From c9e58aa5ff75351a5bb5af1258e019beef13721a Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 19 Apr 2022 20:48:13 +0200
Subject: [PATCH] Require formatters to be packages

Because of 9b41239d8fdcc3fe50febe718c15833ebc224354, a formatter can
no longer be a package *or* an app. So let's require it to be a
package for now.
---
 src/nix/app.cc   |  4 ++--
 src/nix/flake.cc |  3 +--
 tests/fmt.sh     | 10 ++++++----
 3 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/src/nix/app.cc b/src/nix/app.cc
index 6b6b31a12..df7303e15 100644
--- a/src/nix/app.cc
+++ b/src/nix/app.cc
@@ -35,7 +35,7 @@ struct InstallableDerivedPath : Installable
 
 /**
  * Return the rewrites that are needed to resolve a string whose context is
- * included in `dependencies`
+ * included in `dependencies`.
  */
 StringPairs resolveRewrites(Store & store, const BuiltPaths dependencies)
 {
@@ -51,7 +51,7 @@ StringPairs resolveRewrites(Store & store, const BuiltPaths dependencies)
 }
 
 /**
- * Resolve the given string assuming the given context
+ * Resolve the given string assuming the given context.
  */
 std::string resolveString(Store & store, const std::string & toResolve, const BuiltPaths dependencies)
 {
diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index dbd157248..04b23ed0f 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -1038,7 +1038,7 @@ struct CmdFlakeShow : FlakeCommand, MixJSON
                 }
 
                 else if (
-                    (attrPath.size() == 2 && (attrPath[0] == "defaultPackage" || attrPath[0] == "devShell"))
+                    (attrPath.size() == 2 && (attrPath[0] == "defaultPackage" || attrPath[0] == "devShell" || attrPath[0] == "formatter"))
                     || (attrPath.size() == 3 && (attrPath[0] == "checks" || attrPath[0] == "packages" || attrPath[0] == "devShells"))
                     )
                 {
@@ -1071,7 +1071,6 @@ struct CmdFlakeShow : FlakeCommand, MixJSON
 
                 else if (
                     (attrPath.size() == 2 && attrPath[0] == "defaultApp") ||
-                    (attrPath.size() == 2 && attrPath[0] == "formatter") ||
                     (attrPath.size() == 3 && attrPath[0] == "apps"))
                 {
                     auto aType = visitor.maybeGetAttr("type");
diff --git a/tests/fmt.sh b/tests/fmt.sh
index 7df1c82d3..2b482f14a 100644
--- a/tests/fmt.sh
+++ b/tests/fmt.sh
@@ -14,10 +14,12 @@ nix fmt --help | grep "Format"
 cat << EOF > flake.nix
 {
   outputs = _: {
-    formatter.$system = {
-      type = "app";
-      program = ./fmt.simple.sh;
-    };
+    formatter.$system =
+      with import ./config.nix;
+      mkDerivation {
+        name = "formatter";
+        buildCommand = "mkdir -p \$out/bin; cp \${./fmt.simple.sh} \$out/bin/formatter";
+      };
   };
 }
 EOF