Build with Go 1.20 and update misc dependencies

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

vendor/golang.org/x/tools/internal/tokeninternal/tokeninternal.go

@@ -7,7 +7,9 @@
 package tokeninternal
 
 import (
+	"fmt"
 	"go/token"
+	"sort"
 	"sync"
 	"unsafe"
 )
@@ -57,3 +59,93 @@ func GetLines(file *token.File) []int {
 		panic("unexpected token.File size")
 	}
 }
+
+// AddExistingFiles adds the specified files to the FileSet if they
+// are not already present. It panics if any pair of files in the
+// resulting FileSet would overlap.
+func AddExistingFiles(fset *token.FileSet, files []*token.File) {
+	// Punch through the FileSet encapsulation.
+	type tokenFileSet struct {
+		// This type remained essentially consistent from go1.16 to go1.21.
+		mutex sync.RWMutex
+		base  int
+		files []*token.File
+		_     *token.File // changed to atomic.Pointer[token.File] in go1.19
+	}
+
+	// If the size of token.FileSet changes, this will fail to compile.
+	const delta = int64(unsafe.Sizeof(tokenFileSet{})) - int64(unsafe.Sizeof(token.FileSet{}))
+	var _ [-delta * delta]int
+
+	type uP = unsafe.Pointer
+	var ptr *tokenFileSet
+	*(*uP)(uP(&ptr)) = uP(fset)
+	ptr.mutex.Lock()
+	defer ptr.mutex.Unlock()
+
+	// Merge and sort.
+	newFiles := append(ptr.files, files...)
+	sort.Slice(newFiles, func(i, j int) bool {
+		return newFiles[i].Base() < newFiles[j].Base()
+	})
+
+	// Reject overlapping files.
+	// Discard adjacent identical files.
+	out := newFiles[:0]
+	for i, file := range newFiles {
+		if i > 0 {
+			prev := newFiles[i-1]
+			if file == prev {
+				continue
+			}
+			if prev.Base()+prev.Size()+1 > file.Base() {
+				panic(fmt.Sprintf("file %s (%d-%d) overlaps with file %s (%d-%d)",
+					prev.Name(), prev.Base(), prev.Base()+prev.Size(),
+					file.Name(), file.Base(), file.Base()+file.Size()))
+			}
+		}
+		out = append(out, file)
+	}
+	newFiles = out
+
+	ptr.files = newFiles
+
+	// Advance FileSet.Base().
+	if len(newFiles) > 0 {
+		last := newFiles[len(newFiles)-1]
+		newBase := last.Base() + last.Size() + 1
+		if ptr.base < newBase {
+			ptr.base = newBase
+		}
+	}
+}
+
+// FileSetFor returns a new FileSet containing a sequence of new Files with
+// the same base, size, and line as the input files, for use in APIs that
+// require a FileSet.
+//
+// Precondition: the input files must be non-overlapping, and sorted in order
+// of their Base.
+func FileSetFor(files ...*token.File) *token.FileSet {
+	fset := token.NewFileSet()
+	for _, f := range files {
+		f2 := fset.AddFile(f.Name(), f.Base(), f.Size())
+		lines := GetLines(f)
+		f2.SetLines(lines)
+	}
+	return fset
+}
+
+// CloneFileSet creates a new FileSet holding all files in fset. It does not
+// create copies of the token.Files in fset: they are added to the resulting
+// FileSet unmodified.
+func CloneFileSet(fset *token.FileSet) *token.FileSet {
+	var files []*token.File
+	fset.Iterate(func(f *token.File) bool {
+		files = append(files, f)
+		return true
+	})
+	newFileSet := token.NewFileSet()
+	AddExistingFiles(newFileSet, files)
+	return newFileSet
+}