Fix a bug where toolchain prefix was not properly generated.

FIXES: #13810
PiperOrigin-RevId: 389853136

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

diff --git a/src/main/starlark/builtins_bzl/common/cc/cc_helper.bzl b/src/main/starlark/builtins_bzl/common/cc/cc_helper.bzl
index 7da7993..b7f430b 100644
--- a/src/main/starlark/builtins_bzl/common/cc/cc_helper.bzl
+++ b/src/main/starlark/builtins_bzl/common/cc/cc_helper.bzl
@@ -14,6 +14,8 @@
 
 """Utility functions for C++ rules."""
 
+load(":common/objc/semantics.bzl", "semantics")
+
 CcInfo = _builtins.toplevel.CcInfo
 cc_common = _builtins.toplevel.cc_common
 
@@ -72,9 +74,9 @@
 
     # Check the incompatible flag for toolchain resolution.
     if hasattr(cc_common, "is_cc_toolchain_resolution_enabled_do_not_use") and cc_common.is_cc_toolchain_resolution_enabled_do_not_use(ctx = ctx):
-        if not "@//tools/cpp:toolchain_type" in ctx.toolchains:
+        if not "@" + semantics.get_repo() + "//tools/cpp:toolchain_type" in ctx.toolchains:
             fail("In order to use find_cpp_toolchain, you must include the '//tools/cpp:toolchain_type' in the toolchains argument to your rule.")
-        toolchain_info = ctx.toolchains["@//tools/cpp:toolchain_type"]
+        toolchain_info = ctx.toolchains["@" + semantics.get_repo() + "//tools/cpp:toolchain_type"]
         if hasattr(toolchain_info, "cc_provider_in_toolchain") and hasattr(toolchain_info, "cc"):
             return toolchain_info.cc
         return toolchain_info