+The latest Go release, version 1.5, +is a significant release, including major architectural changes to the implementation. +Despite that, we expect almost all Go programs to continue to compile and run as before, +because the release still maintains the Go 1 promise +of compatibility. +
+ ++The biggest developments in the implementation are: +
+ +GOMAXPROCS set to the
+number of cores available; in prior releases it defaulted to 1.
+go command now provides experimental
+support for "vendoring" external dependencies.
++These and a number of other changes to the implementation and tools +are discussed below. +
+ ++The release also contains one small language change involving map literals. +
+ ++Finally, the timing of the release +strays from the usual six-month interval, +both to provide more time to prepare this major release and to shift the schedule thereafter to +time the release dates more conveniently. +
+ ++Due to an oversight, the rule that allowed the element type to be elided from slice literals was not +applied to map keys. +This has been corrected in Go 1.5. +An example will make this clear: as of Go 1.5, this map literal, +
+
-Overall:
-- toolchain in Go
-- new GC
-- go tool asm, go tool compile, go tool link
-- default output files changed: now file.o and a.out
-- internal enforced even outside standard library (golang.org/s/go14internal; https://golang.org/cl/9156)
-- gomaxprocs=numcpu (golang.org/s/go15gomaxprocs)
+m := map[Point]string{
+ Point{29.935523, 52.891566}: "Persepolis",
+ Point{-25.352594, 131.034361}: "Uluru",
+ Point{37.422455, -122.084306}: "Googleplex",
+}
+
-Language:
-- permit omission of key type in map composite literals where key is a composite literal (https://golang.org/cl/2591)
+
+may be written as follows, without the Point type listed explicitly:
+
+m := map[Point]string{
+ {29.935523, 52.891566}: "Persepolis",
+ {-25.352594, 131.034361}: "Uluru",
+ {37.422455, -122.084306}: "Googleplex",
+}
+
-New Ports:
-- darwin/arm, a.k.a iOS. (https://golang.org/cl/2118, 2119, 3273, 2121, 2122, ..., 2127)
-- darwin/arm64
-- linux/arm64 (cgo is supported, but only with external linking)
-- openbsd/arm (no cgo or external linking)
+
+The compiler and runtime are now implemented in Go and assembler, without C.
+The only C source left in the tree is related to testing or to cgo.
+There was a C compiler in the tree in 1.4 and earlier.
+It was used to build the runtime; a custom compiler was necessary in part to
+guarantee the C code would work with the stack management of goroutines.
+Since the runtime is in Go now, there is no need for this C compiler and it is gone.
+Details of the process to eliminate C are discussed elsewhere.
+
+The conversion from C was done with the help of custom tools created for the job. +Most important, the compiler was actually moved by automatic translation of +the C code into Go. +It is in effect the same program in a different language. +It is not a new implementation +of the compiler so we expect the process will not have introduced new compiler +bugs. +An overview of this process is available in the slides for +this presentation. +
+ +
+Independent of but encouraged by the move to Go, the names of the tools have changed.
+The old names 6g, 8g and so on are gone; instead there
+is just one binary, accessible as go tool compile,
+that compiles Go source into binaries suitable for the architecture and operating system
+specified by $GOARCH and $GOOS.
+Simlarly, there is now one linker (go tool link)
+and one assembler (go tool asm).
+The linker was translated automatically from the old C implementation,
+but the assembler is a new native Go implementation discussed
+in more detail below.
+
+Similar to the drop of the names 6g, 8g, and so on,
+the output of the compiler and assembler are now given a plain .o suffix
+rather than .8, .6, etc.
+
+TODO +
+ ++In Go 1.5, the order in which goroutines are scheduled has been changed. +The properties of the scheduler were never defined by the language, +but programs that depended on the scheduling order may be broken +by this change. +We have seen a few (erroneous) programs affected by this change. +If you have programs that implicitly depend on the scheduling +order, you will need to update them. +
+ +
+Another potentially breaking change is that the runtime now
+sets the default number of threads to run simultaneously,
+defined by GOMAXPROCS, to the number
+of cores available on the CPU.
+In prior releases it defaulted to 1.
+Programs that do not expect to run with multiple cores may
+break inadvertently.
+They can be updated by removing the restriction or by setting
+GOMAXPROCS explicitly.
+
+Now that the Go compiler and runtime are implemented in Go, a Go compiler
+must be available to compile the distribution from source.
+Thus, to build the Go core, a working Go distribution must already be in place.
+(Go programmers who do not work on the core are unaffected by this change.)
+Any Go 1.4 or later distribution (including gccgo) will serve.
+For details, see the design document.
+
+Due mostly to the industry's move away the 32-bit x86 architecture,
+the set of binary downloads provided is reduced in 1.5.
+A distribution for the OS X operating system is provided only for the
+amd64 architecture, not 386.
+Similarly, the ports for Snow Leopard (Apple OS X 10.6) still work but are no
+longer released as a download or maintained since Apple no longer maintains that version
+of the operating system.
+Also, the dragonfly/386 port is no longer supported at all
+because DragonflyBSD itself no longer supports the 32-bit 386 architecture.
+
+There are however several new ports available to be built from source.
+These include darwin/arm and darwin/arm64.
+The new port linux/arm64 is mostly in place, but cgo
+is only supported using external linking.
+
API additions and behavior changes: -archive/zip: add (*Writer).SetOffset method (https://golang.org/cl/7445) -bufio: add Reader.Discard (https://golang.org/cl/2260) -bytes: add Buffer.Cap (https://golang.org/cl/8342) -bytes, strings: add Reader.Size (https://golang.org/cl/3199) -bytes, strings: add LastIndexByte (https://golang.org/cl/9500) -crypto/cipher: clarify what will happen if len(src) != len(dst) for the Stream interface. (https://golang.org/cl/1754) -crypto/cipher: support non-standard nonce lengths for GCM. (https://golang.org/cl/8946) -crypto/elliptic: add Name field to CurveParams struct (https://golang.org/cl/2133) -crypto/elliptic: Unmarshaling points now automatically checks that the point is on the curve (https://golang.org/cl/2421) -crypto/tls: change default minimum version to TLS 1.0. (https://golang.org/cl/1791) -crypto/tls: including Certificate Transparency SCTs in the handshake is now supported (https://golang.org/cl/8988) -crypto/tls: session ticket keys can now be rotated at runtime (https://golang.org/cl/9072) -crypto/tls: servers will now always call GetCertificate to pick a certificate for a connection when Certificates is empty (https://golang.org/cl/8792) -crypto/x509: wildcards are now only accepted as the first label (https://golang.org/cl/5691) -crypto/x509: unknown critical extensions now cause errors in Verify, not when parsing (https://golang.org/cl/9390) -database/sql: add Stats (https://golang.org/cl/7950) -encoding/base64: add unpadded encodings (https://golang.org/cl/1511) flag: new nicer format for PrintDefaults (https://golang.org/cl/7330) -fmt: empty slices now print nothing with %x (bug fix) (https://golang.org/cl/8864) -fmt: reflect.Value now prints what it holds (https://golang.org/cl/8731) -go/ast: add Implicit field to ast.EmptyStmt; changed meaning of ast.EmptyStmt.Semicolon position (https://golang.org/cl/5720) -go/build: reserved GOARCHes for common architectures (https://golang.org/cl/9644) -io: add CopyBuffer, Copy with user-provided buffer (https://golang.org/cl/8730) -log: add SetOutput functions (https://golang.org/cl/2686, https://golang.org/cl/3023) -log: add LUTC flag (https://golang.org/cl/8761) math/big: add arbitrary precision Floats (many cl's) -math/big: add Jacobi and Int.ModSqrt (https://golang.org/cl/1886) -mime: add ExtensionByType (https://golang.org/cl/7444) mime/quotedprintable: new package (https://golang.org/cl/5940 + others) -net: add sequential and RFC 6555-compliant TCP dialing (https://golang.org/cl/8768) -net: add Source field to OpError (https://go-review.googlesource.com/9231) -net: fix inconsistent errors (https://golang.org/cl/9236) -net: add SocketConn, SocketPacketConn (https://golang.org/cl/9275) -net: use Go's DNS resolver when system configuration permits (https://golang.org/cl/8945) -net/http: support for setting trailers from a server Handler (https://golang.org/cl/2157) -net/http: ignore the Unix epoch time in ServeContent (https://golang.org/cl/7915) -net/http/cgi: fix REMOTE_ADDR, REMOTE_HOST, add REMOTE_PORT (https://golang.org/cl/4933) -net/mail: adds AddressParser type (https://golang.org/cl/10392) -net/smtp: add TLSConnectionState accessor (https://golang.org/cl/2151) -os: add LookupEnv (https://golang.org/cl/9741) -os/signal: add Ignore and Reset (https://golang.org/cl/3580) reflect: add ArrayOf (https://golang.org/cl/4111) reflect: add FuncOf (https://golang.org/cl/1996) -runtime, syscall: use SYSCALL instruction on FreeBSD (Go 1.5 now requires FreeBSD 8-STABLE+) (https://golang.org/cl/3020) -runtime, syscall: use get_random_bytes syscall for NaCl (Go 1.5 now requires NaCl SDK pepper-39 or above) (https://golang.org/cl/1755) -runtime/pprof: memory profiles include overall memory statistics by default (https://golang.org/cl/9491) -strings: add Compare(x, y string) int, for symmetry with bytes.Compare (https://golang.org/cl/2828) -syscall: Add Foreground and Pgid to SysProcAttr (https://golang.org/cl/5130) -syscall: add missing Syscall9 for darwin/amd64 (https://golang.org/cl/6555) -syscall: Add GidMappingsEnableSetgroups to linux SysProcAttr (http://golang.org/cl/10670) -testing/quick: support generation of arrays (https://golang.org/cl/3865) -testing/quick: generated pointers can now be nil (https://golang.org/cl/10821) -text/template: add Options method (https://golang.org/cl/8462) -text/template: huge integers are now parse errors (https://golang.org/cl/9651) -time: add time.AppendFormat(https://golang.org/cl/1760) Tools: @@ -104,6 +228,7 @@ cmd/go: .swig/.swigcxx files now require SWIG 3.0.6 or later cmd/go: add -run flag to go generate (https://golang.org/cl/9005) cmd/go: add $GOLINE to generate's variables (https://golang.org/cl/9007) cmd/go: add go doc (https://golang.org/cl/9227) +cmd/go: internal enforced even outside standard library (golang.org/s/go14internal; https://golang.org/cl/9156) cmd/go, testing: add go test -count (https://golang.org/cl/10669) cmd/go: add preliminary support for vendor directories (https://golang.org/cl/10923) cmd/vet: better validation of struct tags (https://golang.org/cl/2685) @@ -115,6 +240,7 @@ cmd/go: add -buildmode build option cmd/gc: add -dynlink option (for amd64 only) cmd/ld: add -buildmode option cmd/trace: new command to view traces (https://golang.org/cl/3601) + Performance: cmd/gc: evaluate concrete == interface without allocating (https://golang.org/cl/2096) @@ -167,3 +293,209 @@ were fixed in fmt, archive/zip, archive/tar, encoding/gob, image/jpeg, image/png image/gif, compress/flate, text/template, html/template. The fixes harden implementation against incorrect and malicious inputs.+ +