From b141e7f03fd89223cd031a74d97f44ffe9475862 Mon Sep 17 00:00:00 2001
From: Harendra Kumar <harendra@composewell.com>
Date: Fri, 17 Apr 2026 02:02:28 +0530
Subject: [PATCH 1/3] Issue a warning before unsetting GHC_PACKAGE_PATH

---
 packcheck.sh | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/packcheck.sh b/packcheck.sh
index 439c7cd..e230daa 100755
--- a/packcheck.sh
+++ b/packcheck.sh
@@ -2560,10 +2560,6 @@ setup_environment() {
   #  TOOLS_DIR="$GHCUP_PATH"
   #fi
 
-  # if we are running from a stack environment remove GHC_PACKAGE_PATH so that
-  # cabal does not complain
-  # XXX this should be done from outside via env
-  unset GHC_PACKAGE_PATH
   # stack does not work well with empty STACK_YAML env var
   test -n "$STACK_YAML" || unset STACK_YAML
 
@@ -2612,6 +2608,14 @@ case $BUILD in
   *) ;;
 esac
 
+# if we are running from a stack environment remove GHC_PACKAGE_PATH so that
+# cabal does not complain.
+# XXX this should be done from outside via env
+# NOTE: do this before eval_env, so that it can later be set by eval_env if
+# passed on command line.
+echo "WARNING! unsetting GHC_PACKAGE_PATH if you really want to use it pass it on the command line"
+unset GHC_PACKAGE_PATH
+
 # This allows only SYSTEM_ENVVARS to be set on the command line
 eval_env "$@"
 # After eval_env the PATH changes

From 4e27c500a3a324342a9fa9468657d7d1b0e1c584 Mon Sep 17 00:00:00 2001
From: Harendra Kumar <harendra@composewell.com>
Date: Fri, 17 Apr 2026 02:19:45 +0530
Subject: [PATCH 2/3] Do not add a prefix to the PATH

---
 packcheck.sh | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/packcheck.sh b/packcheck.sh
index e230daa..17ec3b8 100755
--- a/packcheck.sh
+++ b/packcheck.sh
@@ -2540,15 +2540,21 @@ setup_environment() {
   # XXX add paths only if not already on PATH, but sometimes we have to add path
   # at head for precedence even if it is already on PATH.
   #echo "Original PATH is [$PATH]..."
-  PATH_PREFIX=$LOCAL_BIN:$GHCUP_BIN
-  if test "$BUILD" = "cabal-v2"
-  then
-      PATH_PREFIX=$PATH_PREFIX:$OS_APP_HOME/$OS_CABAL_DIR/bin
-  fi
 
-  echo "Prefixing [$PATH_PREFIX] to PATH"
-  export PATH=$PATH_PREFIX:$PATH
-  echo
+  # We should not add anything to PATH, respect the user's PATH. For example,
+  # we may be running in a nix shell which has overridden ghc, and adding
+  # ghcup/bin to the front of PATH will change the ghc and all the packages
+  # that were available.
+  #
+  #PATH_PREFIX=$LOCAL_BIN:$GHCUP_BIN
+  #if test "$BUILD" = "cabal-v2"
+  #then
+  #    PATH_PREFIX=$PATH_PREFIX:$OS_APP_HOME/$OS_CABAL_DIR/bin
+  #fi
+
+  #echo "Prefixing [$PATH_PREFIX] to PATH"
+  #export PATH=$PATH_PREFIX:$PATH
+  #echo
 
   # XXX we should be able to set multiple paths in it
   # One advantage of using GHCUP_PATH as TOOLS_DIR is that we can pick ghc right

From 7a63cf8e3741009c94a1b02dfca6ed2fedc099e6 Mon Sep 17 00:00:00 2001
From: Harendra Kumar <harendra@composewell.com>
Date: Fri, 17 Apr 2026 03:12:22 +0530
Subject: [PATCH 3/3] Use PATH suffix instead

---
 packcheck.sh | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/packcheck.sh b/packcheck.sh
index 17ec3b8..9fb527b 100755
--- a/packcheck.sh
+++ b/packcheck.sh
@@ -2541,20 +2541,20 @@ setup_environment() {
   # at head for precedence even if it is already on PATH.
   #echo "Original PATH is [$PATH]..."
 
-  # We should not add anything to PATH, respect the user's PATH. For example,
+  # XXX We should not add anything to PATH, respect the user's PATH. For example,
   # we may be running in a nix shell which has overridden ghc, and adding
   # ghcup/bin to the front of PATH will change the ghc and all the packages
   # that were available.
   #
-  #PATH_PREFIX=$LOCAL_BIN:$GHCUP_BIN
-  #if test "$BUILD" = "cabal-v2"
-  #then
-  #    PATH_PREFIX=$PATH_PREFIX:$OS_APP_HOME/$OS_CABAL_DIR/bin
-  #fi
+  PATH_SUFFIX=$LOCAL_BIN:$GHCUP_BIN
+  if test "$BUILD" = "cabal-v2"
+  then
+      PATH_SUFFIX=$PATH_PREFIX:$OS_APP_HOME/$OS_CABAL_DIR/bin
+  fi
 
-  #echo "Prefixing [$PATH_PREFIX] to PATH"
-  #export PATH=$PATH_PREFIX:$PATH
-  #echo
+  echo "Suffixing [$PATH_SUFFIX] to PATH"
+  export PATH=$PATH:$PATH_SUFFIX
+  echo
 
   # XXX we should be able to set multiple paths in it
   # One advantage of using GHCUP_PATH as TOOLS_DIR is that we can pick ghc right