internal/gcimporter: add support for reading unified IR export data

This does not include writing export data in the unified IR format.

Most of this change is an import of code from the Go implementation,
with minor tweaks and gaskets added.

This does not (yet) address the registry issue mentioned in golang/go#52163.

Updates golang/go#52163.

Change-Id: I98030e6c9ff35c6ff678b8a7ce9b653b18e65e17
Reviewed-on: https://go-review.googlesource.com/c/tools/+/412821
TryBot-Result: Gopher Robot <[email protected]>
Run-TryBot: David Chase <[email protected]>
Reviewed-by: Matthew Dempsky <[email protected]>
gopls-CI: kokoro <[email protected]>

Author: dr2chase

go/gcexportdata/gcexportdata.go

@@ -116,13 +116,29 @@ func Read(in io.Reader, fset *token.FileSet, imports map[string]*types.Package,
 	// The indexed export format starts with an 'i'; the older
 	// binary export format starts with a 'c', 'd', or 'v'
 	// (from "version"). Select appropriate importer.
-	if len(data) > 0 && data[0] == 'i' {
-		_, pkg, err := gcimporter.IImportData(fset, imports, data[1:], path)
-		return pkg, err
-	}
+	if len(data) > 0 {
+		switch data[0] {
+		case 'i':
+			_, pkg, err := gcimporter.IImportData(fset, imports, data[1:], path)
+			return pkg, err
+
+		case 'v', 'c', 'd':
+			_, pkg, err := gcimporter.BImportData(fset, imports, data, path)
+			return pkg, err
 
-	_, pkg, err := gcimporter.BImportData(fset, imports, data, path)
-	return pkg, err
+		case 'u':
+			_, pkg, err := gcimporter.UImportData(fset, imports, data[1:], path)
+			return pkg, err
+
+		default:
+			l := len(data)
+			if l > 10 {
+				l = 10
+			}
+			return nil, fmt.Errorf("unexpected export data with prefix %q for path %s", string(data[:l]), path)
+		}
+	}
+	return nil, fmt.Errorf("empty export data for %s", path)
 }
 
 // Write writes encoded type information for the specified package to out.

go/internal/gcimporter/gcimporter.go

@@ -181,8 +181,9 @@ func Import(packages map[string]*types.Package, path, srcDir string, lookup func
 	defer rc.Close()
 
 	var hdr string
+	var size int64
 	buf := bufio.NewReader(rc)
-	if hdr, _, err = FindExportData(buf); err != nil {
+	if hdr, size, err = FindExportData(buf); err != nil {
 		return
 	}
 
@@ -210,10 +211,27 @@ func Import(packages map[string]*types.Package, path, srcDir string, lookup func
 		// The indexed export format starts with an 'i'; the older
 		// binary export format starts with a 'c', 'd', or 'v'
 		// (from "version"). Select appropriate importer.
-		if len(data) > 0 && data[0] == 'i' {
-			_, pkg, err = IImportData(fset, packages, data[1:], id)
-		} else {
-			_, pkg, err = BImportData(fset, packages, data, id)
+		if len(data) > 0 {
+			switch data[0] {
+			case 'i':
+				_, pkg, err := IImportData(fset, packages, data[1:], id)
+				return pkg, err
+
+			case 'v', 'c', 'd':
+				_, pkg, err := BImportData(fset, packages, data, id)
+				return pkg, err
+
+			case 'u':
+				_, pkg, err := UImportData(fset, packages, data[1:size], id)
+				return pkg, err
+
+			default:
+				l := len(data)
+				if l > 10 {
+					l = 10
+				}
+				return nil, fmt.Errorf("unexpected export data with prefix %q for path %s", string(data[:l]), id)
+			}
 		}
 
 	default:

go/internal/gcimporter/gcimporter_test.go

@@ -45,6 +45,10 @@ func needsCompiler(t *testing.T, compiler string) {
 // compile runs the compiler on filename, with dirname as the working directory,
 // and writes the output file to outdirname.
 func compile(t *testing.T, dirname, filename, outdirname string) string {
+	return compilePkg(t, dirname, filename, outdirname, "p")
+}
+
+func compilePkg(t *testing.T, dirname, filename, outdirname, pkg string) string {
 	testenv.NeedsGoBuild(t)
 
 	// filename must end with ".go"
@@ -53,12 +57,12 @@ func compile(t *testing.T, dirname, filename, outdirname string) string {
 	}
 	basename := filepath.Base(filename)
 	outname := filepath.Join(outdirname, basename[:len(basename)-2]+"o")
-	cmd := exec.Command("go", "tool", "compile", "-p=p", "-o", outname, filename)
+	cmd := exec.Command("go", "tool", "compile", "-p="+pkg, "-o", outname, filename)
 	cmd.Dir = dirname
 	out, err := cmd.CombinedOutput()
 	if err != nil {
 		t.Logf("%s", out)
-		t.Fatalf("go tool compile %s failed: %s", filename, err)
+		t.Fatalf("(cd %v && %v) failed: %s", cmd.Dir, cmd, err)
 	}
 	return outname
 }
@@ -140,7 +144,11 @@ func TestImportTestdata(t *testing.T) {
 		// For now, we just test the presence of a few packages
 		// that we know are there for sure.
 		got := fmt.Sprint(pkg.Imports())
-		for _, want := range []string{"go/ast", "go/token"} {
+		wants := []string{"go/ast", "go/token"}
+		if unifiedIR {
+			wants = []string{"go/ast"}
+		}
+		for _, want := range wants {
 			if !strings.Contains(got, want) {
 				t.Errorf(`Package("exports").Imports() = %s, does not contain %s`, got, want)
 			}
@@ -364,6 +372,14 @@ func verifyInterfaceMethodRecvs(t *testing.T, named *types.Named, level int) {
 		return // not an interface
 	}
 
+	// The unified IR importer always sets interface method receiver
+	// parameters to point to the Interface type, rather than the Named.
+	// See #49906.
+	var want types.Type = named
+	if unifiedIR {
+		want = iface
+	}
+
 	// check explicitly declared methods
 	for i := 0; i < iface.NumExplicitMethods(); i++ {
 		m := iface.ExplicitMethod(i)
@@ -372,8 +388,8 @@ func verifyInterfaceMethodRecvs(t *testing.T, named *types.Named, level int) {
 			t.Errorf("%s: missing receiver type", m)
 			continue
 		}
-		if recv.Type() != named {
-			t.Errorf("%s: got recv type %s; want %s", m, recv.Type(), named)
+		if recv.Type() != want {
+			t.Errorf("%s: got recv type %s; want %s", m, recv.Type(), want)
 		}
 	}
 
@@ -451,7 +467,7 @@ func TestIssue13566(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	compile(t, "testdata", "a.go", testoutdir)
+	compilePkg(t, "testdata", "a.go", testoutdir, apkg(testoutdir))
 	compile(t, testoutdir, bpath, testoutdir)
 
 	// import must succeed (test for issue at hand)
@@ -611,13 +627,22 @@ func TestIssue51836(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	compile(t, dir, "a.go", testoutdir)
+	compilePkg(t, dir, "a.go", testoutdir, apkg(testoutdir))
 	compile(t, testoutdir, bpath, testoutdir)
 
 	// import must succeed (test for issue at hand)
 	_ = importPkg(t, "./testdata/aa", tmpdir)
 }
 
+// apkg returns the package "a" prefixed by (as a package) testoutdir
+func apkg(testoutdir string) string {
+	apkg := testoutdir + "/a"
+	if os.PathSeparator != '/' {
+		apkg = strings.ReplaceAll(apkg, string(os.PathSeparator), "/")
+	}
+	return apkg
+}
+
 func importPkg(t *testing.T, path, srcDir string) *types.Package {
 	pkg, err := Import(make(map[string]*types.Package), path, srcDir, nil)
 	if err != nil {

go/internal/gcimporter/unified_no.go

@@ -0,0 +1,10 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !(go1.18 && goexperiment.unified)
+// +build !go1.18 !goexperiment.unified
+
+package gcimporter
+
+const unifiedIR = false

go/internal/gcimporter/unified_yes.go

@@ -0,0 +1,10 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build go1.18 && goexperiment.unified
+// +build go1.18,goexperiment.unified
+
+package gcimporter
+
+const unifiedIR = true

go/internal/gcimporter/ureader_no.go

@@ -0,0 +1,19 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !go1.18
+// +build !go1.18
+
+package gcimporter
+
+import (
+	"fmt"
+	"go/token"
+	"go/types"
+)
+
+func UImportData(fset *token.FileSet, imports map[string]*types.Package, data []byte, path string) (_ int, pkg *types.Package, err error) {
+	err = fmt.Errorf("go/tools compiled with a Go version earlier than 1.18 cannot read unified IR export data")
+	return
+}