nixpkgs/pkgs/development/tools/ocaml/opam/opam-shebangs.patch

diff --git a/src/client/opamInitDefaults.ml b/src/client/opamInitDefaults.ml
index eca13a7c..1fd66f43 100644
--- a/src/client/opamInitDefaults.ml
+++ b/src/client/opamInitDefaults.ml
@@ -35,11 +35,15 @@ let eval_variables = [
 let os_filter os =
   FOp (FIdent ([], OpamVariable.of_string "os", None), `Eq, FString os)
 
+let os_distribution_filter distro =
+  FOp (FIdent ([], OpamVariable.of_string "os-distribution", None), `Eq, FString distro)
+
 let linux_filter = os_filter "linux"
 let macos_filter = os_filter "macos"
 let openbsd_filter = os_filter "openbsd"
 let freebsd_filter = os_filter "freebsd"
 let sandbox_filter = FOr (linux_filter, macos_filter)
+let nixos_filter = os_distribution_filter "nixos"
 
 let gpatch_filter = FOr (openbsd_filter, freebsd_filter)
 let patch_filter = FNot gpatch_filter
@@ -50,6 +54,11 @@ let wrappers ~sandboxing () =
     CString t, None;
   ] in
   let w = OpamFile.Wrappers.empty in
+  let w = { w with
+            OpamFile.Wrappers.
+            pre_build = [[CString "%{hooks}%/shebangs.sh", None], Some nixos_filter];
+          }
+  in
   if sandboxing then
     { w with
       OpamFile.Wrappers.
@@ -113,6 +122,7 @@ let required_tools ~sandboxing () =
 let init_scripts () = [
   ("sandbox.sh", OpamScript.bwrap), Some bwrap_filter;
   ("sandbox.sh", OpamScript.sandbox_exec), Some macos_filter;
+  ("shebangs.sh", OpamScript.patch_shebangs), Some nixos_filter;
 ]
 
 module I = OpamFile.InitConfig
diff --git a/src/state/opamScript.mli b/src/state/opamScript.mli
index 03449970..83de0b53 100644
--- a/src/state/opamScript.mli
+++ b/src/state/opamScript.mli
@@ -20,3 +20,4 @@ val env_hook : string
 val env_hook_zsh : string
 val env_hook_csh : string
 val env_hook_fish : string
+val patch_shebangs : string
diff --git a/src/state/shellscripts/patch_shebangs.sh b/src/state/shellscripts/patch_shebangs.sh
new file mode 100755
index 00000000..3ea84e2d
--- /dev/null
+++ b/src/state/shellscripts/patch_shebangs.sh
@@ -0,0 +1,73 @@
+#!/usr/bin/env bash
+# This setup hook causes the fixup phase to rewrite all script
+# interpreter file names (`#!  /path') to paths found in $PATH.  E.g.,
+# /bin/sh will be rewritten to /nix/store/<hash>-some-bash/bin/sh.
+# /usr/bin/env gets special treatment so that ".../bin/env python" is
+# rewritten to /nix/store/<hash>/bin/python.  Interpreters that are
+# already in the store are left untouched.
+
+header() { echo "$1"; }
+stopNest() { true; }
+
+fixupOutputHooks+=('if [ -z "$dontPatchShebangs" -a -e "$prefix" ]; then patchShebangs "$prefix"; fi')
+
+patchShebangs() {
+    local dir="$1"
+    header "patching script interpreter paths in $dir"
+    local f
+    local oldPath
+    local newPath
+    local arg0
+    local args
+    local oldInterpreterLine
+    local newInterpreterLine
+
+    find "$dir" -type f -perm -0100 | while read f; do
+        if [ "$(head -1 "$f" | head -c+2)" != '#!' ]; then
+            # missing shebang => not a script
+            continue
+        fi
+
+        oldInterpreterLine=$(head -1 "$f" | tail -c+3)
+        read -r oldPath arg0 args <<< "$oldInterpreterLine"
+
+        if $(echo "$oldPath" | grep -q "/bin/env$"); then
+            # Check for unsupported 'env' functionality:
+            # - options: something starting with a '-'
+            # - environment variables: foo=bar
+            if $(echo "$arg0" | grep -q -- "^-.*\|.*=.*"); then
+                echo "unsupported interpreter directive \"$oldInterpreterLine\" (set dontPatchShebangs=1 and handle shebang patching yourself)"
+                exit 1
+            fi
+            newPath="$(command -v "$arg0" || true)"
+        else
+            if [ "$oldPath" = "" ]; then
+                # If no interpreter is specified linux will use /bin/sh. Set
+                # oldpath="/bin/sh" so that we get /nix/store/.../sh.
+                oldPath="/bin/sh"
+            fi
+            newPath="$(command -v "$(basename "$oldPath")" || true)"
+            args="$arg0 $args"
+        fi
+
+        # Strip trailing whitespace introduced when no arguments are present
+        newInterpreterLine="$(echo "$newPath $args" | sed 's/[[:space:]]*$//')"
+
+        if [ -n "$oldPath" -a "${oldPath:0:${#NIX_STORE}}" != "$NIX_STORE" ]; then
+            if [ -n "$newPath" -a "$newPath" != "$oldPath" ]; then
+                echo "$f: interpreter directive changed from \"$oldInterpreterLine\" to \"$newInterpreterLine\""
+                # escape the escape chars so that sed doesn't interpret them
+                escapedInterpreterLine=$(echo "$newInterpreterLine" | sed 's|\\|\\\\|g')
+                # Preserve times, see: https://github.com/NixOS/nixpkgs/pull/33281
+                touch -r "$f" "$f.timestamp"
+                sed -i -e "1 s|.*|#\!$escapedInterpreterLine|" "$f"
+                touch -r "$f.timestamp" "$f"
+                rm "$f.timestamp"
+            fi
+        fi
+    done
+
+    stopNest
+}
+
+patchShebangs .