fix bug in complex printing: imaginary didn't have same format as real.

add tests.

R=rsc, ken2, ken3
CC=golang-dev
https://golang.org/cl/261041

src/pkg/fmt/fmt_test.go

@@ -119,6 +119,28 @@ var fmttests = []fmtTest{
 	fmtTest{"% .3g", -1.0, "-1"},
 	fmtTest{"% .3g", 1.0, " 1"},
 
+	/* TODO: Enable when complex support is in all compilers
+	// complex values
+	fmtTest{"%+.3e", 0i, "(+0.000e+00+0.000e+00i)"},
+	fmtTest{"%+.3f", 0i, "(+0.000+0.000i)"},
+	fmtTest{"%+.3g", 0i, "(+0+0i)"},
+	fmtTest{"%+.3e", 1 + 2i, "(+1.000e+00+2.000e+00i)"},
+	fmtTest{"%+.3f", 1 + 2i, "(+1.000+2.000i)"},
+	fmtTest{"%+.3g", 1 + 2i, "(+1+2i)"},
+	fmtTest{"%.3e", 0i, "(0.000e+00+0.000e+00i)"},
+	fmtTest{"%.3f", 0i, "(0.000+0.000i)"},
+	fmtTest{"%.3g", 0i, "(0+0i)"},
+	fmtTest{"%.3e", 1 + 2i, "(1.000e+00+2.000e+00i)"},
+	fmtTest{"%.3f", 1 + 2i, "(1.000+2.000i)"},
+	fmtTest{"%.3g", 1 + 2i, "(1+2i)"},
+	fmtTest{"%.3e", -1 - 2i, "(-1.000e+00-2.000e+00i)"},
+	fmtTest{"%.3f", -1 - 2i, "(-1.000-2.000i)"},
+	fmtTest{"%.3g", -1 - 2i, "(-1-2i)"},
+	fmtTest{"% .3E", -1 - 2i, "(-1.000E+00-2.000E+00i)"},
+	fmtTest{"%+.3g", complex64(1 + 2i), "(+1+2i)"},
+	fmtTest{"%+.3g", complex128(1 + 2i), "(+1+2i)"},
+	*/
+
 	// erroneous formats
 	fmtTest{"", 2, "?(extra int=2)"},
 	fmtTest{"%d", "hello", "%d(string=hello)"},
@@ -210,6 +232,13 @@ var fmttests = []fmtTest{
 	fmtTest{"%v", &array, "&[1 2 3 4 5]"},
 	fmtTest{"%v", &iarray, "&[1 hello 2.5 <nil>]"},
 
+	/* TODO: Enable when complex support is in all compilers
+	// complexes with %v
+	fmtTest{"%v", 1 + 2i, "(1+2i)"},
+	fmtTest{"%v", complex64(1 + 2i), "(1+2i)"},
+	fmtTest{"%v", complex128(1 + 2i), "(1+2i)"},
+	*/
+
 	// structs
 	fmtTest{"%v", A{1, 2, "a", []int{1, 2}}, `{1 2 a [1 2]}`},
 	fmtTest{"%+v", A{1, 2, "a", []int{1, 2}}, `{i:1 j:2 s:a x:[1 2]}`},

src/pkg/fmt/format.go

@@ -43,13 +43,14 @@ type fmt struct {
 	wid  int
 	prec int
 	// flags
-	widPresent  bool
-	precPresent bool
-	minus       bool
-	plus        bool
-	sharp       bool
-	space       bool
-	zero        bool
+	widPresent    bool
+	precPresent   bool
+	minus         bool
+	plus          bool
+	sharp         bool
+	space         bool
+	zero          bool
+	preserveFlags bool // don't clear flags after this print; used to carry over in complex prints
 }
 
 func (f *fmt) clearflags() {
@@ -119,7 +120,9 @@ func (f *fmt) pad(b []byte) {
 	if right > 0 {
 		f.writePadding(right, padding)
 	}
-	f.clearflags()
+	if !f.preserveFlags {
+		f.clearflags()
+	}
 }
 
 // append s to buf, padded on left (w > 0) or right (w < 0 or f.minus).
@@ -137,7 +140,9 @@ func (f *fmt) padString(s string) {
 	if right > 0 {
 		f.writePadding(right, padding)
 	}
-	f.clearflags()
+	if !f.preserveFlags {
+		f.clearflags()
+	}
 }
 
 func putint(buf []byte, base, val uint64, digits string) int {
@@ -425,6 +430,7 @@ func (f *fmt) fmt_fb32(v float32) { f.padString(strconv.Ftoa32(v, 'b', 0)) }
 func (f *fmt) fmt_c64(v complex64, fmt_x byte) {
 	f.buf.WriteByte('(')
 	r := real(v)
+	f.preserveFlags = true
 	for i := 0; ; i++ {
 		switch fmt_x {
 		case 'e':
@@ -438,6 +444,7 @@ func (f *fmt) fmt_c64(v complex64, fmt_x byte) {
 		case 'G':
 			f.fmt_G32(r)
 		}
+		f.preserveFlags = false
 		if i != 0 {
 			break
 		}
@@ -452,6 +459,7 @@ func (f *fmt) fmt_c64(v complex64, fmt_x byte) {
 func (f *fmt) fmt_c128(v complex128, fmt_x byte) {
 	f.buf.WriteByte('(')
 	r := real(v)
+	f.preserveFlags = true
 	for i := 0; ; i++ {
 		switch fmt_x {
 		case 'e':
@@ -465,6 +473,7 @@ func (f *fmt) fmt_c128(v complex128, fmt_x byte) {
 		case 'G':
 			f.fmt_G64(r)
 		}
+		f.preserveFlags = false
 		if i != 0 {
 			break
 		}

src/pkg/fmt/print.go

@@ -927,7 +927,6 @@ func (p *pp) doprintf(format string, a []interface{}) {
 				p.fmt.fmt_c64(v, 'e')
 			} else if v, ok := getComplex128(field); ok {
 				p.fmt.fmt_c128(v, 'e')
-
 			} else {
 				goto badtype
 			}