fmt: cleanup %p and %T code paths

Remove check for %p and %T in printValue.
These verbs are not recursive and are handled already in
printArg which is called on any argument before printValue.

Format the type string for %T directly instead of invoking
the more complex printArg with %s on the type string.

Decouple the %T tests from variables declared in scan_test.go.

Change-Id: Ibd51566bd4cc1a260ce6d052f36382ed05020b48
Reviewed-on: https://go-review.googlesource.com/20622
Run-TryBot: Rob Pike <r@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

src/fmt/fmt_test.go

@@ -723,10 +723,12 @@ var fmtTests = []struct {
 	{"%#v", S{F(7), G(8)}, "fmt_test.S{F:<v=F(7)>, G:GoString(8)}"},
 
 	// %T
+	{"%T", byte(0), "uint8"},
+	{"%T", reflect.ValueOf(nil), "reflect.Value"},
 	{"%T", (4 - 3i), "complex128"},
 	{"%T", renamedComplex128(4 - 3i), "fmt_test.renamedComplex128"},
-	{"%T", intVal, "int"},
-	{"%6T", &intVal, "  *int"},
+	{"%T", intVar, "int"},
+	{"%6T", &intVar, "  *int"},
 	{"%10T", nil, "     <nil>"},
 	{"%-10T", nil, "<nil>     "},
 

src/fmt/print.go

@@ -700,10 +700,10 @@ func (p *pp) printArg(arg interface{}, verb rune, depth int) {
 	// %T (the value's type) and %p (its address) are special; we always do them first.
 	switch verb {
 	case 'T':
-		p.printArg(reflect.TypeOf(arg).String(), 's', 0)
+		p.fmt.fmt_s(reflect.TypeOf(arg).String())
 		return
 	case 'p':
-		p.fmtPointer(reflect.ValueOf(arg), verb)
+		p.fmtPointer(reflect.ValueOf(arg), 'p')
 		return
 	}
 
@@ -760,11 +760,12 @@ func (p *pp) printArg(arg interface{}, verb rune, depth int) {
 	p.arg = nil
 }
 
-// printValue is like printArg but starts with a reflect value, not an interface{} value.
+// printValue is similar to printArg but starts with a reflect value, not an interface{} value.
+// It does not handle 'p' and 'T' verbs because these should have been already handled by printArg.
 func (p *pp) printValue(value reflect.Value, verb rune, depth int) {
 	if !value.IsValid() {
 		switch verb {
-		case 'T', 'v':
+		case 'v':
 			p.buf.WriteString(nilAngleString)
 		default:
 			p.badVerb(verb)
@@ -772,17 +773,6 @@ func (p *pp) printValue(value reflect.Value, verb rune, depth int) {
 		return
 	}
 
-	// Special processing considerations.
-	// %T (the value's type) and %p (its address) are special; we always do them first.
-	switch verb {
-	case 'T':
-		p.printArg(value.Type().String(), 's', 0)
-		return
-	case 'p':
-		p.fmtPointer(value, verb)
-		return
-	}
-
 	// Handle values with special methods.
 	// Call always, even when arg == nil, because handleMethods clears p.fmt.plus for us.
 	p.arg = nil // Make sure it's cleared, for safety.