log/slog: initial commit

The slog structured logging package.

This code was copied from the slog directory of the x/exp repo
at commit 642cacee5cc05231f45555a333d07f1005ffc287, with the
following changes:

- Change import paths.
- Delete unused files list.go, list_test.go.
- Rename example_depth_test.go to example_wrap_test.go and
  adjust example output.
- Change the tag safe_values to safe_slog_values.
- Make captureHandler goroutine-safe to fix a race condition
  in benchmarks.
- Other small changes as suggested in review comments.

Also, add dependencies to go/build/deps_test.go.

Also, add new API for the API checker.

Updates golang/go#56345.

Change-Id: Id8d720967571ced5c5f32c84a8dd9584943cd7df
Reviewed-on: https://go-review.googlesource.com/c/go/+/477295
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Jonathan Amsterdam <jba@google.com>
Reviewed-by: Alan Donovan <adonovan@google.com>

1 files changed, 158 insertions, 0 deletions

diff --git a/api/next/56345.txt b/api/next/56345.txt
new file mode 100644
index 0000000000..7a8f8254b9
--- /dev/null
+++ b/api/next/56345.txt
@@ -0,0 +1,158 @@
+pkg log/slog, const KindAny = 0 #56345
+pkg log/slog, const KindAny Kind #56345
+pkg log/slog, const KindBool = 1 #56345
+pkg log/slog, const KindBool Kind #56345
+pkg log/slog, const KindDuration = 2 #56345
+pkg log/slog, const KindDuration Kind #56345
+pkg log/slog, const KindFloat64 = 3 #56345
+pkg log/slog, const KindFloat64 Kind #56345
+pkg log/slog, const KindGroup = 8 #56345
+pkg log/slog, const KindGroup Kind #56345
+pkg log/slog, const KindInt64 = 4 #56345
+pkg log/slog, const KindInt64 Kind #56345
+pkg log/slog, const KindLogValuer = 9 #56345
+pkg log/slog, const KindLogValuer Kind #56345
+pkg log/slog, const KindString = 5 #56345
+pkg log/slog, const KindString Kind #56345
+pkg log/slog, const KindTime = 6 #56345
+pkg log/slog, const KindTime Kind #56345
+pkg log/slog, const KindUint64 = 7 #56345
+pkg log/slog, const KindUint64 Kind #56345
+pkg log/slog, const LevelDebug = -4 #56345
+pkg log/slog, const LevelDebug Level #56345
+pkg log/slog, const LevelError = 8 #56345
+pkg log/slog, const LevelError Level #56345
+pkg log/slog, const LevelInfo = 0 #56345
+pkg log/slog, const LevelInfo Level #56345
+pkg log/slog, const LevelKey = "level" #56345
+pkg log/slog, const LevelKey ideal-string #56345
+pkg log/slog, const LevelWarn = 4 #56345
+pkg log/slog, const LevelWarn Level #56345
+pkg log/slog, const MessageKey = "msg" #56345
+pkg log/slog, const MessageKey ideal-string #56345
+pkg log/slog, const SourceKey = "source" #56345
+pkg log/slog, const SourceKey ideal-string #56345
+pkg log/slog, const TimeKey = "time" #56345
+pkg log/slog, const TimeKey ideal-string #56345
+pkg log/slog, func Any(string, interface{}) Attr #56345
+pkg log/slog, func AnyValue(interface{}) Value #56345
+pkg log/slog, func Bool(string, bool) Attr #56345
+pkg log/slog, func BoolValue(bool) Value #56345
+pkg log/slog, func Debug(string, ...interface{}) #56345
+pkg log/slog, func DebugCtx(context.Context, string, ...interface{}) #56345
+pkg log/slog, func Default() *Logger #56345
+pkg log/slog, func Duration(string, time.Duration) Attr #56345
+pkg log/slog, func DurationValue(time.Duration) Value #56345
+pkg log/slog, func Error(string, ...interface{}) #56345
+pkg log/slog, func ErrorCtx(context.Context, string, ...interface{}) #56345
+pkg log/slog, func Float64(string, float64) Attr #56345
+pkg log/slog, func Float64Value(float64) Value #56345
+pkg log/slog, func Group(string, ...Attr) Attr #56345
+pkg log/slog, func GroupValue(...Attr) Value #56345
+pkg log/slog, func Info(string, ...interface{}) #56345
+pkg log/slog, func InfoCtx(context.Context, string, ...interface{}) #56345
+pkg log/slog, func Int(string, int) Attr #56345
+pkg log/slog, func Int64(string, int64) Attr #56345
+pkg log/slog, func Int64Value(int64) Value #56345
+pkg log/slog, func IntValue(int) Value #56345
+pkg log/slog, func Log(context.Context, Level, string, ...interface{}) #56345
+pkg log/slog, func LogAttrs(context.Context, Level, string, ...Attr) #56345
+pkg log/slog, func New(Handler) *Logger #56345
+pkg log/slog, func NewJSONHandler(io.Writer) *JSONHandler #56345
+pkg log/slog, func NewLogLogger(Handler, Level) *log.Logger #56345
+pkg log/slog, func NewRecord(time.Time, Level, string, uintptr) Record #56345
+pkg log/slog, func NewTextHandler(io.Writer) *TextHandler #56345
+pkg log/slog, func SetDefault(*Logger) #56345
+pkg log/slog, func String(string, string) Attr #56345
+pkg log/slog, func StringValue(string) Value #56345
+pkg log/slog, func Time(string, time.Time) Attr #56345
+pkg log/slog, func TimeValue(time.Time) Value #56345
+pkg log/slog, func Uint64(string, uint64) Attr #56345
+pkg log/slog, func Uint64Value(uint64) Value #56345
+pkg log/slog, func Warn(string, ...interface{}) #56345
+pkg log/slog, func WarnCtx(context.Context, string, ...interface{}) #56345
+pkg log/slog, func With(...interface{}) *Logger #56345
+pkg log/slog, method (*JSONHandler) Enabled(context.Context, Level) bool #56345
+pkg log/slog, method (*JSONHandler) Handle(context.Context, Record) error #56345
+pkg log/slog, method (*JSONHandler) WithAttrs([]Attr) Handler #56345
+pkg log/slog, method (*JSONHandler) WithGroup(string) Handler #56345
+pkg log/slog, method (*Level) UnmarshalJSON([]uint8) error #56345
+pkg log/slog, method (*Level) UnmarshalText([]uint8) error #56345
+pkg log/slog, method (*LevelVar) Level() Level #56345
+pkg log/slog, method (*LevelVar) MarshalText() ([]uint8, error) #56345
+pkg log/slog, method (*LevelVar) Set(Level) #56345
+pkg log/slog, method (*LevelVar) String() string #56345
+pkg log/slog, method (*LevelVar) UnmarshalText([]uint8) error #56345
+pkg log/slog, method (*Logger) Debug(string, ...interface{}) #56345
+pkg log/slog, method (*Logger) DebugCtx(context.Context, string, ...interface{}) #56345
+pkg log/slog, method (*Logger) Enabled(context.Context, Level) bool #56345
+pkg log/slog, method (*Logger) Error(string, ...interface{}) #56345
+pkg log/slog, method (*Logger) ErrorCtx(context.Context, string, ...interface{}) #56345
+pkg log/slog, method (*Logger) Handler() Handler #56345
+pkg log/slog, method (*Logger) Info(string, ...interface{}) #56345
+pkg log/slog, method (*Logger) InfoCtx(context.Context, string, ...interface{}) #56345
+pkg log/slog, method (*Logger) Log(context.Context, Level, string, ...interface{}) #56345
+pkg log/slog, method (*Logger) LogAttrs(context.Context, Level, string, ...Attr) #56345
+pkg log/slog, method (*Logger) Warn(string, ...interface{}) #56345
+pkg log/slog, method (*Logger) WarnCtx(context.Context, string, ...interface{}) #56345
+pkg log/slog, method (*Logger) With(...interface{}) *Logger #56345
+pkg log/slog, method (*Logger) WithGroup(string) *Logger #56345
+pkg log/slog, method (*Record) Add(...interface{}) #56345
+pkg log/slog, method (*Record) AddAttrs(...Attr) #56345
+pkg log/slog, method (*TextHandler) Enabled(context.Context, Level) bool #56345
+pkg log/slog, method (*TextHandler) Handle(context.Context, Record) error #56345
+pkg log/slog, method (*TextHandler) WithAttrs([]Attr) Handler #56345
+pkg log/slog, method (*TextHandler) WithGroup(string) Handler #56345
+pkg log/slog, method (Attr) Equal(Attr) bool #56345
+pkg log/slog, method (Attr) String() string #56345
+pkg log/slog, method (HandlerOptions) NewJSONHandler(io.Writer) *JSONHandler #56345
+pkg log/slog, method (HandlerOptions) NewTextHandler(io.Writer) *TextHandler #56345
+pkg log/slog, method (Kind) String() string #56345
+pkg log/slog, method (Level) Level() Level #56345
+pkg log/slog, method (Level) MarshalJSON() ([]uint8, error) #56345
+pkg log/slog, method (Level) MarshalText() ([]uint8, error) #56345
+pkg log/slog, method (Level) String() string #56345
+pkg log/slog, method (Record) Attrs(func(Attr)) #56345
+pkg log/slog, method (Record) Clone() Record #56345
+pkg log/slog, method (Record) NumAttrs() int #56345
+pkg log/slog, method (Value) Any() interface{} #56345
+pkg log/slog, method (Value) Bool() bool #56345
+pkg log/slog, method (Value) Duration() time.Duration #56345
+pkg log/slog, method (Value) Equal(Value) bool #56345
+pkg log/slog, method (Value) Float64() float64 #56345
+pkg log/slog, method (Value) Group() []Attr #56345
+pkg log/slog, method (Value) Int64() int64 #56345
+pkg log/slog, method (Value) Kind() Kind #56345
+pkg log/slog, method (Value) LogValuer() LogValuer #56345
+pkg log/slog, method (Value) Resolve() Value #56345
+pkg log/slog, method (Value) String() string #56345
+pkg log/slog, method (Value) Time() time.Time #56345
+pkg log/slog, method (Value) Uint64() uint64 #56345
+pkg log/slog, type Attr struct #56345
+pkg log/slog, type Attr struct, Key string #56345
+pkg log/slog, type Attr struct, Value Value #56345
+pkg log/slog, type Handler interface { Enabled, Handle, WithAttrs, WithGroup } #56345
+pkg log/slog, type Handler interface, Enabled(context.Context, Level) bool #56345
+pkg log/slog, type Handler interface, Handle(context.Context, Record) error #56345
+pkg log/slog, type Handler interface, WithAttrs([]Attr) Handler #56345
+pkg log/slog, type Handler interface, WithGroup(string) Handler #56345
+pkg log/slog, type HandlerOptions struct #56345
+pkg log/slog, type HandlerOptions struct, AddSource bool #56345
+pkg log/slog, type HandlerOptions struct, Level Leveler #56345
+pkg log/slog, type HandlerOptions struct, ReplaceAttr func([]string, Attr) Attr #56345
+pkg log/slog, type JSONHandler struct #56345
+pkg log/slog, type Kind int #56345
+pkg log/slog, type Level int #56345
+pkg log/slog, type LevelVar struct #56345
+pkg log/slog, type Leveler interface { Level } #56345
+pkg log/slog, type Leveler interface, Level() Level #56345
+pkg log/slog, type LogValuer interface { LogValue } #56345
+pkg log/slog, type LogValuer interface, LogValue() Value #56345
+pkg log/slog, type Logger struct #56345
+pkg log/slog, type Record struct #56345
+pkg log/slog, type Record struct, Level Level #56345
+pkg log/slog, type Record struct, Message string #56345
+pkg log/slog, type Record struct, PC uintptr #56345
+pkg log/slog, type Record struct, Time time.Time #56345
+pkg log/slog, type TextHandler struct #56345
+pkg log/slog, type Value struct #56345