fix switch statements with empty expression (fixes #204)

neelance · neelance · commit d5efe76dcb1b · 2015-05-15T18:22:01.000+02:00
diff --git a/compiler/expressions.go b/compiler/expressions.go
@@ -9,6 +9,7 @@ import (
 	"strconv"
 	"strings"
 
+	"github.com/gopherjs/gopherjs/compiler/analysis"
 	"github.com/gopherjs/gopherjs/compiler/astutil"
 	"github.com/gopherjs/gopherjs/compiler/typesutil"
 
@@ -421,6 +422,15 @@ func (c *funcContext) translateExpr(expr ast.Expr) *expression {
 				if _, ok := u.Elem().Underlying().(*types.Array); ok {
 					return c.formatExpr("$equal(%s, %s, %s)", c.translateImplicitConversion(e.X, t), c.translateImplicitConversion(e.Y, t), c.typeName(u.Elem()))
 				}
+			case *types.Basic:
+				if isBoolean(u) {
+					if b, ok := analysis.BoolValue(e.X, c.p.Info.Info); ok && b {
+						return c.translateExpr(e.Y)
+					}
+					if b, ok := analysis.BoolValue(e.Y, c.p.Info.Info); ok && b {
+						return c.translateExpr(e.X)
+					}
+				}
 			}
 			return c.formatExpr("%s === %s", c.translateImplicitConversion(e.X, t), c.translateImplicitConversion(e.Y, t))
 		default:
diff --git a/compiler/statements.go b/compiler/statements.go
@@ -67,17 +67,25 @@ func (c *funcContext) translateStmt(stmt ast.Stmt, label *types.Label) {
 		if s.Init != nil {
 			c.translateStmt(s.Init, nil)
 		}
-		var translateCond func(cond ast.Expr) *expression
-		if s.Tag != nil {
+
+		tag := s.Tag
+		if tag == nil {
+			tag = ast.NewIdent("true")
+			c.p.Types[tag] = types.TypeAndValue{Type: types.Typ[types.Bool], Value: exact.MakeBool(true)}
+		}
+
+		if c.p.Types[tag].Value == nil {
 			refVar := c.newVariable("_ref")
-			c.Printf("%s = %s;", refVar, c.translateExpr(s.Tag))
-			translateCond = func(cond ast.Expr) *expression {
-				return c.translateExpr(&ast.BinaryExpr{
-					X:  c.newIdent(refVar, c.p.Types[s.Tag].Type),
-					Op: token.EQL,
-					Y:  cond,
-				})
-			}
+			c.Printf("%s = %s;", refVar, c.translateExpr(tag))
+			tag = c.newIdent(refVar, c.p.Types[tag].Type)
+		}
+
+		translateCond := func(cond ast.Expr) *expression {
+			return c.translateExpr(&ast.BinaryExpr{
+				X:  tag,
+				Op: token.EQL,
+				Y:  cond,
+			})
 		}
 		c.translateBranchingStmt(s.Body.List, true, translateCond, nil, label, c.Flattened[s])
 
diff --git a/tests/misc_test.go b/tests/misc_test.go
@@ -312,3 +312,14 @@ func TestMapAssign(t *testing.T) {
 		t.Fail()
 	}
 }
+
+func TestSwitchStatement(t *testing.T) {
+	zero := 0
+	var interfaceZero interface{} = zero
+	switch {
+	case interfaceZero:
+		t.Fail()
+	default:
+		// ok
+	}
+}
