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Fix linker feature detection being performed on wrong linker
Bazel forces use of `lld` and `ld.gold` if found, but performed feature detection on the default linker instead. Fixes #20834 Closes #20833. PiperOrigin-RevId: 598565598 Change-Id: I4890f278c5cc33d4e6a6ebb10d796fb1c22f9ba6
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+34
-26
lines changed

3 files changed

+34
-26
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‎MODULE.bazel.lock‎

Lines changed: 1 addition & 1 deletion
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‎src/test/tools/bzlmod/MODULE.bazel.lock‎

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‎tools/cpp/unix_cc_configure.bzl‎

Lines changed: 32 additions & 24 deletions
Original file line numberDiff line numberDiff line change
@@ -161,10 +161,9 @@ def _is_compiler_option_supported(repository_ctx, cc, option):
161161
])
162162
return result.stderr.find(option) == -1
163163

164-
def _is_linker_option_supported(repository_ctx, cc, option, pattern):
164+
def _is_linker_option_supported(repository_ctx, cc, force_linker_flags, option, pattern):
165165
"""Checks that `option` is supported by the C linker. Doesn't %-escape the option."""
166-
result = repository_ctx.execute([
167-
cc,
166+
result = repository_ctx.execute([cc] + force_linker_flags + [
168167
option,
169168
"-o",
170169
"/dev/null",
@@ -213,9 +212,9 @@ def _add_compiler_option_if_supported(repository_ctx, cc, option):
213212
"""Returns `[option]` if supported, `[]` otherwise. Doesn't %-escape the option."""
214213
return [option] if _is_compiler_option_supported(repository_ctx, cc, option) else []
215214

216-
def _add_linker_option_if_supported(repository_ctx, cc, option, pattern):
215+
def _add_linker_option_if_supported(repository_ctx, cc, force_linker_flags, option, pattern):
217216
"""Returns `[option]` if supported, `[]` otherwise. Doesn't %-escape the option."""
218-
return [option] if _is_linker_option_supported(repository_ctx, cc, option, pattern) else []
217+
return [option] if _is_linker_option_supported(repository_ctx, cc, force_linker_flags, option, pattern) else []
219218

220219
def _get_no_canonical_prefixes_opt(repository_ctx, cc):
221220
# If the compiler sometimes rewrites paths in the .d files without symlinks
@@ -420,16 +419,40 @@ def configure_unix_toolchain(repository_ctx, cpu_value, overriden_tools):
420419
False,
421420
), ":")
422421

422+
gold_or_lld_linker_path = (
423+
_find_linker_path(repository_ctx, cc, "lld", is_clang) or
424+
_find_linker_path(repository_ctx, cc, "gold", is_clang)
425+
)
426+
cc_path = repository_ctx.path(cc)
427+
if not str(cc_path).startswith(str(repository_ctx.path(".")) + "/"):
428+
# cc is outside the repository, set -B
429+
bin_search_flags = ["-B" + escape_string(str(cc_path.dirname))]
430+
else:
431+
# cc is inside the repository, don't set -B.
432+
bin_search_flags = []
433+
if not gold_or_lld_linker_path:
434+
ld_path = repository_ctx.path(tool_paths["ld"])
435+
if ld_path.dirname != cc_path.dirname:
436+
bin_search_flags.append("-B" + str(ld_path.dirname))
437+
force_linker_flags = []
438+
if gold_or_lld_linker_path:
439+
force_linker_flags.append("-fuse-ld=" + gold_or_lld_linker_path)
440+
441+
# TODO: It's unclear why these flags aren't added on macOS.
442+
if bin_search_flags and not darwin:
443+
force_linker_flags.extend(bin_search_flags)
423444
use_libcpp = darwin or bsd
424445
is_as_needed_supported = _is_linker_option_supported(
425446
repository_ctx,
426447
cc,
448+
force_linker_flags,
427449
"-Wl,-no-as-needed",
428450
"-no-as-needed",
429451
)
430452
is_push_state_supported = _is_linker_option_supported(
431453
repository_ctx,
432454
cc,
455+
force_linker_flags,
433456
"-Wl,--push-state",
434457
"--push-state",
435458
)
@@ -463,21 +486,6 @@ def configure_unix_toolchain(repository_ctx, cpu_value, overriden_tools):
463486
bazel_linklibs,
464487
False,
465488
), ":")
466-
gold_or_lld_linker_path = (
467-
_find_linker_path(repository_ctx, cc, "lld", is_clang) or
468-
_find_linker_path(repository_ctx, cc, "gold", is_clang)
469-
)
470-
cc_path = repository_ctx.path(cc)
471-
if not str(cc_path).startswith(str(repository_ctx.path(".")) + "/"):
472-
# cc is outside the repository, set -B
473-
bin_search_flags = ["-B" + escape_string(str(cc_path.dirname))]
474-
else:
475-
# cc is inside the repository, don't set -B.
476-
bin_search_flags = []
477-
if not gold_or_lld_linker_path:
478-
ld_path = repository_ctx.path(tool_paths["ld"])
479-
if ld_path.dirname != cc_path.dirname:
480-
bin_search_flags.append("-B" + str(ld_path.dirname))
481489
coverage_compile_flags, coverage_link_flags = _coverage_flags(repository_ctx, darwin)
482490
print_resource_dir_supported = _is_compiler_option_supported(
483491
repository_ctx,
@@ -610,19 +618,18 @@ def configure_unix_toolchain(repository_ctx, cpu_value, overriden_tools):
610618
),
611619
"%{cxx_flags}": get_starlark_list(cxx_opts + _escaped_cplus_include_paths(repository_ctx)),
612620
"%{conly_flags}": get_starlark_list(conly_opts),
613-
"%{link_flags}": get_starlark_list((
614-
["-fuse-ld=" + gold_or_lld_linker_path] if gold_or_lld_linker_path else []
615-
) + (
621+
"%{link_flags}": get_starlark_list(force_linker_flags + (
616622
["-Wl,-no-as-needed"] if is_as_needed_supported else []
617623
) + _add_linker_option_if_supported(
618624
repository_ctx,
619625
cc,
626+
force_linker_flags,
620627
"-Wl,-z,relro,-z,now",
621628
"-z",
622629
) + (
623630
[
624631
"-headerpad_max_install_names",
625-
] if darwin else bin_search_flags + [
632+
] if darwin else [
626633
# Gold linker only? Can we enable this by default?
627634
# "-Wl,--warn-execstack",
628635
# "-Wl,--detect-odr-violations"
@@ -664,6 +671,7 @@ def configure_unix_toolchain(repository_ctx, cpu_value, overriden_tools):
664671
["-Wl,-dead_strip"] if darwin else _add_linker_option_if_supported(
665672
repository_ctx,
666673
cc,
674+
force_linker_flags,
667675
"-Wl,--gc-sections",
668676
"-gc-sections",
669677
),

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