Fix GHC 9.6.7 --this-unit-id problem for GHCJS cross compiles

Author: hamishmack

overlays/bootstrap.nix

@@ -335,6 +335,8 @@ in {
 
                 # Fix for `fatal error: 'rts/Types.h' file not found` when building `primitive`
                 ++ onGhcjs (from        "9.13"         ./patches/ghc/ghc-9.13-ghcjs-rts-types.patch)
+
+                ++ onGhcjs (fromUntil   "9.6.7" "9.7"  ./patches/ghc/ghc-9.6-js-support-this-unit-id-10819.patch)
                 ;
         in ({
             ghc8107 = traceWarnOld "8.10" (final.callPackage ../compiler/ghc {

overlays/patches/ghc/ghc-9.6-js-support-this-unit-id-10819.patch

@@ -0,0 +1,36 @@
+From 168af9c24581bb550e6f352ebb3dd86c8784cea9 Mon Sep 17 00:00:00 2001
+From: Sylvain Henry <[email protected]>
+Date: Thu, 6 Jul 2023 15:59:38 +0200
+Subject: [PATCH] JS: support -this-unit-id for programs in the linker (#23613)
+
+---
+ compiler/GHC/StgToJS/Linker/Linker.hs | 2 +-
+ testsuite/tests/driver/T23613.hs      | 4 ++++
+ testsuite/tests/driver/all.T          | 7 ++++---
+ 3 files changed, 9 insertions(+), 4 deletions(-)
+ create mode 100644 testsuite/tests/driver/T23613.hs
+
+diff --git a/compiler/GHC/StgToJS/Linker/Linker.hs b/compiler/GHC/StgToJS/Linker/Linker.hs
+index 58bcdf2de90..530f8730c6b 100644
+--- a/compiler/GHC/StgToJS/Linker/Linker.hs
++++ b/compiler/GHC/StgToJS/Linker/Linker.hs
+@@ -327,7 +327,7 @@ computeLinkDependencies cfg unit_env link_spec finder_opts finder_cache = do
+   let (rts_wired_units, rts_wired_functions) = rtsDeps units
+ 
+   -- all the units we want to link together, without their dependencies
+-  let root_units = filter (/= mainUnitId)
++  let root_units = filter (/= ue_currentUnit unit_env)
+                    $ filter (/= interactiveUnitId)
+                    $ nub
+                    $ rts_wired_units ++ reverse obj_units ++ reverse units
+diff --git a/testsuite/tests/driver/T23613.hs b/testsuite/tests/driver/T23613.hs
+new file mode 100644
+index 00000000000..d82a4bd93b7
+--- /dev/null
++++ b/testsuite/tests/driver/T23613.hs
+@@ -0,0 +1,4 @@
++module Main where
++
++main :: IO ()
++main = return ()
+