Use includes instead of system_includes for includes attr

Previously even though the attribute was named `includes` it was passed
through the `system_includes` field of the compilation context. This
resulted in toolchains passing these include paths with `-isystem`,
which is unexpected if you use this for first party code.

Many non bazel-first projects have header directory structures that
require custom include paths be propagated throughout the graph, the
alternative to `includes` is to use `strip_include_prefix`. The downside
of `strip_include_prefix` is that you add 1 include path per
`cc_library`, even if the libraries are in the same package. With
`includes` these are deduplicated. In the case of LLVM using `includes`
reduced the number of search paths on the order of hundreds.

If users want to use `-isystem` for third party code that uses
`includes`, they can pass `--features=external_include_paths --host_features=external_include_paths`

If there are first party libraries users want to use `-isystem` with,
they can use `features = ["system_include_paths"]`

Fixes bazelbuild#20267

Author: keith

src/main/starlark/builtins_bzl/common/cc/cc_binary.bzl

@@ -510,7 +510,7 @@ def cc_binary_impl(ctx, additional_linkopts, force_linkstatic = False):
         cxx_flags = cc_helper.get_copts(ctx, feature_configuration, additional_make_variable_substitutions, attr = "cxxopts"),
         defines = cc_helper.defines(ctx, additional_make_variable_substitutions),
         local_defines = cc_helper.local_defines(ctx, additional_make_variable_substitutions) + cc_helper.get_local_defines_for_runfiles_lookup(ctx, ctx.attr.deps),
-        system_includes = cc_helper.system_include_dirs(ctx, additional_make_variable_substitutions),
+        includes = cc_helper.include_dirs(ctx, additional_make_variable_substitutions),
         private_hdrs = cc_helper.get_private_hdrs(ctx),
         public_hdrs = cc_helper.get_public_hdrs(ctx),
         copts_filter = cc_helper.copts_filter(ctx, additional_make_variable_substitutions),

src/main/starlark/builtins_bzl/common/cc/cc_helper.bzl

@@ -1062,7 +1062,7 @@ def _package_source_root(repository, package, sibling_repository_layout):
         repository = repository[1:]
     return paths.get_relative(paths.get_relative("external", repository), package)
 
-def _system_include_dirs(ctx, additional_make_variable_substitutions):
+def _include_dirs(ctx, additional_make_variable_substitutions):
     result = []
     sibling_repository_layout = ctx.configuration.is_sibling_repository_layout()
     package = ctx.label.package
@@ -1264,7 +1264,7 @@ cc_helper = struct(
     get_private_hdrs = _get_private_hdrs,
     get_public_hdrs = _get_public_hdrs,
     report_invalid_options = _report_invalid_options,
-    system_include_dirs = _system_include_dirs,
+    include_dirs = _include_dirs,
     get_coverage_environment = _get_coverage_environment,
     create_cc_instrumented_files_info = _create_cc_instrumented_files_info,
     linkopts = _linkopts,

src/main/starlark/builtins_bzl/common/cc/cc_library.bzl

@@ -63,7 +63,7 @@ def _cc_library_impl(ctx):
         cxx_flags = cc_helper.get_copts(ctx, feature_configuration, additional_make_variable_substitutions, attr = "cxxopts"),
         defines = cc_helper.defines(ctx, additional_make_variable_substitutions),
         local_defines = cc_helper.local_defines(ctx, additional_make_variable_substitutions) + cc_helper.get_local_defines_for_runfiles_lookup(ctx, ctx.attr.deps + ctx.attr.implementation_deps),
-        system_includes = cc_helper.system_include_dirs(ctx, additional_make_variable_substitutions),
+        includes = cc_helper.include_dirs(ctx, additional_make_variable_substitutions),
         copts_filter = cc_helper.copts_filter(ctx, additional_make_variable_substitutions),
         purpose = "cc_library-compile",
         srcs = cc_helper.get_srcs(ctx),

src/main/starlark/builtins_bzl/common/cc/compile/cc_compilation_helper.bzl

@@ -227,7 +227,10 @@ def _init_cc_compilation_context(
     external_include_dirs = []
     declared_include_srcs = []
 
-    if not external:
+    if not external and _enabled(feature_configuration, "system_include_paths"):
+        system_include_dirs_for_context = system_include_dirs + include_dirs
+        include_dirs_for_context = []
+    elif not external:
         system_include_dirs_for_context = list(system_include_dirs)
         include_dirs_for_context = list(include_dirs)
     else:

src/main/starlark/builtins_bzl/common/objc/compilation_support.bzl

@@ -105,7 +105,7 @@ def _build_common_variables(
         has_module_map = has_module_map,
         attr_linkopts = attr_linkopts,
         direct_cc_compilation_contexts = direct_cc_compilation_contexts,
-        includes = cc_helper.system_include_dirs(ctx, {}) if hasattr(ctx.attr, "includes") else [],
+        includes = cc_helper.include_dirs(ctx, {}) if hasattr(ctx.attr, "includes") else [],
     )
 
     return struct(