pkg/proc: fix can not call method of an embedded filed directly (#1691)

`func (v *Variable) findMethod` should support for searching methods of an
embedded filed.

Fixes #1688

_fixtures/fncall.go

@@ -121,6 +121,19 @@ func noreturncall(n int) {
 	return
 }
 
+type Base struct{
+	y int
+}
+
+type Derived struct {
+	x int
+	Base
+}
+
+func (b *Base) Method() int {
+	return b.y
+}
+
 func main() {
 	one, two := 1, 2
 	intslice := []int{1, 2, 3}
@@ -142,9 +155,13 @@ func main() {
 	fn2ptrmeth := pa.PRcvr
 	var fn2nil func()
 
+	d := &Derived{3, Base{4}}
+
 	runtime.Breakpoint()
 	call1(one, two)
 	fn2clos(2)
 	strings.LastIndexByte(stringslice[1], 'w')
-	fmt.Println(one, two, zero, callpanic, callstacktrace, stringsJoin, intslice, stringslice, comma, a.VRcvr, a.PRcvr, pa, vable_a, vable_pa, pable_pa, fn2clos, fn2glob, fn2valmeth, fn2ptrmeth, fn2nil, ga, escapeArg, a2, square, intcallpanic, onetwothree, curriedAdd, getAStruct, getAStructPtr, getVRcvrableFromAStruct, getPRcvrableFromAStructPtr, getVRcvrableFromAStructPtr, pa2, noreturncall, str)
+	d.Method()
+	d.Base.Method()
+	fmt.Println(one, two, zero, callpanic, callstacktrace, stringsJoin, intslice, stringslice, comma, a.VRcvr, a.PRcvr, pa, vable_a, vable_pa, pable_pa, fn2clos, fn2glob, fn2valmeth, fn2ptrmeth, fn2nil, ga, escapeArg, a2, square, intcallpanic, onetwothree, curriedAdd, getAStruct, getAStructPtr, getVRcvrableFromAStruct, getPRcvrableFromAStructPtr, getVRcvrableFromAStructPtr, pa2, noreturncall, str, d)
 }

pkg/proc/eval.go

@@ -1847,7 +1847,32 @@ func (v *Variable) findMethod(mname string) (*Variable, error) {
 		}
 		return r, nil
 	}
+	return v.tryFindMethodInEmbeddedFields(mname)
+}
 
+func (v *Variable) tryFindMethodInEmbeddedFields(mname string) (*Variable, error) {
+	structVar := v.maybeDereference()
+	structVar.Name = v.Name
+	if structVar.Unreadable != nil {
+		return structVar, nil
+	}
+	switch t := structVar.RealType.(type) {
+	case *godwarf.StructType:
+		for _, field := range t.Field {
+			if field.Embedded {
+				// Recursively check for promoted fields on the embedded field
+				embeddedVar, err := structVar.toField(field)
+				if err != nil {
+					return nil, err
+				}
+				if embeddedMethod, err := embeddedVar.findMethod(mname); err != nil {
+					return nil, err
+				} else if embeddedMethod != nil {
+					return embeddedMethod, nil
+				}
+			}
+		}
+	}
 	return nil, nil
 }
 

service/test/variables_test.go

@@ -1181,6 +1181,8 @@ func TestCallFunction(t *testing.T) {
 		{`strings.Join(stringslice, ",")`, []string{`:string:"one,two,three"`}, nil},
 		{`strings.LastIndexByte(stringslice[1], 'w')`, []string{":int:1"}, nil},
 		{`strings.LastIndexByte(stringslice[1], 'o')`, []string{":int:2"}, nil},
+		{`d.Base.Method()`, []string{ `:int:4` }, nil },
+		{`d.Method()`, []string{ `:int:4` }, nil },
 	}
 
 	var testcases113 = []testCaseCallFunction{