racket: fix failure to find executable

Fix #377763.

pkgs/development/interpreters/racket/default.nix

@@ -60,6 +60,15 @@ minimal.overrideAttrs (
       wrapGAppsHook3
     ];
 
+    patches = prevAttrs.patches or [ ] ++ [
+      /*
+        Hardcode variant detection because nixpkgs wraps the Racket binary making it
+        fail to detect its variant at runtime.
+        https://github.com/NixOS/nixpkgs/issues/114993#issuecomment-812951247
+      */
+      ./patches/force-cs-variant.patch
+    ];
+
     preBuild =
       let
         libPaths = makeLibPaths finalAttrs.buildInputs;

pkgs/development/interpreters/racket/patches/force-cs-variant.patch

@@ -0,0 +1,12 @@
+--- old/collects/setup/variant.rkt
++++ new/collects/setup/variant.rkt
+@@ -7,7 +7,8 @@
+ (provide variant-suffix
+          script-variant?)
+
+-(define plain-variant
++(define plain-variant 'cs)
++#;(define plain-variant
+   (delay/sync
+    (cond
+      [(cross-installation?)

pkgs/development/interpreters/racket/tests/get-version-and-variant.nix

@@ -1,27 +1,45 @@
-{ runCommandLocal, racket }:
+{
+  lib,
+  runCommandLocal,
+  racket,
+}:
 
 runCommandLocal "racket-test-get-version-and-variant"
   {
     nativeBuildInputs = [ racket ];
   }
-  ''
-    expectation="${racket.version}"
+  (
+    lib.concatLines (
+      builtins.map
+        (
+          { expectation, output }:
+          ''
+            expectation="${expectation}"
 
-    output="$(racket -e '(display (version))')"
+            output="${output}"
 
-    if test "$output" != "$expectation"; then
-        echo "output mismatch: expected ''${expectation}, but got ''${output}"
-        exit 1
-    fi
-
-    expectation="cs"
-
-    output="$(racket -e '(require launcher/launcher) (display (current-launcher-variant))')"
-
-    if test "$output" != "$expectation"; then
-        echo "output mismatch: expected ''${expectation}, but got ''${output}"
-        exit 1
-    fi
-
-    touch $out
-  ''
+            if test "$output" != "$expectation"; then
+                echo "output mismatch: expected ''${expectation}, but got ''${output}"
+                exit 1
+            fi
+          ''
+        )
+        [
+          {
+            expectation = racket.version;
+            output = "$(racket -e '(display (version))')";
+          }
+          {
+            expectation = "cs";
+            output = "$(racket -e '(require launcher/launcher) (display (current-launcher-variant))')";
+          }
+          {
+            expectation = "${lib.getExe racket}";
+            output = "$(racket -e '(require compiler/find-exe) (display (find-exe))')";
+          }
+        ]
+    )
+    + ''
+      touch $out
+    ''
+  )