feat: version info emits version info about other libs used

also:
- make extconf more consistent in using append_cppflags for CPP flags
- jruby version also emits lib info this way

ext/nokogiri/extconf.rb

@@ -19,6 +19,9 @@
 REQUIRED_MINI_PORTILE_VERSION = "~> 2.5.0"
 REQUIRED_PKG_CONFIG_VERSION = "~> 1.1"
 
+# Keep track of what versions of what libraries we build against
+OTHER_LIBRARY_VERSIONS = {}
+
 NOKOGIRI_HELP_MESSAGE = <<~HELP
   USAGE: ruby #{$0} [options]
 
@@ -339,6 +342,10 @@ def process_recipe(name, version, static_p, cross_p)
   require 'mini_portile2'
   message "Using mini_portile version #{MiniPortile::VERSION}\n"
 
+  if name != "libxml2" && name != "libxslt"
+    OTHER_LIBRARY_VERSIONS[name] = version
+  end
+
   MiniPortile.new(name, version).tap do |recipe|
     recipe.target = File.join(PACKAGE_ROOT_DIR, "ports")
     # Prefer host_alias over host in order to use i586-mingw32msvc as
@@ -695,8 +702,8 @@ def configure
     ]
   end
 
-  append_cflags("-DNOKOGIRI_PACKAGED_LIBRARIES")
-  append_cflags("-DNOKOGIRI_PRECOMPILED_LIBRARIES") if cross_build_p
+  append_cppflags("-DNOKOGIRI_PACKAGED_LIBRARIES")
+  append_cppflags("-DNOKOGIRI_PRECOMPILED_LIBRARIES") if cross_build_p
 
   $LIBPATH = ["#{zlib_recipe.path}/lib"] | $LIBPATH if zlib_recipe
   $LIBPATH = ["#{libiconv_recipe.path}/lib"] | $LIBPATH if libiconv_recipe
@@ -724,8 +731,8 @@ def configure
         end
       end
 
-      # Defining a macro that expands to a C string; double quotes are significant.
-      $CPPFLAGS << ' ' << "-DNOKOGIRI_#{recipe.name.upcase}_PATCHES=\"#{recipe.patch_files.map { |path| File.basename(path) }.join(' ')}\"".inspect
+      patches_string = recipe.patch_files.map { |path| File.basename(path) }.join(' ')
+      append_cppflags(%Q[-DNOKOGIRI_#{recipe.name.upcase}_PATCHES="\\\"#{patches_string}\\\""])
 
       case libname
       when 'xml2'
@@ -770,6 +777,9 @@ def configure
 
 have_func('vasprintf')
 
+other_library_versions_string = OTHER_LIBRARY_VERSIONS.map { |k,v| [k,v].join(":") }.join(",")
+append_cppflags(%Q[-DNOKOGIRI_OTHER_LIBRARY_VERSIONS="\\\"#{other_library_versions_string}\\\""])
+
 unless using_system_libraries?
   if cross_build_p
     # When precompiling native gems, copy packaged libraries' headers to ext/nokogiri/include

ext/nokogiri/nokogiri.c

@@ -94,6 +94,10 @@ void Init_nokogiri()
   rb_const_set(mNokogiri, rb_intern("LIBXML_ICONV_ENABLED"), Qfalse);
 #endif
 
+#ifdef NOKOGIRI_OTHER_LIBRARY_VERSIONS
+  rb_const_set(mNokogiri, rb_intern("OTHER_LIBRARY_VERSIONS"), NOKOGIRI_STR_NEW2(NOKOGIRI_OTHER_LIBRARY_VERSIONS));
+#endif
+
   xmlInitParser();
 
   init_xml_document();

lib/nokogiri/version/info.rb

@@ -114,9 +114,16 @@ def to_hash
           end
 
           vi["warnings"] = warnings
+        end
+
+        if defined?(Nokogiri::OTHER_LIBRARY_VERSIONS)
+          # see extconf for how this string is assembled: "lib1name:lib1version,lib2name:lib2version"
+          vi["other_libraries"] = Hash[*Nokogiri::OTHER_LIBRARY_VERSIONS.split(/[,:]/)]
         elsif jruby?
-          vi["xerces"] = Nokogiri::XERCES_VERSION
-          vi["nekohtml"] = Nokogiri::NEKO_VERSION
+          vi["other_libraries"] = {}.tap do |ol|
+            ol["xerces"] = Nokogiri::XERCES_VERSION
+            ol["nekohtml"] = Nokogiri::NEKO_VERSION
+          end
         end
       end
     end

test/test_version.rb

@@ -20,12 +20,12 @@ def test_version_info_basics
 
   def test_version_info_for_xerces
     skip("xerces is only used for JRuby") unless Nokogiri.jruby?
-    assert_equal(Nokogiri::XERCES_VERSION, version_info["xerces"])
+    assert_equal(Nokogiri::XERCES_VERSION, version_info["other_libraries"]["xerces"])
   end
 
   def test_version_info_for_nekohtml
     skip("nekohtml is only used for JRuby") unless Nokogiri.jruby?
-    assert_equal(Nokogiri::NEKO_VERSION, version_info["nekohtml"])
+    assert_equal(Nokogiri::NEKO_VERSION, version_info["other_libraries"]["nekohtml"])
   end
 
   def test_version_info_for_libxml