proc: make PushPackageVarOrSelect check local variables first

Fixes #4179

Author: aarzilli

_fixtures/internal/issue4179helper/test.go

@@ -0,0 +1,6 @@
+package issue4179helper
+
+type Test struct {
+	Name interface{}
+	Age  int
+}

_fixtures/testvariables2.go

@@ -9,6 +9,8 @@ import (
 	"runtime"
 	"time"
 	"unsafe"
+
+	"github.com/go-delve/delve/_fixtures/internal/issue4179helper"
 )
 
 type (
@@ -175,6 +177,10 @@ type OnlyUsedInInterface struct {
 
 type Message []byte
 
+type Config struct {
+	*issue4179helper.Test
+}
+
 var _ I = (*W2)(nil)
 
 type pptr *pptr
@@ -433,6 +439,8 @@ func main() {
 
 	var iface7 interface{} = OnlyUsedInInterface{"test"}
 
+	issue4179helper := &Config{Test: &issue4179helper.Test{}}
+
 	var amb1 = 1
 	runtime.Breakpoint()
 	for amb1 := 0; amb1 < 10; amb1++ {
@@ -443,5 +451,5 @@ func main() {
 	longslice := make([]int, 100, 100)
 
 	runtime.Breakpoint()
-	fmt.Println(i1, i2, i3, p1, pp1, amb1, s1, s3, a0, a1, p2, p3, s2, as1, str1, f1, fn1, fn2, nilslice, nilptr, ch1, chnil, m1, mnil, m2, m3, m4, m5, upnil, up1, i4, i5, i6, err1, err2, errnil, iface1, iface2, ifacenil, arr1, parr, cpx1, const1, iface3, iface4, recursive1, recursive1.x, iface5, iface2fn1, iface2fn2, bencharr, benchparr, mapinf, mainMenu, b, b2, sd, anonstruct1, anonstruct2, anoniface1, anonfunc, mapanonstruct1, ifacearr, efacearr, ni8, ni16, ni32, ni64, pinf, ninf, nan, zsvmap, zsslice, zsvar, tm, rettm, errtypednil, emptyslice, emptymap, byteslice, bytestypeslice, runeslice, bytearray, bytetypearray, runearray, longstr, nilstruct, as2, as2.NonPointerReceiverMethod, s4, iface2map, issue1578, ll, unread, w2, w3, w4, w5, longarr, longslice, val, m6, m7, cl, tim1, tim2, typedstringvar, namedA1, namedA2, astructName1(namedA2), badslice, tim3, int3chan, longbyteslice, enum1, enum2, enum3, enum4, enum5, enum6, zeropoint4, mlarge, messageVar, iface7)
+	fmt.Println(i1, i2, i3, p1, pp1, amb1, s1, s3, a0, a1, p2, p3, s2, as1, str1, f1, fn1, fn2, nilslice, nilptr, ch1, chnil, m1, mnil, m2, m3, m4, m5, upnil, up1, i4, i5, i6, err1, err2, errnil, iface1, iface2, ifacenil, arr1, parr, cpx1, const1, iface3, iface4, recursive1, recursive1.x, iface5, iface2fn1, iface2fn2, bencharr, benchparr, mapinf, mainMenu, b, b2, sd, anonstruct1, anonstruct2, anoniface1, anonfunc, mapanonstruct1, ifacearr, efacearr, ni8, ni16, ni32, ni64, pinf, ninf, nan, zsvmap, zsslice, zsvar, tm, rettm, errtypednil, emptyslice, emptymap, byteslice, bytestypeslice, runeslice, bytearray, bytetypearray, runearray, longstr, nilstruct, as2, as2.NonPointerReceiverMethod, s4, iface2map, issue1578, ll, unread, w2, w3, w4, w5, longarr, longslice, val, m6, m7, cl, tim1, tim2, typedstringvar, namedA1, namedA2, astructName1(namedA2), badslice, tim3, int3chan, longbyteslice, enum1, enum2, enum3, enum4, enum5, enum6, zeropoint4, mlarge, messageVar, iface7, issue4179helper)
 }

pkg/proc/eval.go

@@ -916,7 +916,9 @@ func (s *evalStack) fncallPeek() *functionCallState {
 
 func (s *evalStack) pushErr(v *Variable, err error) {
 	s.err = err
-	s.stack = append(s.stack, v)
+	if err == nil {
+		s.stack = append(s.stack, v)
+	}
 }
 
 // eval evaluates ops. When it returns if callInjectionContinue is set the
@@ -1148,27 +1150,30 @@ func (stack *evalStack) executeOp() {
 		stack.push(nilVariable)
 
 	case *evalop.PushPackageVarOrSelect:
-		v, err := scope.findGlobal(op.Name, op.Sel)
-		if err != nil && !isSymbolNotFound(err) {
-			stack.err = err
-			return
-		}
-		if v != nil {
-			stack.push(v)
-		} else {
-			if op.NameIsString {
-				stack.err = fmt.Errorf("%q (type string) is not a struct", op.Name)
-				return
-			}
-			found := stack.pushIdent(scope, op.Name)
+		var savedErr error
+		found := false
+		if !op.NameIsString {
+			found = stack.pushIdent(scope, op.Name)
 			if stack.err != nil {
-				return
+				savedErr = stack.err
+				stack.err = nil
+				found = false
 			}
 			if found {
 				scope.evalStructSelector(&evalop.Select{Name: op.Sel}, stack)
-			} else {
-				stack.err = fmt.Errorf("could not find symbol value for %s", op.Name)
+				if stack.err != nil {
+					savedErr = stack.err
+					stack.err = nil
+					found = false
+				}
+			}
+		}
+		if !found {
+			v, err := scope.findGlobal(op.Name, op.Sel)
+			if err != nil && savedErr != nil {
+				err = savedErr
 			}
+			stack.pushErr(v, err)
 		}
 
 	case *evalop.PushIdent:

pkg/proc/variables_test.go

@@ -909,7 +909,7 @@ func getEvalExpressionTestCases() []varTest {
 		{"(*afunc)(2)", false, "", "", "", errors.New("*")},
 		{"unknownthing(2)", false, "", "", "", altErrors("function calls not allowed without using 'call'", "could not find symbol value for unknownthing")},
 		{"(*unknownthing)(2)", false, "", "", "", altErrors("function calls not allowed without using 'call'", "could not find symbol value for unknownthing")},
-		{"(*strings.Split)(2)", false, "", "", "", altErrors("function calls not allowed without using 'call'", "could not find symbol value for strings")},
+		{"(*strings.Split)(2)", false, "", "", "", altErrors("function calls not allowed without using 'call'", "could not find symbol value for strings", "could not find symbol strings.Split")},
 
 		// pretty printing special types
 		{"tim1", false, `time.Time(1977-05-25T18:00:00Z)…`, `time.Time(1977-05-25T18:00:00Z)…`, "time.Time", nil},
@@ -947,6 +947,9 @@ func getEvalExpressionTestCases() []varTest {
 		{`*(*uint)(unsafe.Pointer(p1))`, false, `1`, `1`, "uint", nil},
 		{`*(*uint)(unsafe.Pointer(&i1))`, false, `1`, `1`, "uint", nil},
 
+		// issue #4179 local variable shadows package
+		{`issue4179helper.Test`, false, `*github.com/go-delve/delve/_fixtures/internal/issue4179helper.Test {Name: interface {} nil, Age: 0}`, `("*github.com/go-delve/delve/_fixtures/internal/issue4179helper.Test")(…`, "*github.com/go-delve/delve/_fixtures/internal/issue4179helper.Test", nil},
+
 		// Malformed values
 		{`badslice`, false, `(unreadable non-zero length array with nil base)`, `(unreadable non-zero length array with nil base)`, "[]int", nil},
 	}
@@ -1336,7 +1339,7 @@ func TestCallFunction(t *testing.T) {
 		{"x.CallMe()", nil, nil, 0},
 		{"x2.CallMe(5)", []string{":int:25"}, nil, 0},
 
-		{"\"delve\".CallMe()", nil, errors.New("\"delve\" (type string) is not a struct"), 0},
+		{"\"delve\".CallMe()", nil, altErrors("\"delve\" (type string) is not a struct", "could not find symbol delve.CallMe"), 0},
 
 		// Nested function calls tests