Fixing serialization of files for go1.20

Author: grantnelson-wf

compiler/sources/serializer.go

@@ -104,15 +104,15 @@ func (s *Sources) Read(decode func(any) error) error {
 	if err := decode(&s.Files); err != nil {
 		return err
 	}
-	for _, f := range s.Files {
-		unpackFile(f)
-	}
 	if s.FileSet == nil {
 		s.FileSet = token.NewFileSet()
 	}
 	if err := s.FileSet.Read(decode); err != nil {
 		return err
 	}
+	for _, f := range s.Files {
+		unpackFile(f, s.FileSet)
+	}
 	if err := decode(&s.JSFiles); err != nil {
 		return err
 	}
@@ -153,9 +153,14 @@ func prepareFile(file *ast.File) *ast.File {
 	return file
 }
 
+// finishUnpackingFile is an optional function that is run after unpacking
+// a file during deserialization to perform any additional processing needed
+// for specific Go versions.
+var finishUnpackingFile func(f *ast.File, fs *token.FileSet)
+
 // unpackFile is run when deserializing a source to reconstruct the
 // Imports and Comments fields that were cleared when serializing the file.
-func unpackFile(file *ast.File) {
+func unpackFile(file *ast.File, fs *token.FileSet) {
 	var imports []*ast.ImportSpec
 	var comments []*ast.CommentGroup
 	ast.Inspect(file, func(n ast.Node) bool {
@@ -169,6 +174,9 @@ func unpackFile(file *ast.File) {
 	})
 	file.Imports = imports
 	file.Comments = comments
+	if finishUnpackingFile != nil {
+		finishUnpackingFile(file, fs)
+	}
 }
 
 // prepareGob registers the AST node types with the gob package
@@ -181,6 +189,13 @@ func unpackFile(file *ast.File) {
 // an interface field in the AST.
 var prepareGob = func() func() {
 	registerTypes := func() {
+		gob.Register(token.NoPos)
+		gob.Register(&ast.File{})
+		gob.Register(&ast.Comment{})
+		gob.Register(&ast.CommentGroup{})
+		gob.Register(&ast.Field{})
+		gob.Register(&ast.FieldList{})
+
 		// Register expression nodes.
 		gob.Register(&ast.BadExpr{})
 		gob.Register(&ast.Ident{})

compiler/sources/serializer_120.go

@@ -0,0 +1,36 @@
+//go:build go1.20
+
+package sources
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+)
+
+func init() {
+	finishUnpackingFile = finishUnpackingFile120
+}
+
+// finishUnpackingFile120 performs additional processing needed
+// after unpacking a file during deserialization for Go 1.20+.
+//
+// Specifically, it sets the FileStart and FileEnd fields
+// that were added in Go 1.20 to ensure correct position calculations
+// used by the type checker (when checking file versions).
+// For some reason the gob encoding/decoding isn't automatically setting this.
+//
+// TODO(grantnelson-wf): Determine why the gob encoding/decoding isn't doing this automatically.
+func finishUnpackingFile120(f *ast.File, fs *token.FileSet) {
+	fp := fs.File(f.Pos())
+	if fp == nil {
+		panic(fmt.Errorf(`failed to find token.File for ast.File (in %s at %d) during unpacking`, f.Name.Name, f.Pos()))
+	}
+
+	if !f.FileStart.IsValid() {
+		f.FileStart = token.Pos(fp.Base())
+	}
+	if !f.FileEnd.IsValid() {
+		f.FileEnd = token.Pos(fp.Base() + fp.Size())
+	}
+}

compiler/sources/sources.go

@@ -1,7 +1,6 @@
 package sources
 
 import (
-	"fmt"
 	"go/ast"
 	"go/token"
 	"go/types"
@@ -138,21 +137,6 @@ func (s *Sources) TypeCheck(importer Importer, sizes types.Sizes, tContext *type
 		Sizes:    sizes,
 		Error:    func(err error) { typeErrs = typeErrs.AppendDistinct(err) },
 	}
-
-	if s.ImportPath == `internal/goarch` { // TODO(grantnelson-wf): Remove
-		fmt.Println("Type checking package:", s.ImportPath)
-		s.FileSet.Iterate(func(f *token.File) bool {
-			fmt.Println(`   File:`, f.Name(), `Base:`, f.Base(), `Size:`, f.Size())
-			return true
-		})
-		for _, f := range s.Files {
-			fmt.Println(`   Pos:`, f.Pos(), `End:`, f.End())
-			if s.FileSet.File(f.Pos()) == nil {
-				fmt.Println(`      Failed to find file`)
-			}
-		}
-	}
-
 	typesPkg, err := config.Check(s.ImportPath, s.FileSet, s.Files, typesInfo)
 	// If we encountered any import errors, it is likely that the other type errors
 	// are not meaningful and would be resolved by fixing imports. Return them