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diff --git a/doc/go1.10.html b/doc/go1.10.html deleted file mode 100644 index 853f874ded..0000000000 --- a/doc/go1.10.html +++ /dev/null @@ -1,1448 +0,0 @@ -<!--{ - "Title": "Go 1.10 Release Notes", - "Path": "/doc/go1.10", - "Template": true -}--> - -<!-- -NOTE: In this document and others in this directory, the convention is to -set fixed-width phrases with non-fixed-width spaces, as in -<code>hello</code> <code>world</code>. -Do not send CLs removing the interior tags from such phrases. ---> - -<style> - main ul li { margin: 0.5em 0; } -</style> - -<h2 id="introduction">Introduction to Go 1.10</h2> - -<p> -The latest Go release, version 1.10, arrives six months after <a href="go1.9">Go 1.9</a>. -Most of its changes are in the implementation of the toolchain, runtime, and libraries. -As always, the release maintains the Go 1 <a href="/doc/go1compat.html">promise of compatibility</a>. -We expect almost all Go programs to continue to compile and run as before. -</p> - -<p> -This release improves <a href="#build">caching of built packages</a>, -adds <a href="#test">caching of successful test results</a>, -runs <a href="#test-vet">vet automatically during tests</a>, -and -permits <a href="#cgo">passing string values directly between Go and C using cgo</a>. -A new <a href="#cgo">hard-coded set of safe compiler options</a> may cause -unexpected <a href="https://golang.org/s/invalidflag"><code>invalid -flag</code></a> errors in code that built successfully with older -releases. -</p> - -<h2 id="language">Changes to the language</h2> - -<p> -There are no significant changes to the language specification. -</p> - -<p><!-- CL 60230 --> -A corner case involving shifts of untyped constants has been clarified, -and as a result the compilers have been updated to allow the index expression -<code>x[1.0</code> <code><<</code> <code>s]</code> where <code>s</code> is an unsigned integer; -the <a href="/pkg/go/types/">go/types</a> package already did. -</p> - -<p><!-- CL 73233 --> -The grammar for method expressions has been updated to relax the -syntax to allow any type expression as a receiver; -this matches what the compilers were already implementing. -For example, <code>struct{io.Reader}.Read</code> is a valid, if unusual, -method expression that the compilers already accepted and is -now permitted by the language grammar. -</p> - -<h2 id="ports">Ports</h2> - -<p> -There are no new supported operating systems or processor architectures in this release. -Most of the work has focused on strengthening the support for existing ports, -in particular <a href="#asm">new instructions in the assembler</a> -and improvements to the code generated by the compilers. -</p> - -<p id="freebsd"> -As <a href="go1.9#freebsd">announced in the Go 1.9 release notes</a>, -Go 1.10 now requires FreeBSD 10.3 or later; -support for FreeBSD 9.3 has been removed. -</p> - -<p id="netbsd"> -Go now runs on NetBSD again but requires the unreleased NetBSD 8. -Only <code>GOARCH</code> <code>amd64</code> and <code>386</code> have -been fixed. The <code>arm</code> port is still broken. -</p> - -<p id="mips"> -On 32-bit MIPS systems, the new environment variable settings -<code>GOMIPS=hardfloat</code> (the default) and -<code>GOMIPS=softfloat</code> select whether to use -hardware instructions or software emulation for floating-point computations. -</p> - -<p id="openbsd"> -Go 1.10 is the last release that will run on OpenBSD 6.0. -Go 1.11 will require OpenBSD 6.2. -</p> - -<p id="darwin"> -Go 1.10 is the last release that will run on OS X 10.8 Mountain Lion or OS X 10.9 Mavericks. -Go 1.11 will require OS X 10.10 Yosemite or later. -</p> - -<p id="windows"> -Go 1.10 is the last release that will run on Windows XP or Windows Vista. -Go 1.11 will require Windows 7 or later. -</p> - -<h2 id="tools">Tools</h2> - -<h3 id="goroot">Default GOROOT & GOTMPDIR</h3> - -<p> -If the environment variable <code>$GOROOT</code> is unset, -the go tool previously used the default <code>GOROOT</code> -set during toolchain compilation. -Now, before falling back to that default, the go tool attempts to -deduce <code>GOROOT</code> from its own executable path. -This allows binary distributions to be unpacked anywhere in the -file system and then be used without setting <code>GOROOT</code> -explicitly. -</p> - -<p> -By default, the go tool creates its temporary files and directories -in the system temporary directory (for example, <code>$TMPDIR</code> on Unix). -If the new environment variable <code>$GOTMPDIR</code> is set, -the go tool will creates its temporary files and directories in that directory instead. -</p> - -<h3 id="build">Build & Install</h3> - -<p> -The <code>go</code> <code>build</code> command now detects out-of-date packages -purely based on the content of source files, specified build flags, and metadata stored in the compiled packages. -Modification times are no longer consulted or relevant. -The old advice to add <code>-a</code> to force a rebuild in cases where -the modification times were misleading for one reason or another -(for example, changes in build flags) is no longer necessary: -builds now always detect when packages must be rebuilt. -(If you observe otherwise, please file a bug.) -</p> - -<p> -The <code>go</code> <code>build</code> <code>-asmflags</code>, <code>-gcflags</code>, <code>-gccgoflags</code>, and <code>-ldflags</code> options -now apply by default only to the packages listed directly on the command line. -For example, <code>go</code> <code>build</code> <code>-gcflags=-m</code> <code>mypkg</code> -passes the compiler the <code>-m</code> flag when building <code>mypkg</code> -but not its dependencies. -The new, more general form <code>-asmflags=pattern=flags</code> (and similarly for the others) -applies the <code>flags</code> only to the packages matching the pattern. -For example: <code>go</code> <code>install</code> <code>-ldflags=cmd/gofmt=-X=main.version=1.2.3</code> <code>cmd/...</code> -installs all the commands matching <code>cmd/...</code> but only applies the <code>-X</code> option -to the linker flags for <code>cmd/gofmt</code>. -For more details, see <a href="/cmd/go/#hdr-Compile_packages_and_dependencies"><code>go</code> <code>help</code> <code>build</code></a>. -</p> - -<p> -The <code>go</code> <code>build</code> command now maintains a cache of -recently built packages, separate from the installed packages in <code>$GOROOT/pkg</code> or <code>$GOPATH/pkg</code>. -The effect of the cache should be to speed builds that do not explicitly install packages -or when switching between different copies of source code (for example, when changing -back and forth between different branches in a version control system). -The old advice to add the <code>-i</code> flag for speed, as in <code>go</code> <code>build</code> <code>-i</code> -or <code>go</code> <code>test</code> <code>-i</code>, -is no longer necessary: builds run just as fast without <code>-i</code>. -For more details, see <a href="/cmd/go/#hdr-Build_and_test_caching"><code>go</code> <code>help</code> <code>cache</code></a>. -</p> - -<p> -The <code>go</code> <code>install</code> command now installs only the -packages and commands listed directly on the command line. -For example, <code>go</code> <code>install</code> <code>cmd/gofmt</code> -installs the gofmt program but not any of the packages on which it depends. -The new build cache makes future commands still run as quickly as if the -dependencies had been installed. -To force the installation of dependencies, use the new -<code>go</code> <code>install</code> <code>-i</code> flag. -Installing dependency packages should not be necessary in general, -and the very concept of installed packages may disappear in a future release. -</p> - -<p> -Many details of the <code>go</code> <code>build</code> implementation have changed to support these improvements. -One new requirement implied by these changes is that -binary-only packages must now declare accurate import blocks in their -stub source code, so that those imports can be made available when -linking a program using the binary-only package. -For more details, see <a href="/cmd/go/#hdr-File_types"><code>go</code> <code>help</code> <code>filetype</code></a>. -</p> - -<h3 id="test">Test</h3> - -<p> -The <code>go</code> <code>test</code> command now caches test results: -if the test executable and command line match a previous run -and the files and environment variables consulted by that run -have not changed either, <code>go</code> <code>test</code> will print -the previous test output, replacing the elapsed time with the string “(cached).” -Test caching applies only to successful test results; -only to <code>go</code> <code>test</code> -commands with an explicit list of packages; and -only to command lines using a subset of the -<code>-cpu</code>, <code>-list</code>, <code>-parallel</code>, -<code>-run</code>, <code>-short</code>, and <code>-v</code> test flags. -The idiomatic way to bypass test caching is to use <code>-count=1</code>. -</p> - -<p id="test-vet"> -The <code>go</code> <code>test</code> command now automatically runs -<code>go</code> <code>vet</code> on the package being tested, -to identify significant problems before running the test. -Any such problems are treated like build errors and prevent execution of the test. -Only a high-confidence subset of the available <code>go</code> <code>vet</code> -checks are enabled for this automatic check. -To disable the running of <code>go</code> <code>vet</code>, use -<code>go</code> <code>test</code> <code>-vet=off</code>. -</p> - -<p> -The <code>go</code> <code>test</code> <code>-coverpkg</code> flag now -interprets its argument as a comma-separated list of patterns to match against -the dependencies of each test, not as a list of packages to load anew. -For example, <code>go</code> <code>test</code> <code>-coverpkg=all</code> -is now a meaningful way to run a test with coverage enabled for the test package -and all its dependencies. -Also, the <code>go</code> <code>test</code> <code>-coverprofile</code> option is now -supported when running multiple tests. -</p> - -<p> -In case of failure due to timeout, tests are now more likely to write their profiles before exiting. -</p> - -<p> -The <code>go</code> <code>test</code> command now always -merges the standard output and standard error from a given test binary execution -and writes both to <code>go</code> <code>test</code>'s standard output. -In past releases, <code>go</code> <code>test</code> only applied this -merging most of the time. -</p> - -<p> -The <code>go</code> <code>test</code> <code>-v</code> output -now includes <code>PAUSE</code> and <code>CONT</code> status update -lines to mark when <a href="/pkg/testing/#T.Parallel">parallel tests</a> pause and continue. -</p> - -<p> -The new <code>go</code> <code>test</code> <code>-failfast</code> flag -disables running additional tests after any test fails. -Note that tests running in parallel with the failing test are allowed to complete. -</p> - -<p> -Finally, the new <code>go</code> <code>test</code> <code>-json</code> flag -filters test output through the new command -<code>go</code> <code>tool</code> <code>test2json</code> -to produce a machine-readable JSON-formatted description of test execution. -This allows the creation of rich presentations of test execution -in IDEs and other tools. -</p> - - -<p> -For more details about all these changes, -see <a href="/cmd/go/#hdr-Test_packages"><code>go</code> <code>help</code> <code>test</code></a> -and the <a href="/cmd/test2json/">test2json documentation</a>. -</p> - -<h3 id="cgo">Cgo</h3> - -<p> -Options specified by cgo using <code>#cgo CFLAGS</code> and the like -are now checked against a list of permitted options. -This closes a security hole in which a downloaded package uses -compiler options like -<span style="white-space: nowrap"><code>-fplugin</code></span> -to run arbitrary code on the machine where it is being built. -This can cause a build error such as <code>invalid flag in #cgo CFLAGS</code>. -For more background, and how to handle this error, see -<a href="https://golang.org/s/invalidflag">https://golang.org/s/invalidflag</a>. -</p> - -<p> -Cgo now implements a C typedef like “<code>typedef</code> <code>X</code> <code>Y</code>” using a Go type alias, -so that Go code may use the types <code>C.X</code> and <code>C.Y</code> interchangeably. -It also now supports the use of niladic function-like macros. -Also, the documentation has been updated to clarify that -Go structs and Go arrays are not supported in the type signatures of cgo-exported functions. -</p> - -<p> -Cgo now supports direct access to Go string values from C. -Functions in the C preamble may use the type <code>_GoString_</code> -to accept a Go string as an argument. -C code may call <code>_GoStringLen</code> and <code>_GoStringPtr</code> -for direct access to the contents of the string. -A value of type <code>_GoString_</code> -may be passed in a call to an exported Go function that takes an argument of Go type <code>string</code>. -</p> - -<p> -During toolchain bootstrap, the environment variables <code>CC</code> and <code>CC_FOR_TARGET</code> specify -the default C compiler that the resulting toolchain will use for host and target builds, respectively. -However, if the toolchain will be used with multiple targets, it may be necessary to specify a different C compiler for each -(for example, a different compiler for <code>darwin/arm64</code> versus <code>linux/ppc64le</code>). -The new set of environment variables <code>CC_FOR_<i>goos</i>_<i>goarch</i></code> -allows specifying a different default C compiler for each target. -Note that these variables only apply during toolchain bootstrap, -to set the defaults used by the resulting toolchain. -Later <code>go</code> <code>build</code> commands use the <code>CC</code> environment -variable or else the built-in default. -</p> - -<p> -Cgo now translates some C types that would normally map to a pointer -type in Go, to a <code>uintptr</code> instead. These types include -the <code>CFTypeRef</code> hierarchy in Darwin's CoreFoundation -framework and the <code>jobject</code> hierarchy in Java's JNI -interface. -</p> - -<p> -These types must be <code>uintptr</code> on the Go side because they -would otherwise confuse the Go garbage collector; they are sometimes -not really pointers but data structures encoded in a pointer-sized integer. -Pointers to Go memory must not be stored in these <code>uintptr</code> values. -</p> - -<p> -Because of this change, values of the affected types need to be -zero-initialized with the constant <code>0</code> instead of the -constant <code>nil</code>. Go 1.10 provides <code>gofix</code> -modules to help with that rewrite: -</p> - -<pre> -go tool fix -r cftype <pkg> -go tool fix -r jni <pkg> -</pre> - -<p> -For more details, see the <a href="/cmd/cgo/">cgo documentation</a>. -</p> - -<h3 id="doc">Doc</h3> - -<p> -The <code>go</code> <code>doc</code> tool now adds functions returning slices of <code>T</code> or <code>*T</code> -to the display of type <code>T</code>, similar to the existing behavior for functions returning single <code>T</code> or <code>*T</code> results. -For example: -</p> - -<pre> -$ go doc mail.Address -package mail // import "net/mail" - -type Address struct { - Name string - Address string -} - Address represents a single mail address. - -func ParseAddress(address string) (*Address, error) -func ParseAddressList(list string) ([]*Address, error) -func (a *Address) String() string -$ -</pre> - -<p> -Previously, <code>ParseAddressList</code> was only shown in the package overview (<code>go</code> <code>doc</code> <code>mail</code>). -</p> - -<h3 id="fix">Fix</h3> - -<p> -The <code>go</code> <code>fix</code> tool now replaces imports of <code>"golang.org/x/net/context"</code> -with <code>"context"</code>. -(Forwarding aliases in the former make it completely equivalent to the latter when using Go 1.9 or later.) -</p> - -<h3 id="get">Get</h3> - -<p> -The <code>go</code> <code>get</code> command now supports Fossil source code repositories. -</p> - -<h3 id="pprof">Pprof</h3> - -<p> -The blocking and mutex profiles produced by the <code>runtime/pprof</code> package -now include symbol information, so they can be viewed -in <code>go</code> <code>tool</code> <code>pprof</code> -without the binary that produced the profile. -(All other profile types were changed to include symbol information in Go 1.9.) -</p> - -<p> -The <a href="/cmd/pprof/"><code>go</code> <code>tool</code> <code>pprof</code></a> -profile visualizer has been updated to git version 9e20b5b (2017-11-08) -from <a href="https://github.com/google/pprof">github.com/google/pprof</a>, -which includes an updated web interface. -</p> - -<h3 id="vet">Vet</h3> - -<p> -The <a href="/cmd/vet/"><code>go</code> <code>vet</code></a> command now always has access to -complete, up-to-date type information when checking packages, even for packages using cgo or vendored imports. -The reports should be more accurate as a result. -Note that only <code>go</code> <code>vet</code> has access to this information; -the more low-level <code>go</code> <code>tool</code> <code>vet</code> does not -and should be avoided except when working on <code>vet</code> itself. -(As of Go 1.9, <code>go</code> <code>vet</code> provides access to all the same flags as -<code>go</code> <code>tool</code> <code>vet</code>.) -</p> - -<h3 id="diag">Diagnostics</h3> - -<p> -This release includes a new <a href="/doc/diagnostics.html">overview of available Go program diagnostic tools</a>. -</p> - -<h3 id="gofmt">Gofmt</h3> - -<p> -Two minor details of the default formatting of Go source code have changed. -First, certain complex three-index slice expressions previously formatted like -<code>x[i+1</code> <code>:</code> <code>j:k]</code> and now -format with more consistent spacing: <code>x[i+1</code> <code>:</code> <code>j</code> <code>:</code> <code>k]</code>. -Second, single-method interface literals written on a single line, -which are sometimes used in type assertions, -are no longer split onto multiple lines. -</p> - -<p> -Note that these kinds of minor updates to gofmt are expected from time to time. -In general, we recommend against building systems that check that source code -matches the output of a specific version of gofmt. -For example, a continuous integration test that fails if any code already checked into -a repository is not “properly formatted” is inherently fragile and not recommended. -</p> - -<p> -If multiple programs must agree about which version of gofmt is used to format a source file, -we recommend that they do this by arranging to invoke the same gofmt binary. -For example, in the Go open source repository, our Git pre-commit hook is written in Go -and could import <code>go/format</code> directly, but instead it invokes the <code>gofmt</code> -binary found in the current path, so that the pre-commit hook need not be recompiled -each time <code>gofmt</code> changes. -</p> - -<h3 id="compiler">Compiler Toolchain</h3> - -<p> -The compiler includes many improvements to the performance of generated code, -spread fairly evenly across the supported architectures. -</p> - -<p> -The DWARF debug information recorded in binaries has been improved in a few ways: -constant values are now recorded; -line number information is more accurate, making source-level stepping through a program work better; -and each package is now presented as its own DWARF compilation unit. -</p> - -<p> -The various <a href="https://docs.google.com/document/d/1nr-TQHw_er6GOQRsF6T43GGhFDelrAP0NqSS_00RgZQ/edit">build modes</a> -have been ported to more systems. -Specifically, <code>c-shared</code> now works on <code>linux/ppc64le</code>, <code>windows/386</code>, and <code>windows/amd64</code>; -<code>pie</code> now works on <code>darwin/amd64</code> and also forces the use of external linking on all systems; -and <code>plugin</code> now works on <code>linux/ppc64le</code> and <code>darwin/amd64</code>. -</p> - -<p> -The <code>linux/ppc64le</code> port now requires the use of external linking -with any programs that use cgo, even uses by the standard library. -</p> - -<h3 id="asm">Assembler</h3> - -<p> -For the ARM 32-bit port, the assembler now supports the instructions -<code><small>BFC</small></code>, -<code><small>BFI</small></code>, -<code><small>BFX</small></code>, -<code><small>BFXU</small></code>, -<code><small>FMULAD</small></code>, -<code><small>FMULAF</small></code>, -<code><small>FMULSD</small></code>, -<code><small>FMULSF</small></code>, -<code><small>FNMULAD</small></code>, -<code><small>FNMULAF</small></code>, -<code><small>FNMULSD</small></code>, -<code><small>FNMULSF</small></code>, -<code><small>MULAD</small></code>, -<code><small>MULAF</small></code>, -<code><small>MULSD</small></code>, -<code><small>MULSF</small></code>, -<code><small>NMULAD</small></code>, -<code><small>NMULAF</small></code>, -<code><small>NMULD</small></code>, -<code><small>NMULF</small></code>, -<code><small>NMULSD</small></code>, -<code><small>NMULSF</small></code>, -<code><small>XTAB</small></code>, -<code><small>XTABU</small></code>, -<code><small>XTAH</small></code>, -and -<code><small>XTAHU</small></code>. -</p> - -<p> -For the ARM 64-bit port, the assembler now supports the -<code><small>VADD</small></code>, -<code><small>VADDP</small></code>, -<code><small>VADDV</small></code>, -<code><small>VAND</small></code>, -<code><small>VCMEQ</small></code>, -<code><small>VDUP</small></code>, -<code><small>VEOR</small></code>, -<code><small>VLD1</small></code>, -<code><small>VMOV</small></code>, -<code><small>VMOVI</small></code>, -<code><small>VMOVS</small></code>, -<code><small>VORR</small></code>, -<code><small>VREV32</small></code>, -and -<code><small>VST1</small></code> -instructions. -</p> - -<p> -For the PowerPC 64-bit port, the assembler now supports the POWER9 instructions -<code><small>ADDEX</small></code>, -<code><small>CMPEQB</small></code>, -<code><small>COPY</small></code>, -<code><small>DARN</small></code>, -<code><small>LDMX</small></code>, -<code><small>MADDHD</small></code>, -<code><small>MADDHDU</small></code>, -<code><small>MADDLD</small></code>, -<code><small>MFVSRLD</small></code>, -<code><small>MTVSRDD</small></code>, -<code><small>MTVSRWS</small></code>, -<code><small>PASTECC</small></code>, -<code><small>VCMPNEZB</small></code>, -<code><small>VCMPNEZBCC</small></code>, -and -<code><small>VMSUMUDM</small></code>. -</p> - -<p> -For the S390X port, the assembler now supports the -<code><small>TMHH</small></code>, -<code><small>TMHL</small></code>, -<code><small>TMLH</small></code>, -and -<code><small>TMLL</small></code> -instructions. -</p> - -<p> -For the X86 64-bit port, the assembler now supports 359 new instructions, -including the full AVX, AVX2, BMI, BMI2, F16C, FMA3, SSE2, SSE3, SSSE3, SSE4.1, and SSE4.2 extension sets. -The assembler also no longer implements <code><small>MOVL</small></code> <code><small>$0,</small></code> <code><small>AX</small></code> -as an <code><small>XORL</small></code> instruction, -to avoid clearing the condition flags unexpectedly. -</p> - -<h3 id="gccgo">Gccgo</h3> - -<p> -Due to the alignment of Go's semiannual release schedule with GCC's -annual release schedule, -GCC release 7 contains the Go 1.8.3 version of gccgo. -We expect that the next release, GCC 8, will contain the Go 1.10 -version of gccgo. -</p> - -<h2 id="runtime">Runtime</h2> - -<p> -The behavior of nested calls to -<a href="/pkg/runtime/#LockOSThread"><code>LockOSThread</code></a> and -<a href="/pkg/runtime/#UnlockOSThread"><code>UnlockOSThread</code></a> -has changed. -These functions control whether a goroutine is locked to a specific operating system thread, -so that the goroutine only runs on that thread, and the thread only runs that goroutine. -Previously, calling <code>LockOSThread</code> more than once in a row -was equivalent to calling it once, and a single <code>UnlockOSThread</code> -always unlocked the thread. -Now, the calls nest: if <code>LockOSThread</code> is called multiple times, -<code>UnlockOSThread</code> must be called the same number of times -in order to unlock the thread. -Existing code that was careful not to nest these calls will remain correct. -Existing code that incorrectly assumed the calls nested will become correct. -Most uses of these functions in public Go source code falls into the second category. -</p> - -<p> -Because one common use of <code>LockOSThread</code> and <code>UnlockOSThread</code> -is to allow Go code to reliably modify thread-local state (for example, Linux or Plan 9 name spaces), -the runtime now treats locked threads as unsuitable for reuse or for creating new threads. -</p> - -<p> -Stack traces no longer include implicit wrapper functions (previously marked <code><autogenerated></code>), -unless a fault or panic happens in the wrapper itself. -As a result, skip counts passed to functions like <a href="/pkg/runtime/#Caller"><code>Caller</code></a> -should now always match the structure of the code as written, rather than depending on -optimization decisions and implementation details. -</p> - -<p> -The garbage collector has been modified to reduce its impact on allocation latency. -It now uses a smaller fraction of the overall CPU when running, but it may run more of the time. -The total CPU consumed by the garbage collector has not changed significantly. -</p> - -<p> -The <a href="/pkg/runtime/#GOROOT"><code>GOROOT</code></a> function -now defaults (when the <code>$GOROOT</code> environment variable is not set) -to the <code>GOROOT</code> or <code>GOROOT_FINAL</code> in effect -at the time the calling program was compiled. -Previously it used the <code>GOROOT</code> or <code>GOROOT_FINAL</code> in effect -at the time the toolchain that compiled the calling program was compiled. -</p> - -<p> -There is no longer a limit on the <a href="/pkg/runtime/#GOMAXPROCS"><code>GOMAXPROCS</code></a> setting. -(In Go 1.9 the limit was 1024.) -</p> - -<h2 id="performance">Performance</h2> - -<p> -As always, the changes are so general and varied that precise -statements about performance are difficult to make. Most programs -should run a bit faster, due to speedups in the garbage collector, -better generated code, and optimizations in the core library. -</p> - -<h2 id="gc">Garbage Collector</h2> - -<p> -Many applications should experience significantly lower allocation latency and overall performance overhead when the garbage collector is active. -</p> - -<h2 id="library">Core library</h2> - -<p> -All of the changes to the standard library are minor. -The changes in <a href="#bytes">bytes</a> -and <a href="#net/url">net/url</a> are the most likely to require updating of existing programs. -</p> - -<h3 id="minor_library_changes">Minor changes to the library</h3> - -<p> -As always, there are various minor changes and updates to the library, -made with the Go 1 <a href="/doc/go1compat">promise of compatibility</a> -in mind. -</p> - -<dl id="archive/tar"><dt><a href="/pkg/archive/tar/">archive/tar</a></dt> -<dd> -<p> -In general, the handling of special header formats is significantly improved and expanded. -</p> -<p> -<a href="/pkg/archive/tar/#FileInfoHeader"><code>FileInfoHeader</code></a> has always -recorded the Unix UID and GID numbers from its <a href="/pkg/os/#FileInfo"><code>os.FileInfo</code></a> argument -(specifically, from the system-dependent information returned by the <code>FileInfo</code>'s <code>Sys</code> method) -in the returned <a href="/pkg/archive/tar/#Header"><code>Header</code></a>. -Now it also records the user and group names corresponding to those IDs, -as well as the major and minor device numbers for device files. -</p> -<p> -The new <a href="/pkg/archive/tar/#Header"><code>Header.Format</code></a> field -of type <a href="/pkg/archive/tar/#Format"><code>Format</code></a> -controls which tar header format the <a href="/pkg/archive/tar/#Writer"><code>Writer</code></a> uses. -The default, as before, is to select the most widely-supported header type -that can encode the fields needed by the header (USTAR if possible, or else PAX if possible, or else GNU). -The <a href="/pkg/archive/tar/#Reader"><code>Reader</code></a> sets <code>Header.Format</code> for each header it reads. -</p> -<p> -<code>Reader</code> and the <code>Writer</code> now support arbitrary PAX records, -using the new <a href="/pkg/archive/tar/#Header"><code>Header.PAXRecords</code></a> field, -a generalization of the existing <code>Xattrs</code> field. -</p> -<p> -The <code>Reader</code> no longer insists that the file name or link name in GNU headers -be valid UTF-8. -</p> -<p> -When writing PAX- or GNU-format headers, the <code>Writer</code> now includes -the <code>Header.AccessTime</code> and <code>Header.ChangeTime</code> fields (if set). -When writing PAX-format headers, the times include sub-second precision. -</p> -</dl> - -<dl id="archive/zip"><dt><a href="/pkg/archive/zip/">archive/zip</a></dt> -<dd> -<p> -Go 1.10 adds more complete support for times and character set encodings in ZIP archives. -</p> -<p> -The original ZIP format used the standard MS-DOS encoding of year, month, day, hour, minute, and second into fields in two 16-bit values. -That encoding cannot represent time zones or odd seconds, so multiple extensions have been -introduced to allow richer encodings. -In Go 1.10, the <a href="/pkg/archive/zip/#Reader"><code>Reader</code></a> and <a href="/pkg/archive/zip/#Writer"><code>Writer</code></a> -now support the widely-understood Info-Zip extension that encodes the time separately in the 32-bit Unix “seconds since epoch” form. -The <a href="/pkg/archive/zip/#FileHeader"><code>FileHeader</code></a>'s new <code>Modified</code> field of type <a href="/pkg/time/#Time"><code>time.Time</code></a> -obsoletes the <code>ModifiedTime</code> and <code>ModifiedDate</code> fields, which continue to hold the MS-DOS encoding. -The <code>Reader</code> and <code>Writer</code> now adopt the common -convention that a ZIP archive storing a time zone-independent Unix time -also stores the local time in the MS-DOS field, -so that the time zone offset can be inferred. -For compatibility, the <a href="/pkg/archive/zip/#FileHeader.ModTime"><code>ModTime</code></a> and -<a href="/pkg/archive/zip/#FileHeader.SetModTime"><code>SetModTime</code></a> methods -behave the same as in earlier releases; new code should use <code>Modified</code> directly. -</p> -<p> -The header for each file in a ZIP archive has a flag bit indicating whether -the name and comment fields are encoded as UTF-8, as opposed to a system-specific default encoding. -In Go 1.8 and earlier, the <code>Writer</code> never set the UTF-8 bit. -In Go 1.9, the <code>Writer</code> changed to set the UTF-8 bit almost always. -This broke the creation of ZIP archives containing Shift-JIS file names. -In Go 1.10, the <code>Writer</code> now sets the UTF-8 bit only when -both the name and the comment field are valid UTF-8 and at least one is non-ASCII. -Because non-ASCII encodings very rarely look like valid UTF-8, the new -heuristic should be correct nearly all the time. -Setting a <code>FileHeader</code>'s new <code>NonUTF8</code> field to true -disables the heuristic entirely for that file. -</p> -<p> -The <code>Writer</code> also now supports setting the end-of-central-directory record's comment field, -by calling the <code>Writer</code>'s new <a href="/pkg/archive/zip/#Writer.SetComment"><code>SetComment</code></a> method. -</p> -</dl> - -<dl id="bufio"><dt><a href="/pkg/bufio/">bufio</a></dt> -<dd> -<p> -The new <a href="/pkg/bufio/#Reader.Size"><code>Reader.Size</code></a> -and <a href="/pkg/bufio/#Writer.Size"><code>Writer.Size</code></a> -methods report the <code>Reader</code> or <code>Writer</code>'s underlying buffer size. -</p> -</dl> - -<dl id="bytes"><dt><a href="/pkg/bytes/">bytes</a></dt> -<dd> -<p> -The -<a href="/pkg/bytes/#Fields"><code>Fields</code></a>, -<a href="/pkg/bytes/#FieldsFunc"><code>FieldsFunc</code></a>, -<a href="/pkg/bytes/#Split"><code>Split</code></a>, -and -<a href="/pkg/bytes/#SplitAfter"><code>SplitAfter</code></a> -functions have always returned subslices of their inputs. -Go 1.10 changes each returned subslice to have capacity equal to its length, -so that appending to one cannot overwrite adjacent data in the original input. -</p> -</dl> - -<dl id="crypto/cipher"><dt><a href="/pkg/crypto/cipher/">crypto/cipher</a></dt> -<dd> -<p> -<a href="/pkg/crypto/cipher/#NewOFB"><code>NewOFB</code></a> now panics if given -an initialization vector of incorrect length, like the other constructors in the -package always have. -(Previously it returned a nil <code>Stream</code> implementation.) -</p> -</dl> - -<dl id="crypto/tls"><dt><a href="/pkg/crypto/tls/">crypto/tls</a></dt> -<dd> -<p> -The TLS server now advertises support for SHA-512 signatures when using TLS 1.2. -The server already supported the signatures, but some clients would not select -them unless explicitly advertised. -</p> -</dl> - -<dl id="crypto/x509"><dt><a href="/pkg/crypto/x509/">crypto/x509</a></dt> -<dd> -<p> -<a href="/pkg/crypto/x509/#Certificate.Verify"><code>Certificate.Verify</code></a> -now enforces the name constraints for all -names contained in the certificate, not just the one name that a client has asked about. -Extended key usage restrictions are similarly now checked all at once. -As a result, after a certificate has been validated, now it can be trusted in its entirety. -It is no longer necessary to revalidate the certificate for each additional name -or key usage. -</p> - -<p> -Parsed certificates also now report URI names and IP, email, and URI constraints, using the new -<a href="/pkg/crypto/x509/#Certificate"><code>Certificate</code></a> fields -<code>URIs</code>, <code>PermittedIPRanges</code>, <code>ExcludedIPRanges</code>, -<code>PermittedEmailAddresses</code>, <code>ExcludedEmailAddresses</code>, -<code>PermittedURIDomains</code>, and <code>ExcludedURIDomains</code>. Certificates with -invalid values for those fields are now rejected. -</p> - -<p> -The new <a href="/pkg/crypto/x509/#MarshalPKCS1PublicKey"><code>MarshalPKCS1PublicKey</code></a> -and <a href="/pkg/crypto/x509/#ParsePKCS1PublicKey"><code>ParsePKCS1PublicKey</code></a> -functions convert an RSA public key to and from PKCS#1-encoded form. -</p> - -<p> -The new <a href="/pkg/crypto/x509/#MarshalPKCS8PrivateKey"><code>MarshalPKCS8PrivateKey</code></a> -function converts a private key to PKCS#8-encoded form. -(<a href="/pkg/crypto/x509/#ParsePKCS8PrivateKey"><code>ParsePKCS8PrivateKey</code></a> -has existed since Go 1.) -</p> -</dl> - -<dl id="crypto/x509/pkix"><dt><a href="/pkg/crypto/x509/pkix/">crypto/x509/pkix</a></dt> -<dd> -<p> -<a href="/pkg/crypto/x509/pkix/#Name"><code>Name</code></a> now implements a -<a href="/pkg/crypto/x509/pkix/#Name.String"><code>String</code></a> method that -formats the X.509 distinguished name in the standard RFC 2253 format. -</p> -</dl> - -<dl id="database/sql/driver"><dt><a href="/pkg/database/sql/driver/">database/sql/driver</a></dt> -<dd> -<p> -Drivers that currently hold on to the destination buffer provided by -<a href="/pkg/database/sql/driver/#Rows.Next"><code>driver.Rows.Next</code></a> should ensure they no longer -write to a buffer assigned to the destination array outside of that call. -Drivers must be careful that underlying buffers are not modified when closing -<a href="/pkg/database/sql/driver/#Rows"><code>driver.Rows</code></a>. -</p> -<p> -Drivers that want to construct a <a href="/pkg/database/sql/#DB"><code>sql.DB</code></a> for -their clients can now implement the <a href="/pkg/database/sql/driver/#Connector"><code>Connector</code></a> interface -and call the new <a href="/pkg/database/sql/#OpenDB"><code>sql.OpenDB</code></a> function, -instead of needing to encode all configuration into a string -passed to <a href="/pkg/database/sql/#Open"><code>sql.Open</code></a>. -</p> -<p> -Drivers that want to parse the configuration string only once per <code>sql.DB</code> -instead of once per <a href="/pkg/database/sql/#Conn"><code>sql.Conn</code></a>, -or that want access to each <code>sql.Conn</code>'s underlying context, -can make their <a href="/pkg/database/sql/driver/#Driver"><code>Driver</code></a> -implementations also implement <a href="/pkg/database/sql/driver/#DriverContext"><code>DriverContext</code></a>'s -new <code>OpenConnector</code> method. -</p> -<p> -Drivers that implement <a href="/pkg/database/sql/driver/#ExecerContext"><code>ExecerContext</code></a> -no longer need to implement <a href="/pkg/database/sql/driver/#Execer"><code>Execer</code></a>; -similarly, drivers that implement <a href="/pkg/database/sql/driver/#QueryerContext"><code>QueryerContext</code></a> -no longer need to implement <a href="/pkg/database/sql/driver/#Queryer"><code>Queryer</code></a>. -Previously, even if the context-based interfaces were implemented they were ignored -unless the non-context-based interfaces were also implemented. -</p> -<p> -To allow drivers to better isolate different clients using a cached driver connection in succession, -if a <a href="/pkg/database/sql/driver/#Conn"><code>Conn</code></a> implements the new -<a href="/pkg/database/sql/driver/#SessionResetter"><code>SessionResetter</code></a> interface, -<code>database/sql</code> will now call <code>ResetSession</code> before -reusing the <code>Conn</code> for a new client. -</p> -</dl> - -<dl id="debug/elf"><dt><a href="/pkg/debug/elf/">debug/elf</a></dt> -<dd> -<p> -This release adds 348 new relocation constants divided between the relocation types -<a href="/pkg/debug/elf/#R_386"><code>R_386</code></a>, -<a href="/pkg/debug/elf/#R_AARCH64"><code>R_AARCH64</code></a>, -<a href="/pkg/debug/elf/#R_ARM"><code>R_ARM</code></a>, -<a href="/pkg/debug/elf/#R_PPC64"><code>R_PPC64</code></a>, -and -<a href="/pkg/debug/elf/#R_X86_64"><code>R_X86_64</code></a>. -</p> -</dl> - -<dl id="debug/macho"><dt><a href="/pkg/debug/macho/">debug/macho</a></dt> -<dd> -<p> -Go 1.10 adds support for reading relocations from Mach-O sections, -using the <a href="/pkg/debug/macho#Section"><code>Section</code></a> struct's new <code>Relocs</code> field -and the new <a href="/pkg/debug/macho/#Reloc"><code>Reloc</code></a>, -<a href="/pkg/debug/macho/#RelocTypeARM"><code>RelocTypeARM</code></a>, -<a href="/pkg/debug/macho/#RelocTypeARM64"><code>RelocTypeARM64</code></a>, -<a href="/pkg/debug/macho/#RelocTypeGeneric"><code>RelocTypeGeneric</code></a>, -and -<a href="/pkg/debug/macho/#RelocTypeX86_64"><code>RelocTypeX86_64</code></a> -types and associated constants. -</p> -<p> -Go 1.10 also adds support for the <code>LC_RPATH</code> load command, -represented by the types -<a href="/pkg/debug/macho/#RpathCmd"><code>RpathCmd</code></a> and -<a href="/pkg/debug/macho/#Rpath"><code>Rpath</code></a>, -and new <a href="/pkg/debug/macho/#pkg-constants">named constants</a> -for the various flag bits found in headers. -</p> -</dl> - -<dl id="encoding/asn1"><dt><a href="/pkg/encoding/asn1/">encoding/asn1</a></dt> -<dd> -<p> -<a href="/pkg/encoding/asn1/#Marshal"><code>Marshal</code></a> now correctly encodes -strings containing asterisks as type UTF8String instead of PrintableString, -unless the string is in a struct field with a tag forcing the use of PrintableString. -<code>Marshal</code> also now respects struct tags containing <code>application</code> directives. -</p> -<p> -The new <a href="/pkg/encoding/asn1/#MarshalWithParams"><code>MarshalWithParams</code></a> -function marshals its argument as if the additional params were its associated -struct field tag. -</p> -<p> -<a href="/pkg/encoding/asn1/#Unmarshal"><code>Unmarshal</code></a> now respects -struct field tags using the <code>explicit</code> and <code>tag</code> -directives. -</p> -<p> -Both <code>Marshal</code> and <code>Unmarshal</code> now support a new struct field tag -<code>numeric</code>, indicating an ASN.1 NumericString. -</p> -</dl> - -<dl id="encoding/csv"><dt><a href="/pkg/encoding/csv/">encoding/csv</a></dt> -<dd> -<p> -<a href="/pkg/encoding/csv/#Reader"><code>Reader</code></a> now disallows the use of -nonsensical <code>Comma</code> and <code>Comment</code> settings, -such as NUL, carriage return, newline, invalid runes, and the Unicode replacement character, -or setting <code>Comma</code> and <code>Comment</code> equal to each other. -</p> -<p> -In the case of a syntax error in a CSV record that spans multiple input lines, <code>Reader</code> -now reports the line on which the record started in the <a href="/pkg/encoding/csv/#ParseError"><code>ParseError</code></a>'s new <code>StartLine</code> field. -</p> -</dl> - -<dl id="encoding/hex"><dt><a href="/pkg/encoding/hex/">encoding/hex</a></dt> -<dd> -<p> -The new functions -<a href="/pkg/encoding/hex/#NewEncoder"><code>NewEncoder</code></a> -and -<a href="/pkg/encoding/hex/#NewDecoder"><code>NewDecoder</code></a> -provide streaming conversions to and from hexadecimal, -analogous to equivalent functions already in -<a href="/pkg/encoding/base32/">encoding/base32</a> -and -<a href="/pkg/encoding/base64/">encoding/base64</a>. -</p> - -<p> -When the functions -<a href="/pkg/encoding/hex/#Decode"><code>Decode</code></a> -and -<a href="/pkg/encoding/hex/#DecodeString"><code>DecodeString</code></a> -encounter malformed input, -they now return the number of bytes already converted -along with the error. -Previously they always returned a count of 0 with any error. -</p> -</dl> - -<dl id="encoding/json"><dt><a href="/pkg/encoding/json/">encoding/json</a></dt> -<dd> -<p> -The <a href="/pkg/encoding/json/#Decoder"><code>Decoder</code></a> -adds a new method -<a href="/pkg/encoding/json/#Decoder.DisallowUnknownFields"><code>DisallowUnknownFields</code></a> -that causes it to report inputs with unknown JSON fields as a decoding error. -(The default behavior has always been to discard unknown fields.) -</p> - -<p> -As a result of <a href="#reflect">fixing a reflect bug</a>, -<a href="/pkg/encoding/json/#Unmarshal"><code>Unmarshal</code></a> -can no longer decode into fields inside -embedded pointers to unexported struct types, -because it cannot initialize the unexported embedded pointer -to point at fresh storage. -<code>Unmarshal</code> now returns an error in this case. -</p> -</dl> - -<dl id="encoding/pem"><dt><a href="/pkg/encoding/pem/">encoding/pem</a></dt> -<dd> -<p> -<a href="/pkg/encoding/pem/#Encode"><code>Encode</code></a> -and -<a href="/pkg/encoding/pem/#EncodeToMemory"><code>EncodeToMemory</code></a> -no longer generate partial output when presented with a -block that is impossible to encode as PEM data. -</p> -</dl> - -<dl id="encoding/xml"><dt><a href="/pkg/encoding/xml/">encoding/xml</a></dt> -<dd> -<p> -The new function -<a href="/pkg/encoding/xml/#NewTokenDecoder"><code>NewTokenDecoder</code></a> -is like -<a href="/pkg/encoding/xml/#NewDecoder"><code>NewDecoder</code></a> -but creates a decoder reading from a <a href="/pkg/encoding/xml/#TokenReader"><code>TokenReader</code></a> -instead of an XML-formatted byte stream. -This is meant to enable the construction of XML stream transformers in client libraries. -</p> -</dl> - -<dl id="flag"><dt><a href="/pkg/flag/">flag</a></dt> -<dd> -<p> -The default -<a href="/pkg/flag/#Usage"><code>Usage</code></a> function now prints -its first line of output to -<code>CommandLine.Output()</code> -instead of assuming <code>os.Stderr</code>, -so that the usage message is properly redirected for -clients using <code>CommandLine.SetOutput</code>. -</p> -<p> -<a href="/pkg/flag/#PrintDefaults"><code>PrintDefaults</code></a> now -adds appropriate indentation after newlines in flag usage strings, -so that multi-line usage strings display nicely. -</p> -<p> -<a href="/pkg/flag/#FlagSet"><code>FlagSet</code></a> adds new methods -<a href="/pkg/flag/#FlagSet.ErrorHandling"><code>ErrorHandling</code></a>, -<a href="/pkg/flag/#FlagSet.Name"><code>Name</code></a>, -and -<a href="/pkg/flag/#FlagSet.Output"><code>Output</code></a>, -to retrieve the settings passed to -<a href="/pkg/flag/#NewFlagSet"><code>NewFlagSet</code></a> -and -<a href="/pkg/flag/#FlagSet.SetOutput"><code>FlagSet.SetOutput</code></a>. -</p> -</dl> - -<dl id="go/doc"><dt><a href="/pkg/go/doc/">go/doc</a></dt> -<dd> -<p> -To support the <a href="#doc">doc change</a> described above, -functions returning slices of <code>T</code>, <code>*T</code>, <code>**T</code>, and so on -are now reported in <code>T</code>'s <a href="/pkg/go/doc/#Type"><code>Type</code></a>'s <code>Funcs</code> list, -instead of in the <a href="/pkg/go/doc/#Package"><code>Package</code></a>'s <code>Funcs</code> list. -</p> -</dl> - -<dl id="go/importer"><dt><a href="/pkg/go/importer/">go/importer</a></dt> -<dd> -<p> -The <a href="/pkg/go/importer/#For"><code>For</code></a> function now accepts a non-nil lookup argument. -</p> -</dl> - -<dl id="go/printer"><dt><a href="/pkg/go/printer/">go/printer</a></dt> -<dd> -<p> -The changes to the default formatting of Go source code -discussed in the <a href="#gofmt">gofmt section</a> above -are implemented in the <a href="/pkg/go/printer/">go/printer</a> package -and also affect the output of the higher-level <a href="/pkg/go/format/">go/format</a> package. -</p> -</dl> - -<dl id="hash"><dt><a href="/pkg/hash/">hash</a></dt> -<dd> -<p> -Implementations of the <a href="/pkg/hash/#Hash"><code>Hash</code></a> interface are now -encouraged to implement <a href="/pkg/encoding/#BinaryMarshaler"><code>encoding.BinaryMarshaler</code></a> -and <a href="/pkg/encoding/#BinaryUnmarshaler"><code>encoding.BinaryUnmarshaler</code></a> -to allow saving and recreating their internal state, -and all implementations in the standard library -(<a href="/pkg/hash/crc32/">hash/crc32</a>, <a href="/pkg/crypto/sha256/">crypto/sha256</a>, and so on) -now implement those interfaces. -</p> -</dl> - -<dl id="html/template"><dt><a href="/pkg/html/template/">html/template</a></dt> -<dd> -<p> -The new <a href="/pkg/html/template#Srcset"><code>Srcset</code></a> content -type allows for proper handling of values within the -<a href="https://w3c.github.io/html/semantics-embedded-content.html#element-attrdef-img-srcset"><code>srcset</code></a> -attribute of <code>img</code> tags. -</p> -</dl> - -<dl id="math/big"><dt><a href="/pkg/math/big/">math/big</a></dt> -<dd> -<p> -<a href="/pkg/math/big/#Int"><code>Int</code></a> now supports conversions to and from bases 2 through 62 -in its <a href="/pkg/math/big/#Int.SetString"><code>SetString</code></a> and <a href="/pkg/math/big/#Text"><code>Text</code></a> methods. -(Previously it only allowed bases 2 through 36.) -The value of the constant <code>MaxBase</code> has been updated. -</p> -<p> -<a href="/pkg/math/big/#Int"><code>Int</code></a> adds a new -<a href="/pkg/math/big/#CmpAbs"><code>CmpAbs</code></a> method -that is like <a href="/pkg/math/big/#Cmp"><code>Cmp</code></a> but -compares only the absolute values (not the signs) of its arguments. -</p> -<p> -<a href="/pkg/math/big/#Float"><code>Float</code></a> adds a new -<a href="/pkg/math/big/#Float.Sqrt"><code>Sqrt</code></a> method to -compute square roots. -</p> -</dl> - -<dl id="math/cmplx"><dt><a href="/pkg/math/cmplx/">math/cmplx</a></dt> -<dd> -<p> -Branch cuts and other boundary cases in -<a href="/pkg/math/cmplx/#Asin"><code>Asin</code></a>, -<a href="/pkg/math/cmplx/#Asinh"><code>Asinh</code></a>, -<a href="/pkg/math/cmplx/#Atan"><code>Atan</code></a>, -and -<a href="/pkg/math/cmplx/#Sqrt"><code>Sqrt</code></a> -have been corrected to match the definitions used in the C99 standard. -</p> -</dl> - -<dl id="math/rand"><dt><a href="/pkg/math/rand/">math/rand</a></dt> -<dd> -<p> -The new <a href="/pkg/math/rand/#Shuffle"><code>Shuffle</code></a> function and corresponding -<a href="/pkg/math/rand/#Rand.Shuffle"><code>Rand.Shuffle</code></a> method -shuffle an input sequence. -</p> -</dl> - -<dl id="math"><dt><a href="/pkg/math/">math</a></dt> -<dd> -<p> -The new functions -<a href="/pkg/math/#Round"><code>Round</code></a> -and -<a href="/pkg/math/#RoundToEven"><code>RoundToEven</code></a> -round their arguments to the nearest floating-point integer; -<code>Round</code> rounds a half-integer to its larger integer neighbor (away from zero) -while <code>RoundToEven</code> rounds a half-integer to its even integer neighbor. -</p> - -<p> -The new functions -<a href="/pkg/math/#Erfinv"><code>Erfinv</code></a> -and -<a href="/pkg/math/#Erfcinv"><code>Erfcinv</code></a> -compute the inverse error function and the -inverse complementary error function. -</p> -</dl> - -<dl id="mime/multipart"><dt><a href="/pkg/mime/multipart/">mime/multipart</a></dt> -<dd> -<p> -<a href="/pkg/mime/multipart/#Reader"><code>Reader</code></a> -now accepts parts with empty filename attributes. -</p> -</dl> - -<dl id="mime"><dt><a href="/pkg/mime/">mime</a></dt> -<dd> -<p> -<a href="/pkg/mime/#ParseMediaType"><code>ParseMediaType</code></a> now discards -invalid attribute values; previously it returned those values as empty strings. -</p> -</dl> - -<dl id="net"><dt><a href="/pkg/net/">net</a></dt> -<dd> -<p> -The <a href="/pkg/net/#Conn"><code>Conn</code></a> and -<a href="/pkg/net/#Conn"><code>Listener</code></a> implementations -in this package now guarantee that when <code>Close</code> returns, -the underlying file descriptor has been closed. -(In earlier releases, if the <code>Close</code> stopped pending I/O -in other goroutines, the closing of the file descriptor could happen in one of those -goroutines shortly after <code>Close</code> returned.) -</p> - -<p> -<a href="/pkg/net/#TCPListener"><code>TCPListener</code></a> and -<a href="/pkg/net/#UnixListener"><code>UnixListener</code></a> -now implement -<a href="/pkg/syscall/#Conn"><code>syscall.Conn</code></a>, -to allow setting options on the underlying file descriptor -using <a href="/pkg/syscall/#RawConn"><code>syscall.RawConn.Control</code></a>. -</p> - -<p> -The <code>Conn</code> implementations returned by <a href="/pkg/net/#Pipe"><code>Pipe</code></a> -now support setting read and write deadlines. -</p> - -<p> -The <a href="/pkg/net/#IPConn.ReadMsgIP"><code>IPConn.ReadMsgIP</code></a>, -<a href="/pkg/net/#IPConn.WriteMsgIP"><code>IPConn.WriteMsgIP</code></a>, -<a href="/pkg/net/#UDPConn.ReadMsgUDP"><code>UDPConn.ReadMsgUDP</code></a>, -and -<a href="/pkg/net/#UDPConn.WriteMsgUDP"><code>UDPConn.WriteMsgUDP</code></a>, -methods are now implemented on Windows. -</p> -</dl> - -<dl id="net/http"><dt><a href="/pkg/net/http/">net/http</a></dt> -<dd> -<p> -On the client side, an HTTP proxy (most commonly configured by -<a href="/pkg/net/http/#ProxyFromEnvironment"><code>ProxyFromEnvironment</code></a>) -can now be specified as an <code>https://</code> URL, -meaning that the client connects to the proxy over HTTPS before issuing a standard, proxied HTTP request. -(Previously, HTTP proxy URLs were required to begin with <code>http://</code> or <code>socks5://</code>.) -</p> -<p> -On the server side, <a href="/pkg/net/http/#FileServer"><code>FileServer</code></a> and its single-file equivalent <a href="/pkg/net/http/#ServeFile"><code>ServeFile</code></a> -now apply <code>If-Range</code> checks to <code>HEAD</code> requests. -<code>FileServer</code> also now reports directory read failures to the <a href="/pkg/net/http/#Server"><code>Server</code></a>'s <code>ErrorLog</code>. -The content-serving handlers also now omit the <code>Content-Type</code> header when serving zero-length content. -</p> -<p> -<a href="/pkg/net/http/#ResponseWriter"><code>ResponseWriter</code></a>'s <code>WriteHeader</code> method now panics -if passed an invalid (non-3-digit) status code. -</p> -<p> -<!-- CL 46631 --> -The <code>Server</code> will no longer add an implicit Content-Type when a <code>Handler</code> does not write any output. -</p> -<p> -<a href="/pkg/net/http/#Redirect"><code>Redirect</code></a> now sets the <code>Content-Type</code> header before writing its HTTP response. -</p> -</dl> - -<dl id="net/mail"><dt><a href="/pkg/net/mail/">net/mail</a></dt> -<dd> -<p> -<a href="/pkg/net/mail/#ParseAddress"><code>ParseAddress</code></a> and -<a href="/pkg/net/mail/#ParseAddressList"><code>ParseAddressList</code></a> -now support a variety of obsolete address formats. -</p> -</dl> - -<dl id="net/smtp"><dt><a href="/pkg/net/smtp/">net/smtp</a></dt> -<dd> -<p> -The <a href="/pkg/net/smtp/#Client"><code>Client</code></a> adds a new -<a href="/pkg/net/smtp/#Client.Noop"><code>Noop</code></a> method, -to test whether the server is still responding. -It also now defends against possible SMTP injection in the inputs -to the <a href="/pkg/net/smtp/#Client.Hello"><code>Hello</code></a> -and <a href="/pkg/net/smtp/#Client.Verify"><code>Verify</code></a> methods. -</p> -</dl> - -<dl id="net/textproto"><dt><a href="/pkg/net/textproto/">net/textproto</a></dt> -<dd> -<p> -<a href="/pkg/net/textproto/#ReadMIMEHeader"><code>ReadMIMEHeader</code></a> -now rejects any header that begins with a continuation (indented) header line. -Previously a header with an indented first line was treated as if the first line -were not indented. -</p> -</dl> - -<dl id="net/url"><dt><a href="/pkg/net/url/">net/url</a></dt> -<dd> -<p> -<a href="/pkg/net/url/#ResolveReference"><code>ResolveReference</code></a> -now preserves multiple leading slashes in the target URL. -Previously it rewrote multiple leading slashes to a single slash, -which resulted in the <a href="/pkg/net/http/#Client"><code>http.Client</code></a> -following certain redirects incorrectly. -</p> -<p> -For example, this code's output has changed: -</p> -<pre> -base, _ := url.Parse("http://host//path//to/page1") -target, _ := url.Parse("page2") -fmt.Println(base.ResolveReference(target)) -</pre> -<p> -Note the doubled slashes around <code>path</code>. -In Go 1.9 and earlier, the resolved URL was <code>http://host/path//to/page2</code>: -the doubled slash before <code>path</code> was incorrectly rewritten -to a single slash, while the doubled slash after <code>path</code> was -correctly preserved. -Go 1.10 preserves both doubled slashes, resolving to <code>http://host//path//to/page2</code> -as required by <a href="https://tools.ietf.org/html/rfc3986#section-5.2">RFC 3986</a>. -</p> - -<p>This change may break existing buggy programs that unintentionally -construct a base URL with a leading doubled slash in the path and inadvertently -depend on <code>ResolveReference</code> to correct that mistake. -For example, this can happen if code adds a host prefix -like <code>http://host/</code> to a path like <code>/my/api</code>, -resulting in a URL with a doubled slash: <code>http://host//my/api</code>. -</p> - -<p> -<a href="/pkg/net/url/#UserInfo"><code>UserInfo</code></a>'s methods -now treat a nil receiver as equivalent to a pointer to a zero <code>UserInfo</code>. -Previously, they panicked. -</p> -</dl> - -<dl id="os"><dt><a href="/pkg/os/">os</a></dt> -<dd> -<p> -<a href="/pkg/os/#File"><code>File</code></a> adds new methods -<a href="/pkg/os/#File.SetDeadline"><code>SetDeadline</code></a>, -<a href="/pkg/os/#File.SetReadDeadline"><code>SetReadDeadline</code></a>, -and -<a href="/pkg/os/#File.SetWriteDeadline"><code>SetWriteDeadline</code></a> -that allow setting I/O deadlines when the -underlying file descriptor supports non-blocking I/O operations. -The definition of these methods matches those in <a href="/pkg/net/#Conn"><code>net.Conn</code></a>. -If an I/O method fails due to missing a deadline, it will return a -timeout error; the -new <a href="/pkg/os/#IsTimeout"><code>IsTimeout</code></a> function -reports whether an error represents a timeout. -</p> - -<p> -Also matching <code>net.Conn</code>, -<code>File</code>'s -<a href="/pkg/os/#File.Close"><code>Close</code></a> method -now guarantee that when <code>Close</code> returns, -the underlying file descriptor has been closed. -(In earlier releases, -if the <code>Close</code> stopped pending I/O -in other goroutines, the closing of the file descriptor could happen in one of those -goroutines shortly after <code>Close</code> returned.) -</p> - -<p> -On BSD, macOS, and Solaris systems, -<a href="/pkg/os/#Chtimes"><code>Chtimes</code></a> -now supports setting file times with nanosecond precision -(assuming the underlying file system can represent them). -</p> -</dl> - -<dl id="reflect"><dt><a href="/pkg/reflect/">reflect</a></dt> -<dd> -<p> -The <a href="/pkg/reflect/#Copy"><code>Copy</code></a> function now allows copying -from a string into a byte array or byte slice, to match the -<a href="/pkg/builtin/#copy">built-in copy function</a>. -</p> - -<p> -In structs, embedded pointers to unexported struct types were -previously incorrectly reported with an empty <code>PkgPath</code> -in the corresponding <a href="/pkg/reflect/#StructField">StructField</a>, -with the result that for those fields, -and <a href="/pkg/reflect/#Value.CanSet"><code>Value.CanSet</code></a> -incorrectly returned true and -<a href="/pkg/reflect/#Value.Set"><code>Value.Set</code></a> -incorrectly succeeded. -The underlying metadata has been corrected; -for those fields, -<code>CanSet</code> now correctly returns false -and <code>Set</code> now correctly panics. -This may affect reflection-based unmarshalers -that could previously unmarshal into such fields -but no longer can. -For example, see the <a href="#encoding/json"><code>encoding/json</code> notes</a>. -</p> -</dl> - -<dl id="runtime/pprof"><dt><a href="/pkg/runtime/pprof/">runtime/pprof</a></dt> -<dd> -<p> -As <a href="#pprof">noted above</a>, the blocking and mutex profiles -now include symbol information so that they can be viewed without needing -the binary that generated them. -</p> -</dl> - -<dl id="strconv"><dt><a href="/pkg/strconv/">strconv</a></dt> -<dd> -<p> -<a href="/pkg/strconv/#ParseUint"><code>ParseUint</code></a> now returns -the maximum magnitude integer of the appropriate size -with any <code>ErrRange</code> error, as it was already documented to do. -Previously it returned 0 with <code>ErrRange</code> errors. -</p> -</dl> - -<dl id="strings"><dt><a href="/pkg/strings/">strings</a></dt> -<dd> -<p> -A new type -<a href="/pkg/strings/#Builder"><code>Builder</code></a> is a replacement for -<a href="/pkg/bytes/#Buffer"><code>bytes.Buffer</code></a> for the use case of -accumulating text into a <code>string</code> result. -The <code>Builder</code>'s API is a restricted subset of <code>bytes.Buffer</code>'s -that allows it to safely avoid making a duplicate copy of the data -during the <a href="/pkg/strings/#Builder.String"><code>String</code></a> method. -</p> -</dl> - -<dl id="syscall"><dt><a href="/pkg/syscall/">syscall</a></dt> -<dd> -<p> -On Windows, -the new <a href="/pkg/syscall/#SysProcAttr"><code>SysProcAttr</code></a> field <code>Token</code>, -of type <a href="/pkg/syscall/#Token"><code>Token</code></a> allows the creation of a process that -runs as another user during <a href="/pkg/syscall/#StartProcess"><code>StartProcess</code></a> -(and therefore also during <a href="/pkg/os/#StartProcess"><code>os.StartProcess</code></a> and -<a href="/pkg/os/exec/#Cmd.Start"><code>exec.Cmd.Start</code></a>). -The new function <a href="/pkg/syscall/#CreateProcessAsUser"><code>CreateProcessAsUser</code></a> -gives access to the underlying system call. -</p> - -<p> -On BSD, macOS, and Solaris systems, <a href="/pkg/syscall/#UtimesNano"><code>UtimesNano</code></a> -is now implemented. -</p> -</dl> - -<dl id="time"><dt><a href="/pkg/time/">time</a></dt> -<dd> -<p> -<a href="/pkg/time/#LoadLocation"><code>LoadLocation</code></a> now uses the directory -or uncompressed zip file named by the <code>$ZONEINFO</code> -environment variable before looking in the default system-specific list of -known installation locations or in <code>$GOROOT/lib/time/zoneinfo.zip</code>. -</p> -<p> -The new function <a href="/pkg/time/#LoadLocationFromTZData"><code>LoadLocationFromTZData</code></a> -allows conversion of IANA time zone file data to a <a href="/pkg/time/#Location"><code>Location</code></a>. -</p> -</dl> - -<dl id="unicode"><dt><a href="/pkg/unicode/">unicode</a></dt> -<dd> -<p> -The <a href="/pkg/unicode/"><code>unicode</code></a> package and associated -support throughout the system has been upgraded from Unicode 9.0 to -<a href="http://www.unicode.org/versions/Unicode10.0.0/">Unicode 10.0</a>, -which adds 8,518 new characters, including four new scripts, one new property, -a Bitcoin currency symbol, and 56 new emoji. -</p> -</dl> |