Add support for clang-cl compiler

BUILD

@@ -45,6 +45,17 @@ create_msvc_config()
 
 STRICT_C_OPTIONS = select({
     ":msvc": [],
+    ":clang-cl": [
+        "/W4",
+        "-Wconversion",
+        "-Wlong-long",
+        "-Wmissing-declarations",
+        "-Wmissing-prototypes",
+        "-Wno-strict-aliasing",
+        "-Wshadow",
+        "-Wsign-compare",
+        "-Wno-sign-conversion",
+    ],
     "//conditions:default": [
         "--pedantic-errors",
         "-Wall",
@@ -124,6 +135,7 @@ cc_library(
     hdrs = [":enc_headers"],
     copts = STRICT_C_OPTIONS,
     linkopts = select({
+        ":clang-cl": [],
         ":msvc": [],
         "//conditions:default": ["-lm"],
     }),

compiler_config_setting.bzl

@@ -13,6 +13,13 @@ def create_msvc_config():
   # flag_values{"@bazel_tools//tools/cpp:compiler"} and the else branch can
   # be removed.
   if hasattr(cc_common, "do_not_use_tools_cpp_compiler_present"):
+    native.config_setting(
+      name = "clang-cl",
+      flag_values = {
+          "@bazel_tools//tools/cpp:compiler": "clang-cl",
+      },
+      visibility = ["//visibility:public"],
+    )
     native.config_setting(
       name = "msvc",
       flag_values = {
@@ -21,6 +28,11 @@ def create_msvc_config():
       visibility = ["//visibility:public"],
     )
   else:
+    native.config_setting(
+      name = "clang-cl",
+      values = {"compiler": "clang-cl"},
+      visibility = ["//visibility:public"],
+    )
     native.config_setting(
       name = "msvc",
       values = {"compiler": "msvc-cl"},