1 files changed, 137 insertions, 0 deletions
diff --git a/third_party/bazel/rules_haskell/haskell/lint.bzl b/third_party/bazel/rules_haskell/haskell/lint.bzl
new file mode 100644
index 000000000000..1ee7d47a2e11
--- /dev/null
+++ b/third_party/bazel/rules_haskell/haskell/lint.bzl
@@ -0,0 +1,137 @@
+"""Linting"""
+
+load(
+    "@io_tweag_rules_haskell//haskell:providers.bzl",
+    "HaskellInfo",
+    "HaskellLibraryInfo",
+    "HaskellLintInfo",
+)
+load(":private/context.bzl", "haskell_context", "render_env")
+load(":private/packages.bzl", "expose_packages", "pkg_info_to_compile_flags")
+load(
+    ":private/path_utils.bzl",
+    "target_unique_name",
+)
+load(":providers.bzl", "get_libs_for_ghc_linker")
+load(":private/set.bzl", "set")
+
+def _collect_lint_logs(deps):
+    lint_logs = set.empty()
+    for dep in deps:
+        if HaskellLintInfo in dep:
+            set.mutable_union(lint_logs, dep[HaskellLintInfo].outputs)
+    return lint_logs
+
+def _haskell_lint_rule_impl(ctx):
+    return [DefaultInfo(
+        files = set.to_depset(_collect_lint_logs(ctx.attr.deps)),
+    )]
+
+def _haskell_lint_aspect_impl(target, ctx):
+    hs = haskell_context(ctx, ctx.rule.attr)
+
+    if HaskellInfo not in target:
+        return []
+
+    hs_info = target[HaskellInfo]
+    lib_info = target[HaskellLibraryInfo] if HaskellLibraryInfo in target else None
+
+    args = ctx.actions.args()
+
+    args.add_all([
+        "-O0",
+        "-v0",
+        "-fno-code",
+        "-Wall",
+        "-Werror",
+        "-Wcompat",
+        "-Wincomplete-record-updates",
+        "-Wincomplete-uni-patterns",
+        "-Wredundant-constraints",
+        "-Wnoncanonical-monad-instances",
+        "--make",
+    ])
+
+    args.add_all(pkg_info_to_compile_flags(expose_packages(
+        hs_info,
+        lib_info,
+        use_direct = False,
+        use_my_pkg_id = None,
+        custom_package_databases = None,
+        version = ctx.rule.attr.version,
+    )))
+
+    sources = set.to_list(hs_info.source_files)
+
+    args.add_all(sources)
+
+    lint_log = ctx.actions.declare_file(
+        target_unique_name(hs, "lint-log"),
+    )
+
+    # Transitive library dependencies for runtime.
+    (library_deps, ld_library_deps, _ghc_env) = get_libs_for_ghc_linker(
+        hs,
+        hs_info.transitive_cc_dependencies,
+    )
+
+    ctx.actions.run_shell(
+        inputs = depset(transitive = [
+            depset(sources),
+            set.to_depset(hs_info.package_databases),
+            set.to_depset(hs_info.interface_dirs),
+            set.to_depset(hs_info.dynamic_libraries),
+            depset(library_deps),
+            depset(ld_library_deps),
+            depset([hs.tools.ghc]),
+        ]),
+        outputs = [lint_log],
+        mnemonic = "HaskellLint",
+        progress_message = "HaskellLint {}".format(ctx.label),
+        command = """
+        {env}
+        {ghc} "$@" > {output} 2>&1 || rc=$? && cat {output} && exit $rc
+        """.format(
+            ghc = hs.tools.ghc.path,
+            output = lint_log.path,
+            # XXX Workaround
+            # https://github.com/bazelbuild/bazel/issues/5980.
+            env = render_env(hs.env),
+        ),
+        arguments = [args],
+        use_default_shell_env = True,
+    )
+
+    lint_info = HaskellLintInfo(outputs = set.singleton(lint_log))
+    output_files = OutputGroupInfo(default = [lint_log])
+
+    return [lint_info, output_files]
+
+haskell_lint_aspect = aspect(
+    _haskell_lint_aspect_impl,
+    attr_aspects = ["deps"],
+    toolchains = ["@io_tweag_rules_haskell//haskell:toolchain"],
+)
+
+haskell_lint = rule(
+    _haskell_lint_rule_impl,
+    attrs = {
+        "deps": attr.label_list(
+            aspects = [haskell_lint_aspect],
+            doc = "List of Haskell targets to lint.",
+        ),
+    },
+    toolchains = ["@io_tweag_rules_haskell//haskell:toolchain"],
+)
+"""Check source code of targets in `deps` using a restrictive set of GHC
+flags.
+
+The following flags will be used:
+
+* `-Wall`
+* `-Werror`
+* `-Wcompat`
+* `-Wincomplete-record-updates`
+* `-Wincomplete-uni-patterns`
+* `-Wredundant-constraints`
+"""