mirror of
https://github.com/golang/go
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cbbc6a102d
This CL adds a flag parser that matches the semantics of Go's
package flag. It also changes the linkers and compilers to use
the new flag parser.
Command lines that used to work, like
8c -FVw
6c -Dfoo
5g -I/foo/bar
now need to be split into separate arguments:
8c -F -V -w
6c -D foo
5g -I /foo/bar
The new spacing will work with both old and new tools.
The new parser also allows = for arguments, as in
6c -D=foo
5g -I=/foo/bar
but that syntax will not work with the old tools.
In addition to matching standard Go binary flag parsing,
the new flag parser generates more detailed usage messages
and opens the door to long flag names.
The recently added gc flag -= has been renamed -complete.
R=remyoudompheng, daniel.morsing, minux.ma, iant
CC=golang-dev
https://golang.org/cl/7035043
137 lines
4.9 KiB
HTML
137 lines
4.9 KiB
HTML
<!--{
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"Title": "Go 1.1 Release Notes",
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"Path": "/doc/go1.1",
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"Template": true
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}-->
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<h2 id="introduction">Introduction to Go 1.1</h2>
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TODO
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- overview
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- link back to Go 1 and also Go 1 Compatibility docs.
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<h2 id="language">Changes to the language</h2>
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TODO
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<h2 id="impl">Changes to the implementations and tools</h2>
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TODO: more
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<h3 id="gc-flag">Command-line flag parsing</h3>
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<p>
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In the gc toolchain, the compilers and linkers now use the
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same command-line flag parsing rules as the Go flag package, a departure
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from the traditional Unix flag parsing. This may affect scripts that invoke
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the tool directly.
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For example,
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<code>go tool 6c -Fw -Dfoo</code> must now be written
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<code>go tool 6c -F -w -D foo</code>.
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</p>
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<h3 id="int">Size of int on 64-bit platforms</h3>
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<p>
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The language allows the implementation to choose whether the <code>int</code> type and <code>uint</code> types are 32 or 64 bits. Previous Go implementations made <code>int</code> and <code>uint</code> 32 bits on all systems. Both the gc and gccgo implementations (TODO: check that gccgo does) <a href="http://golang.org/issue/2188">now make <code>int</code> and <code>uint</code> 64 bits on 64-bit platforms such as AMD64/x86-64</a>.
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Among other things, this enables the allocation of slices with
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more than 2 billion elements on 64-bit platforms.
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</p>
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<p>
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<em>Updating</em>:
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Most programs will be unaffected by this change.
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Because Go does not allow implicit conversions between distinct
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<a href="/ref/spec#Numeric_types">numeric types</a>,
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no programs will stop compiling due to this change.
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However, programs that contain implicit assumptions
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that <code>int</code> is only 32 bits may change behavior.
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For example, this code prints a positive number on 64-bit systems and
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a negative one on 32-bit systems:
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<pre>
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x := ^uint32(0) // x is 0xffffffff
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i := int(x) // i is -1 on 32-bit systems, 0xffffffff on 64-bit
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fmt.Println(i)
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</pre>
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<p>Portable code intending 32-bit sign extension (yielding -1 on all systems)
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would instead say:
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</p>
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<pre>
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i := int(int32(x))
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</pre>
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<h3 id="asm">Assembler</h3>
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<p>
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Due to the <a href="#int">int</a> and TODO: OTHER changes,
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the placement of function arguments on the stack has changed.
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Functions written in assembly will need to be revised at least
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to adjust frame pointer offsets.
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</p>
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<h3 id="race">Data race detector</h3>
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<p>
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The implementation now includes a built-in <a href="/doc/articles/race_detector.html">data race detector</a>.
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</p>
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<h3 id="symtab">Symbol table</h3>
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<p>
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In the gc toolchain, the symbol table format has been extended to allow
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little-endian encoding of symbol values, and the extension is used in
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binaries generated by the Go 1.1 version of the gc linker.
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To the Go 1.0 toolchain and libraries, these new symbol tables appear empty.
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</p>
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<h2 id="library">Changes to the standard library</h2>
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<h3 id="debug/elf">debug/elf</h3>
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<p>
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Previous versions of the debug/elf package intentionally skipped over the first
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symbol in the ELF symbol table, since it is always an empty symbol. This symbol
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is no longer skipped since indexes into the symbol table returned by debug/elf,
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will be different to indexes into the original ELF symbol table. Any code that
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calls the debug/elf functions Symbols or ImportedSymbols may need to be
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adjusted to account for the additional symbol and the change in symbol offsets.
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</p>
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<h3 id="net">net</h3>
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<p>
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The protocol-specific resolvers were formerly
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lax about the network name passed in. For example, although the documentation was clear
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that the only valid networks for <code>ResolveTCPAddr</code> are <code>"tcp"</code>,
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<code>"tcp4"</code>, and <code>"tcp6"</code>, the Go 1.0 implementation silently accepted
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any string. The Go 1.1 implementation returns an error if the network is not one of those strings.
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The same is true of the other protocol-specific resolvers <code>ResolveIPAddr</code>, <code>ResolveUDPAddr</code>, and
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<code>ResolveUnixAddr</code>.
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</p>
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<p>
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The previous <code>ListenUnixgram</code> returned <code>UDPConn</code> as
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arepresentation of the connection endpoint. The Go 1.1 implementation
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returns <code>UnixConn</code> to allow reading and writing
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with <code>ReadFrom</code> and <code>WriteTo</code> methods on
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the <code>UnixConn</code>.
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</p>
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<h3 id="time">time</h3>
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<p>
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On FreeBSD, Linux, NetBSD, OS X and OpenBSD, previous versions of the time package
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returned times with microsecond precision. The Go 1.1 implementation of time on these
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systems now returns times with nanosecond precision. Code may exist that expects to be
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able to store such a time in an external format with only microsecond precision,
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read it back, and recover exactly the same time instant.
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In Go 1.1 the same time will not be recovered, since the external storage
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will have discarded nanoseconds.
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To address this case, there are two new methods of time.Time, Round and Truncate,
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that can be used to remove precision from a time before passing it to
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external storage.
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</p>
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TODO
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