+RED TEXT IS FROM THE 1.1 DOC AND NEEDS TO BE UPDATED. (It is here for +formatting and style reference.) +
+ +The release of Go version 1 (Go 1 or Go 1.0 for short) +in March of 2012 introduced a new period +of stability in the Go language and libraries. +That stability has helped nourish a growing community of Go users +and systems around the world. +Several "point" releases since +then—1.0.1, 1.0.2, and 1.0.3—have been issued. +These point releases fixed known bugs but made +no non-critical changes to the implementation. + +
+ ++ +This new release, Go 1.1, keeps the promise +of compatibility but adds a couple of significant +(backwards-compatible, of course) language changes, has a long list +of (again, compatible) library changes, and +includes major work on the implementation of the compilers, +libraries, and run-time. +The focus is on performance. +Benchmarking is an inexact science at best, but we see significant, +sometimes dramatic speedups for many of our test programs. +We trust that many of our users' programs will also see improvements +just by updating their Go installation and recompiling. + +
+ ++ +This document summarizes the changes between Go 1 and Go 1.2. +Very little if any code will need modification to run with Go 1.1, +although a couple of rare error cases surface with this release +and need to be addressed if they arise. +Details appear below; see the discussion of XXX. + +
+ ++ +The Go compatibility document promises +that programs written to the Go 1 language specification will continue to operate, +and those promises are maintained. +In the interest of firming up the specification, though, there are +details about some error cases that have been clarified. +There are also some new language features. + +
+ ++cmd/gc: three-index slicing to set cap as well as length (CL 10743046). +
+ + +
+
+The GCC release schedule does not coincide with the Go release schedule, so some skew is inevitable in
+gccgo's releases.
+The 4.8.0 version of GCC shipped in March, 2013 and includes a nearly-Go 1.1 version of gccgo.
+Its library is a little behind the release, but the biggest difference is that method values are not implemented.
+Sometime around July 2013, we expect 4.8.2 of GCC to ship with a gccgo
+providing a complete Go 1.1 implementaiton.
+
+
+TODO: write prose +
+ +
+
+The Go 1.1 tool chain adds experimental support for freebsd/arm,
+netbsd/386, netbsd/amd64, netbsd/arm,
+openbsd/386 and openbsd/amd64 platforms.
+
+
+
+An ARMv6 or later processor is required for freebsd/arm or
+netbsd/arm.
+
+
+
+Go 1.1 adds experimental support for cgo on linux/arm.
+
+
+ +The performance of code compiled with the Go 1.1 gc tool suite should be noticeably +better for most Go programs. +Typical improvements relative to Go 1.0 seem to be about 30%-40%, sometimes +much more, but occasionally less or even non-existent. +There are too many small performance-driven tweaks through the tools and libraries +to list them all here, but the following major changes are worth noting: + +
+ +
+TODO: choose which to call out
+
+The various routines to scan textual input in the
+bufio
+package,
+ReadBytes,
+ReadString
+and particularly
+ReadLine,
+are needlessly complex to use for simple purposes.
+In Go 1.1, a new type,
+Scanner,
+has been added to make it easier to do simple tasks such as
+read the input as a sequence of lines or space-delimited words.
+It simplifies the problem by terminating the scan on problematic
+input such as pathologically long lines, and having a simple
+default: line-oriented input, with each line stripped of its terminator.
+Here is code to reproduce the input a line at a time:
+
+
+
+
+Updating:
+To correct breakage caused by the new struct field,
+go fix will rewrite code to add tags for these types.
+More generally, go vet will identify composite literals that
+should be revised to use field tags.
+
+
+
+To make it easier for binary distributions to access them if desired, the exp
+and old source subtrees, which are not included in binary distributions,
+have been moved to the new go.exp subrepository at
+code.google.com/p/go.exp. To access the ssa package,
+for example, run
+
+
+ +There are three new packages. + +
+ +go/format package provides
+a convenient way for a program to access the formatting capabilities of the
+go fmt command.
+It has two functions,
+Node to format a Go parser
+Node,
+and
+Source
+to reformat arbitrary Go source code into the standard format as provided by the
+go fmt command.
+
++The following list summarizes a number of minor changes to the library, mostly additions. +See the relevant package documentation for more information about each change. +
+ +archive/zip package
+adds the
+DataOffset accessor
+to return the offset of a file's (possibly compressed) data within the archive.
+bufio package
+adds Reset
+methods to Reader and
+Writer.
+These methods allow the Readers
+and Writers
+to be re-used on new input and output readers and writers, saving
+allocation overhead.
+compress/bzip2
+can now decompress concatenated archives.
+compress/flate
+package adds a Reset
+method on the Writer,
+allowing compression of one file to start with another's dictionary.
+container/heap package
+adds a Fix
+method to provide a more efficient way to update an item's position in the heap.
+container/list package
+adds the MoveBefore
+and
+MoveAfter
+methods, which implement the obvious rearrangement.
+crypto/cipher package
+adds the a new GCM mode (Galois Counter Mode), which is almost always
+used with AES encryption.
+crypto/md5 package
+adds a new Sum function
+to simplify hashing without sacrificing performance.
+crypto/sha1 package
+adds a new Sum function.
+crypto/sha256 package
+adds Sum256
+and Sum224 functions.
+crypto/sha512 package
+adds Sum512 and
+Sum384 functions.
+crypto/x509 package
+adds support for reading and writing arbitrary extensions.
+crypto/tls package adds
+support for TLS 1.1, 1.2 and AES-GCM.
+database/sql package adds a
+SetMaxOpenConns
+method on DB to limit the
+number of open connections to the database.
+encoding/csv package
+now always allows trailing commas on fields.
+encoding/gob package
+now supports the generic encoding interfaces of the
+encoding package
+described above.
+encoding/json package
+now will alway escape ampersands as "\u0026" when printing strings.
+It will now accept but correct invalid UTF-8 in
+Marshal
+(such input was previously rejected).
+Finally, it now supports the generic encoding interfaces of the
+encoding package
+described above.
+encoding/xml package
+now allows attributes stored in pointers to be marshaled.
+It also supports the generic encoding interfaces of the
+encoding package
+described above through the new
+Marshaler,
+UnMarshaler,
+and related
+MarshalerAttr and
+UnmarshalerAttr
+interfaces.
+flag package now
+has a Getter interface
+to allow the value of a flag to be retrieved. Due to the
+Go 1 compatibility guidelines, this method cannot be added to the existing
+Value
+interface, but all the existing standard flag types implement it.
+The package also now exports the CommandLine
+flag set, which holds the flags from the command line.
+go/build package adds
+the AllTags field
+to the Package type,
+to make it easier to process build tags.
+image/draw package now
+exports an interface, Drawer,
+that wraps the standard Draw method.
+The Porter-Duff operators now implement this interface, in effect binding an operation to
+the draw operator rather than providing it explicitly.
+Given a paletted image as its destination, the new
+FloydSteinberg
+implementation of the
+Drawer
+interface will use the Floyd-Steinberg error diffusion algorithm to draw the image.
+To create palettes suitable for such processing, the new
+Quantizer interface
+represents implementations of quantization algorithms that choose a palette
+given a full-color image.
+There are no implementations of this interface in the library.
+image/gif package
+can now create GIF files using the new
+Encode
+and EncodeAll
+functions.
+Their options argument allows specification of an image
+Quantizer to use;
+if it is nil, the generated GIF will use the
+Plan9
+color map (palette) defined in the new
+image/color/palette package.
+The options also specify a
+Drawer
+to use to create the output image;
+if it is nil, Floyd-Steinberg error diffusion is used.
+Copy method of the
+io package now prioritizes its
+arguments differently.
+If one argument implements WriterTo
+and the other implements iReaderFrom,
+Copy will now invoke
+WriterTo to do the work,
+so that less intermediate buffering is required in general.
+runtime package relaxes
+the constraints on finalizer functions in
+SetFinalizer: the
+actual argument can now be any type that is assignable to the formal type of
+the function, as is the case for any normal function call in Go.
+sort package has a new
+Stable function that implements
+stable sorting. It is less efficient than the normal sort algorithm, however.
+strings package adds
+an IndexByte
+function for consistency with the bytes package.
+testing package
+now exports theTB interface.
+It records the methods in common with the
+T
+and
+B types,
+to make it easier to share code between tests and benchmarks.
+Also, the
+AllocsPerRun
+function now quantizes the return value to an integer (although it
+still has type float64), to round off any error caused by
+initialization and make the result more repeatable.
+text/template package
+now automatically dereferences pointer values when evaluating the arguments
+to "escape" functions such as "html", to bring the behavior of such functions
+in agreement with that of other printing functions such as "printf".
+time package, the
+Parse function
+and
+Format
+method
+now handle time zone offsets with seconds, such as in the historical
+date "1871-01-01T05:33:02+00:34:08".
+Also, pattern matching in the formats for those routines is stricter: a non-lowercase letter
+must now follow the standard words such as "Jan" and "Mon".
+unicode package
+adds In,
+a nicer-to-use but equivalent version of the original
+IsOneOf,
+to see whether a character is a member of a Unicode category.
+