feat(third_party/bazel): Check in rules_haskell from Tweag

third_party/bazel/rules_haskell/tests/cpp_macro_conflict/BUILD.bazel

@@ -0,0 +1,36 @@
+load(
+    "@io_tweag_rules_haskell//haskell:haskell.bzl",
+    "haskell_library",
+    "haskell_test",
+)
+
+package(default_testonly = 1)
+
+# empty library with package name "bytestring"
+haskell_library(
+    name = "bytestring",
+    srcs = ["src/BS.hs"],
+    deps = ["//tests/hackage:base"],
+)
+
+# This depends on two packages "bytestring"
+# There should be no CPP macro conflict
+haskell_test(
+    name = "macro_conflict",
+    srcs = ["Main.hs"],
+    compiler_flags = [
+        "-XCPP",
+        "-Werror",
+    ] + select({
+        # clang on darwin fails because of unused command line argument, it fails because of -Werror
+        "@bazel_tools//src/conditions:darwin": [
+            "-optP-Wno-unused-command-line-argument",
+        ],
+        "//conditions:default": [],
+    }),
+    deps = [
+        ":bytestring",
+        "//tests/hackage:base",
+        "//tests/hackage:bytestring",
+    ],
+)

third_party/bazel/rules_haskell/tests/cpp_macro_conflict/Main.hs

@@ -0,0 +1,4 @@
+import qualified Data.ByteString
+import BS
+
+main = putStrLn "hello"

third_party/bazel/rules_haskell/tests/cpp_macro_conflict/src/BS.hs

@@ -0,0 +1 @@
+module BS where