Merge pull request #20682 from Homebrew/libstdcxx

Check host libstdc++ for brew `gcc` dependency

Library/Homebrew/extend/os/linux/development_tools.rb

@@ -42,14 +42,14 @@ module OS
           @needs_libc_formula ||= OS::Linux::Glibc.below_ci_version?
         end
 
-        # Keep this method around for now to make it easier to add this functionality later.
-        # rubocop:disable Lint/UselessMethodDefinition
         sig { returns(Pathname) }
         def host_gcc_path
-          # TODO: override this if/when we to pick the GCC based on e.g. the Ubuntu version.
+          # Prioritise versioned path if installed
+          path = Pathname.new("/usr/bin/#{OS::LINUX_PREFERRED_GCC_COMPILER_FORMULA.tr("@", "-")}")
+          return path if path.exist?
+
           super
         end
-        # rubocop:enable Lint/UselessMethodDefinition
 
         sig { returns(T::Boolean) }
         def needs_compiler_formula?
@@ -60,12 +60,7 @@ module OS
           # Undocumented environment variable to make it easier to test compiler
           # formula automatic installation.
           @needs_compiler_formula = true if ENV["HOMEBREW_FORCE_COMPILER_FORMULA"]
-
-          @needs_compiler_formula ||= if host_gcc_path.exist?
-            ::DevelopmentTools.gcc_version(host_gcc_path.to_s) < OS::LINUX_GCC_CI_VERSION
-          else
-            true
-          end
+          @needs_compiler_formula ||= OS::Linux::Libstdcxx.below_ci_version?
         end
 
         sig { returns(T::Hash[String, T.nilable(String)]) }

Library/Homebrew/extend/os/linux/install.rb

@@ -2,6 +2,7 @@
 # frozen_string_literal: true
 
 require "os/linux/ld"
+require "os/linux/libstdcxx"
 require "utils/output"
 
 module OS
@@ -12,12 +13,12 @@ module OS
         # which are linked by the GCC formula. We only use the versioned shared libraries
         # as the other shared and static libraries are only used at build time where
         # GCC can find its own libraries.
-        GCC_RUNTIME_LIBS = %w[
+        GCC_RUNTIME_LIBS = T.let(%W[
           libatomic.so.1
           libgcc_s.so.1
           libgomp.so.1
-          libstdc++.so.6
-        ].freeze
+          #{OS::Linux::Libstdcxx::SONAME}
+        ].freeze, T::Array[String])
 
         sig { params(all_fatal: T::Boolean).void }
         def perform_preinstall_checks(all_fatal: false)

Library/Homebrew/extend/os/linux/linkage_checker.rb

@@ -2,12 +2,13 @@
 # frozen_string_literal: true
 
 require "compilers"
+require "os/linux/libstdcxx"
 
 module OS
   module Linux
     module LinkageChecker
       # Libraries provided by glibc and gcc.
-      SYSTEM_LIBRARY_ALLOWLIST = %w[
+      SYSTEM_LIBRARY_ALLOWLIST = %W[
         ld-linux-x86-64.so.2
         ld-linux-aarch64.so.1
         libanl.so.1
@@ -24,7 +25,7 @@ module OS
         libutil.so.1
         libgcc_s.so.1
         libgomp.so.1
-        libstdc++.so.6
+        #{OS::Linux::Libstdcxx::SONAME}
         libquadmath.so.0
       ].freeze
 

Library/Homebrew/extend/os/linux/system_config.rb

@@ -3,6 +3,7 @@
 
 require "compilers"
 require "os/linux/glibc"
+require "os/linux/libstdcxx"
 require "system_command"
 
 module OS
@@ -20,6 +21,13 @@ module OS
           version
         end
 
+        def host_libstdcxx_version
+          version = OS::Linux::Libstdcxx.system_version
+          return "N/A" if version.null?
+
+          version
+        end
+
         def host_gcc_version
           gcc = ::DevelopmentTools.host_gcc_path
           return "N/A" unless gcc.executable?
@@ -49,6 +57,7 @@ module OS
           out.puts "OS: #{OS::Linux.os_version}"
           out.puts "WSL: #{OS::Linux.wsl_version}" if OS::Linux.wsl?
           out.puts "Host glibc: #{host_glibc_version}"
+          out.puts "Host libstdc++: #{host_libstdcxx_version}"
           out.puts "#{::DevelopmentTools.host_gcc_path}: #{host_gcc_version}"
           out.puts "/usr/bin/ruby: #{host_ruby_version}" if RUBY_PATH != HOST_RUBY_PATH
           ["glibc", ::CompilerSelector.preferred_gcc, OS::LINUX_PREFERRED_GCC_RUNTIME_FORMULA, "xorg"].each do |f|

Library/Homebrew/os.rb

@@ -50,6 +50,7 @@ module OS
   LINUX_GLIBC_CI_VERSION = "2.35"
   LINUX_GLIBC_NEXT_CI_VERSION = "2.39"
   LINUX_GCC_CI_VERSION = "11.0"
+  LINUX_LIBSTDCXX_CI_VERSION = "6.0.30" # https://packages.ubuntu.com/jammy/libstdc++6
   LINUX_PREFERRED_GCC_COMPILER_FORMULA = "gcc@11" # https://packages.ubuntu.com/jammy/gcc
   LINUX_PREFERRED_GCC_RUNTIME_FORMULA = "gcc"
 

Library/Homebrew/os/linux/libstdcxx.rb

@@ -0,0 +1,47 @@
+# typed: strict
+# frozen_string_literal: true
+
+require "os/linux/ld"
+
+module OS
+  module Linux
+    # Helper functions for querying `libstdc++` information.
+    module Libstdcxx
+      SOVERSION = 6
+      SONAME = T.let("libstdc++.so.#{SOVERSION}".freeze, String)
+
+      sig { returns(T::Boolean) }
+      def self.below_ci_version?
+        system_version < LINUX_LIBSTDCXX_CI_VERSION
+      end
+
+      sig { returns(Version) }
+      def self.system_version
+        @system_version ||= T.let(nil, T.nilable(Version))
+        @system_version ||= if (path = system_path)
+          Version.new("#{SOVERSION}#{path.realpath.basename.to_s.delete_prefix!(SONAME)}")
+        else
+          Version::NULL
+        end
+      end
+
+      sig { returns(T.nilable(Pathname)) }
+      def self.system_path
+        @system_path ||= T.let(nil, T.nilable(Pathname))
+        @system_path ||= find_library(OS::Linux::Ld.library_paths(brewed: false))
+        @system_path ||= find_library(OS::Linux::Ld.system_dirs(brewed: false))
+      end
+
+      sig { params(paths: T::Array[String]).returns(T.nilable(Pathname)) }
+      private_class_method def self.find_library(paths)
+        paths.each do |path|
+          next if path.start_with?(HOMEBREW_PREFIX)
+
+          candidate = Pathname(path)/SONAME
+          return candidate if candidate.exist? && candidate.elf?
+        end
+        nil
+      end
+    end
+  end
+end

Library/Homebrew/test/os/linux/libstdcxx_spec.rb

@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+require "os/linux/libstdcxx"
+
+RSpec.describe OS::Linux::Libstdcxx do
+  describe "::below_ci_version?" do
+    it "returns false when system version matches CI version" do
+      allow(described_class).to receive(:system_version).and_return(Version.new(OS::LINUX_LIBSTDCXX_CI_VERSION))
+      expect(described_class.below_ci_version?).to be false
+    end
+
+    it "returns true when system version cannot be detected" do
+      allow(described_class).to receive(:system_version).and_return(Version::NULL)
+      expect(described_class.below_ci_version?).to be true
+    end
+  end
+
+  describe "::system_version" do
+    let(:tmpdir) { mktmpdir }
+    let(:libstdcxx) { tmpdir/described_class::SONAME }
+    let(:soversion) { Version.new(described_class::SOVERSION.to_s) }
+
+    before do
+      tmpdir.mkpath
+      described_class.instance_variable_set(:@system_version, nil)
+      allow(described_class).to receive(:system_path).and_return(libstdcxx)
+    end
+
+    after do
+      FileUtils.rm_rf(tmpdir)
+    end
+
+    it "returns NULL when unable to find system path" do
+      allow(described_class).to receive(:system_path).and_return(nil)
+      expect(described_class.system_version).to be Version::NULL
+    end
+
+    it "returns full version from filename" do
+      full_version = Version.new("#{soversion}.0.999")
+      libstdcxx_real = libstdcxx.sub_ext(".#{full_version}")
+      FileUtils.touch libstdcxx_real
+      FileUtils.ln_s libstdcxx_real, libstdcxx
+      expect(described_class.system_version).to eq full_version
+    end
+
+    it "returns major version when non-standard libstdc++ filename without full version" do
+      FileUtils.touch libstdcxx
+      expect(described_class.system_version).to eq soversion
+    end
+
+    it "returns major version when non-standard libstdc++ filename with unexpected realpath" do
+      libstdcxx_real = tmpdir/"libstdc++.so.real"
+      FileUtils.touch libstdcxx_real
+      FileUtils.ln_s libstdcxx_real, libstdcxx
+      expect(described_class.system_version).to eq soversion
+    end
+  end
+end