fmt: display contained values when formatting atomic booleans and integers

* treat `atomic.{Int32,Int64,Uint32,Uint64}` values as integers when
  formatting, using the underlying integer value (by calling Load). This
  has the effect of, for example, formatting an atomic integer type
  containing 42 as "42", not "{{}, 42}").

* treat `atomic.Bool` values as booleans when formatting, using the
  contained boolean value (by calling Load). This has the effect of, for
  example, formatting an true atomic.Bool value containing as "true",
  not "{{}, 1}" or "{{} %!t(uint32=1)}" as before.

Fixes #54731

Author: jamespwilliams

src/fmt/fmt_test.go

@@ -13,6 +13,7 @@ import (
 	"reflect"
 	"runtime"
 	"strings"
+	"sync/atomic"
 	"testing"
 	"time"
 	"unicode"
@@ -39,6 +40,36 @@ type (
 	renamedComplex128 complex128
 )
 
+func newAtomicInt32(val int32) *atomic.Int32 {
+	var r atomic.Int32
+	r.Store(val)
+	return &r
+}
+
+func newAtomicUint32(val uint32) *atomic.Uint32 {
+	var r atomic.Uint32
+	r.Store(val)
+	return &r
+}
+
+func newAtomicInt64(val int64) *atomic.Int64 {
+	var r atomic.Int64
+	r.Store(val)
+	return &r
+}
+
+func newAtomicUint64(val uint64) *atomic.Uint64 {
+	var r atomic.Uint64
+	r.Store(val)
+	return &r
+}
+
+func newAtomicBool(val bool) *atomic.Bool {
+	var r atomic.Bool
+	r.Store(val)
+	return &r
+}
+
 func TestFmtInterface(t *testing.T) {
 	var i1 any
 	i1 = "abc"
@@ -1081,6 +1112,32 @@ var fmtTests = []struct {
 	{"%☠", SI{&[]any{I(1), G(2)}}, "{%!☠(*[]interface {}=&[1 2])}"},
 	{"%☠", reflect.Value{}, "<invalid reflect.Value>"},
 	{"%☠", map[float64]int{NaN: 1}, "map[%!☠(float64=NaN):%!☠(int=1)]"},
+
+	// atomics
+	{"%d", newAtomicInt32(25), "25"},
+	{"%d", newAtomicInt32(math.MaxInt32), "2147483647"},
+	{"%d", newAtomicInt32(-5), "-5"},
+	{"%d", newAtomicInt32(math.MinInt32), "-2147483648"},
+
+	{"%d", newAtomicUint32(19), "19"},
+	{"%d", newAtomicUint32(math.MaxUint32), "4294967295"},
+
+	{"%d", newAtomicInt64(99), "99"},
+	{"%d", newAtomicInt64(math.MaxInt64), "9223372036854775807"},
+	{"%d", newAtomicInt64(-7), "-7"},
+	{"%d", newAtomicInt64(math.MinInt64), "-9223372036854775808"},
+
+	{"%d", newAtomicUint64(12), "12"},
+	{"%d", newAtomicUint64(math.MaxUint64), "18446744073709551615"},
+
+	{"%t", newAtomicBool(true), "true"},
+	{"%t", newAtomicBool(false), "false"},
+
+	{"%v", newAtomicInt32(42), "42"},
+	{"%v", newAtomicUint32(4242), "4242"},
+	{"%v", newAtomicInt64(424242), "424242"},
+	{"%v", newAtomicUint64(42424242), "42424242"},
+	{"%v", newAtomicBool(true), "true"},
 }
 
 // zeroFill generates zero-filled strings of the specified width. The length

src/fmt/print.go

@@ -11,6 +11,7 @@ import (
 	"reflect"
 	"strconv"
 	"sync"
+	"sync/atomic"
 	"unicode/utf8"
 )
 
@@ -747,6 +748,26 @@ func (p *pp) printArg(arg any, verb rune) {
 		p.fmtInteger(f, unsigned, verb)
 	case uintptr:
 		p.fmtInteger(uint64(f), unsigned, verb)
+	case atomic.Int32:
+		p.fmtInteger(uint64(f.Load()), signed, verb)
+	case *atomic.Int32:
+		p.fmtInteger(uint64(f.Load()), signed, verb)
+	case atomic.Int64:
+		p.fmtInteger(uint64(f.Load()), signed, verb)
+	case *atomic.Int64:
+		p.fmtInteger(uint64(f.Load()), signed, verb)
+	case atomic.Uint32:
+		p.fmtInteger(uint64(f.Load()), unsigned, verb)
+	case *atomic.Uint32:
+		p.fmtInteger(uint64(f.Load()), unsigned, verb)
+	case atomic.Uint64:
+		p.fmtInteger(uint64(f.Load()), unsigned, verb)
+	case *atomic.Uint64:
+		p.fmtInteger(uint64(f.Load()), unsigned, verb)
+	case atomic.Bool:
+		p.fmtBool(f.Load(), verb)
+	case *atomic.Bool:
+		p.fmtBool(f.Load(), verb)
 	case string:
 		p.fmtString(f, verb)
 	case []byte: