Build libgumbo via autotools and rebuild on source changes

- Implement a minimal autotools build for libgumbo.
- Make `rake gumbo:test` use the same libgumbo.a used to build the
  nokogiri extension.
- Make changes to `gumbo-parser/src` trigger a rebuild of libgumbo.

Author: stevecheckoway

ext/nokogiri/extconf.rb

@@ -1056,54 +1056,8 @@ def configure
   find_header("nokogiri_gumbo.h") || abort("nokogiri_gumbo.h not found")
 else
   libgumbo_recipe = process_recipe("libgumbo", "1.0.0-nokogiri", static_p, cross_build_p, false) do |recipe|
-    recipe.configure_options = []
-
-    class << recipe
-      def downloaded?
-        true
-      end
-
-      def extract
-        target = File.join(tmp_path, "gumbo-parser")
-        output("Copying gumbo-parser files into #{target}...")
-        FileUtils.mkdir_p(target)
-        FileUtils.cp(Dir.glob(File.join(PACKAGE_ROOT_DIR, "gumbo-parser/src/*")), target)
-      end
-
-      def configured?
-        true
-      end
-
-      def install
-        lib_dir = File.join(port_path, "lib")
-        inc_dir = File.join(port_path, "include")
-        FileUtils.mkdir_p([lib_dir, inc_dir])
-        FileUtils.cp(File.join(work_path, "libgumbo.a"), lib_dir)
-        FileUtils.cp(Dir.glob(File.join(work_path, "*.h")), inc_dir)
-      end
-
-      def compile
-        cflags = concat_flags(ENV["CFLAGS"], "-fPIC", "-O2", "-g")
-
-        env = { "CC" => gcc_cmd, "CFLAGS" => cflags }
-        if config_cross_build?
-          if host.include?("darwin")
-            env["AR"] = "#{host}-libtool"
-            env["ARFLAGS"] = "-o"
-          else
-            env["AR"] = "#{host}-ar"
-          end
-          env["RANLIB"] = "#{host}-ranlib"
-        end
-
-        execute("compile", make_cmd, { env: env })
-      end
-    end
+    recipe.source_directory = File.join(PACKAGE_ROOT_DIR, "gumbo-parser")
   end
-  append_cppflags("-I#{File.join(libgumbo_recipe.path, "include")}")
-  $libs = $libs + " " + File.join(libgumbo_recipe.path, "lib", "libgumbo.a")
-  $LIBPATH = $LIBPATH | [File.join(libgumbo_recipe.path, "lib")]
-  ensure_func("gumbo_parse_with_options", "nokogiri_gumbo.h")
 end
 
 have_func("xmlHasFeature") || abort("xmlHasFeature() is missing.") # introduced in libxml 2.6.21
@@ -1142,11 +1096,23 @@ def compile
   File.open("Makefile", "at") do |mk|
     mk.print(<<~EOF)
 
+      .PHONY: clean-ports
       all: clean-ports
       clean-ports: $(DLLIB)
       \t-$(Q)$(RUBY) $(srcdir)/extconf.rb --clean --#{static_p ? "enable" : "disable"}-static
     EOF
   end
+  File.open("Makefile", "at") do |mk|
+    mk.print(<<~EOF)
+
+      .PHONY: rebuild-libgumbo
+
+      $(TARGET_SO): rebuild-libgumbo
+      rebuild-libgumbo:
+      \t-$(Q)$(MAKE) -C tmp/#{libgumbo_recipe.host}/ports/libgumbo/1.0.0-nokogiri/libgumbo-1.0.0-nokogiri install
+    EOF
+  end
+
 end
 
 # rubocop:enable Style/GlobalVars

gumbo-parser/.gitignore

@@ -1,5 +1,10 @@
-build
-googletest
-src/*.o
-fuzzer/build
-src/libgumbo.a
+/build
+/googletest
+/src/*.o
+/fuzzer/build
+/src/libgumbo.a
+/aclocal.m4
+/autom4te.cache/
+/configure
+/configure.in
+Makefile.in

gumbo-parser/Makefile.am

@@ -0,0 +1,5 @@
+if HAS_TESTS
+  SUBDIRS = src test
+else
+  SUBDIRS = src
+endif

gumbo-parser/Makefile gumbo-parser/Makefile.oldgumbo-parser/Makefile renamed to gumbo-parser/Makefile.old

@@ -0,0 +1,4 @@
+# Ignore everything in this directory except for this file.
+# Credit: https://stackoverflow.com/a/932982
+*
+!/.gitignore

gumbo-parser/build-aux/.gitignore

@@ -0,0 +1,11 @@
+AC_INIT([Gumbo], [1.0])
+AC_CONFIG_SRCDIR([src/nokogiri_gumbo.h])
+AC_CONFIG_AUX_DIR([build-aux])
+AM_INIT_AUTOMAKE([subdir-objects foreign serial-tests no-dist no-installinfo no-installman -Wall])
+AC_PROG_RANLIB
+AC_PROG_CC
+AC_PROG_CXX
+AM_PROG_AR
+AM_CONDITIONAL([HAS_TESTS], [test -d "${srcdir}/test"])
+AC_CONFIG_FILES([Makefile src/Makefile test/Makefile])
+AC_OUTPUT

gumbo-parser/configure.ac

@@ -0,0 +1,20 @@
+lib_LIBRARIES = libgumbo.a
+libgumbo_a_SOURCES = \
+	ascii.c \
+	attribute.c \
+	char_ref.c \
+	error.c \
+	foreign_attrs.c \
+	parser.c \
+	string_buffer.c \
+	string_piece.c \
+	svg_attrs.c \
+	svg_tags.c \
+	tag.c \
+	tag_lookup.c \
+	token_buffer.c \
+	tokenizer.c \
+	utf8.c \
+	util.c \
+	vector.c
+include_HEADERS = nokogiri_gumbo.h

gumbo-parser/src/Makefile

@@ -0,0 +1,21 @@
+check_LIBRARIES = libgtest_main.a
+libgtest_main_a_SOURCES = ../googletest/src/gtest-all.cc ../googletest/src/gtest_main.cc
+libgtest_main_a_CPPFLAGS = -I$(top_srcdir)/googletest/include -I$(top_srcdir)/googletest
+libgtest_main_a_CXXFLAGS = -pthread
+
+check_PROGRAMS = gumbotest
+gumbotest_SOURCES = attribute.cc \
+    parser.cc \
+    string_buffer.cc \
+    string_piece.cc \
+    test_utils.cc \
+    token_buffer.cc \
+    tokenizer.cc \
+    utf8.cc \
+    vector.cc
+
+gumbotest_LDADD = libgtest_main.a ../src/libgumbo.a
+gumbotest_LDFLAGS = -pthread
+gumbotest_CPPFLAGS = -I$(top_srcdir)/googletest/include -I$(top_srcdir)/src
+
+TESTS = gumbotest

gumbo-parser/src/Makefile.am

@@ -182,9 +182,13 @@ Gem::Specification.new do |spec|
     "ext/nokogiri/xml_xpath_context.c",
     "ext/nokogiri/xslt_stylesheet.c",
     "gumbo-parser/CHANGES.md",
-    "gumbo-parser/Makefile",
+    "gumbo-parser/Makefile.am",
+    "gumbo-parser/Makefile.in",
     "gumbo-parser/THANKS",
-    "gumbo-parser/src/Makefile",
+    "gumbo-parser/configure",
+    "gumbo-parser/configure.ac",
+    "gumbo-parser/src/Makefile.am",
+    "gumbo-parser/src/Makefile.in",
     "gumbo-parser/src/README.md",
     "gumbo-parser/src/ascii.c",
     "gumbo-parser/src/ascii.h",