1 files changed, 59 insertions, 0 deletions
diff --git a/third_party/bazel/rules_haskell/haskell/private/ghci_repl_wrapper.sh b/third_party/bazel/rules_haskell/haskell/private/ghci_repl_wrapper.sh
new file mode 100644
index 0000000000..cd6acefc7a
--- /dev/null
+++ b/third_party/bazel/rules_haskell/haskell/private/ghci_repl_wrapper.sh
@@ -0,0 +1,59 @@
+#!/usr/bin/env bash
+#
+# Usage: ghci_repl_wrapper.sh <ARGS>
+
+# this variable is set by `bazel run`
+if [ "$BUILD_WORKSPACE_DIRECTORY" = "" ]
+then
+    cat <<EOF
+It looks like you are trying to invoke the REPL incorrectly.
+We only support calling the repl script with
+
+$ bazel run <target>
+
+for now.
+
+If you are on bazel < 0.15 you must invoke as follows:
+
+$ bazel run --direct_run <target>
+EOF
+    exit 1
+fi
+
+# Derived from Bazel's Bash runfiles library (tools/bash/runfiles/runfiles.bash).
+if [[ -z "$RUNFILES_DIR" ]]; then
+  if [[ -d "$0.runfiles" ]]; then
+    export RUNFILES_DIR="$0.runfiles"
+  fi
+fi
+if [[ -z "$RUNFILES_MANIFEST_FILE" ]]; then
+  if [[ -f "$0.runfiles_manifest" ]]; then
+    export RUNFILES_MANIFEST_FILE="$0.runfiles_manifest"
+  elif [[ -f "$0.runfiles/MANIFEST" ]]; then
+    export RUNFILES_MANIFEST_FILE="$0.runfiles/MANIFEST"
+  fi
+fi
+
+# GHCi script and libraries are loaded relative to workspace directory.
+# bazel run //some:target@repl will be executed from the workspace directory.
+# bazel run //some:haskell_repl will be executed from its execroot.
+# Explicitly change into the workspace root in that case.
+cd "$BUILD_WORKSPACE_DIRECTORY"
+
+# This is a workaround for https://github.com/bazelbuild/bazel/issues/5506
+# and also for the fact that REPL script relies on so-called “convenience
+# links” and the names of those links are controlled by the --symlink_prefix
+# option, which can be set by the user to something unpredictable.
+#
+# It seems that we can't locate the files of interest/build outputs in
+# general. However, due to “internal issues” in Bazel mentioned e.g.
+# https://github.com/bazelbuild/bazel/issues/3796, the directory bazel-out
+# is always created under the workspace directory. We exploit this to get
+# location of exec root reliably and then prefix locations of various
+# components, such as shared libraries with that exec root.
+
+RULES_HASKELL_EXEC_ROOT=$(dirname $(readlink ${BUILD_WORKSPACE_DIRECTORY}/bazel-out))
+TOOL_LOCATION="$RULES_HASKELL_EXEC_ROOT/{TOOL}"
+
+{ENV}
+"$TOOL_LOCATION" {ARGS} "$@"