Use a 'current' directory junction for the current version of apps, so that path is maintained across app updates (see #1179)

bin/uninstall.ps1

@@ -25,7 +25,13 @@ function do_uninstall($app, $global) {
     echo "uninstalling $app"
     run_uninstaller $manifest $architecture $dir
     rm_shims $manifest $global
-    env_rm_path $manifest $dir $global
+
+    # If a junction was used during install, that will have been used
+    # as the reference directory. Othewise it will just be the version
+    # directory.
+    $refdir = unlink_current (appdir $app $global)
+
+    env_rm_path $manifest $refdir $global
     env_rm $manifest $global
 
     $appdir = appdir $app $global

lib/install.ps1

@@ -37,6 +37,7 @@ function install_app($app, $architecture, $global) {
     pre_install $manifest $architecture
     run_installer $fname $manifest $architecture $dir $global
     ensure_install_dir_not_in_path $dir $global
+    $dir = link_current $dir
     create_shims $manifest $dir $global $architecture
     create_startmenu_shortcuts $manifest $dir $global
     if($global) { ensure_scoop_in_path $global } # can assume local scoop is in path
@@ -597,6 +598,59 @@ function rm_shims($manifest, $global) {
     }
 }
 
+# Gets the path for the 'current' directory junction for
+# the specified version directory.
+function current_dir($versiondir) {
+    $parent = split-path $versiondir
+    return "$parent\current"
+}
+
+
+# Creates or updates the directory junction for [app]/current,
+# pointing to the specified version directory for the app.
+#
+# Returns the 'current' junction directory if in use, otherwise
+# the version directory.
+function link_current($versiondir) {
+    if(!(get_config USE_JUNCTIONS)) { return $versiondir }
+
+    $currentdir = current_dir $versiondir
+
+    write-host "linking $(friendly_path $currentdir) => $(friendly_path $versiondir)"
+
+    if($currentdir -eq $versiondir) {
+        abort "error: version 'current' is not allowed!"
+    }
+
+    if(test-path $currentdir) {
+        # remove the junction
+        cmd /c rmdir $currentdir
+    }
+
+    cmd /c mklink /j $currentdir $versiondir | out-null
+    return $currentdir
+}
+
+# Removes the directory junction for [app]/current which
+# points to the current version directory for the app.
+#
+# Returns the 'current' junction directory (if it exists),
+# otherwise the normal version directory.
+function unlink_current($versiondir) {
+    if(!(get_config USE_JUNCTIONS)) { return $versiondir }
+
+    $currentdir = current_dir $versiondir
+
+    if(test-path $currentdir) {
+        write-host "unlinking $(friendly_path $currentdir)"
+
+        # remove the junction
+        cmd /c rmdir $currentdir
+        return $currentdir
+    }
+    return $appdir
+}
+
 # to undo after installers add to path so that scoop manifest can keep track of this instead
 function ensure_install_dir_not_in_path($dir, $global) {
     $path = (env 'path' $global)

lib/versions.ps1

@@ -9,7 +9,7 @@ function versions($app, $global) {
     $appdir = appdir $app $global
     if(!(test-path $appdir)) { return @() }
 
-    sort_versions (gci $appdir -dir | % { $_.name })
+    sort_versions (gci $appdir -dir -attr !reparsePoint | % { $_.name })
 }
 
 function version($ver) {

libexec/scoop-reset.ps1

@@ -26,6 +26,7 @@ $manifest = installed_manifest $app $version
 $install = install_info $app $version
 $architecture = $install.architecture
 
+$dir = link_current $dir
 create_shims $manifest $dir $false $architecture
 env_add_path $manifest $dir
 env_set $manifest $dir

libexec/scoop-uninstall.ps1

@@ -11,6 +11,7 @@
 . "$psscriptroot\..\lib\shortcuts.ps1"
 . "$psscriptroot\..\lib\versions.ps1"
 . "$psscriptroot\..\lib\getopt.ps1"
+. "$psscriptroot\..\lib\config.ps1"
 
 reset_aliases
 
@@ -61,7 +62,13 @@ foreach($app in $apps) {
     run_uninstaller $manifest $architecture $dir
     rm_shims $manifest $global
     rm_startmenu_shortcuts $manifest $global
-    env_rm_path $manifest $dir $global
+
+    # If a junction was used during install, that will have been used
+    # as the reference directory. Othewise it will just be the version
+    # directory.
+    $refdir = unlink_current $dir
+
+    env_rm_path $manifest $refdir $global
     env_rm $manifest $global
 
     try { rm -r $dir -ea stop -force }

libexec/scoop-update.ps1

@@ -148,6 +148,7 @@ function update($app, $global, $quiet = $false, $independent) {
     pre_install $manifest $architecture
     run_installer $fname $manifest $architecture $dir $global
     ensure_install_dir_not_in_path $dir
+    $dir = link_current $dir
     create_shims $manifest $dir $global $architecture
     env_add_path $manifest $dir $global
     env_set $manifest $dir $global