[C++] Drop support for the gold linker

[kou]

Describe the enhancement requested

Because the gold linker is deprecated in GNU Binutils 2.44:

https://lists.gnu.org/archive/html/info-gnu/2025-02/msg00001.html

In a change to our previous practice, in this release the
binutils-2.44.tar tarball does not contain the sources for the gold
linker. This is because the gold linker is now deprecated and will
eventually be removed unless volunteers step forward and offer to
continue development and maintenance.

Component(s)

C++

[pitrou]

cc @raulcd

[raulcd]

This is basically removing all usages of ARROW_USE_LD_GOLD:

arrow/cpp/cmake_modules/DefineOptions.cmake

Line 173 in 41659b8

define_option(ARROW_USE_LD_GOLD "Use ld.gold for linking on Linux (if available)" OFF)

and related code like:

arrow/cpp/cmake_modules/SetupCxxFlags.cmake

Lines 543 to 630 in 41659b8

	# ----------------------------------------------------------------------
	# Setup Gold linker, if available. Code originally from Apache Kudu
	# Interrogates the linker version via the C++ compiler to determine whether
	# we're using the gold linker, and if so, extracts its version.
	#
	# If the gold linker is being used, sets GOLD_VERSION in the parent scope with
	# the extracted version.
	#
	# Any additional arguments are passed verbatim into the C++ compiler invocation.
	function(GET_GOLD_VERSION)
	# The gold linker is only for ELF binaries, which macOS doesn't use.
	execute_process(COMMAND ${CMAKE_CXX_COMPILER} "-Wl,--version" ${ARGN}
	ERROR_QUIET
	OUTPUT_VARIABLE LINKER_OUTPUT)
	# We're expecting LINKER_OUTPUT to look like one of these:
	# GNU gold (version 2.24) 1.11
	# GNU gold (GNU Binutils for Ubuntu 2.30) 1.15
	if(LINKER_OUTPUT MATCHES "GNU gold")
	string(REGEX MATCH "GNU gold \\([^\\)]*\\) (([0-9]+\\.?)+)" _ "${LINKER_OUTPUT}")
	if(NOT CMAKE_MATCH_1)
	message(SEND_ERROR "Could not extract GNU gold version. "
	"Linker version output: ${LINKER_OUTPUT}")
	endif()
	set(GOLD_VERSION
	"${CMAKE_MATCH_1}"
	PARENT_SCOPE)
	endif()
	endfunction()
	# Is the compiler hard-wired to use the gold linker?
	if(NOT WIN32 AND NOT APPLE)
	get_gold_version()
	if(GOLD_VERSION)
	set(MUST_USE_GOLD 1)
	elseif(ARROW_USE_LD_GOLD)
	# Can the compiler optionally enable the gold linker?
	get_gold_version("-fuse-ld=gold")
	# We can't use the gold linker if it's inside devtoolset because the compiler
	# won't find it when invoked directly from make/ninja (which is typically
	# done outside devtoolset).
	execute_process(COMMAND which ld.gold
	OUTPUT_VARIABLE GOLD_LOCATION
	OUTPUT_STRIP_TRAILING_WHITESPACE ERROR_QUIET)
	if("${GOLD_LOCATION}" MATCHES "^/opt/rh/devtoolset")
	message(STATUS "Skipping optional gold linker (version ${GOLD_VERSION}) because "
	"it's in devtoolset")
	set(GOLD_VERSION)
	endif()
	endif()
	if(GOLD_VERSION)
	# Older versions of the gold linker are vulnerable to a bug [1] which
	# prevents weak symbols from being overridden properly. This leads to
	# omitting of dependencies like tcmalloc (used in Kudu, where this
	# workaround was written originally)
	#
	# How we handle this situation depends on other factors:
	# - If gold is optional, we won't use it.
	# - If gold is required, we'll either:
	# - Raise an error in RELEASE builds (we shouldn't release such a product), or
	# - Drop tcmalloc in all other builds.
	#
	# 1. https://sourceware.org/bugzilla/show_bug.cgi?id=16979.
	if("${GOLD_VERSION}" VERSION_LESS "1.12")
	set(ARROW_BUGGY_GOLD 1)
	endif()
	if(MUST_USE_GOLD)
	message(STATUS "Using hard-wired gold linker (version ${GOLD_VERSION})")
	if(ARROW_BUGGY_GOLD)
	if("${ARROW_LINK}" STREQUAL "d" AND "${UPPERCASE_BUILD_TYPE}" STREQUAL "RELEASE")
	message(SEND_ERROR "Configured to use buggy gold with dynamic linking "
	"in a RELEASE build")
	endif()
	endif()
	elseif(NOT ARROW_BUGGY_GOLD)
	# The Gold linker must be manually enabled.
	set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fuse-ld=gold")
	set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fuse-ld=gold")
	message(STATUS "Using optional gold linker (version ${GOLD_VERSION})")
	else()
	message(STATUS "Optional gold linker is buggy, using ld linker instead")
	endif()
	else()
	message(STATUS "Using ld linker")
	endif()
	endif()

[kou]

Issue resolved by pull request 47780
#47780