patch to strconv to allow heap allocations to be removed for ParseInt(string(someBytes), ...), etc.

strconv.patch

diff --git src/strconv/atoi.go src/strconv/atoi.go
index 631b487d97..916d60e60a 100644
--- src/strconv/atoi.go
+++ src/strconv/atoi.go
@@ -33,20 +33,22 @@ func (e *NumError) Error() string {
 
 func (e *NumError) Unwrap() error { return e.Err }
 
+func copyString(x string) string { return string([]byte(x)) }
+
 func syntaxError(fn, str string) *NumError {
-	return &NumError{fn, str, ErrSyntax}
+	return &NumError{fn, copyString(str), ErrSyntax}
 }
 
 func rangeError(fn, str string) *NumError {
-	return &NumError{fn, str, ErrRange}
+	return &NumError{fn, copyString(str), ErrRange}
 }
 
 func baseError(fn, str string, base int) *NumError {
-	return &NumError{fn, str, errors.New("invalid base " + Itoa(base))}
+	return &NumError{fn, copyString(str), errors.New("invalid base " + Itoa(base))}
 }
 
 func bitSizeError(fn, str string, bitSize int) *NumError {
-	return &NumError{fn, str, errors.New("invalid bit size " + Itoa(bitSize))}
+	return &NumError{fn, copyString(str), errors.New("invalid bit size " + Itoa(bitSize))}
 }
 
 const intSize = 32 << (^uint(0) >> 63)
@@ -203,7 +205,7 @@ func ParseInt(s string, base int, bitSize int) (i int64, err error) {
 	un, err = ParseUint(s, base, bitSize)
 	if err != nil && err.(*NumError).Err != ErrRange {
 		err.(*NumError).Func = fnParseInt
-		err.(*NumError).Num = s0
+		err.(*NumError).Num = copyString(s0)
 		return 0, err
 	}
 
@@ -237,7 +239,7 @@ func Atoi(s string) (int, error) {
 		if s[0] == '-' || s[0] == '+' {
 			s = s[1:]
 			if len(s) < 1 {
-				return 0, &NumError{fnAtoi, s0, ErrSyntax}
+				return 0, syntaxError(fnAtoi, s0)
 			}
 		}
 
@@ -245,7 +247,7 @@ func Atoi(s string) (int, error) {
 		for _, ch := range []byte(s) {
 			ch -= '0'
 			if ch > 9 {
-				return 0, &NumError{fnAtoi, s0, ErrSyntax}
+				return 0, syntaxError(fnAtoi, s0)
 			}
 			n = n*10 + int(ch)
 		}
diff --git src/strconv/atoi_test.go src/strconv/atoi_test.go
index 867fa66a14..51c7595243 100644
--- src/strconv/atoi_test.go
+++ src/strconv/atoi_test.go
@@ -609,6 +609,34 @@ func TestNumErrorUnwrap(t *testing.T) {
 	}
 }
 
+func TestParseAllocationsFromBytes(t *testing.T) {
+	s := []byte(fmt.Sprintf("%d", 1<<63-1))
+
+	intAllocs := testing.AllocsPerRun(1000, func() {
+		out, _ := ParseInt(string(s), 10, 64)
+		BenchSink += int(out)
+	})
+	if intAllocs != 0 {
+		t.Error("ParseInt: wanted 0 allocs but got:", intAllocs)
+	}
+
+	uintAllocs := testing.AllocsPerRun(1000, func() {
+		out, _ := ParseUint(string(s), 10, 64)
+		BenchSink += int(out)
+	})
+	if uintAllocs != 0 {
+		t.Error("ParseUint: wanted 0 allocs but got:", uintAllocs)
+	}
+
+	atoiAllocs := testing.AllocsPerRun(1000, func() {
+		out, _ := Atoi(string(s))
+		BenchSink += int(out)
+	})
+	if atoiAllocs != 0 {
+		t.Error("Atoi: wanted 0 allocs but got:", atoiAllocs)
+	}
+}
+
 func BenchmarkParseInt(b *testing.B) {
 	b.Run("Pos", func(b *testing.B) {
 		benchmarkParseInt(b, 1)