Add ld path to binary search path when appropriate.

The binary search path does not presently include the path of ld if the
path of ld differs from the path of the cc compiler. This change adds
the path of ld when its path differs from that of the cc compiler.

Fixes: #13857

Closes #13942.

PiperOrigin-RevId: 397720260

tools/cpp/unix_cc_configure.bzl

@@ -424,11 +424,14 @@ def configure_unix_toolchain(repository_ctx, cpu_value, overriden_tools):
     cc_path = repository_ctx.path(cc)
     if not str(cc_path).startswith(str(repository_ctx.path(".")) + "/"):
         # cc is outside the repository, set -B
-        bin_search_flag = ["-B" + escape_string(str(cc_path.dirname))]
+        bin_search_flags = ["-B" + escape_string(str(cc_path.dirname))]
     else:
         # cc is inside the repository, don't set -B.
-        bin_search_flag = []
-
+        bin_search_flags = []
+    if not gold_or_lld_linker_path:
+        ld_path = repository_ctx.path(tool_paths["ld"])
+        if ld_path.dirname != cc_path.dirname:
+            bin_search_flags.append("-B" + str(ld_path.dirname))
     coverage_compile_flags, coverage_link_flags = _coverage_flags(repository_ctx, darwin)
     builtin_include_directories = _uniq(
         _get_cxx_include_directories(repository_ctx, cc, "-xc") +
@@ -566,7 +569,7 @@ def configure_unix_toolchain(repository_ctx, cpu_value, overriden_tools):
                     "-undefined",
                     "dynamic_lookup",
                     "-headerpad_max_install_names",
-                ] if darwin else bin_search_flag + [
+                ] if darwin else bin_search_flags + [
                     # Gold linker only? Can we enable this by default?
                     # "-Wl,--warn-execstack",
                     # "-Wl,--detect-odr-violations"