flutter: Redesign wrapping architecture

The following principles are now in place:

- All wrappers will include SDK file symlinks. There is not much of a reason to not do so, and removing the option to omit it makes it easier to understand what each wrapper does.
- There is no longer a way to get the previous derivation from a wrapper. This could yield unexpected results based on the wrapping order. Instead, "sdk", "unwrapped", and "noFHS" passthru attributes are provided where appropriate.

pkgs/development/compilers/flutter/default.nix

@@ -3,7 +3,6 @@ let
   mkFlutter = opts: callPackage (import ./flutter.nix opts) { };
   wrapFlutter = flutter: callPackage (import ./wrapper.nix) { flutter = flutter; };
   mkFlutterFHS = flutter: callPackage (import ./fhs.nix) { flutter = flutter; };
-  mkFakeSdk = flutter: callPackage (import ./fake-sdk.nix) { flutter = flutter; };
   getPatches = dir:
     let files = builtins.attrNames (builtins.readDir dir);
     in map (f: dir + ("/" + f)) files;
@@ -29,7 +28,7 @@ let
   };
 in
 {
-  inherit mkFlutter wrapFlutter mkFlutterFHS mkFakeSdk flutterDrv;
+  inherit mkFlutter wrapFlutter mkFlutterFHS flutterDrv;
   stable = flutterDrv {
     version = "3.3.3";
     dartVersion = "2.18.2";

pkgs/development/compilers/flutter/fake-sdk.nix

@@ -1,15 +0,0 @@
-{ flutter, symlinkJoin }:
-
-symlinkJoin {
-  name = "flutter-fake-${flutter.name}";
-  paths = [ flutter flutter.unwrapped ];
-
-  inherit (flutter) passthru;
-
-  meta = flutter.meta // {
-    longDescription = ''
-      ${flutter.meta.longDescription}
-      Modified binaries are linked into the original SDK directory for use with tools that use the whole SDK.
-    '';
-  };
-}

pkgs/development/compilers/flutter/fhs.nix

@@ -7,11 +7,11 @@
 , supportsAndroidEmulator ? stdenv.isLinux
 }:
 
-let
+
 # Wrap flutter inside an fhs user env to allow execution of binary,
 # like adb from $ANDROID_HOME or java from android-studio.
-  self = buildFHSUserEnv {
-    name = flutter.name;
+(callPackage ./sdk-symlink.nix { }) (buildFHSUserEnv rec {
+  name = "${flutter.name}-fhs";
 
   multiPkgs = pkgs: with pkgs; ([
     # Flutter only use these certificates
@@ -60,12 +60,18 @@ let
 
   runScript = "flutter";
 
+  extraInstallCommands = ''
+    # By default, the derivation name is used as the binary name.
+    # This is not the desired behaviour in this case.
+    # https://github.com/NixOS/nixpkgs/blob/cb4536bf3606a7b6b54b69afe22ccd82e2906d92/pkgs/build-support/build-fhs-userenv/default.nix#L43
+    mv $out/bin/${name} $out/bin/flutter
+  '';
+
   passthru = flutter.passthru // {
-      wrapped = flutter;
+    nonFHS = flutter;
     mkFlutterApp = callPackage ../../../build-support/flutter {
       flutter = callPackage ./fhs.nix { supportsAndroidEmulator = false; };
     };
-      fakeSdk = callPackage ./fake-sdk.nix { flutter = self; };
   };
 
   meta = flutter.meta // {
@@ -74,6 +80,4 @@ let
       Wrapped in a FHS environment to improve compatibility with internal tools and tools in the ecosystem.
     '';
   };
-  };
-in
-self
+})

pkgs/development/compilers/flutter/flutter.nix

@@ -10,6 +10,8 @@
 , which
 }:
 
+let
+  self =
     stdenv.mkDerivation {
       name = "$flutter-${version}-unwrapped";
 
@@ -73,6 +75,11 @@ stdenv.mkDerivation {
 
       passthru = {
         inherit dart;
+
+        # The derivation containing the original Flutter SDK files.
+        # When other derivations wrap this one, any unmodified files
+        # found here should be included as-is, for tooling compatibility.
+        sdk = self;
       };
 
       meta = with lib; {
@@ -87,3 +94,6 @@ stdenv.mkDerivation {
         maintainers = with maintainers; [ babariviere ericdallo ];
       };
     }
+  ;
+in
+self

pkgs/development/compilers/flutter/sdk-symlink.nix

@@ -0,0 +1,24 @@
+{ symlinkJoin }: flutter:
+
+let
+  self =
+    symlinkJoin {
+      name = "${flutter.name}-sdk-links";
+      paths = [ flutter flutter.sdk ];
+
+      passthru = flutter.passthru // {
+        # Update the SDK attribute.
+        # This allows any modified SDK files to be included
+        # in future invocations.
+        sdk = self;
+      };
+
+      meta = flutter.meta // {
+        longDescription = ''
+          ${flutter.meta.longDescription}
+          Modified binaries are linked into the original SDK directory for use with tools that use the whole SDK.
+        '';
+      };
+    };
+in
+self

pkgs/development/compilers/flutter/wrapper.nix

@@ -79,7 +79,7 @@ let
   cppFlags = map (pkg: "-isystem ${lib.getOutput "dev" pkg}/include") appStaticBuildDeps;
   linkerFlags = map (pkg: "-rpath,${lib.getOutput "lib" pkg}/lib") appRuntimeDeps;
 in
-runCommandLocal "flutter"
+(callPackage ./sdk-symlink.nix { }) (runCommandLocal "flutter-wrapped"
 {
   buildInputs = [ makeWrapper ];
 
@@ -90,10 +90,6 @@ runCommandLocal "flutter"
   inherit (flutter) meta;
 } ''
   mkdir -p $out/bin
-
-  mkdir -p $out/bin/cache/
-  ln -sf ${flutter.dart} $out/bin/cache/dart-sdk
-
   makeWrapper '${immutableFlutter}' $out/bin/flutter \
     --set-default ANDROID_EMULATOR_USE_SYSTEM_LIBS 1 \
     --prefix PATH : '${lib.makeBinPath buildTools}' \
@@ -101,4 +97,4 @@ runCommandLocal "flutter"
     --prefix CXXFLAGS "''\t" '${builtins.concatStringsSep " " cppFlags}' \
     --prefix LDFLAGS "''\t" '${builtins.concatStringsSep " " (map (flag: "-Wl,${flag}") linkerFlags)}' \
     --suffix LD_LIBRARY_PATH : '${lib.makeLibraryPath appPrebuiltDeps}'
-''
+'')