fmt format verb %b bug

fmt.Printf("%b", int8(-1)) prints 64 ones instead of 8.
This happens only for signed integers (int8, in16 and int32). I guess it's because of the way the conversion between integer types works. From go spec: "Conversions between integer types. If the value is a signed quantity, it is sign extended to implicit infinite precision ....". And there are several conversions to int64 and uint64 in the fmt package. This pathch solves only half of the problem. On a 32 bit system, an fmt.Printf("%b", int(-1)) should still print 64 ones.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/891049

diff --git a/src/pkg/fmt/fmt_test.go b/src/pkg/fmt/fmt_test.go
index b601b6ef57419334ad45b518f74824d490655617..54006dff8b4af8005d84e2900e7601a0802db4fe 100644 (file)
--- a/src/pkg/fmt/fmt_test.go
+++ b/src/pkg/fmt/fmt_test.go
@@ -162,6 +162,7 @@ var fmttests = []fmtTest{
        fmtTest{"%x", b64, "ffffffffffffffff"},
        fmtTest{"%b", 7, "111"},
        fmtTest{"%b", b64, "1111111111111111111111111111111111111111111111111111111111111111"},
+       fmtTest{"%b", -6, "-110"},
        fmtTest{"%e", float64(1), "1.000000e+00"},
        fmtTest{"%e", float64(1234.5678e3), "1.234568e+06"},
        fmtTest{"%e", float64(1234.5678e-8), "1.234568e-05"},

diff --git a/src/pkg/fmt/format.go b/src/pkg/fmt/format.go
index 137c355bbbad9df17ca97cac3778e636b6ed2bc5..2637eb4cd662c72b3ed8839c0ffe01339eb92f12 100644 (file)
--- a/src/pkg/fmt/format.go
+++ b/src/pkg/fmt/format.go
@@ -306,14 +306,11 @@ func (f *fmt) fmt_uo32(v uint32) { f.integer(int64(v), 8, unsigned, ldigits) }
 // fmt_uo formats a uint in octal.
 func (f *fmt) fmt_uo(v uint) { f.integer(int64(v), 8, unsigned, ldigits) }
 
-// fmt_b64 formats a uint64 in binary.
-func (f *fmt) fmt_b64(v uint64) { f.integer(int64(v), 2, unsigned, ldigits) }
+// fmt_b64 formats an int64 in binary.
+func (f *fmt) fmt_b64(v int64) { f.integer(v, 2, signed, ldigits) }
 
-// fmt_b32 formats a uint32 in binary.
-func (f *fmt) fmt_b32(v uint32) { f.integer(int64(v), 2, unsigned, ldigits) }
-
-// fmt_b formats a uint in binary.
-func (f *fmt) fmt_b(v uint) { f.integer(int64(v), 2, unsigned, ldigits) }
+// fmt_ub64 formats a uint64 in binary.
+func (f *fmt) fmt_ub64(v uint64) { f.integer(int64(v), 2, unsigned, ldigits) }
 
 // fmt_c formats a Unicode character.
 func (f *fmt) fmt_c(v int) { f.padString(string(v)) }

diff --git a/src/pkg/fmt/print.go b/src/pkg/fmt/print.go
index 71a4a662ab16b4d3f1a8ed21c90c3327e2b0b21c..c8d9e753a15e8bc5d8839ada8d978b150edb6ea0 100644 (file)
--- a/src/pkg/fmt/print.go
+++ b/src/pkg/fmt/print.go
@@ -857,8 +857,12 @@ func (p *pp) doprintf(format string, a []interface{}) {
 
                // int
                case 'b':
-                       if v, _, ok := getInt(field); ok {
-                               p.fmt.fmt_b64(uint64(v)) // always unsigned
+                       if v, signed, ok := getInt(field); ok {
+                               if signed {
+                                       p.fmt.fmt_b64(v)
+                               } else {
+                                       p.fmt.fmt_ub64(uint64(v))
+                               }
                        } else if v, ok := getFloat32(field); ok {
                                p.fmt.fmt_fb32(v)
                        } else if v, ok := getFloat64(field); ok {