[flakes] Fix flakes with fragments (#1069)

## Summary

URLs were getting normalized without fragments which breaks flakes for
for non default exports or flakes that export more than 1 package. This
fixes it.

## How was it tested?

PHP flake example

---------

Co-authored-by: John Lago <750845+Lagoja@users.noreply.github.com>

Author: mikeland73

examples/flakes/php-extension/devbox.json

@@ -1,11 +1,11 @@
 {
     "packages": [
-        "path:my-php-flake#php"
+        "path:my-php-flake"
     ],
     "shell": {
         "init_hook": null
     },
     "nixpkgs": {
         "commit": "f80ac848e3d6f0c12c52758c0f25c10c97ca3b62"
     }
-}
+}

examples/flakes/php-extension/devbox.lock

@@ -0,0 +1,4 @@
+{
+  "lockfile_version": "1",
+  "packages": {}
+}

examples/flakes/php-extension/my-php-flake/flake.nix

@@ -9,17 +9,20 @@
 
   outputs = { self, nixpkgs, flake-utils }:
     flake-utils.lib.eachDefaultSystem (system:
-      let pkgs = nixpkgs.legacyPackages.${system};
-      in {
-        packages = {
-          # Customize and export the PHP package with some extra config
-          php = pkgs.php.buildEnv {
-            # extraConfig will add the line below to our php.ini
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+        # Customize and export the PHP package with some extra configuration
+        php-ext = pkgs.php.buildEnv {
+            # extraConfig will add the line below to the php.ini in our Nix store.
             # ${self} is a variable representing the current flake
             extraConfig = ''
-              extension=${self}/skeleton.so 
+              extension=${self}/skeleton.so
             '';
-          };
+        };
+      in {
+        packages = {
+          # Export the PHP package with our custom extension as the default
+          default = php-ext;
         };
       });
-}
+}

examples/flakes/php/devbox.json

@@ -4,7 +4,10 @@
     "path:my-php-flake#hello"
   ],
   "shell": {
-    "init_hook": null
+    "init_hook": null,
+    "scripts": {
+      "run_test": "php -m | grep ds || exit 1"
+    }
   },
   "nixpkgs": {
     "commit": "f80ac848e3d6f0c12c52758c0f25c10c97ca3b62"

examples/flakes/php/my-php-flake/flake.lock

@@ -20,7 +20,7 @@
 
           # If you only want to export a single package, you can name it default which allows
           # installation without using url fragment (.e.g. "path:my-flake")
-          default = pkgs.php.withExtensions ({ enabled, all }: enabled ++ (with all; [ ds memcached ]));
+          # default = pkgs.php.withExtensions ({ enabled, all }: enabled ++ (with all; [ ds memcached ]));
         };
       });
 }

examples/flakes/php/my-php-flake/flake.nix

@@ -35,14 +35,18 @@ func InputsFromStrings(names []string, l lock.Locker) []*Input {
 	return inputs
 }
 
-func InputFromString(s string, l lock.Locker) *Input {
-	u, _ := url.Parse(s)
+func InputFromString(raw string, locker lock.Locker) *Input {
+	u, _ := url.Parse(raw)
 	if u.Path == "" && u.Opaque != "" && u.Scheme == "path" {
 		// This normalizes url paths to be absolute. It also ensures all
 		// path urls have a single slash (instead of possibly 3 slashes)
-		u, _ = url.Parse("path:" + filepath.Join(l.ProjectDir(), u.Opaque))
+		normalizedURL := "path:" + filepath.Join(locker.ProjectDir(), u.Opaque)
+		if u.Fragment != "" {
+			normalizedURL += "#" + u.Fragment
+		}
+		u, _ = url.Parse(normalizedURL)
 	}
-	return &Input{*u, l, s}
+	return &Input{*u, locker, raw}
 }
 
 func (i *Input) IsLocal() bool {

internal/nix/input.go

@@ -29,14 +29,14 @@ func TestInput(t *testing.T) {
 		{
 			pkg:                "path:path/to/my-flake#my-package",
 			isFlake:            true,
-			name:               "my-flake-eaedce",
+			name:               "my-flake-773986",
 			urlWithoutFragment: "path:" + filepath.Join(projectDir, "path/to/my-flake"),
 			urlForInput:        "path:" + filepath.Join(projectDir, "path/to/my-flake"),
 		},
 		{
 			pkg:                "path:.#my-package",
 			isFlake:            true,
-			name:               "my-project-bbeb05",
+			name:               "my-project-20698c",
 			urlWithoutFragment: "path:" + projectDir,
 			urlForInput:        "path:" + projectDir,
 		},