proc: early fixes for Go 1.26 (#4070)

Change 091ff506 fixed loading the direct flag for Go 1.26 when we go
from a runtime type to a dwarf type, we also did the same check from
the dwarf type to a runtime type when converting variables into
'interface {}'.
This commit deletes unifies the two code paths deleting the one that
wasn't updated.

Fixes the tests on tip.

pkg/proc/stepping_test.go

@@ -1227,7 +1227,7 @@ func TestRangeOverFuncNextInlined(t *testing.T) {
 	if !goversion.VersionAfterOrEqual(runtime.Version(), 1, 23) {
 		t.Skip("N/A")
 	}
-	if goversion.VersionAfterOrEqual(runtime.Version(), 1, 24) && !goversion.VersionAfterOrEqual(runtime.Version(), 1, 26) {
+	if goversion.VersionAfterOrEqual(runtime.Version(), 1, 24) && !goversion.VersionAfterOrEqual(runtime.Version(), 1, 27) {
 		t.Skip("broken due to inlined symbol names")
 	}
 

pkg/proc/types.go

@@ -95,30 +95,7 @@ func RuntimeTypeToDIE(_type *Variable, dataAddr uint64, mds []ModuleData) (typ g
 				if err != nil {
 					return nil, false, fmt.Errorf("invalid interface type: %v", err)
 				}
-				// Figure out whether interfaces with this concrete type are direct or not.
+				return typ, getRuntimeTypeDirect(_type), nil
-				// Go 1.26 and beyond have this flag in the TFlag field.
-				// Go 1.25 and earlier have this flag in the Kind field.
-				// If either flag is set, consider it direct.
-				var direct bool
-				if tflagField := _type.loadFieldNamed("TFlag"); tflagField != nil && tflagField.Value != nil {
-					tflag, _ := constant.Int64Val(tflagField.Value)
-					if tflag&tflagDirectIface != 0 {
-						direct = true
-					}
-				}
-				if kindField := _type.loadFieldNamed("kind"); kindField != nil && kindField.Value != nil {
-					kind, _ := constant.Int64Val(kindField.Value)
-					if kind&kindDirectIface != 0 {
-						direct = true
-					}
-				} else if kindField := _type.loadFieldNamed("Kind_"); kindField != nil && kindField.Value != nil {
-					kind, _ := constant.Int64Val(kindField.Value)
-					if kind&kindDirectIface != 0 {
-						direct = true
-					}
-				}
-
-				return typ, direct, nil
 			}
 		}
 	}
@@ -159,30 +136,30 @@ func resolveParametricType(bi *BinaryInfo, mem MemoryReadWriter, t godwarf.Type,
 	return typ, nil
 }
 
-func dwarfToRuntimeType(bi *BinaryInfo, mem MemoryReadWriter, typ godwarf.Type) (typeAddr uint64, typeKind uint64, found bool, err error) {
+func dwarfToRuntimeType(bi *BinaryInfo, mem MemoryReadWriter, typ godwarf.Type) (typeAddr uint64, direct, found bool, err error) {
 	so := bi.typeToImage(typ)
 	rdr := so.DwarfReader()
 	rdr.Seek(typ.Common().Offset)
 	e, err := rdr.Next()
 	if err != nil {
-		return 0, 0, false, err
+		return 0, false, false, err
 	}
 	off, ok := e.Val(godwarf.AttrGoRuntimeType).(uint64)
 	if !ok {
-		return 0, 0, false, nil
+		return 0, false, false, nil
 	}
 
 	mds, err := LoadModuleData(bi, mem)
 	if err != nil {
-		return 0, 0, false, err
+		return 0, false, false, err
 	}
 
 	md := bi.imageToModuleData(so, mds)
 	if md == nil {
 		if so.index > 0 {
-			return 0, 0, false, fmt.Errorf("could not find module data for type %s (shared object: %q)", typ, so.Path)
+			return 0, false, false, fmt.Errorf("could not find module data for type %s (shared object: %q)", typ, so.Path)
 		} else {
-			return 0, 0, false, fmt.Errorf("could not find module data for type %s", typ)
+			return 0, false, false, fmt.Errorf("could not find module data for type %s", typ)
 		}
 	}
 
@@ -190,19 +167,35 @@ func dwarfToRuntimeType(bi *BinaryInfo, mem MemoryReadWriter, typ godwarf.Type)
 
 	rtyp, err := bi.findType(bi.runtimeTypeTypename())
 	if err != nil {
-		return 0, 0, false, err
+		return 0, false, false, err
 	}
 	_type := newVariable("", typeAddr, rtyp, bi, mem)
-	kindv := _type.loadFieldNamed("kind")
+
-	if kindv == nil || kindv.Unreadable != nil || kindv.Kind != reflect.Uint {
+	return typeAddr, getRuntimeTypeDirect(_type), true, nil
-		kindv = _type.loadFieldNamed("Kind_")
+}
-	}
+
-	if kindv == nil {
+// getRuntimeTypeDirect returns a bool that says if the type in _type can be stored directly into an interface variable.
-		return 0, 0, false, fmt.Errorf("unreadable interface type (no kind field)")
+func getRuntimeTypeDirect(_type *Variable) bool {
-	}
+	// Go 1.26 and beyond have this flag in the TFlag field.
-	if kindv.Unreadable != nil || kindv.Kind != reflect.Uint {
+	// Go 1.25 and earlier have this flag in the Kind field.
-		return 0, 0, false, fmt.Errorf("unreadable interface type: %v", kindv.Unreadable)
+	// If either flag is set, consider it direct.
-	}
+	var direct bool
-	typeKind, _ = constant.Uint64Val(kindv.Value)
+	if tflagField := _type.loadFieldNamed("TFlag"); tflagField != nil && tflagField.Value != nil {
-	return typeAddr, typeKind, true, nil
+		tflag, _ := constant.Int64Val(tflagField.Value)
+		if tflag&tflagDirectIface != 0 {
+			direct = true
+		}
+	}
+	if kindField := _type.loadFieldNamed("kind"); kindField != nil && kindField.Value != nil {
+		kind, _ := constant.Int64Val(kindField.Value)
+		if kind&kindDirectIface != 0 {
+			direct = true
+		}
+	} else if kindField := _type.loadFieldNamed("Kind_"); kindField != nil && kindField.Value != nil {
+		kind, _ := constant.Int64Val(kindField.Value)
+		if kind&kindDirectIface != 0 {
+			direct = true
+		}
+	}
+	return direct
 }

pkg/proc/variables.go

@@ -1514,11 +1514,11 @@ func convertToEface(srcv, dstv *Variable) error {
 		dstv.writeEmptyInterface(_type.Addr, data)
 		return nil
 	}
-	typeAddr, typeKind, runtimeTypeFound, err := dwarfToRuntimeType(srcv.bi, srcv.mem, srcv.RealType)
+	typeAddr, direct, runtimeTypeFound, err := dwarfToRuntimeType(srcv.bi, srcv.mem, srcv.RealType)
 	if err != nil {
 		return fmt.Errorf("can not convert value of type %s to %s: %v", srcv.DwarfType.String(), dstv.DwarfType.String(), err)
 	}
-	if !runtimeTypeFound || typeKind&kindDirectIface == 0 {
+	if !runtimeTypeFound || !direct {
 		return &typeConvErr{srcv.DwarfType, dstv.RealType}
 	}
 	return dstv.writeEmptyInterface(typeAddr, srcv)