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Support static linking of re2 library #64

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Support static linking of re2 library #64

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52 changes: 48 additions & 4 deletions ext/re2/extconf.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@
# Released under the BSD Licence, please see LICENSE.txt

require 'mkmf'
require 'shellwords'

if ENV["CC"]
RbConfig::MAKEFILE_CONFIG["CC"] = ENV["CC"]
Expand All @@ -22,13 +23,40 @@
"/usr/include"
]

lib_dirs = [
LIB_DIRS = [
"/usr/local/lib",
"/opt/homebrew/lib",
"/usr/lib"
]
"/usr/lib",
"/usr/lib/x86_64-linux-gnu"
].select { |dir| Dir.exist?(dir) }

def libflag_to_filename(ldflag)
case ldflag
when /\A-l(.+)/
"lib#{Regexp.last_match(1)}.#{$LIBEXT}"
end
end

dir_config("re2", header_dirs, lib_dirs)
def resolve_static_library(arg)
libs_path = pkg_config('re2', 'libs-only-L')
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On Linux, this appears to return an empty list.

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It looks like the static library isn't shipped in the libre2-5 package.

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However, the static library is shipped in libre2-dev under /usr/lib/x86_64-linux-gnu/libre2.a.

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Hmm, still getting:

g++ -shared -o re2.so re2.o -L. -L/home/stanhu/.rbenv/versions/2.7.5/lib -Wl,-rpath,/home/stanhu/.rbenv/versions/2.7.5/lib -L/usr/local/lib -Wl,-rpath,/usr/local/lib -L/opt/homebrew/lib -Wl,-rpath,/opt/homebrew/lib -L/usr/lib -Wl,-rpath,/usr/lib -L/usr/lib/x86_64-linux-gnu -Wl,-rpath,/usr/lib/x86_64-linux-gnu -L. -L/home/stanhu/.rbenv/versions/2.7.5/lib  -fstack-protector-strong -rdynamic -Wl,-export-dynamic -L/home/stanhu/.rbenv/versions/2.7.5/lib  -Wl,--compress-debug-sections=zlib    -Wl,-rpath,/home/stanhu/.rbenv/versions/2.7.5/lib -L/home/stanhu/.rbenv/versions/2.7.5/lib -lruby /usr/lib/x86_64-linux-gnu/libre2.a -lstdc++ -lm   -lc
/usr/bin/ld: /usr/lib/x86_64-linux-gnu/libre2.a(re2.o): relocation R_X86_64_PC32 against symbol `_ZTVSt9basic_iosIcSt11char_traitsIcEE@@GLIBCXX_3.4' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: final link failed: bad value
collect2: error: ld returned 1 exit status

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Could be related to Ubuntu's compilation: google/re2#178

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Perhaps we're better off doing #61.

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@stanhu stanhu Jan 6, 2023 •
edited
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Confirmed that the installed Ubuntu shared library appears to be missing -fPIC in some objects. Recompiling with CPPFLAGS=-fPIC make seems to work.

It's not the default because here we're making a shared object from a static library: https://stackoverflow.com/a/4036497


re2_dirs =
if libs_path.nil? || libs_path.empty?
LIB_DIRS
else
# There should only be one path, but assume there can be multiple.
libs_path.strip.split(' ').map { |lib| lib.gsub(/^-L/, '') }
end

filename = libflag_to_filename(arg)
dir = re2_dirs.find { |path| File.exist?(File.join(path, filename)) }

raise "Unable to find #{filename} in #{re2_dirs}" unless dir

File.join(dir, filename)
end

dir_config("re2", header_dirs, LIB_DIRS)

$CFLAGS << " -Wall -Wextra -funroll-loops"

Expand Down Expand Up @@ -112,4 +140,20 @@
end
end

static_p = enable_config('static', false)
message "Static linking is #{static_p ? 'enabled' : 'disabled'}.\n"

if static_p
append_cppflags('-fPIC')

$libs = $libs.shellsplit.map do |arg|
case arg
when '-lre2'
resolve_static_library(arg)
else
arg
end
end.shelljoin
end

create_makefile("re2")