cmd/api: bug fix for goapi's lame type checker

This is blocking me submitting the net fd timeout
CL, since goapi chokes on my constant.

The much more extensive fix to goapi's type checker
in pending review in https://golang.org/cl/6742050

But I'd rather get this quick fix in first.

R=golang-dev, mikioh.mikioh
CC=golang-dev
https://golang.org/cl/6818104

src/cmd/api/goapi.go

@@ -331,20 +331,6 @@ const (
 	loaded
 )
 
-// hardCodedConstantType is a hack until the type checker is sufficient for our needs.
-// Rather than litter the code with unnecessary type annotations, we'll hard-code
-// the cases we can't handle yet.
-func (w *Walker) hardCodedConstantType(name string) (typ string, ok bool) {
-	switch w.scope[0] {
-	case "pkg syscall":
-		switch name {
-		case "darwinAMD64":
-			return "bool", true
-		}
-	}
-	return "", false
-}
-
 func (w *Walker) Features() (fs []string) {
 	for f := range w.features {
 		fs = append(fs, f)
@@ -596,6 +582,10 @@ func (w *Walker) constValueType(vi interface{}) (string, error) {
 		}
 		return constDepPrefix + v.Name, nil
 	case *ast.BinaryExpr:
+		switch v.Op {
+		case token.EQL, token.LSS, token.GTR, token.NOT, token.NEQ, token.LEQ, token.GEQ:
+			return "bool", nil
+		}
 		left, err := w.constValueType(v.X)
 		if err != nil {
 			return "", err
@@ -768,12 +758,7 @@ func (w *Walker) walkConst(vs *ast.ValueSpec) {
 				var err error
 				litType, err = w.constValueType(vs.Values[0])
 				if err != nil {
-					if t, ok := w.hardCodedConstantType(ident.Name); ok {
-						litType = t
-						err = nil
-					} else {
-						log.Fatalf("unknown kind in const %q (%T): %v", ident.Name, vs.Values[0], err)
-					}
+					log.Fatalf("unknown kind in const %q (%T): %v", ident.Name, vs.Values[0], err)
 				}
 			}
 		}

src/cmd/api/testdata/src/pkg/p1/p1.go

@@ -161,3 +161,9 @@ func (common) OnBothTandBVal()  {}
 type EmbedSelector struct {
 	time.Time
 }
+
+const (
+	foo          = "foo"
+	foo2  string = "foo2"
+	truth        = foo == "foo" || foo2 == "foo2"
+)