rename src/dst to original/link

this is consistent with std and makes it much easier to understand what's actually happening

Author: jyn514

src/bootstrap/doc.rs

@@ -959,21 +959,21 @@ impl Step for UnstableBookGen {
     }
 }
 
-fn symlink_dir_force(config: &Config, src: &Path, dst: &Path) -> io::Result<()> {
+fn symlink_dir_force(config: &Config, original: &Path, link: &Path) -> io::Result<()> {
     if config.dry_run() {
         return Ok(());
     }
-    if let Ok(m) = fs::symlink_metadata(dst) {
+    if let Ok(m) = fs::symlink_metadata(link) {
         if m.file_type().is_dir() {
-            fs::remove_dir_all(dst)?;
+            fs::remove_dir_all(link)?;
         } else {
             // handle directory junctions on windows by falling back to
             // `remove_dir`.
-            fs::remove_file(dst).or_else(|_| fs::remove_dir(dst))?;
+            fs::remove_file(link).or_else(|_| fs::remove_dir(link))?;
         }
     }
 
-    symlink_dir(config, src, dst)
+    symlink_dir(config, original, link)
 }
 
 #[derive(Ord, PartialOrd, Debug, Copy, Clone, Hash, PartialEq, Eq)]

src/bootstrap/util.rs

@@ -134,17 +134,17 @@ pub(crate) fn program_out_of_date(stamp: &Path, key: &str) -> bool {
 
 /// Symlinks two directories, using junctions on Windows and normal symlinks on
 /// Unix.
-pub fn symlink_dir(config: &Config, src: &Path, dest: &Path) -> io::Result<()> {
+pub fn symlink_dir(config: &Config, original: &Path, link: &Path) -> io::Result<()> {
     if config.dry_run() {
         return Ok(());
     }
-    let _ = fs::remove_dir(dest);
-    return symlink_dir_inner(src, dest);
+    let _ = fs::remove_dir(link);
+    return symlink_dir_inner(original, link);
 
     #[cfg(not(windows))]
-    fn symlink_dir_inner(src: &Path, dest: &Path) -> io::Result<()> {
+    fn symlink_dir_inner(original: &Path, link: &Path) -> io::Result<()> {
         use std::os::unix::fs;
-        fs::symlink(src, dest)
+        fs::symlink(original, link)
     }
 
     #[cfg(windows)]