allow printing of unexported fields and methods

Also guard against panics in the eval library.

lib/debug.go

@@ -8,6 +8,7 @@ import (
 	"strings"
 	"sync/atomic"
 	"unicode"
+	"unsafe"
 
 	"github.com/mailgun/godebug/Godeps/_workspace/src/github.com/0xfaded/eval"
 )
@@ -334,6 +335,13 @@ func waitForInput(scope *Scope, line int) {
 				default:
 					s := make([]string, len(results))
 					for i, r := range results {
+						if !r.CanInterface() {
+							if r.CanAddr() {
+								r = reflect.NewAt(r.Type(), unsafe.Pointer(r.UnsafeAddr())).Elem()
+							} else {
+								s[i] = fmt.Sprintf("godebug cannot access this field or method. Sorry! Let us know about it at github.com/mailgun/godebug/issues/new and we'll fix it")
+							}
+						}
 						ifc := r.Interface()
 						if _, ok := ifc.(*eval.ConstNumber); ok {
 							s[i] = fmt.Sprintf("%v", ifc)
@@ -357,10 +365,16 @@ func waitForInput(scope *Scope, line int) {
 
 // goEval runs eval.EvalEnv in a new goroutine. This is a quick hack to
 // keep the debugger from pausing while running eval.EvalEnv.
+// It is also used to recover from panics in the eval library.
 func goEval(expr string, env eval.Env) (result []reflect.Value, panik error, compileErrors []error) {
 	c := make(chan struct{})
 	go func() {
-		defer close(c)
+		defer func() {
+			if r := recover(); r != nil {
+				panik = fmt.Errorf("%v", r)
+			}
+			close(c)
+		}()
 		result, panik, compileErrors = eval.EvalEnv(expr, env)
 	}()
 	<-c

testdata/single-file-tests/regression-in.go

@@ -123,10 +123,6 @@ func a() int {
 	return 0
 }
 
-func init() {
-	switchInit()
-}
-
 // Don't repeat switch initialization, use correct scope inside switch.
 func switchInit() {
 	_ = "breakpoint"
@@ -141,3 +137,14 @@ func constants() {
 	const tooSmallForInt32 = (-1 << 31) - 1
 	const tooBigForInt64 = 1 << 63
 }
+
+func unexportedField() {
+	var f struct{ bar int }
+	f.bar = 5
+	_ = "breakpoint"
+}
+
+func init() {
+	switchInit()
+	unexportedField()
+}

testdata/single-file-tests/regression-out.go

@@ -283,31 +283,27 @@ func a() int {
 	return 0
 }
 
-func init() {
-	switchInit()
-}
-
 func switchInit() {
 	ctx, _ok := godebug.EnterFunc(switchInit)
 	if !_ok {
 		return
 	}
 	defer godebug.ExitFunc(ctx)
 	godebug.SetTraceGen(ctx)
-	godebug.Line(ctx, regression_in_go_scope, 132)
+	godebug.Line(ctx, regression_in_go_scope, 128)
 	{
-		godebug.Line(ctx, regression_in_go_scope, 133)
+		godebug.Line(ctx, regression_in_go_scope, 129)
 		a := a()
 		scope := regression_in_go_scope.EnteringNewChildScope()
 		scope.Declare("a", &a)
 		switch {
 		default:
-			godebug.Line(ctx, scope, 134)
-			godebug.Line(ctx, scope, 135)
+			godebug.Line(ctx, scope, 130)
+			godebug.Line(ctx, scope, 131)
 			_ = a
 		}
 	}
-	godebug.Line(ctx, regression_in_go_scope, 137)
+	godebug.Line(ctx, regression_in_go_scope, 133)
 	_ = "the variable a should be out of scope"
 }
 
@@ -317,15 +313,37 @@ func constants() {
 		return
 	}
 	defer godebug.ExitFunc(ctx)
-	godebug.Line(ctx, regression_in_go_scope, 141)
+	godebug.Line(ctx, regression_in_go_scope, 137)
 	const tooSmallForInt32 = (-1 << 31) - 1
 	scope := regression_in_go_scope.EnteringNewChildScope()
 	scope.Constant("tooSmallForInt32", int64(tooSmallForInt32))
-	godebug.Line(ctx, scope, 142)
+	godebug.Line(ctx, scope, 138)
 	const tooBigForInt64 = 1 << 63
 	scope.Constant("tooBigForInt64", uint64(tooBigForInt64))
 }
 
+func unexportedField() {
+	ctx, _ok := godebug.EnterFunc(unexportedField)
+	if !_ok {
+		return
+	}
+	defer godebug.ExitFunc(ctx)
+	godebug.Line(ctx, regression_in_go_scope, 142)
+	var f struct{ bar int }
+	scope := regression_in_go_scope.EnteringNewChildScope()
+	scope.Declare("f", &f)
+	godebug.Line(ctx, scope, 143)
+	f.bar = 5
+	godebug.SetTraceGen(ctx)
+	godebug.Line(ctx, scope, 144)
+
+}
+
+func init() {
+	switchInit()
+	unexportedField()
+}
+
 var regression_in_go_contents = `package main
 
 func main() {
@@ -451,10 +469,6 @@ func a() int {
 	return 0
 }
 
-func init() {
-	switchInit()
-}
-
 // Don't repeat switch initialization, use correct scope inside switch.
 func switchInit() {
 	_ = "breakpoint"
@@ -469,6 +483,17 @@ func constants() {
 	const tooSmallForInt32 = (-1 << 31) - 1
 	const tooBigForInt64 = 1 << 63
 }
+
+func unexportedField() {
+	var f struct{ bar int }
+	f.bar = 5
+	_ = "breakpoint"
+}
+
+func init() {
+	switchInit()
+	unexportedField()
+}
 `
 
 
@@ -492,6 +517,7 @@ func init() {
 		"a": a,
 		"switchInit": switchInit,
 		"constants": constants,
+		"unexportedField": unexportedField,
 
 	}
 }

testdata/single-file-tests/regression-session.txt

@@ -12,6 +12,10 @@
 (godebug) p a
 undefined: a
 (godebug) continue
+-> _ = "breakpoint"
+(godebug) p f.bar
+5
+(godebug) continue
 hello
 test
 -> _ = "breakpoint"