$ gcj -o hecl --main=Hecl jars/j2se/Hecl.jar
/tmp/ccXDa4Dl.o: In function `int jline::WindowsTerminal::readCharacter(java::io::InputStream*)':
Hecl.jar:(.text+0x1bad3): undefined reference to `hidden alias for int jline::WindowsTerminal::readByte()'
/tmp/ccXDa4Dl.o: In function `void jline::WindowsTerminal::initializeTerminal()':
Hecl.jar:(.text+0x1bb8f): undefined reference to `hidden alias for int jline::WindowsTerminal::getConsoleMode()'
Hecl.jar:(.text+0x1bbe3): undefined reference to `hidden alias for void jline::WindowsTerminal::setConsoleMode(int)'
Hecl.jar:(.text+0x1bc5a): undefined reference to `hidden alias for void jline::WindowsTerminal::setConsoleMode(int)'
/tmp/ccXDa4Dl.o: In function `int jline::WindowsTerminal::getTerminalWidth()':
Hecl.jar:(.text+0x1c83d): undefined reference to `hidden alias for int jline::WindowsTerminal::getWindowsTerminalWidth()'
/tmp/ccXDa4Dl.o: In function `int jline::WindowsTerminal::getTerminalHeight()':
Hecl.jar:(.text+0x1c869): undefined reference to `hidden alias for int jline::WindowsTerminal::getWindowsTerminalHeight()'
/tmp/ccXDa4Dl.o: In function `void jline::WindowsTerminal::enableEcho()':
Hecl.jar:(.text+0x1c960): undefined reference to `hidden alias for int jline::WindowsTerminal::getConsoleMode()'
Hecl.jar:(.text+0x1c9cf): undefined reference to `hidden alias for void jline::WindowsTerminal::setConsoleMode(int)'
/tmp/ccXDa4Dl.o: In function `void jline::WindowsTerminal::disableEcho()':
Hecl.jar:(.text+0x1ca64): undefined reference to `hidden alias for int jline::WindowsTerminal::getConsoleMode()'
Hecl.jar:(.text+0x1ca9a): undefined reference to `hidden alias for void jline::WindowsTerminal::setConsoleMode(int)'
/tmp/ccXDa4Dl.o: In function `void jline::WindowsTerminal::access$000(jline::WindowsTerminal*, int)':
Hecl.jar:(.text+0x1cb9b): undefined reference to `hidden alias for void jline::WindowsTerminal::setConsoleMode(int)'
/tmp/ccXDa4Dl.o:(.data+0x5ac0): undefined reference to `hidden alias for int jline::WindowsTerminal::getConsoleMode()'
/tmp/ccXDa4Dl.o:(.data+0x5ad4): undefined reference to `hidden alias for void jline::WindowsTerminal::setConsoleMode(int)'
/tmp/ccXDa4Dl.o:(.data+0x5ae8): undefined reference to `hidden alias for int jline::WindowsTerminal::readByte()'
/tmp/ccXDa4Dl.o:(.data+0x5afc): undefined reference to `hidden alias for int jline::WindowsTerminal::getWindowsTerminalWidth()'
/tmp/ccXDa4Dl.o:(.data+0x5b10): undefined reference to `hidden alias for int jline::WindowsTerminal::getWindowsTerminalHeight()'
collect2: ld returned 1 exit status