卜部昌平 13064fe5db avoid undefined behaviour when n==0
ISO/IEC 9899:1999 section 6.5.7 states that "If the value of the right
operand is negative or is greater than or equal to the width of the
promoted left operand, the behavior is undefined".  So we have to take
care of such situations.

This has not been a problem because contemporary C compilers are
extraordinary smart to compile the series of shifts into a single
ROTLQ/ROTRQ machine instruction.  In contrast to what C says those
instructions have fully defined behaviour for all possible inputs.
Hence it has been quite difficult to observe the undefined-ness of such
situations.  But undefined is undefined.  We should not rely on such
target-specific assumptions.

We are fixing the situation by carefully avoiding shifts with out-of-
range values.  At least GCC since 4.6.3 and Clang since 8.0 can issue
the exact same instructions like before the changeset.

Also in case of Intel processors, there supposedly be intrinsics named
_rotr/_rotl that do exactly what we need.  They, in practice, are absent
on Clang before 9.x so we cannot blindly use.  But we can at least save
MSVC.

See also:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57157
https://bugs.llvm.org/show_bug.cgi?id=17332
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Build Status Build status Actions Status Actions Status Actions Status Actions Status Actions Status Actions Status

What's Ruby

Ruby is an interpreted object-oriented programming language often used for web development. It also offers many scripting features to process plain text and serialized files, or manage system tasks. It is simple, straightforward, and extensible.

Features of Ruby

  • Simple Syntax
  • Normal Object-oriented Features (e.g. class, method calls)
  • Advanced Object-oriented Features (e.g. mix-in, singleton-method)
  • Operator Overloading
  • Exception Handling
  • Iterators and Closures
  • Garbage Collection
  • Dynamic Loading of Object Files (on some architectures)
  • Highly Portable (works on many Unix-like/POSIX compatible platforms as well as Windows, macOS, Haiku, etc.) cf. https://github.com/ruby/ruby/blob/master/doc/contributing.rdoc#platform-maintainers

How to get Ruby

For a complete list of ways to install Ruby, including using third-party tools like rvm, see:

https://www.ruby-lang.org/en/downloads/

Git

The mirror of the Ruby source tree can be checked out with the following command:

$ git clone https://github.com/ruby/ruby.git

There are some other branches under development. Try the following command to see the list of branches:

$ git ls-remote https://github.com/ruby/ruby.git

You may also want to use https://git.ruby-lang.org/ruby.git (actual master of Ruby source) if you are a committer.

Subversion

Stable branches for older Ruby versions can be checked out with the following command:

$ svn co https://svn.ruby-lang.org/repos/ruby/branches/ruby_2_6/ ruby

Try the following command to see the list of branches:

$ svn ls https://svn.ruby-lang.org/repos/ruby/branches/

Ruby home page

https://www.ruby-lang.org/

Mailing list

There is a mailing list to discuss Ruby. To subscribe to this list, please send the following phrase:

subscribe

in the mail body (not subject) to the address ruby-talk-request@ruby-lang.org.

How to compile and install

  1. If you want to use Microsoft Visual C++ to compile Ruby, read win32/README.win32 instead of this document.

  2. If ./configure does not exist or is older than configure.ac, run autoconf to (re)generate configure.

  3. Run ./configure, which will generate config.h and Makefile.

    Some C compiler flags may be added by default depending on your environment. Specify optflags=.. and warnflags=.. as necessary to override them.

  4. Edit defines.h if you need. Usually this step will not be needed.

  5. Remove comment mark(#) before the module names from ext/Setup (or add module names if not present), if you want to link modules statically.

    If you don't want to compile non static extension modules (probably on architectures which do not allow dynamic loading), remove comment mark from the line "#option nodynamic" in ext/Setup.

    Usually this step will not be needed.

  6. Run make.

    • On Mac, set RUBY_CODESIGN environment variable with a signing identity. It uses the identity to sign ruby binary. See also codesign(1).
  7. Optionally, run 'make check' to check whether the compiled Ruby interpreter works well. If you see the message "check succeeded", your Ruby works as it should (hopefully).

  8. Optionally, run make update-gems and make extract-gems.

    If you want to install bundled gems, run make update-gems and make extract-gems before running make install.

  9. Run 'make install'.

    This command will create the following directories and install files into them.

    • ${DESTDIR}${prefix}/bin
    • ${DESTDIR}${prefix}/include/ruby-${MAJOR}.${MINOR}.${TEENY}
    • ${DESTDIR}${prefix}/include/ruby-${MAJOR}.${MINOR}.${TEENY}/${PLATFORM}
    • ${DESTDIR}${prefix}/lib
    • ${DESTDIR}${prefix}/lib/ruby
    • ${DESTDIR}${prefix}/lib/ruby/${MAJOR}.${MINOR}.${TEENY}
    • ${DESTDIR}${prefix}/lib/ruby/${MAJOR}.${MINOR}.${TEENY}/${PLATFORM}
    • ${DESTDIR}${prefix}/lib/ruby/site_ruby
    • ${DESTDIR}${prefix}/lib/ruby/site_ruby/${MAJOR}.${MINOR}.${TEENY}
    • ${DESTDIR}${prefix}/lib/ruby/site_ruby/${MAJOR}.${MINOR}.${TEENY}/${PLATFORM}
    • ${DESTDIR}${prefix}/lib/ruby/vendor_ruby
    • ${DESTDIR}${prefix}/lib/ruby/vendor_ruby/${MAJOR}.${MINOR}.${TEENY}
    • ${DESTDIR}${prefix}/lib/ruby/vendor_ruby/${MAJOR}.${MINOR}.${TEENY}/${PLATFORM}
    • ${DESTDIR}${prefix}/lib/ruby/gems/${MAJOR}.${MINOR}.${TEENY}
    • ${DESTDIR}${prefix}/share/man/man1
    • ${DESTDIR}${prefix}/share/ri/${MAJOR}.${MINOR}.${TEENY}/system

    If Ruby's API version is 'x.y.z', the ${MAJOR} is 'x', the ${MINOR} is 'y', and the ${TEENY} is 'z'.

    NOTE: teeny of the API version may be different from one of Ruby's program version

    You may have to be a super user to install Ruby.

If you fail to compile Ruby, please send the detailed error report with the error log and machine/OS type, to help others.

Some extension libraries may not get compiled because of lack of necessary external libraries and/or headers, then you will need to run 'make distclean-ext' to remove old configuration after installing them in such case.

Copying

See the file COPYING.

Feedback

Questions about the Ruby language can be asked on the Ruby-Talk mailing list (https://www.ruby-lang.org/en/community/mailing-lists) or on websites like (https://stackoverflow.com).

Bugs should be reported at https://bugs.ruby-lang.org. Read HowToReport for more information.

Contributing

See the file CONTRIBUTING.md

The Author

Ruby was originally designed and developed by Yukihiro Matsumoto (Matz) in 1995.

matz@ruby-lang.org

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