Make the library path of libpq available in ruby and add it to the DLL search paths on Windows which lacks rpath.

Gemfile

@@ -8,7 +8,7 @@ source "https://rubygems.org/"
 gem "hoe-mercurial", "~>1.4", :group => [:development, :test]
 gem "hoe-deveiate", "~>0.9", :group => [:development, :test]
 gem "hoe-highline", "~>0.2", :group => [:development, :test]
-gem "rake-compiler", "~>1.0", :group => [:development, :test]
+gem "rake-compiler", "1.1.1", :group => [:development, :test]
 gem "rake-compiler-dock", "~>1.0", :group => [:development, :test]
 gem "hoe-bundler", "~>1.0", :group => [:development, :test]
 gem "rspec", "~>3.5", :group => [:development, :test]

Rakefile

@@ -6,6 +6,7 @@ require 'tmpdir'
 
 begin
 	require 'rake/extensiontask'
+	require_relative 'misc/rake-compiler-make-install-patch'
 rescue LoadError
 	abort "This Rakefile requires rake-compiler (gem install rake-compiler)"
 end
@@ -37,6 +38,7 @@ CLOBBER.include( TESTDIR.to_s )
 CLEAN.include( PKGDIR.to_s, TMPDIR.to_s )
 CLEAN.include "lib/*/libpq.dll"
 CLEAN.include "lib/pg_ext.*"
+CLEAN.include "lib/pg/postgresql_lib_path.rb"
 
 # Set up Hoe plugins
 Hoe.plugin :mercurial
@@ -62,7 +64,7 @@ $hoespec = Hoe.spec 'pg' do
 	self.developer 'Michael Granger', 'ged@FaerieMUD.org'
 	self.developer 'Lars Kanis', 'lars@greiz-reinsdorf.de'
 
-	self.dependency 'rake-compiler', '~> 1.0', :developer
+	self.dependency 'rake-compiler', '1.1.1', :developer
 	self.dependency 'rake-compiler-dock', ['~> 1.0'], :developer
 	self.dependency 'hoe-deveiate', '~> 0.9', :developer
 	self.dependency 'hoe-bundler', '~> 1.0', :developer

appveyor.yml

@@ -19,7 +19,6 @@ install:
         $(new-object net.webclient).DownloadFile('http://get.enterprisedb.com/postgresql/postgresql-' + $env:PGVERSION + '.exe', 'C:/postgresql-setup.exe')
         cmd /c "C:/postgresql-setup.exe" --mode unattended --extract-only 1
       }
-      $env:RUBY_DLL_PATH = 'C:/Program Files/PostgreSQL/' + $env:PGVER + '/bin;C:/Program Files (x86)/PostgreSQL/' + $env:PGVER + '/bin'
       $env:PATH = 'C:/Program Files/PostgreSQL/' + $env:PGVER + '/bin;' + $env:PATH
       $env:PATH = 'C:/Program Files (x86)/PostgreSQL/' + $env:PGVER + '/bin;' + $env:PATH
 build_script:

ext/extconf.rb

@@ -34,19 +34,33 @@
 		libdir = `"#{pgconfig}" --libdir`.chomp
 		dir_config 'pg', incdir, libdir
 
-		# Try to use runtime path linker option, even if RbConfig doesn't know about it.
-		# The rpath option is usually set implicit by dir_config(), but so far not
-		# on MacOS-X.
-		if RbConfig::CONFIG["RPATHFLAG"].to_s.empty? && try_link('int main() {return 0;}', " -Wl,-rpath,#{libdir}")
-			$LDFLAGS << " -Wl,-rpath,#{libdir}"
-		end
+		# Windows traditionally stores DLLs beside executables, not in libdir
+		dlldir = RUBY_PLATFORM=~/mingw|mswin/ ? `"#{pgconfig}" --bindir`.chomp : libdir
+
 	else
 		$stderr.puts "No pg_config... trying anyway. If building fails, please try again with",
 			" --with-pg-config=/path/to/pg_config"
-		dir_config 'pg'
+		incdir, libdir = dir_config 'pg'
+		dlldir = libdir
+	end
+
+	# Try to use runtime path linker option, even if RbConfig doesn't know about it.
+	# The rpath option is usually set implicit by dir_config(), but so far not
+	# on MacOS-X.
+	if dlldir && RbConfig::CONFIG["RPATHFLAG"].to_s.empty?
+		append_ldflags "-Wl,-rpath,#{dlldir.quote}"
 	end
 end
 
+File.write("postgresql_lib_path.rb", <<-EOT)
+module PG
+	POSTGRESQL_LIB_PATH = #{dlldir.inspect}
+end
+EOT
+$INSTALLFILES = {
+	"./postgresql_lib_path.rb" => "$(RUBYLIBDIR)/pg/"
+}
+
 if RUBY_VERSION >= '2.3.0' && /solaris/ =~ RUBY_PLATFORM
 	append_cppflags( '-D__EXTENSIONS__' )
 end

lib/pg.rb

@@ -1,15 +1,28 @@
+
 # -*- ruby -*-
 # frozen_string_literal: true
 
-begin
-	require 'pg_ext'
-rescue LoadError
-	# If it's a Windows binary gem, try the <major>.<minor> subdirectory
-	if RUBY_PLATFORM =~/(mswin|mingw)/i
-		major_minor = RUBY_VERSION[ /^(\d+\.\d+)/ ] or
-			raise "Oops, can't extract the major/minor version from #{RUBY_VERSION.dump}"
+# The top-level PG namespace.
+module PG
+
+	# Is this file part of a fat binary gem with bundled libpq?
+	bundled_libpq_path = File.join(__dir__, RUBY_PLATFORM.gsub(/^i386-/, "x86-"))
+	if File.exist?(bundled_libpq_path)
+		POSTGRESQL_LIB_PATH = bundled_libpq_path
+	else
+		bundled_libpq_path = nil
+		# Try to load libpq path as found by extconf.rb
+		begin
+			require "pg/postgresql_lib_path"
+		rescue LoadError
+			# rake-compiler doesn't use regular "make install", but uses it's own install tasks.
+			# It therefore doesn't copy pg/postgresql_lib_path.rb in case of "rake compile".
+			POSTGRESQL_LIB_PATH = false
+		end
+	end
 
-		add_dll_path = proc do |path, &block|
+	add_dll_path = proc do |path, &block|
+		if RUBY_PLATFORM =~/(mswin|mingw)/i && path && File.exist?(path)
 			begin
 				require 'ruby_installer/runtime'
 				RubyInstaller::Runtime.add_dll_directory(path, &block)
@@ -19,22 +32,24 @@
 				block.call
 				ENV['PATH'] = old_path
 			end
+		else
+			# No need to set a load path manually - it's set as library rpath.
+			block.call
 		end
+	end
 
-		# Temporary add this directory for DLL search, so that libpq.dll can be found.
-		# mingw32-platform strings differ (RUBY_PLATFORM=i386-mingw32 vs. x86-mingw32 for rubygems)
-		add_dll_path.call(File.join(__dir__, RUBY_PLATFORM.gsub(/^i386-/, "x86-"))) do
+	# Add a load path to the one retrieved from pg_config
+	add_dll_path.call(POSTGRESQL_LIB_PATH) do
+		if bundled_libpq_path
+			# It's a Windows binary gem, try the <major>.<minor> subdirectory
+			major_minor = RUBY_VERSION[ /^(\d+\.\d+)/ ] or
+				raise "Oops, can't extract the major/minor version from #{RUBY_VERSION.dump}"
 			require "#{major_minor}/pg_ext"
+		else
+			require 'pg_ext'
 		end
-	else
-		raise
 	end
 
-end
-
-
-# The top-level PG namespace.
-module PG
 
 	# Library version
 	VERSION = '1.2.3'

misc/rake-compiler-make-install-patch.rb

@@ -0,0 +1,153 @@
+require 'rake/baseextensiontask'
+
+module Rake
+  class ExtensionTask < BaseExtensionTask
+
+    # Replace method
+    undef define_compile_tasks
+
+    def define_compile_tasks(for_platform = nil, ruby_ver = RUBY_VERSION)
+      # platform usage
+      platf = for_platform || platform
+
+      binary_path = binary(platf)
+
+      # lib_path
+      lib_path = lib_dir
+
+      lib_binary_path = "#{lib_path}/#{binary_path}"
+      lib_binary_dir_path = File.dirname(lib_binary_path)
+
+      # tmp_path
+      tmp_path = "#{@tmp_dir}/#{platf}/#{@name}/#{ruby_ver}"
+      stage_path = "#{@tmp_dir}/#{platf}/stage"
+
+      siteconf_path = "#{tmp_path}/.rake-compiler-siteconf.rb"
+      tmp_binary_path = "#{tmp_path}/#{binary_path}"
+      tmp_binary_dir_path = File.dirname(tmp_binary_path)
+      stage_binary_path = "#{stage_path}/#{lib_path}/#{binary_path}"
+      stage_binary_dir_path = File.dirname(stage_binary_path)
+
+      # cleanup and clobbering
+      CLEAN.include(tmp_path)
+      CLEAN.include(stage_path)
+      CLOBBER.include("#{lib_path}/#{binary(platf)}")
+      CLOBBER.include("#{@tmp_dir}")
+
+      # directories we need
+      directory tmp_path
+      directory tmp_binary_dir_path
+      directory lib_binary_dir_path
+      directory stage_binary_dir_path
+
+      directory File.dirname(siteconf_path)
+      # Set paths for "make install" destinations
+      file siteconf_path => File.dirname(siteconf_path) do
+        File.open(siteconf_path, "w") do |siteconf|
+          siteconf.puts "require 'rbconfig'"
+          siteconf.puts "require 'mkmf'"
+          siteconf.puts "dest_path = mkintpath(#{File.expand_path(lib_path).dump})"
+          %w[sitearchdir sitelibdir].each do |dir|
+            siteconf.puts "RbConfig::MAKEFILE_CONFIG['#{dir}'] = dest_path"
+            siteconf.puts "RbConfig::CONFIG['#{dir}'] = dest_path"
+          end
+        end
+      end
+
+      # copy binary from temporary location to final lib
+      # tmp/extension_name/extension_name.{so,bundle} => lib/
+      task "copy:#{@name}:#{platf}:#{ruby_ver}" => [lib_binary_dir_path, tmp_binary_path, "#{tmp_path}/Makefile"] do
+        # install in lib for native platform only
+        unless for_platform
+          sh "#{make} install", chdir: tmp_path
+        end
+      end
+      # copy binary from temporary location to staging directory
+      task "copy:#{@name}:#{platf}:#{ruby_ver}" => [stage_binary_dir_path, tmp_binary_path] do
+        cp tmp_binary_path, stage_binary_path
+      end
+
+      # copy other gem files to staging directory
+      define_staging_file_tasks(@gem_spec.files, lib_path, stage_path, platf, ruby_ver) if @gem_spec
+
+      # binary in temporary folder depends on makefile and source files
+      # tmp/extension_name/extension_name.{so,bundle}
+      file tmp_binary_path => [tmp_binary_dir_path, "#{tmp_path}/Makefile"] + source_files do
+        jruby_compile_msg = <<-EOF
+Compiling a native C extension on JRuby. This is discouraged and a
+Java extension should be preferred.
+        EOF
+        warn_once(jruby_compile_msg) if defined?(JRUBY_VERSION)
+
+        chdir tmp_path do
+          sh make
+          if binary_path != File.basename(binary_path)
+            cp File.basename(binary_path), binary_path
+          end
+        end
+      end
+
+      # makefile depends of tmp_dir and config_script
+      # tmp/extension_name/Makefile
+      file "#{tmp_path}/Makefile" => [tmp_path, extconf, siteconf_path] do |t|
+        options = @config_options.dup
+
+        # include current directory
+        include_dirs = ['.'].concat(@config_includes).uniq.join(File::PATH_SEPARATOR)
+        cmd = [Gem.ruby, "-I#{include_dirs}", "-r#{File.basename(siteconf_path)}"]
+
+        # build a relative path to extconf script
+        abs_tmp_path = (Pathname.new(Dir.pwd) + tmp_path).realpath
+        abs_extconf = (Pathname.new(Dir.pwd) + extconf).realpath
+
+        # now add the extconf script
+        cmd << abs_extconf.relative_path_from(abs_tmp_path)
+
+        # fake.rb will be present if we are cross compiling
+        if t.prerequisites.include?("#{tmp_path}/fake.rb") then
+          options.push(*cross_config_options(platf))
+        end
+
+        # add options to command
+        cmd.push(*options)
+
+        # add any extra command line options
+        unless extra_options.empty?
+          cmd.push(*extra_options)
+        end
+
+        chdir tmp_path do
+          # FIXME: Rake is broken for multiple arguments system() calls.
+          # Add current directory to the search path of Ruby
+          sh cmd.join(' ')
+        end
+      end
+
+      # compile tasks
+      unless Rake::Task.task_defined?('compile') then
+        desc "Compile all the extensions"
+        task "compile"
+      end
+
+      # compile:name
+      unless Rake::Task.task_defined?("compile:#{@name}") then
+        desc "Compile #{@name}"
+        task "compile:#{@name}"
+      end
+
+      # Allow segmented compilation by platform (open door for 'cross compile')
+      task "compile:#{@name}:#{platf}" => ["copy:#{@name}:#{platf}:#{ruby_ver}"]
+      task "compile:#{platf}" => ["compile:#{@name}:#{platf}"]
+
+      # Only add this extension to the compile chain if current
+      # platform matches the indicated one.
+      if platf == RUBY_PLATFORM then
+        # ensure file is always copied
+        file "#{lib_path}/#{binary_path}" => ["copy:#{name}:#{platf}:#{ruby_ver}"]
+
+        task "compile:#{@name}" => ["compile:#{@name}:#{platf}"]
+        task "compile" => ["compile:#{platf}"]
+      end
+    end
+  end
+end

spec/pg_spec.rb

@@ -46,5 +46,8 @@
 		        ])
 	end
 
-end
+	it "tells about the libpq library path" do
+		expect( PG::POSTGRESQL_LIB_PATH ).to include("/")
+	end
 
+end