anchor.diff:  lots of assertions and sanity checks that could help you pinpoint the problem.
   
   
  -== COMMON PROBLEMS
  -
  -* The Makefiles use the `include` directive, which is not supported by all
  -  versions of make. Use GNU Make if this is a problem.
  -
  -* Solaris make mishandles a space in our Makefiles, so you have to use GNU make
  -  to build on Solaris.
  +== Common problems
   
   * The Makefiles assume that make executes commands by calling `/bin/sh`. They
     won't work if `/bin/csh` is called instead.  You may have to unset the `SHELL`
  
positive.code:   to be able to process `.cmxs` files.  `diffutils` is necessary to run the test
    suite.
  
  == INSTALLATION INSTRUCTIONS
  
  1. Configure the system. From the top directory, do:
  
          ./configure
  +
  This generates the three configuration files `Makefile.config`,
  `runtime/caml/m.h` and `runtime/caml/s.h`.
  +
  The `configure` script accepts the following options:
  +
  `-prefix <dir>`::                   (default: `/usr/local`)
          Set the `PREFIX` variable used to define the defaults of the following
          three options.  Must be an absolute path name.
  
  `-bindir <dir>`::                   (default: `$(PREFIX)/bin`)
          Directory where the binaries will be installed.  Must be an absolute
          path name, or start with `$(PREFIX)`.
  
  `-libdir <dir>`::                   (default: `$(PREFIX)/lib/ocaml`)
          Directory where the OCaml library will be installed.  Must be an
          absolute path name, or start with `$(PREFIX)`.
  
  `-mandir <dir>`::                   (default: `$(PREFIX)/man/man1`)
          Directory where the manual pages will be installed.  Must be an absolute
          path name, or start with `$(PREFIX)`.
  
  `-cc <C compiler and options>`::    (default: `gcc` if found, otherwise `cc`)
          C compiler to use for building the system.
  
  `-libs <extra libraries>`::         (default: none)
          Extra libraries to link with the system.
  
  `-no-curses`::
          Do not use the curses library.
          The only use for this is to highlight errors in the toplevel using
          'standout' mode, e.g. underline, rather than with '^' on a newline.
  
  `-host <hosttype>`::                (default: determined automatically)
          The type of the host machine, in GNU's "configuration name" format
          (CPU-COMPANY-SYSTEM or CPU-COMPANY-KERNEL-SYSTEM).  This info is
          generally determined automatically by the `configure` script, and rarely
          ever needs to be provided by hand.  The installation instructions for
          GCC or GNU Emacs contain a complete list of configuration names.
  
  `-target <targettype>`::            (default: same as `-host`)
          The type of the target machine, in GNU's "configuration name" format
          (CPU-COMPANY-SYSTEM or CPU-COMPANY-KERNEL-SYSTEM). Setting this will
          setup OCaml as a cross-compiler which runs on `$host` and produces code
          for `$target`. This requires a C toolchain which also produces code for
          `$target` and a native OCaml compiler of the exact same version (if you
          want a cross 4.00.1, you need a native 4.00.1).
  
  `-x11include <include_dir>`::       (default: determined automatically)
  `-x11lib <lib_dir>`::               (default: determined automatically)
          Location of the X11 include directory (e.g. `/usr/X11R6/include`) and
          the X11 library directory (e.g. `/usr/X11R6/lib`).
  
  `-no-pthread`::
          Do not attempt to use POSIX threads.
  
  `-with-pthread`::
          Attempt to use POSIX threads (this is the default).
  
  `-no-shared-libs`::
          Do not configure support for shared libraries.
  
  `-dldefs <cpp flags>`::
  `-dllibs <flags and libraries>`::
          These options specify where to find the libraries for dynamic linking
          (i.e. use of shared libraries).  `-dldefs` specifies options for finding
          the header files, and `-dllibs` for finding the C libraries.
  
  `-as <assembler and options>`::     (default: determined automatically)
          The assembler to use for assembling ocamlopt-generated code.
  
  `-aspp <assembler and options>`::   (default: determined automatically)
          The assembler to use for assembling the parts of the run-time system
          manually written in assembly language. This assembler must pre-process
          its input with the C preprocessor.
  
  `-with-debug-runtime`::
          Compile and install the debug version of the runtimes, useful for
          debugging C stubs and other low-level code.
  
  `-with-instrumented-runtime`::
          Compile and install the instrumented version of the runtimes, useful
          mainly for fine-tuning the GC.  Works only on Linux.
  
  `-verbose`::
          Verbose output of the configuration tests.  Use it if the outcome of
          `configure` is not what you were expecting.
  
  `-no-debugger`::
          Do not build `ocamldebug`.
  
  `-no-native-compiler`::
          Do not build the native compiler -- bytecode compilation only.
  
  `-no-ocamldoc`::
          Do not build `ocamldoc`.
  
  `-no-ocamlbuild`::
          Deprecated since 4.03.0, as `ocamlbuild` is now distributed separately
          from the compiler distribution.
  
  `-partialld <linker and options>`:: (default: determined automatically)
          The linker and options to use for producing an object file (rather than
          an executable) from several other object files.
  
  `-no-cfi`::
          Do not compile support for CFI directives.
  +
  Examples:
  
  * Standard installation in `/usr/{bin,lib,man}` instead of `/usr/local`:
      ./configure -prefix /usr
  
  
  * Installation in `/usr`, man pages in section "l":
  
      ./configure -bindir /usr/bin -libdir /usr/lib/ocaml -mandir /usr/man/manl
  +
  or:
  
      ./configure -prefix /usr -mandir '$(PREFIX)/man/manl'
  
  * On a Linux x86-64 host, to build a 32-bit version of OCaml:
  
      ./configure -cc "gcc -m32" -as "as --32" -aspp "gcc -m32 -c" \
                  -host i386-linux -partialld "ld -r -melf_i386"
  
  * On a Linux x86-64 host, to build the run-time system in PIC mode, no special
    options should be required -- the libraries should be built automatically.
    The old instructions were:
  
      ./configure -cc "gcc -fPIC" -aspp "gcc -c -fPIC"
  +
  On a 64-bit POWER architecture host running Linux, OCaml only operates in a
    32-bit environment.  If your system compiler is configured as 32-bit, e.g.
    Red Hat 5.9, you don't need to do anything special.  If that is not the case
    (e.g. Red Hat 6.4), then IBM's "Advance Toolchain" can be used.  For example:
  
      export PATH=/opt/at7.0/bin:$PATH
      ./configure -cc "gcc -m32" -as "as -a32" -aspp "gcc -m32 -c" \
        -partialld "ld -r -m elf32ppc"
  
  * On a OS X 10.5/Intel Core 2 or OS X 10.5/PowerPC host, to build a 64-bit
    version of OCaml:
  
      ./configure -cc "gcc -m64"
  
  * On OS X Intel, to build a 32-bit version of OCaml:
  
      ./configure -host "i386-apple-darwin13.2.0" -cc "gcc -arch i386 -m32" \
        -as "as -arch i386" -aspp "gcc -arch i386 -m32 -c"
  
  * For Sun Solaris with the `acc` compiler:
  
      ./configure -cc "acc -fast" -libs "-lucb"
  
  * For AIX 7.x with the IBM compiler `xlc`:
  
  
negative.code: = Installing OCaml from sources on a Unix(-like) machine =
  
  == Prerequisites
  
  * The GNU C Compiler (gcc) is recommended, as the bytecode interpreter takes
    advantage of GCC-specific features to enhance performance. gcc is the standard
  