Update dependencies (#1784)

8 files changed, 291 insertions, 140 deletions

diff --git a/vendor/golang.org/x/tools/go/internal/gcimporter/bexport.go b/vendor/golang.org/x/tools/go/internal/gcimporter/bexport.go
index 072005af..0a3cdb9a 100644
--- a/vendor/golang.org/x/tools/go/internal/gcimporter/bexport.go
+++ b/vendor/golang.org/x/tools/go/internal/gcimporter/bexport.go
@@ -34,9 +34,6 @@ import (
 // (suspected) format errors, and whenever a change is made to the format.
 const debugFormat = false // default: false
 
-// If trace is set, debugging output is printed to std out.
-const trace = false // default: false
-
 // Current export format version. Increase with each format change.
 // Note: The latest binary (non-indexed) export format is at version 6.
 //       This exporter is still at level 4, but it doesn't matter since
diff --git a/vendor/golang.org/x/tools/go/internal/gcimporter/bimport.go b/vendor/golang.org/x/tools/go/internal/gcimporter/bimport.go
index b0231200..b85de014 100644
--- a/vendor/golang.org/x/tools/go/internal/gcimporter/bimport.go
+++ b/vendor/golang.org/x/tools/go/internal/gcimporter/bimport.go
@@ -74,9 +74,10 @@ func BImportData(fset *token.FileSet, imports map[string]*types.Package, data []
 		pathList:   []string{""}, // empty string is mapped to 0
 		fake: fakeFileSet{
 			fset:  fset,
-			files: make(map[string]*token.File),
+			files: make(map[string]*fileInfo),
 		},
 	}
+	defer p.fake.setLines() // set lines for files in fset
 
 	// read version info
 	var versionstr string
@@ -338,37 +339,49 @@ func (p *importer) pos() token.Pos {
 // Synthesize a token.Pos
 type fakeFileSet struct {
 	fset  *token.FileSet
-	files map[string]*token.File
+	files map[string]*fileInfo
 }
 
+type fileInfo struct {
+	file     *token.File
+	lastline int
+}
+
+const maxlines = 64 * 1024
+
 func (s *fakeFileSet) pos(file string, line, column int) token.Pos {
 	// TODO(mdempsky): Make use of column.
 
-	// Since we don't know the set of needed file positions, we
-	// reserve maxlines positions per file.
-	const maxlines = 64 * 1024
+	// Since we don't know the set of needed file positions, we reserve maxlines
+	// positions per file. We delay calling token.File.SetLines until all
+	// positions have been calculated (by way of fakeFileSet.setLines), so that
+	// we can avoid setting unnecessary lines. See also golang/go#46586.
 	f := s.files[file]
 	if f == nil {
-		f = s.fset.AddFile(file, -1, maxlines)
+		f = &fileInfo{file: s.fset.AddFile(file, -1, maxlines)}
 		s.files[file] = f
-		// Allocate the fake linebreak indices on first use.
-		// TODO(adonovan): opt: save ~512KB using a more complex scheme?
-		fakeLinesOnce.Do(func() {
-			fakeLines = make([]int, maxlines)
-			for i := range fakeLines {
-				fakeLines[i] = i
-			}
-		})
-		f.SetLines(fakeLines)
 	}
-
 	if line > maxlines {
 		line = 1
 	}
+	if line > f.lastline {
+		f.lastline = line
+	}
 
-	// Treat the file as if it contained only newlines
-	// and column=1: use the line number as the offset.
-	return f.Pos(line - 1)
+	// Return a fake position assuming that f.file consists only of newlines.
+	return token.Pos(f.file.Base() + line - 1)
+}
+
+func (s *fakeFileSet) setLines() {
+	fakeLinesOnce.Do(func() {
+		fakeLines = make([]int, maxlines)
+		for i := range fakeLines {
+			fakeLines[i] = i
+		}
+	})
+	for _, f := range s.files {
+		f.file.SetLines(fakeLines[:f.lastline])
+	}
 }
 
 var (
diff --git a/vendor/golang.org/x/tools/go/internal/gcimporter/exportdata.go b/vendor/golang.org/x/tools/go/internal/gcimporter/exportdata.go
index f33dc561..f6437feb 100644
--- a/vendor/golang.org/x/tools/go/internal/gcimporter/exportdata.go
+++ b/vendor/golang.org/x/tools/go/internal/gcimporter/exportdata.go
@@ -16,7 +16,7 @@ import (
 	"strings"
 )
 
-func readGopackHeader(r *bufio.Reader) (name string, size int, err error) {
+func readGopackHeader(r *bufio.Reader) (name string, size int64, err error) {
 	// See $GOROOT/include/ar.h.
 	hdr := make([]byte, 16+12+6+6+8+10+2)
 	_, err = io.ReadFull(r, hdr)
@@ -28,7 +28,8 @@ func readGopackHeader(r *bufio.Reader) (name string, size int, err error) {
 		fmt.Printf("header: %s", hdr)
 	}
 	s := strings.TrimSpace(string(hdr[16+12+6+6+8:][:10]))
-	size, err = strconv.Atoi(s)
+	length, err := strconv.Atoi(s)
+	size = int64(length)
 	if err != nil || hdr[len(hdr)-2] != '`' || hdr[len(hdr)-1] != '\n' {
 		err = fmt.Errorf("invalid archive header")
 		return
@@ -42,8 +43,8 @@ func readGopackHeader(r *bufio.Reader) (name string, size int, err error) {
 // file by reading from it. The reader must be positioned at the
 // start of the file before calling this function. The hdr result
 // is the string before the export data, either "$$" or "$$B".
-//
-func FindExportData(r *bufio.Reader) (hdr string, err error) {
+// The size result is the length of the export data in bytes, or -1 if not known.
+func FindExportData(r *bufio.Reader) (hdr string, size int64, err error) {
 	// Read first line to make sure this is an object file.
 	line, err := r.ReadSlice('\n')
 	if err != nil {
@@ -54,7 +55,7 @@ func FindExportData(r *bufio.Reader) (hdr string, err error) {
 	if string(line) == "!<arch>\n" {
 		// Archive file. Scan to __.PKGDEF.
 		var name string
-		if name, _, err = readGopackHeader(r); err != nil {
+		if name, size, err = readGopackHeader(r); err != nil {
 			return
 		}
 
@@ -70,6 +71,7 @@ func FindExportData(r *bufio.Reader) (hdr string, err error) {
 			err = fmt.Errorf("can't find export data (%v)", err)
 			return
 		}
+		size -= int64(len(line))
 	}
 
 	// Now at __.PKGDEF in archive or still at beginning of file.
@@ -86,8 +88,12 @@ func FindExportData(r *bufio.Reader) (hdr string, err error) {
 			err = fmt.Errorf("can't find export data (%v)", err)
 			return
 		}
+		size -= int64(len(line))
 	}
 	hdr = string(line)
+	if size < 0 {
+		size = -1
+	}
 
 	return
 }
diff --git a/vendor/golang.org/x/tools/go/internal/gcimporter/gcimporter.go b/vendor/golang.org/x/tools/go/internal/gcimporter/gcimporter.go
index e8cba6b2..3ab66830 100644
--- a/vendor/golang.org/x/tools/go/internal/gcimporter/gcimporter.go
+++ b/vendor/golang.org/x/tools/go/internal/gcimporter/gcimporter.go
@@ -29,8 +29,14 @@ import (
 	"text/scanner"
 )
 
-// debugging/development support
-const debug = false
+const (
+	// Enable debug during development: it adds some additional checks, and
+	// prevents errors from being recovered.
+	debug = false
+
+	// If trace is set, debugging output is printed to std out.
+	trace = false
+)
 
 var pkgExts = [...]string{".a", ".o"}
 
@@ -179,7 +185,7 @@ func Import(packages map[string]*types.Package, path, srcDir string, lookup func
 
 	var hdr string
 	buf := bufio.NewReader(rc)
-	if hdr, err = FindExportData(buf); err != nil {
+	if hdr, _, err = FindExportData(buf); err != nil {
 		return
 	}
 
diff --git a/vendor/golang.org/x/tools/go/internal/gcimporter/iexport.go b/vendor/golang.org/x/tools/go/internal/gcimporter/iexport.go
index be8b7459..20955340 100644
--- a/vendor/golang.org/x/tools/go/internal/gcimporter/iexport.go
+++ b/vendor/golang.org/x/tools/go/internal/gcimporter/iexport.go
@@ -11,6 +11,7 @@ package gcimporter
 import (
 	"bytes"
 	"encoding/binary"
+	"fmt"
 	"go/ast"
 	"go/constant"
 	"go/token"
@@ -19,6 +20,8 @@ import (
 	"math/big"
 	"reflect"
 	"sort"
+	"strconv"
+	"strings"
 
 	"golang.org/x/tools/internal/typeparams"
 )
@@ -33,15 +36,15 @@ const bundleVersion = 0
 // The package path of the top-level package will not be recorded,
 // so that calls to IImportData can override with a provided package path.
 func IExportData(out io.Writer, fset *token.FileSet, pkg *types.Package) error {
-	return iexportCommon(out, fset, false, []*types.Package{pkg})
+	return iexportCommon(out, fset, false, iexportVersion, []*types.Package{pkg})
 }
 
 // IExportBundle writes an indexed export bundle for pkgs to out.
 func IExportBundle(out io.Writer, fset *token.FileSet, pkgs []*types.Package) error {
-	return iexportCommon(out, fset, true, pkgs)
+	return iexportCommon(out, fset, true, iexportVersion, pkgs)
 }
 
-func iexportCommon(out io.Writer, fset *token.FileSet, bundle bool, pkgs []*types.Package) (err error) {
+func iexportCommon(out io.Writer, fset *token.FileSet, bundle bool, version int, pkgs []*types.Package) (err error) {
 	if !debug {
 		defer func() {
 			if e := recover(); e != nil {
@@ -57,9 +60,11 @@ func iexportCommon(out io.Writer, fset *token.FileSet, bundle bool, pkgs []*type
 
 	p := iexporter{
 		fset:        fset,
+		version:     version,
 		allPkgs:     map[*types.Package]bool{},
 		stringIndex: map[string]uint64{},
 		declIndex:   map[types.Object]uint64{},
+		tparamNames: map[types.Object]string{},
 		typIndex:    map[types.Type]uint64{},
 	}
 	if !bundle {
@@ -119,7 +124,7 @@ func iexportCommon(out io.Writer, fset *token.FileSet, bundle bool, pkgs []*type
 	if bundle {
 		hdr.uint64(bundleVersion)
 	}
-	hdr.uint64(iexportVersion)
+	hdr.uint64(uint64(p.version))
 	hdr.uint64(uint64(p.strings.Len()))
 	hdr.uint64(dataLen)
 
@@ -136,8 +141,12 @@ func iexportCommon(out io.Writer, fset *token.FileSet, bundle bool, pkgs []*type
 // non-compiler tools and includes a complete package description
 // (i.e., name and height).
 func (w *exportWriter) writeIndex(index map[types.Object]uint64) {
+	type pkgObj struct {
+		obj  types.Object
+		name string // qualified name; differs from obj.Name for type params
+	}
 	// Build a map from packages to objects from that package.
-	pkgObjs := map[*types.Package][]types.Object{}
+	pkgObjs := map[*types.Package][]pkgObj{}
 
 	// For the main index, make sure to include every package that
 	// we reference, even if we're not exporting (or reexporting)
@@ -150,7 +159,8 @@ func (w *exportWriter) writeIndex(index map[types.Object]uint64) {
 	}
 
 	for obj := range index {
-		pkgObjs[obj.Pkg()] = append(pkgObjs[obj.Pkg()], obj)
+		name := w.p.exportName(obj)
+		pkgObjs[obj.Pkg()] = append(pkgObjs[obj.Pkg()], pkgObj{obj, name})
 	}
 
 	var pkgs []*types.Package
@@ -158,7 +168,7 @@ func (w *exportWriter) writeIndex(index map[types.Object]uint64) {
 		pkgs = append(pkgs, pkg)
 
 		sort.Slice(objs, func(i, j int) bool {
-			return indexName(objs[i]) < indexName(objs[j])
+			return objs[i].name < objs[j].name
 		})
 	}
 
@@ -175,29 +185,25 @@ func (w *exportWriter) writeIndex(index map[types.Object]uint64) {
 		objs := pkgObjs[pkg]
 		w.uint64(uint64(len(objs)))
 		for _, obj := range objs {
-			w.string(indexName(obj))
-			w.uint64(index[obj])
+			w.string(obj.name)
+			w.uint64(index[obj.obj])
 		}
 	}
 }
 
-// indexName returns the 'indexed' name of an object. It differs from
-// obj.Name() only for type parameter names, where we include the subscripted
-// type parameter ID.
-//
-// TODO(rfindley): remove this once we no longer need subscripts.
-func indexName(obj types.Object) (res string) {
-	if _, ok := obj.(*types.TypeName); ok {
-		if tparam, ok := obj.Type().(*typeparams.TypeParam); ok {
-			return types.TypeString(tparam, func(*types.Package) string { return "" })
-		}
+// exportName returns the 'exported' name of an object. It differs from
+// obj.Name() only for type parameters (see tparamExportName for details).
+func (p *iexporter) exportName(obj types.Object) (res string) {
+	if name := p.tparamNames[obj]; name != "" {
+		return name
 	}
 	return obj.Name()
 }
 
 type iexporter struct {
-	fset *token.FileSet
-	out  *bytes.Buffer
+	fset    *token.FileSet
+	out     *bytes.Buffer
+	version int
 
 	localpkg *types.Package
 
@@ -211,9 +217,21 @@ type iexporter struct {
 	strings     intWriter
 	stringIndex map[string]uint64
 
-	data0     intWriter
-	declIndex map[types.Object]uint64
-	typIndex  map[types.Type]uint64
+	data0       intWriter
+	declIndex   map[types.Object]uint64
+	tparamNames map[types.Object]string // typeparam->exported name
+	typIndex    map[types.Type]uint64
+
+	indent int // for tracing support
+}
+
+func (p *iexporter) trace(format string, args ...interface{}) {
+	if !trace {
+		// Call sites should also be guarded, but having this check here allows
+		// easily enabling/disabling debug trace statements.
+		return
+	}
+	fmt.Printf(strings.Repeat("..", p.indent)+format+"\n", args...)
 }
 
 // stringOff returns the offset of s within the string section.
@@ -239,7 +257,7 @@ func (p *iexporter) pushDecl(obj types.Object) {
 		return
 	}
 
-	p.declIndex[obj] = ^uint64(0) // mark n present in work queue
+	p.declIndex[obj] = ^uint64(0) // mark obj present in work queue
 	p.declTodo.pushTail(obj)
 }
 
@@ -262,6 +280,14 @@ func (w *exportWriter) exportPath(pkg *types.Package) string {
 }
 
 func (p *iexporter) doDecl(obj types.Object) {
+	if trace {
+		p.trace("exporting decl %v (%T)", obj, obj)
+		p.indent++
+		defer func() {
+			p.indent--
+			p.trace("=> %s", obj)
+		}()
+	}
 	w := p.newWriter()
 	w.setPkg(obj.Pkg(), false)
 
@@ -284,14 +310,15 @@ func (p *iexporter) doDecl(obj types.Object) {
 			w.tag('G')
 		}
 		w.pos(obj.Pos())
-		// The tparam list of the function type is the
-		// declaration of the type params. So, write out the type
-		// params right now. Then those type params will be
-		// referenced via their type offset (via typOff) in all
-		// other places in the signature and function that they
-		// are used.
+		// The tparam list of the function type is the declaration of the type
+		// params. So, write out the type params right now. Then those type params
+		// will be referenced via their type offset (via typOff) in all other
+		// places in the signature and function where they are used.
+		//
+		// While importing the type parameters, tparamList computes and records
+		// their export name, so that it can be later used when writing the index.
 		if tparams := typeparams.ForSignature(sig); tparams.Len() > 0 {
-			w.tparamList(tparams, obj.Pkg())
+			w.tparamList(obj.Name(), tparams, obj.Pkg())
 		}
 		w.signature(sig)
 
@@ -306,7 +333,15 @@ func (p *iexporter) doDecl(obj types.Object) {
 		if tparam, ok := t.(*typeparams.TypeParam); ok {
 			w.tag('P')
 			w.pos(obj.Pos())
-			w.typ(tparam.Constraint(), obj.Pkg())
+			constraint := tparam.Constraint()
+			if p.version >= iexportVersionGo1_18 {
+				implicit := false
+				if iface, _ := constraint.(*types.Interface); iface != nil {
+					implicit = typeparams.IsImplicit(iface)
+				}
+				w.bool(implicit)
+			}
+			w.typ(constraint, obj.Pkg())
 			break
 		}
 
@@ -331,7 +366,9 @@ func (p *iexporter) doDecl(obj types.Object) {
 		w.pos(obj.Pos())
 
 		if typeparams.ForNamed(named).Len() > 0 {
-			w.tparamList(typeparams.ForNamed(named), obj.Pkg())
+			// While importing the type parameters, tparamList computes and records
+			// their export name, so that it can be later used when writing the index.
+			w.tparamList(obj.Name(), typeparams.ForNamed(named), obj.Pkg())
 		}
 
 		underlying := obj.Type().Underlying()
@@ -348,6 +385,17 @@ func (p *iexporter) doDecl(obj types.Object) {
 			w.pos(m.Pos())
 			w.string(m.Name())
 			sig, _ := m.Type().(*types.Signature)
+
+			// Receiver type parameters are type arguments of the receiver type, so
+			// their name must be qualified before exporting recv.
+			if rparams := typeparams.RecvTypeParams(sig); rparams.Len() > 0 {
+				prefix := obj.Name() + "." + m.Name()
+				for i := 0; i < rparams.Len(); i++ {
+					rparam := rparams.At(i)
+					name := tparamExportName(prefix, rparam)
+					w.p.tparamNames[rparam.Obj()] = name
+				}
+			}
 			w.param(sig.Recv())
 			w.signature(sig)
 		}
@@ -364,7 +412,7 @@ func (w *exportWriter) tag(tag byte) {
 }
 
 func (w *exportWriter) pos(pos token.Pos) {
-	if iexportVersion >= iexportVersionPosCol {
+	if w.p.version >= iexportVersionPosCol {
 		w.posV1(pos)
 	} else {
 		w.posV0(pos)
@@ -447,9 +495,11 @@ func (w *exportWriter) pkg(pkg *types.Package) {
 }
 
 func (w *exportWriter) qualifiedIdent(obj types.Object) {
+	name := w.p.exportName(obj)
+
 	// Ensure any referenced declarations are written out too.
 	w.p.pushDecl(obj)
-	w.string(indexName(obj))
+	w.string(name)
 	w.pkg(obj.Pkg())
 }
 
@@ -483,6 +533,14 @@ func (w *exportWriter) startType(k itag) {
 }
 
 func (w *exportWriter) doTyp(t types.Type, pkg *types.Package) {
+	if trace {
+		w.p.trace("exporting type %s (%T)", t, t)
+		w.p.indent++
+		defer func() {
+			w.p.indent--
+			w.p.trace("=> %s", t)
+		}()
+	}
 	switch t := t.(type) {
 	case *types.Named:
 		if targs := typeparams.NamedTypeArgs(t); targs.Len() > 0 {
@@ -619,14 +677,49 @@ func (w *exportWriter) typeList(ts *typeparams.TypeList, pkg *types.Package) {
 	}
 }
 
-func (w *exportWriter) tparamList(list *typeparams.TypeParamList, pkg *types.Package) {
+func (w *exportWriter) tparamList(prefix string, list *typeparams.TypeParamList, pkg *types.Package) {
 	ll := uint64(list.Len())
 	w.uint64(ll)
 	for i := 0; i < list.Len(); i++ {
+		tparam := list.At(i)
+		// Set the type parameter exportName before exporting its type.
+		exportName := tparamExportName(prefix, tparam)
+		w.p.tparamNames[tparam.Obj()] = exportName
 		w.typ(list.At(i), pkg)
 	}
 }
 
+const blankMarker = "$"
+
+// tparamExportName returns the 'exported' name of a type parameter, which
+// differs from its actual object name: it is prefixed with a qualifier, and
+// blank type parameter names are disambiguated by their index in the type
+// parameter list.
+func tparamExportName(prefix string, tparam *typeparams.TypeParam) string {
+	assert(prefix != "")
+	name := tparam.Obj().Name()
+	if name == "_" {
+		name = blankMarker + strconv.Itoa(tparam.Index())
+	}
+	return prefix + "." + name
+}
+
+// tparamName returns the real name of a type parameter, after stripping its
+// qualifying prefix and reverting blank-name encoding. See tparamExportName
+// for details.
+func tparamName(exportName string) string {
+	// Remove the "path" from the type param name that makes it unique.
+	ix := strings.LastIndex(exportName, ".")
+	if ix < 0 {
+		errorf("malformed type parameter export name %s: missing prefix", exportName)
+	}
+	name := exportName[ix+1:]
+	if strings.HasPrefix(name, blankMarker) {
+		return "_"
+	}
+	return name
+}
+
 func (w *exportWriter) paramList(tup *types.Tuple) {
 	n := tup.Len()
 	w.uint64(uint64(n))
@@ -643,6 +736,9 @@ func (w *exportWriter) param(obj types.Object) {
 
 func (w *exportWriter) value(typ types.Type, v constant.Value) {
 	w.typ(typ, nil)
+	if w.p.version >= iexportVersionGo1_18 {
+		w.int64(int64(v.Kind()))
+	}
 
 	switch b := typ.Underlying().(*types.Basic); b.Info() & types.IsConstType {
 	case types.IsBoolean:
@@ -832,7 +928,7 @@ func (w *exportWriter) localIdent(obj types.Object) {
 		return
 	}
 
-	name := indexName(obj)
+	name := obj.Name()
 	if name == "_" {
 		w.string("_")
 		return
diff --git a/vendor/golang.org/x/tools/go/internal/gcimporter/iimport.go b/vendor/golang.org/x/tools/go/internal/gcimporter/iimport.go
index 1fcc87e5..1a33cd5c 100644
--- a/vendor/golang.org/x/tools/go/internal/gcimporter/iimport.go
+++ b/vendor/golang.org/x/tools/go/internal/gcimporter/iimport.go
@@ -18,6 +18,7 @@ import (
 	"go/types"
 	"io"
 	"sort"
+	"strings"
 
 	"golang.org/x/tools/internal/typeparams"
 )
@@ -45,12 +46,10 @@ func (r *intReader) uint64() uint64 {
 
 // Keep this in sync with constants in iexport.go.
 const (
-	iexportVersionGo1_11 = 0
-	iexportVersionPosCol = 1
-	// TODO: before release, change this back to 2.
-	iexportVersionGenerics = iexportVersionPosCol
-
-	iexportVersionCurrent = iexportVersionGenerics
+	iexportVersionGo1_11   = 0
+	iexportVersionPosCol   = 1
+	iexportVersionGo1_18   = 2
+	iexportVersionGenerics = 2
 )
 
 type ident struct {
@@ -123,9 +122,9 @@ func iimportCommon(fset *token.FileSet, imports map[string]*types.Package, data
 
 	version = int64(r.uint64())
 	switch version {
-	case /* iexportVersionGenerics, */ iexportVersionPosCol, iexportVersionGo1_11:
+	case iexportVersionGo1_18, iexportVersionPosCol, iexportVersionGo1_11:
 	default:
-		if version > iexportVersionGenerics {
+		if version > iexportVersionGo1_18 {
 			errorf("unstable iexport format version %d, just rebuild compiler and std library", version)
 		} else {
 			errorf("unknown iexport format version %d", version)
@@ -141,9 +140,8 @@ func iimportCommon(fset *token.FileSet, imports map[string]*types.Package, data
 	r.Seek(sLen+dLen, io.SeekCurrent)
 
 	p := iimporter{
-		exportVersion: version,
-		ipath:         path,
-		version:       int(version),
+		version: int(version),
+		ipath:   path,
 
 		stringData:  stringData,
 		stringCache: make(map[uint64]string),
@@ -153,14 +151,15 @@ func iimportCommon(fset *token.FileSet, imports map[string]*types.Package, data
 		pkgIndex: make(map[*types.Package]map[string]uint64),
 		typCache: make(map[uint64]types.Type),
 		// Separate map for typeparams, keyed by their package and unique
-		// name (name with subscript).
+		// name.
 		tparamIndex: make(map[ident]types.Type),
 
 		fake: fakeFileSet{
 			fset:  fset,
-			files: make(map[string]*token.File),
+			files: make(map[string]*fileInfo),
 		},
 	}
+	defer p.fake.setLines() // set lines for files in fset
 
 	for i, pt := range predeclared() {
 		p.typCache[uint64(i)] = pt
@@ -246,9 +245,8 @@ func iimportCommon(fset *token.FileSet, imports map[string]*types.Package, data
 }
 
 type iimporter struct {
-	exportVersion int64
-	ipath         string
-	version       int
+	version int
+	ipath   string
 
 	stringData  []byte
 	stringCache map[uint64]string
@@ -261,9 +259,28 @@ type iimporter struct {
 
 	fake          fakeFileSet
 	interfaceList []*types.Interface
+
+	indent int // for tracing support
+}
+
+func (p *iimporter) trace(format string, args ...interface{}) {
+	if !trace {
+		// Call sites should also be guarded, but having this check here allows
+		// easily enabling/disabling debug trace statements.
+		return
+	}
+	fmt.Printf(strings.Repeat("..", p.indent)+format+"\n", args...)
 }
 
 func (p *iimporter) doDecl(pkg *types.Package, name string) {
+	if debug {
+		p.trace("import decl %s", name)
+		p.indent++
+		defer func() {
+			p.indent--
+			p.trace("=> %s", name)
+		}()
+	}
 	// See if we've already imported this declaration.
 	if obj := pkg.Scope().Lookup(name); obj != nil {
 		return
@@ -305,7 +322,7 @@ func (p *iimporter) pkgAt(off uint64) *types.Package {
 }
 
 func (p *iimporter) typAt(off uint64, base *types.Named) types.Type {
-	if t, ok := p.typCache[off]; ok && (base == nil || !isInterface(t)) {
+	if t, ok := p.typCache[off]; ok && canReuse(base, t) {
 		return t
 	}
 
@@ -317,12 +334,30 @@ func (p *iimporter) typAt(off uint64, base *types.Named) types.Type {
 	r.declReader.Reset(p.declData[off-predeclReserved:])
 	t := r.doType(base)
 
-	if base == nil || !isInterface(t) {
+	if canReuse(base, t) {
 		p.typCache[off] = t
 	}
 	return t
 }
 
+// canReuse reports whether the type rhs on the RHS of the declaration for def
+// may be re-used.
+//
+// Specifically, if def is non-nil and rhs is an interface type with methods, it
+// may not be re-used because we have a convention of setting the receiver type
+// for interface methods to def.
+func canReuse(def *types.Named, rhs types.Type) bool {
+	if def == nil {
+		return true
+	}
+	iface, _ := rhs.(*types.Interface)
+	if iface == nil {
+		return true
+	}
+	// Don't use iface.Empty() here as iface may not be complete.
+	return iface.NumEmbeddeds() == 0 && iface.NumExplicitMethods() == 0
+}
+
 type importReader struct {
 	p          *iimporter
 	declReader bytes.Reader
@@ -352,8 +387,7 @@ func (r *importReader) obj(name string) {
 		if tag == 'G' {
 			tparams = r.tparamList()
 		}
-		sig := r.signature(nil)
-		typeparams.SetForSignature(sig, tparams)
+		sig := r.signature(nil, nil, tparams)
 		r.declare(types.NewFunc(pos, r.currPkg, name, sig))
 
 	case 'T', 'U':
@@ -377,23 +411,21 @@ func (r *importReader) obj(name string) {
 				mpos := r.pos()
 				mname := r.ident()
 				recv := r.param()
-				msig := r.signature(recv)
 
 				// If the receiver has any targs, set those as the
 				// rparams of the method (since those are the
 				// typeparams being used in the method sig/body).
-				targs := typeparams.NamedTypeArgs(baseType(msig.Recv().Type()))
+				base := baseType(recv.Type())
+				assert(base != nil)
+				targs := typeparams.NamedTypeArgs(base)
+				var rparams []*typeparams.TypeParam
 				if targs.Len() > 0 {
-					rparams := make([]*typeparams.TypeParam, targs.Len())
+					rparams = make([]*typeparams.TypeParam, targs.Len())
 					for i := range rparams {
-						// TODO(rfindley): this is less tolerant than the standard library
-						// go/internal/gcimporter, which calls under(...) and is tolerant
-						// of nil rparams. Bring them in sync by making the standard
-						// library importer stricter.
 						rparams[i] = targs.At(i).(*typeparams.TypeParam)
 					}
-					typeparams.SetRecvTypeParams(msig, rparams)
 				}
+				msig := r.signature(recv, rparams, nil)
 
 				named.AddMethod(types.NewFunc(mpos, r.currPkg, mname, msig))
 			}
@@ -403,25 +435,30 @@ func (r *importReader) obj(name string) {
 		// We need to "declare" a typeparam in order to have a name that
 		// can be referenced recursively (if needed) in the type param's
 		// bound.
-		if r.p.exportVersion < iexportVersionGenerics {
+		if r.p.version < iexportVersionGenerics {
 			errorf("unexpected type param type")
 		}
-		name0, sub := parseSubscript(name)
+		name0 := tparamName(name)
 		tn := types.NewTypeName(pos, r.currPkg, name0, nil)
 		t := typeparams.NewTypeParam(tn, nil)
-		if sub == 0 {
-			errorf("name %q missing subscript", name)
-		}
-
-		// TODO(rfindley): can we use a different, stable ID?
-		// t.SetId(sub)
 
 		// To handle recursive references to the typeparam within its
 		// bound, save the partial type in tparamIndex before reading the bounds.
 		id := ident{r.currPkg.Name(), name}
 		r.p.tparamIndex[id] = t
-
-		typeparams.SetTypeParamConstraint(t, r.typ())
+		var implicit bool
+		if r.p.version >= iexportVersionGo1_18 {
+			implicit = r.bool()
+		}
+		constraint := r.typ()
+		if implicit {
+			iface, _ := constraint.(*types.Interface)
+			if iface == nil {
+				errorf("non-interface constraint marked implicit")
+			}
+			typeparams.MarkImplicit(iface)
+		}
+		typeparams.SetTypeParamConstraint(t, constraint)
 
 	case 'V':
 		typ := r.typ()
@@ -439,6 +476,10 @@ func (r *importReader) declare(obj types.Object) {
 
 func (r *importReader) value() (typ types.Type, val constant.Value) {
 	typ = r.typ()
+	if r.p.version >= iexportVersionGo1_18 {
+		// TODO: add support for using the kind.
+		_ = constant.Kind(r.int64())
+	}
 
 	switch b := typ.Underlying().(*types.Basic); b.Info() & types.IsConstType {
 	case types.IsBoolean:
@@ -581,7 +622,7 @@ func (r *importReader) qualifiedIdent() (*types.Package, string) {
 }
 
 func (r *importReader) pos() token.Pos {
-	if r.p.exportVersion >= iexportVersionPosCol {
+	if r.p.version >= iexportVersionPosCol {
 		r.posv1()
 	} else {
 		r.posv0()
@@ -629,8 +670,17 @@ func isInterface(t types.Type) bool {
 func (r *importReader) pkg() *types.Package { return r.p.pkgAt(r.uint64()) }
 func (r *importReader) string() string      { return r.p.stringAt(r.uint64()) }
 
-func (r *importReader) doType(base *types.Named) types.Type {
-	switch k := r.kind(); k {
+func (r *importReader) doType(base *types.Named) (res types.Type) {
+	k := r.kind()
+	if debug {
+		r.p.trace("importing type %d (base: %s)", k, base)
+		r.p.indent++
+		defer func() {
+			r.p.indent--
+			r.p.trace("=> %s", res)
+		}()
+	}
+	switch k {
 	default:
 		errorf("unexpected kind tag in %q: %v", r.p.ipath, k)
 		return nil
@@ -653,7 +703,7 @@ func (r *importReader) doType(base *types.Named) types.Type {
 		return types.NewMap(r.typ(), r.typ())
 	case signatureType:
 		r.currPkg = r.pkg()
-		return r.signature(nil)
+		return r.signature(nil, nil, nil)
 
 	case structType:
 		r.currPkg = r.pkg()
@@ -693,7 +743,7 @@ func (r *importReader) doType(base *types.Named) types.Type {
 				recv = types.NewVar(token.NoPos, r.currPkg, "", base)
 			}
 
-			msig := r.signature(recv)
+			msig := r.signature(recv, nil, nil)
 			methods[i] = types.NewFunc(mpos, r.currPkg, mname, msig)
 		}
 
@@ -702,7 +752,7 @@ func (r *importReader) doType(base *types.Named) types.Type {
 		return typ
 
 	case typeParamType:
-		if r.p.exportVersion < iexportVersionGenerics {
+		if r.p.version < iexportVersionGenerics {
 			errorf("unexpected type param type")
 		}
 		pkg, name := r.qualifiedIdent()
@@ -716,7 +766,7 @@ func (r *importReader) doType(base *types.Named) types.Type {
 		return r.p.tparamIndex[id]
 
 	case instanceType:
-		if r.p.exportVersion < iexportVersionGenerics {
+		if r.p.version < iexportVersionGenerics {
 			errorf("unexpected instantiation type")
 		}
 		// pos does not matter for instances: they are positioned on the original
@@ -735,7 +785,7 @@ func (r *importReader) doType(base *types.Named) types.Type {
 		return t
 
 	case unionType:
-		if r.p.exportVersion < iexportVersionGenerics {
+		if r.p.version < iexportVersionGenerics {
 			errorf("unexpected instantiation type")
 		}
 		terms := make([]*typeparams.Term, r.uint64())
@@ -750,11 +800,11 @@ func (r *importReader) kind() itag {
 	return itag(r.uint64())
 }
 
-func (r *importReader) signature(recv *types.Var) *types.Signature {
+func (r *importReader) signature(recv *types.Var, rparams []*typeparams.TypeParam, tparams []*typeparams.TypeParam) *types.Signature {
 	params := r.paramList()
 	results := r.paramList()
 	variadic := params.Len() > 0 && r.bool()
-	return types.NewSignature(recv, params, results, variadic)
+	return typeparams.NewSignatureType(recv, rparams, tparams, params, results, variadic)
 }
 
 func (r *importReader) tparamList() []*typeparams.TypeParam {
@@ -823,23 +873,3 @@ func baseType(typ types.Type) *types.Named {
 	n, _ := typ.(*types.Named)
 	return n
 }
-
-func parseSubscript(name string) (string, uint64) {
-	// Extract the subscript value from the type param name. We export
-	// and import the subscript value, so that all type params have
-	// unique names.
-	sub := uint64(0)
-	startsub := -1
-	for i, r := range name {
-		if '₀' <= r && r < '₀'+10 {
-			if startsub == -1 {
-				startsub = i
-			}
-			sub = sub*10 + uint64(r-'₀')
-		}
-	}
-	if startsub >= 0 {
-		name = name[:startsub]
-	}
-	return name, sub
-}
diff --git a/vendor/golang.org/x/tools/go/internal/gcimporter/support_go117.go b/vendor/golang.org/x/tools/go/internal/gcimporter/support_go117.go
index 817a147e..d892273e 100644
--- a/vendor/golang.org/x/tools/go/internal/gcimporter/support_go117.go
+++ b/vendor/golang.org/x/tools/go/internal/gcimporter/support_go117.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build !typeparams || !go1.18
-// +build !typeparams !go1.18
+//go:build !go1.18
+// +build !go1.18
 
 package gcimporter
 
diff --git a/vendor/golang.org/x/tools/go/internal/gcimporter/support_go118.go b/vendor/golang.org/x/tools/go/internal/gcimporter/support_go118.go
index e6b81fc5..a9938432 100644
--- a/vendor/golang.org/x/tools/go/internal/gcimporter/support_go118.go
+++ b/vendor/golang.org/x/tools/go/internal/gcimporter/support_go118.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build typeparams && go1.18
-// +build typeparams,go1.18
+//go:build go1.18
+// +build go1.18
 
 package gcimporter
 
@@ -16,5 +16,8 @@ func additionalPredeclared() []types.Type {
 	return []types.Type{
 		// comparable
 		types.Universe.Lookup("comparable").Type(),
+
+		// any
+		types.Universe.Lookup("any").Type(),
 	}
 }