Compile ruby-odbc on Cygwin 1.7

The ruby-odbc gem won't compile in Cygwin 1.7 because the uft8 version failed.

You can solve this by run the followings in a shell

$ export cflags="-DHAVE_SQLCONFIGDATASOURCEW -DHAVE_SQLWRITEFILEDSNW -DHAVE_SQLREADFILEDSNW -DHAVE_SQLINSTALLERERROR -DHAVE_SQLINSTALLERERRORW"
$ gem install ruby-odbc

And you can also use this modified "extconf.rb"

require 'mkmf'

if ! defined? PLATFORM
  PLATFORM = RUBY_PLATFORM
end

def have_library_ex(lib, func="main", headers=nil)
  checking_for "#{func}() in -l#{lib}" do
    libs = append_library($libs, lib)
    if !func.nil? && !func.empty? && COMMON_LIBS.include?(lib)
      true
    elsif try_func(func, libs, headers)
      $libs = libs
      true
    else
      false
    end
  end
end

def try_func_nolink(func, libs, headers = nil, &b)
  headers = cpp_include(headers)
  try_compile(<<"SRC", libs, &b)
#{COMMON_HEADERS}
#{headers}
/*top*/
int t() { void ((*volatile p)()); p = (void ((*)()))#{func}; return 0; }
SRC
end

def have_func_nolink(func, headers = nil, &b)
  checking_for "#{func}()" do
    if try_func_nolink(func, $libs, headers, &b)
      $defs.push(format("-DHAVE_%s", func.upcase))
      true
    else
      false
    end
  end
end

def headers(header)
  if PLATFORM !~ /(mingw|cygwin)/ then
    hdrs = header
  else
    hdrs = ["windows.h", header]
  end
  hdrs
end
 
def check_for_type(type)
  begin
    if defined? have_type
      have_type(type, headers("sqltypes.h"))
    else
      throw
    end
  rescue
    puts "WARNING: please check sqltypes.h for #{type} manually,"
    puts "WARNING: if defined, modify CFLAGS in Makefile to contain"
    puts "WARNING: the option -DHAVE_TYPE_#{type}"
  end
end

dir_config("odbc")
have_header("sql.h") || begin
  puts "ERROR: sql.h not found"
  exit 1
end
have_header("sqlext.h") || begin
  puts "ERROR: sqlext.h not found"
  exit 1
end
testdlopen = enable_config("dlopen", true)

check_for_type("SQLTCHAR")
check_for_type("SQLLEN")
check_for_type("SQLULEN")

$have_odbcinst_h = have_header("odbcinst.h")

if PLATFORM =~ /mswin32/ then
  if !have_library_ex("odbc32", "SQLAllocConnect", "sql.h") ||
     !have_library_ex("odbccp32", "SQLConfigDataSource", "odbcinst.h") ||
     !have_library_ex("odbccp32", "SQLInstallerError", "odbcinst.h") ||
     !have_library("user32", "CharUpper") then
    puts "Can not locate odbc libraries"
    exit 1
  end
  have_func("SQLConfigDataSourceW", "odbcinst.h")
  have_func("SQLWriteFileDSNW", "odbcinst.h")
  have_func("SQLReadFileDSNW", "odbcinst.h")
  have_func("SQLInstallerError", "odbcinst.h")
  have_func("SQLInstallerErrorW", "odbcinst.h")
# mingw untested !!!
elsif PLATFORM =~ /(mingw|cygwin)/ then
  have_library("odbc32", "")
  have_library("odbccp32", "")
  have_library("user32", "")
  hdrs = headers("odbcinst.h")
  have_func("SQLConfigDataSourceW", hdrs)
  have_func("SQLWriteFileDSNW", hdrs)
  have_func("SQLReadFileDSNW", hdrs)
  have_func("SQLInstallerError", hdrs)
  have_func("SQLInstallerErrorW", hdrs)
elsif (testdlopen && PLATFORM !~ /(macos|darwin)/ && CONFIG["CC"] =~ /gcc/ && have_func("dlopen", "dlfcn.h") && have_library("dl", "dlopen")) then
  $LDFLAGS+=" -Wl,-init -Wl,ruby_odbc_init -Wl,-fini -Wl,ruby_odbc_fini"
  $CPPFLAGS+=" -DHAVE_SQLCONFIGDATASOURCE"
  $CPPFLAGS+=" -DHAVE_SQLINSTALLERERROR"
  $CPPFLAGS+=" -DUSE_DLOPEN_FOR_ODBC_LIBS"
  # but test the UNICODE installer functions w/o linking
  # in case we need to provide fwd declarations
  have_func_nolink("SQLConfigDataSourceW", "odbcinst.h")
  have_func_nolink("SQLWriteFileDSNW", "odbcinst.h")
  have_func_nolink("SQLReadFileDSNW", "odbcinst.h")
  have_func_nolink("SQLInstallerErrorW", "odbcinst.h")
else
  have_library("odbc", "SQLAllocConnect") ||
    have_library("iodbc", "SQLAllocConnect")
  ($have_odbcinst_h &&
    have_library("odbcinst", "SQLConfigDataSource")) ||
  ($have_odbcinst_h &&
    have_library("iodbcinst", "SQLConfigDataSource"))
  $have_odbcinst_h &&
    have_func("SQLConfigDataSourceW", "odbcinst.h")
  $have_odbcinst_h &&
    have_func("SQLWriteFileDSNW", "odbcinst.h")
  $have_odbcinst_h &&
    have_func("SQLReadFileDSNW", "odbcinst.h")
  $have_odbcinst_h &&
    have_func("SQLInstallerError", "odbcinst.h")
  $have_odbcinst_h &&
    have_func("SQLInstallerErrorW", "odbcinst.h")
end

create_makefile("odbc_utf8")