use x/xerrors to create new errors

go.mod

@@ -5,4 +5,5 @@ go 1.11
 require (
 	golang.org/x/net v0.0.0-20190311183353-d8887717615a
 	golang.org/x/sync v0.0.0-20190423024810-112230192c58
+	golang.org/x/xerrors v0.0.0-20190513163551-3ee3066db522
 )

go.sum

@@ -5,3 +5,5 @@ golang.org/x/sync v0.0.0-20190423024810-112230192c58 h1:8gQV6CLnAEikrhgkHFbMAEha
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/xerrors v0.0.0-20190513163551-3ee3066db522 h1:bhOzK9QyoD0ogCnFro1m2mz41+Ib0oOhfJnBp5MR4K4=
+golang.org/x/xerrors v0.0.0-20190513163551-3ee3066db522/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

internal/lsp/browser/README.md

@@ -1 +1 @@
-This package is a copy of cmd/internal/browser from the go distribution
+This package is a copy of cmd/internal/browser from the go distribution

internal/lsp/cache/check.go

@@ -6,7 +6,6 @@ package cache
 
 import (
 	"context"
-	"fmt"
 	"go/ast"
 	"go/scanner"
 	"go/token"
@@ -15,6 +14,7 @@ import (
 	"golang.org/x/tools/go/analysis"
 	"golang.org/x/tools/go/packages"
 	"golang.org/x/tools/internal/span"
+	"golang.org/x/xerrors"
 )
 
 type importer struct {
@@ -38,7 +38,7 @@ func (imp *importer) Import(pkgPath string) (*types.Package, error) {
 
 func (imp *importer) getPkg(pkgPath string) (*pkg, error) {
 	if _, ok := imp.seen[pkgPath]; ok {
-		return nil, fmt.Errorf("circular import detected")
+		return nil, xerrors.Errorf("circular import detected")
 	}
 	imp.view.pcache.mu.Lock()
 	e, ok := imp.view.pcache.packages[pkgPath]
@@ -67,7 +67,7 @@ func (imp *importer) getPkg(pkgPath string) (*pkg, error) {
 func (imp *importer) typeCheck(pkgPath string) (*pkg, error) {
 	meta, ok := imp.view.mcache.packages[pkgPath]
 	if !ok {
-		return nil, fmt.Errorf("no metadata for %v", pkgPath)
+		return nil, xerrors.Errorf("no metadata for %v", pkgPath)
 	}
 	// Use the default type information for the unsafe package.
 	var typ *types.Package

internal/lsp/cache/load.go

@@ -7,6 +7,7 @@ import (
 
 	"golang.org/x/tools/go/packages"
 	"golang.org/x/tools/internal/span"
+	"golang.org/x/xerrors"
 )
 
 func (v *view) loadParseTypecheck(ctx context.Context, f *goFile) ([]packages.Error, error) {
@@ -29,7 +30,7 @@ func (v *view) loadParseTypecheck(ctx context.Context, f *goFile) ([]packages.Er
 		return errs, err
 	}
 	if f.meta == nil {
-		return nil, fmt.Errorf("no metadata found for %v", f.filename())
+		return nil, xerrors.Errorf("no metadata found for %v", f.filename())
 	}
 	imp := &importer{
 		view: v,
@@ -48,7 +49,7 @@ func (v *view) loadParseTypecheck(ctx context.Context, f *goFile) ([]packages.Er
 	}
 	// If we still have not found the package for the file, something is wrong.
 	if f.pkg == nil {
-		return nil, fmt.Errorf("parse: no package found for %v", f.filename())
+		return nil, xerrors.Errorf("parse: no package found for %v", f.filename())
 	}
 	return nil, nil
 }
@@ -59,7 +60,7 @@ func (v *view) checkMetadata(ctx context.Context, f *goFile) ([]packages.Error,
 		pkgs, err := packages.Load(cfg, fmt.Sprintf("file=%s", f.filename()))
 		if len(pkgs) == 0 {
 			if err == nil {
-				err = fmt.Errorf("%s: no packages found", f.filename())
+				err = xerrors.Errorf("%s: no packages found", f.filename())
 			}
 			// Return this error as a diagnostic to the user.
 			return []packages.Error{
@@ -73,7 +74,7 @@ func (v *view) checkMetadata(ctx context.Context, f *goFile) ([]packages.Error,
 			// If the package comes back with errors from `go list`, don't bother
 			// type-checking it.
 			if len(pkg.Errors) > 0 {
-				return pkg.Errors, fmt.Errorf("package %s has errors, skipping type-checking", pkg.PkgPath)
+				return pkg.Errors, xerrors.Errorf("package %s has errors, skipping type-checking", pkg.PkgPath)
 			}
 			v.link(ctx, pkg.PkgPath, pkg, nil)
 		}

internal/lsp/cache/parse.go

@@ -6,7 +6,6 @@ package cache
 
 import (
 	"context"
-	"fmt"
 	"go/ast"
 	"go/parser"
 	"go/scanner"
@@ -17,6 +16,7 @@ import (
 	"sync"
 
 	"golang.org/x/tools/internal/span"
+	"golang.org/x/xerrors"
 )
 
 func parseFile(fset *token.FileSet, filename string, src []byte) (*ast.File, error) {
@@ -54,7 +54,7 @@ func (imp *importer) parseFiles(filenames []string) ([]*ast.File, []error) {
 		}
 		gof, ok := f.(*goFile)
 		if !ok {
-			parsed[i], errors[i] = nil, fmt.Errorf("Non go file in parse call: %v", filename)
+			parsed[i], errors[i] = nil, xerrors.Errorf("Non go file in parse call: %v", filename)
 			continue
 		}
 
@@ -72,7 +72,7 @@ func (imp *importer) parseFiles(filenames []string) ([]*ast.File, []error) {
 				}
 				src := gof.fc.Data
 				if src == nil {
-					parsed[i], errors[i] = nil, fmt.Errorf("No source for %v", filename)
+					parsed[i], errors[i] = nil, xerrors.Errorf("No source for %v", filename)
 				} else {
 					// ParseFile may return both an AST and an error.
 					parsed[i], errors[i] = parseFile(imp.fset, filename, src)
@@ -175,7 +175,7 @@ func (v *view) parseDeferOrGoStmt(bad *ast.BadStmt, parent ast.Node, tok *token.
 	var lit string
 	for {
 		if tkn == token.EOF {
-			return fmt.Errorf("reached the end of the file")
+			return xerrors.Errorf("reached the end of the file")
 		}
 		if pos >= bad.From {
 			break
@@ -193,7 +193,7 @@ func (v *view) parseDeferOrGoStmt(bad *ast.BadStmt, parent ast.Node, tok *token.
 			Go: pos,
 		}
 	default:
-		return fmt.Errorf("no defer or go statement found")
+		return xerrors.Errorf("no defer or go statement found")
 	}
 
 	// The expression after the "defer" or "go" starts at this position.
@@ -218,15 +218,15 @@ FindTo:
 		to = curr
 	}
 	if !from.IsValid() || tok.Offset(from) >= len(src) {
-		return fmt.Errorf("invalid from position")
+		return xerrors.Errorf("invalid from position")
 	}
 	if !to.IsValid() || tok.Offset(to)+1 >= len(src) {
-		return fmt.Errorf("invalid to position")
+		return xerrors.Errorf("invalid to position")
 	}
 	exprstr := string(src[tok.Offset(from) : tok.Offset(to)+1])
 	expr, err := parser.ParseExpr(exprstr)
 	if expr == nil {
-		return fmt.Errorf("no expr in %s: %v", exprstr, err)
+		return xerrors.Errorf("no expr in %s: %v", exprstr, err)
 	}
 	// parser.ParseExpr returns undefined positions.
 	// Adjust them for the current file.

internal/lsp/cache/session.go

@@ -6,14 +6,14 @@ package cache
 
 import (
 	"context"
-	"fmt"
 	"os"
 	"strings"
 	"sync"
 
 	"golang.org/x/tools/internal/lsp/source"
 	"golang.org/x/tools/internal/lsp/xlog"
 	"golang.org/x/tools/internal/span"
+	"golang.org/x/xerrors"
 )
 
 type session struct {
@@ -150,7 +150,7 @@ func (s *session) removeView(ctx context.Context, view *view) error {
 			return nil
 		}
 	}
-	return fmt.Errorf("view %s for %v not found", view.Name(), view.Folder())
+	return xerrors.Errorf("view %s for %v not found", view.Name(), view.Folder())
 }
 
 func (s *session) Logger() xlog.Logger {

internal/lsp/cache/view.go

@@ -6,7 +6,6 @@ package cache
 
 import (
 	"context"
-	"fmt"
 	"go/ast"
 	"go/parser"
 	"go/types"
@@ -17,6 +16,7 @@ import (
 	"golang.org/x/tools/go/packages"
 	"golang.org/x/tools/internal/lsp/source"
 	"golang.org/x/tools/internal/span"
+	"golang.org/x/xerrors"
 )
 
 type view struct {
@@ -340,7 +340,7 @@ func (v *view) getFile(uri span.URI) (viewFile, error) {
 			},
 		}
 	default:
-		return nil, fmt.Errorf("unsupported file extension: %s", ext)
+		return nil, xerrors.Errorf("unsupported file extension: %s", ext)
 	}
 	v.mapFile(uri, f)
 	return f, nil

internal/lsp/cmd/check.go

@@ -11,6 +11,7 @@ import (
 	"time"
 
 	"golang.org/x/tools/internal/span"
+	"golang.org/x/xerrors"
 )
 
 // check implements the check verb for gopls.
@@ -60,14 +61,14 @@ func (c *check) Run(ctx context.Context, args ...string) error {
 		select {
 		case <-file.hasDiagnostics:
 		case <-time.Tick(30 * time.Second):
-			return fmt.Errorf("timed out waiting for results from %v", file.uri)
+			return xerrors.Errorf("timed out waiting for results from %v", file.uri)
 		}
 		file.diagnosticsMu.Lock()
 		defer file.diagnosticsMu.Unlock()
 		for _, d := range file.diagnostics {
 			spn, err := file.mapper.RangeSpan(d.Range)
 			if err != nil {
-				return fmt.Errorf("Could not convert position %v for %q", d.Range, d.Message)
+				return xerrors.Errorf("Could not convert position %v for %q", d.Range, d.Message)
 			}
 			fmt.Printf("%v: %v\n", spn, d.Message)
 		}

internal/lsp/cmd/cmd.go

@@ -26,6 +26,7 @@ import (
 	"golang.org/x/tools/internal/lsp/source"
 	"golang.org/x/tools/internal/span"
 	"golang.org/x/tools/internal/tool"
+	"golang.org/x/xerrors"
 )
 
 // Application is the main application as passed to tool.Main
@@ -320,12 +321,12 @@ func (c *cmdClient) getFile(ctx context.Context, uri span.URI) *cmdFile {
 	if file.mapper == nil {
 		fname, err := uri.Filename()
 		if err != nil {
-			file.err = fmt.Errorf("%v: %v", uri, err)
+			file.err = xerrors.Errorf("%v: %v", uri, err)
 			return file
 		}
 		content, err := ioutil.ReadFile(fname)
 		if err != nil {
-			file.err = fmt.Errorf("%v: %v", uri, err)
+			file.err = xerrors.Errorf("%v: %v", uri, err)
 			return file
 		}
 		f := c.fset.AddFile(fname, -1, len(content))
@@ -345,7 +346,7 @@ func (c *connection) AddFile(ctx context.Context, uri span.URI) *cmdFile {
 		p.TextDocument.URI = string(uri)
 		p.TextDocument.Text = string(file.mapper.Content)
 		if err := c.Server.DidOpen(ctx, p); err != nil {
-			file.err = fmt.Errorf("%v: %v", uri, err)
+			file.err = xerrors.Errorf("%v: %v", uri, err)
 		}
 	}
 	return file

internal/lsp/cmd/definition.go

@@ -16,6 +16,7 @@ import (
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/span"
 	"golang.org/x/tools/internal/tool"
+	"golang.org/x/xerrors"
 )
 
 // A Definition is the result of a 'definition' query.
@@ -79,26 +80,26 @@ func (d *definition) Run(ctx context.Context, args ...string) error {
 	}
 	locs, err := conn.Definition(ctx, &p)
 	if err != nil {
-		return fmt.Errorf("%v: %v", from, err)
+		return xerrors.Errorf("%v: %v", from, err)
 	}
 
 	if len(locs) == 0 {
-		return fmt.Errorf("%v: not an identifier", from)
+		return xerrors.Errorf("%v: not an identifier", from)
 	}
 	hover, err := conn.Hover(ctx, &p)
 	if err != nil {
-		return fmt.Errorf("%v: %v", from, err)
+		return xerrors.Errorf("%v: %v", from, err)
 	}
 	if hover == nil {
-		return fmt.Errorf("%v: not an identifier", from)
+		return xerrors.Errorf("%v: not an identifier", from)
 	}
 	file = conn.AddFile(ctx, span.NewURI(locs[0].URI))
 	if file.err != nil {
-		return fmt.Errorf("%v: %v", from, file.err)
+		return xerrors.Errorf("%v: %v", from, file.err)
 	}
 	definition, err := file.mapper.Span(locs[0])
 	if err != nil {
-		return fmt.Errorf("%v: %v", from, err)
+		return xerrors.Errorf("%v: %v", from, err)
 	}
 	description := strings.TrimSpace(hover.Contents.Value)
 	var result interface{}
@@ -115,7 +116,7 @@ func (d *definition) Run(ctx context.Context, args ...string) error {
 			Desc:   description,
 		}
 	default:
-		return fmt.Errorf("unknown emulation for definition: %s", d.query.Emulate)
+		return xerrors.Errorf("unknown emulation for definition: %s", d.query.Emulate)
 	}
 	if err != nil {
 		return err
@@ -131,7 +132,7 @@ func (d *definition) Run(ctx context.Context, args ...string) error {
 	case *guru.Definition:
 		fmt.Printf("%s: defined here as %s", d.ObjPos, d.Desc)
 	default:
-		return fmt.Errorf("no printer for type %T", result)
+		return xerrors.Errorf("no printer for type %T", result)
 	}
 	return nil
 }

internal/lsp/cmd/format.go

@@ -16,6 +16,7 @@ import (
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/lsp/source"
 	"golang.org/x/tools/internal/span"
+	"golang.org/x/xerrors"
 )
 
 // format implements the format verb for gopls.
@@ -68,18 +69,18 @@ func (f *format) Run(ctx context.Context, args ...string) error {
 			return err
 		}
 		if loc.Range.Start != loc.Range.End {
-			return fmt.Errorf("only full file formatting supported")
+			return xerrors.Errorf("only full file formatting supported")
 		}
 		p := protocol.DocumentFormattingParams{
 			TextDocument: protocol.TextDocumentIdentifier{URI: loc.URI},
 		}
 		edits, err := conn.Formatting(ctx, &p)
 		if err != nil {
-			return fmt.Errorf("%v: %v", spn, err)
+			return xerrors.Errorf("%v: %v", spn, err)
 		}
 		sedits, err := lsp.FromProtocolEdits(file.mapper, edits)
 		if err != nil {
-			return fmt.Errorf("%v: %v", spn, err)
+			return xerrors.Errorf("%v: %v", spn, err)
 		}
 		ops := source.EditsToDiff(sedits)
 		lines := diff.SplitLines(string(file.mapper.Content))

internal/lsp/cmd/serve.go

@@ -21,6 +21,7 @@ import (
 	"golang.org/x/tools/internal/lsp"
 	"golang.org/x/tools/internal/lsp/debug"
 	"golang.org/x/tools/internal/tool"
+	"golang.org/x/xerrors"
 )
 
 // Serve is a struct that exposes the configurable parts of the LSP server as
@@ -65,7 +66,7 @@ func (s *Serve) Run(ctx context.Context, args ...string) error {
 		}
 		f, err := os.Create(filename)
 		if err != nil {
-			return fmt.Errorf("Unable to create log file: %v", err)
+			return xerrors.Errorf("Unable to create log file: %v", err)
 		}
 		defer f.Close()
 		log.SetOutput(io.MultiWriter(os.Stderr, f))