bazel: roll compiler/linker options to toolchains

.bazelrc

@@ -1,14 +1,3 @@
-build --cxxopt=-std=c++17
-build --cxxopt=-O3
-build --cxxopt=-no-canonical-prefixes
-build --cxxopt=-DEMSCRIPTEN_PROTOBUF_LITE=1
-
-# try to optimize un-used code
-build --cxxopt=-fdata-sections
-build --cxxopt=-ffunction-sections
-
-build --linkopt=-Wl,--gc-sections
-
 # https://github.com/bazelbuild/bazel/issues/9451
 # ideally we want this, but it doesn't work...
 # build --cxxopt=-fno-canonical-system-headers
@@ -22,4 +11,4 @@ build --cpu=wasm
 # Use the default Bazel C++ toolchain to build the tools used during the
 # build.
 
-build --host_crosstool_top=@bazel_tools//tools/cpp:toolchain
+build --host_crosstool_top=@bazel_tools//tools/cpp:toolchain

toolchain/cc_toolchain_config.bzl

@@ -89,6 +89,63 @@ def _impl(ctx):
  ],
  )
 
+ cxx17_feature = feature(
+ name = "c++17",
+ enabled = True,
+ flag_sets = [
+ flag_set(
+ actions = [ACTION_NAMES.cpp_compile],
+ flag_groups = [flag_group(flags = ["-std=c++17"])],
+ ),
+ ],
+ )
+
+ no_canonical_prefixes_feature = feature(
+ name = "no-canonical-prefixes",
+ enabled = True,
+ flag_sets = [
+ flag_set(
+ actions = [
+ ACTION_NAMES.c_compile,
+ ACTION_NAMES.cpp_compile,
+ ACTION_NAMES.cpp_link_executable,
+ ACTION_NAMES.cpp_link_dynamic_library,
+ ACTION_NAMES.cpp_link_nodeps_dynamic_library,
+ ],
+ flag_groups = [
+ flag_group(
+ flags = [
+ "-no-canonical-prefixes",
+ ],
+ ),
+ ],
+ ),
+ ],
+ )
+
+ opt_feature = feature(
+ name = "opt",
+ enabled = True,
+ flag_sets = [
+ flag_set(
+ actions = [ACTION_NAMES.c_compile, ACTION_NAMES.cpp_compile],
+ flag_groups = [
+ flag_group(
+ flags = ["-O3", "-ffunction-sections", "-fdata-sections"],
+ ),
+ ],
+ ),
+ flag_set(
+ actions = [
+ ACTION_NAMES.cpp_link_dynamic_library,
+ ACTION_NAMES.cpp_link_nodeps_dynamic_library,
+ ACTION_NAMES.cpp_link_executable,
+ ],
+ flag_groups = [flag_group(flags = ["-Wl,--gc-sections"])],
+ ),
+ ],
+ )
+
  return cc_common.create_cc_toolchain_config_info(
  ctx = ctx,
  toolchain_identifier = "wasm-toolchain",
@@ -107,7 +164,7 @@ def _impl(ctx):
  "external/emscripten_toolchain/upstream/emscripten/system/include/libcxx",
  "external/emscripten_toolchain/upstream/emscripten/system/include/libc",
  ],
- # features = [toolchain_include_directories_feature],
+ features = [cxx17_feature, no_canonical_prefixes_feature, opt_feature],
  )
 
 cc_toolchain_config = rule(