c")
+    );
 
     t!("a\\b\\c",
     iter: ["a", "b", "c"],
@@ -689,7 +798,8 @@ pub fn test_decompositions_windows() {
     parent: Some("a\\b"),
     file_name: Some("c"),
     file_stem: Some("c"),
-    extension: None
+    extension: None,
+    file_prefix: Some("c")
     );
 
     t!("\\a",
@@ -699,7 +809,8 @@ pub fn test_decompositions_windows() {
     parent: Some("\\"),
     file_name: Some("a"),
     file_stem: Some("a"),
-    extension: None
+    extension: None,
+    file_prefix: Some("a")
     );
 
     t!("c:\\foo.txt",
@@ -709,7 +820,8 @@ pub fn test_decompositions_windows() {
     parent: Some("c:\\"),
     file_name: Some("foo.txt"),
     file_stem: Some("foo"),
-    extension: Some("txt")
+    extension: Some("txt"),
+    file_prefix: Some("foo")
     );
 
     t!("\\\\server\\share\\foo.txt",
@@ -719,7 +831,8 @@ pub fn test_decompositions_windows() {
     parent: Some("\\\\server\\share\\"),
     file_name: Some("foo.txt"),
     file_stem: Some("foo"),
-    extension: Some("txt")
+    extension: Some("txt"),
+    file_prefix: Some("foo")
     );
 
     t!("\\\\server\\share",
@@ -729,7 +842,8 @@ pub fn test_decompositions_windows() {
     parent: None,
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("\\\\server",
@@ -739,7 +853,8 @@ pub fn test_decompositions_windows() {
     parent: Some("\\"),
     file_name: Some("server"),
     file_stem: Some("server"),
-    extension: None
+    extension: None,
+    file_prefix: Some("server")
     );
 
     t!("\\\\?\\bar\\foo.txt",
@@ -749,7 +864,8 @@ pub fn test_decompositions_windows() {
     parent: Some("\\\\?\\bar\\"),
     file_name: Some("foo.txt"),
     file_stem: Some("foo"),
-    extension: Some("txt")
+    extension: Some("txt"),
+    file_prefix: Some("foo")
     );
 
     t!("\\\\?\\bar",
@@ -759,7 +875,8 @@ pub fn test_decompositions_windows() {
     parent: None,
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("\\\\?\\",
@@ -769,7 +886,8 @@ pub fn test_decompositions_windows() {
     parent: None,
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("\\\\?\\UNC\\server\\share\\foo.txt",
@@ -779,7 +897,8 @@ pub fn test_decompositions_windows() {
     parent: Some("\\\\?\\UNC\\server\\share\\"),
     file_name: Some("foo.txt"),
     file_stem: Some("foo"),
-    extension: Some("txt")
+    extension: Some("txt"),
+    file_prefix: Some("foo")
     );
 
     t!("\\\\?\\UNC\\server",
@@ -789,7 +908,8 @@ pub fn test_decompositions_windows() {
     parent: None,
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("\\\\?\\UNC\\",
@@ -799,7 +919,8 @@ pub fn test_decompositions_windows() {
     parent: None,
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("\\\\?\\C:\\foo.txt",
@@ -809,7 +930,8 @@ pub fn test_decompositions_windows() {
     parent: Some("\\\\?\\C:\\"),
     file_name: Some("foo.txt"),
     file_stem: Some("foo"),
-    extension: Some("txt")
+    extension: Some("txt"),
+    file_prefix: Some("foo")
     );
 
     t!("\\\\?\\C:\\",
@@ -819,7 +941,8 @@ pub fn test_decompositions_windows() {
     parent: None,
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("\\\\?\\C:",
@@ -829,7 +952,8 @@ pub fn test_decompositions_windows() {
     parent: None,
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("\\\\?\\foo/bar",
@@ -839,7 +963,8 @@ pub fn test_decompositions_windows() {
     parent: None,
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("\\\\?\\C:/foo",
@@ -849,7 +974,8 @@ pub fn test_decompositions_windows() {
     parent: None,
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("\\\\.\\foo\\bar",
@@ -859,7 +985,8 @@ pub fn test_decompositions_windows() {
     parent: Some("\\\\.\\foo\\"),
     file_name: Some("bar"),
     file_stem: Some("bar"),
-    extension: None
+    extension: None,
+    file_prefix: Some("bar")
     );
 
     t!("\\\\.\\foo",
@@ -869,7 +996,8 @@ pub fn test_decompositions_windows() {
     parent: None,
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("\\\\.\\foo/bar",
@@ -879,7 +1007,8 @@ pub fn test_decompositions_windows() {
     parent: Some("\\\\.\\foo/"),
     file_name: Some("bar"),
     file_stem: Some("bar"),
-    extension: None
+    extension: None,
+    file_prefix: Some("bar")
     );
 
     t!("\\\\.\\foo\\bar/baz",
@@ -889,7 +1018,8 @@ pub fn test_decompositions_windows() {
     parent: Some("\\\\.\\foo\\bar"),
     file_name: Some("baz"),
     file_stem: Some("baz"),
-    extension: None
+    extension: None,
+    file_prefix: Some("baz")
     );
 
     t!("\\\\.\\",
@@ -899,7 +1029,8 @@ pub fn test_decompositions_windows() {
     parent: None,
     file_name: None,
     file_stem: None,
-    extension: None
+    extension: None,
+    file_prefix: None
     );
 
     t!("\\\\?\\a\\b\\",
@@ -909,7 +1040,52 @@ pub fn test_decompositions_windows() {
     parent: Some("\\\\?\\a\\"),
     file_name: Some("b"),
     file_stem: Some("b"),
-    extension: None
+    extension: None,
+    file_prefix: Some("b")
+    );
+
+    t!("\\\\?\\C:\\foo.txt.zip",
+    iter: ["\\\\?\\C:", "\\", "foo.txt.zip"],
+    has_root: true,
+    is_absolute: true,
+    parent: Some("\\\\?\\C:\\"),
+    file_name: Some("foo.txt.zip"),
+    file_stem: Some("foo.txt"),
+    extension: Some("zip"),
+    file_prefix: Some("foo")
+    );
+
+    t!("\\\\?\\C:\\.foo.txt.zip",
+    iter: ["\\\\?\\C:", "\\", ".foo.txt.zip"],
+    has_root: true,
+    is_absolute: true,
+    parent: Some("\\\\?\\C:\\"),
+    file_name: Some(".foo.txt.zip"),
+    file_stem: Some(".foo.txt"),
+    extension: Some("zip"),
+    file_prefix: Some(".foo")
+    );
+
+    t!("\\\\?\\C:\\.foo",
+    iter: ["\\\\?\\C:", "\\", ".foo"],
+    has_root: true,
+    is_absolute: true,
+    parent: Some("\\\\?\\C:\\"),
+    file_name: Some(".foo"),
+    file_stem: Some(".foo"),
+    extension: None,
+    file_prefix: Some(".foo")
+    );
+
+    t!("a/.x.y.z",
+    iter: ["a", ".x.y.z"],
+    has_root: false,
+    is_absolute: false,
+    parent: Some("a"),
+    file_name: Some(".x.y.z"),
+    file_stem: Some(".x.y"),
+    extension: Some("z"),
+    file_prefix: Some(".x")
     );
 }
 
@@ -949,12 +1125,59 @@ pub fn test_stem_ext() {
 
     t!("..", file_stem: None, extension: None);
 
+    t!(".x.y.z", file_stem: Some(".x.y"), extension: Some("z"));
+
+    t!("..x.y.z", file_stem: Some("..x.y"), extension: Some("z"));
+
     t!("", file_stem: None, extension: None);
 }
 
+#[test]
+pub fn test_prefix_ext() {
+    t!("foo",
+    file_prefix: Some("foo"),
+    extension: None
+    );
+
+    t!("foo.",
+    file_prefix: Some("foo"),
+    extension: Some("")
+    );
+
+    t!(".foo",
+    file_prefix: Some(".foo"),
+    extension: None
+    );
+
+    t!("foo.txt",
+    file_prefix: Some("foo"),
+    extension: Some("txt")
+    );
+
+    t!("foo.bar.txt",
+    file_prefix: Some("foo"),
+    extension: Some("txt")
+    );
+
+    t!("foo.bar.",
+    file_prefix: Some("foo"),
+    extension: Some("")
+    );
+
+    t!(".", file_prefix: None, extension: None);
+
+    t!("..", file_prefix: None, extension: None);
+
+    t!(".x.y.z", file_prefix: Some(".x"), extension: Some("z"));
+
+    t!("..x.y.z", file_prefix: Some("."), extension: Some("z"));
+
+    t!("", file_prefix: None, extension: None);
+}
+
 #[test]
 pub fn test_push() {
-    macro_rules! tp(
+    macro_rules! tp (
         ($path:expr, $push:expr, $expected:expr) => ( {
             let mut actual = PathBuf::from($path);
             actual.push($push);
@@ -1042,7 +1265,7 @@ pub fn test_push() {
 
 #[test]
 pub fn test_pop() {
-    macro_rules! tp(
+    macro_rules! tp (
         ($path:expr, $expected:expr, $output:expr) => ( {
             let mut actual = PathBuf::from($path);
             let output = actual.pop();
@@ -1096,7 +1319,7 @@ pub fn test_pop() {
 
 #[test]
 pub fn test_set_file_name() {
-    macro_rules! tfn(
+    macro_rules! tfn (
             ($path:expr, $file:expr, $expected:expr) => ( {
             let mut p = PathBuf::from($path);
             p.set_file_name($file);
@@ -1130,7 +1353,7 @@ pub fn test_set_file_name() {
 
 #[test]
 pub fn test_set_extension() {
-    macro_rules! tfe(
+    macro_rules! tfe (
             ($path:expr, $ext:expr, $expected:expr, $output:expr) => ( {
             let mut p = PathBuf::from($path);
             let output = p.set_extension($ext);
@@ -1192,7 +1415,7 @@ pub fn test_compare() {
         s.finish()
     }
 
-    macro_rules! tc(
+    macro_rules! tc (
         ($path1:expr, $path2:expr, eq: $eq:expr,
          starts_with: $starts_with:expr, ends_with: $ends_with:expr,
          relative_from: $relative_from:expr) => ({