The type information is (and for years has been) included
as an extra field in the address chunk of an instruction.
Unfortunately, suppose there is a string at a+24(FP) and
we have an instruction reading its length. It will say:

        MOVQ x+32(FP), AX

and the type of *that* argument is int (not slice), because
it is the length being read. This confuses the picture seen
by debuggers and now, worse, by the garbage collector.

Instead of attaching the type information to all uses,
emit an explicit list of TYPE instructions with the information.
The TYPE instructions are no-ops whose only role is to
provide an address to attach type information to.

For example, this function:

        func f(x, y, z int) (a, b string) {
                return
        }

now compiles into:

        --- prog list "f" ---
        0000 (/Users/rsc/x.go:3) TEXT    f+0(SB),$0-56
        0001 (/Users/rsc/x.go:3) LOCALS  ,
        0002 (/Users/rsc/x.go:3) TYPE    x+0(FP){int},$8
        0003 (/Users/rsc/x.go:3) TYPE    y+8(FP){int},$8
        0004 (/Users/rsc/x.go:3) TYPE    z+16(FP){int},$8
        0005 (/Users/rsc/x.go:3) TYPE    a+24(FP){string},$16
        0006 (/Users/rsc/x.go:3) TYPE    b+40(FP){string},$16
        0007 (/Users/rsc/x.go:3) MOVQ    $0,b+40(FP)
        0008 (/Users/rsc/x.go:3) MOVQ    $0,b+48(FP)
        0009 (/Users/rsc/x.go:3) MOVQ    $0,a+24(FP)
        0010 (/Users/rsc/x.go:3) MOVQ    $0,a+32(FP)
        0011 (/Users/rsc/x.go:4) RET     ,

The { } show the formerly hidden type information.
The { } syntax is used when printing from within the gc compiler.
It is not accepted by the assemblers.

The same type information is now included on global variables:

0055 (/Users/rsc/x.go:15) GLOBL   slice+0(SB){[]string},$24(AL*0)

This more accurate type information fixes a bug in the
garbage collector's precise heap collection.

The linker only cares about globals right now, but having the
local information should make things a little nicer for Carl
in the future.

Fixes #4907.

R=ken2
CC=golang-dev
https://golang.org/cl/7395056

See also CL 7383051 for details.

R=adonovan, bradfitz
CC=golang-dev
https://golang.org/cl/7378063

It's accessed without mutex protection
in a different goroutine from the one that
sets it.

Also make sure that Client.Call after Client.Close
will reliably return ErrShutdown, and that clients
see ErrShutdown rather than io.EOF when appropriate.

Suggestions welcome for a way to reliably test
the mutex issue.

R=r, iant
CC=golang-dev
https://golang.org/cl/7338045

This CL addresses the comments on CL 7368046 that I've overlooked.

Update #4866.

R=golang-dev, dave
CC=golang-dev
https://golang.org/cl/7369052

Fixes #4888.

R=golang-dev, gri
CC=golang-dev
https://golang.org/cl/7383051

Added the command line flag -ex to godoc to print examples in
text output.

Samples from the generated output:

$ godoc -ex strings Index
...
func Index(s, sep string) int
    Index returns the index of the first instance of sep in s, or -1 if sep
    is not present in s.

    Example:
        fmt.Println(strings.Index("chicken", "ken"))
        fmt.Println(strings.Index("chicken", "dmr"))
        // Output:
        // 4
        // -1
...

$ godoc -ex container/heap
...
package heap
    import "container/heap"

    Package heap provides heap operations for any type that implements
    heap.Interface. A heap is a tree with the property that each node is the
    minimum-valued node in its subtree.

    Example:
        // This example demonstrates an integer heap built using the heap interface.
        package heap_test

        import (
            "container/heap"
            "fmt"
        ...

    Example:
        // This example demonstrates a priority queue built using the heap interface.
        package heap_test

        import (
            "container/heap"
            "fmt"
        )
...

Fixes #3587.

R=golang-dev, minux.ma, adg, rsc, gri
CC=golang-dev
https://golang.org/cl/7356043

R=golang-dev, kamil.kisiel, bradfitz
CC=golang-dev
https://golang.org/cl/7369049

Made possible by go/types, as long as the package type-checks OK.

Fixes #4684.

R=golang-dev
CC=golang-dev
https://golang.org/cl/7407045

The heuristics for BitLen of a product of randomly generated primes
are wrong, and the generated candidates never match the required
size for nprimes > 10. This corner case is not expected to be used in
practice.

R=agl
CC=golang-dev
https://golang.org/cl/7397052

Executable heap is gone on Unix!

R=golang-dev, dave, bradfitz
CC=golang-dev
https://golang.org/cl/7405045

Or gcc (-fPIC) will complain:
cmd/dist/unix.c: In function ‘cansse2’
cmd/dist/unix.c:774: error: can't find a register in class ‘BREG’ while reloading ‘asm’
cmd/dist/unix.c:774: error: ‘asm’ operand has impossible constraints

This affects bootstrapping on native Darwin/386 where all code is
compiled with -fPIC.

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/7394047

This CL allows to receive network interface arrival and depature
notifications through routing sockets on BSD variants. So far
Darwin doesn't support this feature.

Also does small simplification.

Update #4866.

R=golang-dev, lucio.dere, dave
CC=golang-dev
https://golang.org/cl/7365055

Update #4866.

R=golang-dev
CC=golang-dev
https://golang.org/cl/7382053

Update #4866.

R=golang-dev, bradfitz, dave
CC=golang-dev
https://golang.org/cl/7382052

Update #4866.

R=golang-dev, dave
CC=golang-dev
https://golang.org/cl/7398047

Fixes #4404.

R=gri, rsc
CC=golang-dev
https://golang.org/cl/7378061

Replace setsid with c_ISGID since the constant is already defined.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/7403048

1. Workaround the smart clang diagnostics with -Qunused-arguments:
clang: error: argument unused during compilation: '-XXX'
2. if "clang -print-libgcc-file-name" returns non-absolute path, don't
provide that on linker command line.
3. Fix dwarf.PtrType.Size() in cmd/cgo as clang doesn't generate
DW_AT_byte_size for pointer types.
4. Workaround warnings for -Wno-unneeded-internal-declaration with
-Wno-unknown-warning-option.
5. Add -Wno-unused-function.
6. enable race detector test on darwin with clang
(at least Apple clang version 1.7 (tags/Apple/clang-77) works).

Requires CL 7354043.

Update #4829
This should fix most parts of the problem, but one glitch still remains.
DWARF generated by newer clang doesn't differentiate these
two function types:
    void *malloc(size_t);
    void *malloc(unsigned long int);
so you might need to do this to make make.bash pass:
sed -i -e 's/C.malloc(C.size_t/C.malloc(C.ulong/' pkg/os/user/lookup_unix.go

R=golang-dev, dave, iant, rsc
CC=golang-dev
https://golang.org/cl/7351044

R=golang-dev, alex.brainman
CC=golang-dev
https://golang.org/cl/7407044

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/7402047

to minimize diffs of new scheduler

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/7381048

We need go/types to discriminate the Error method from
the error interface and the Error method of the testing package.
Fixes #4753.

R=golang-dev, bradfitz, gri
CC=golang-dev
https://golang.org/cl/7396054

Move Skip and friends into *common so benchmarks can also be skipped.

R=golang-dev, gustav.paul, rsc
CC=golang-dev
https://golang.org/cl/7379046

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/7403049

Fixes #4875.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/7376049

At least one test (in package runtime) depends
on `go' being in $path. We simply bind GOROOT/bin
before /bin to make sure the latest copy of the
binary is accessible there.

R=rsc, rminnich, ality
CC=golang-dev
https://golang.org/cl/7391047

Plan 9 I/O preserves message boundaries, while Go
library code is written for UNIX-like operating
systems which do not. Avoid doing zero-length
writes in package os.

R=rsc, rminnich, ality, rminnich, r
CC=golang-dev
https://golang.org/cl/7406046

R=ken2
CC=golang-dev
https://golang.org/cl/7399050

This is a simple refactoring of main.go that will enable the type checker
to be used during vetting.
The change has an unimportant effect on the arguments: it now assumes
that all files named explicitly on the command line belong to the same
package. When run by the go command, this was true already.

Also restore a missing parenthesis from an error message.

R=golang-dev, gri, bradfitz
CC=golang-dev
https://golang.org/cl/7393052

For now, all the callbacks from C use top-level Go functions,
so they use the equivalent C function pointer, and will continue
to do so. But perhaps some day this will be useful for calling
a Go func value (at least if the type is already known).

More importantly, the Windows callback code needs to be able
to use cgocallback_gofunc to call a Go func value.
Should fix the Windows build.

R=ken2
CC=golang-dev
https://golang.org/cl/7388049

R=adonovan
CC=golang-dev
https://golang.org/cl/7386052

Step 4 of http://golang.org/s/go11func.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/7393049

Step 3 of http://golang.org/s/go11func.

Fixes #3736.
Fixes #3738.
Fixes #4081.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/7393050

We wrap the final '...' argument's type in types.Slice.
Added tests.

Also:
- Function.writeSignature: suppress slice '[]' when printing
  variadic arg '...'.
- Eliminate Package.ImportPath field; redundant
  w.r.t. Package.Types.Path.
- Use "TODO: (opt|fix)" notation more widely.
- Eliminate many redundant/stale TODOs.

R=gri
CC=golang-dev
https://golang.org/cl/7378057

Change ARM context register to R7, to get out of the way
of the register allocator during the compilation of the
prologue statements (it wants to use R0 as a temporary).

Step 2 of http://golang.org/s/go11func.

R=ken2
CC=golang-dev
https://golang.org/cl/7369048

The new src argument is ignored during linking
(that is, CALL r1, r2 is identical to CALL r2 for linking),
but it serves as a hint to the 5g/6g/8g optimizer
that the src register is live on entry to the called
function and must be preserved.

It is possible to avoid exposing this fact to the rest of
the toolchain, keeping it entirely within 5g/6g/8g,
but I think it will help to be able to look in object files
and assembly listings and linker -a / -W output to
see CALL instructions are "Go func value" calls and
which are "C function pointer" calls.

R=ken2
CC=golang-dev
https://golang.org/cl/7364045

This makes Go's quoted-printable decoder more like other
popular ones, allowing through a bare \r or \n, and also
passes through \r\n which looked like a real bug before.

Fixes #4771

R=minux.ma
CC=golang-dev
https://golang.org/cl/7300092

R=golang-dev, dvyukov
CC=golang-dev
https://golang.org/cl/7382049

By appending to the wrong (always empty) list, only the last
anonymous field was being considered for promotion.

Also:
- eliminated "function-local NamedTypes" TODO; nothing to do.
- fixed Function.DumpTo: printing of anon receivers was "( T)",
  now "(T)"; extracted writeSignature into own function.
- eliminated blockNames function;
  thanks to BasicBlock.String, "%s" of []*BasicBlock is fine.
- extracted buildReferrers into own function.

exp/ssa can now build its own transitive closure.

R=gri
CC=golang-dev
https://golang.org/cl/7384054

R=golang-dev, dvyukov
CC=golang-dev
https://golang.org/cl/7395051