From 1ab15fac22484a13835e1d3dee25f68e1c7ba9e0 Mon Sep 17 00:00:00 2001
From: Andrei Vieru <euvieru@gmail.com>
Date: Mon, 12 Apr 2010 10:20:06 -0700
Subject: [PATCH] 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
---
 src/pkg/fmt/fmt_test.go |  1 +
 src/pkg/fmt/format.go   | 11 ++++-------
 src/pkg/fmt/print.go    |  8 ++++++--
 3 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/src/pkg/fmt/fmt_test.go b/src/pkg/fmt/fmt_test.go
index b601b6ef57..54006dff8b 100644
--- 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 137c355bbb..2637eb4cd6 100644
--- 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 71a4a662ab..c8d9e753a1 100644
--- 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 {
-- 
2.50.0