internal/lsp: use x/xerrors to create new errors

This relates to golang/go#31374 and should switch all instances within `gopls` to use `x/errors` instead of `fmt` to create new errors.

Change-Id: I18339b75d12418d852e0dcc2ba0ed6c2970783b3
GitHub-Last-Rev: f4a55d9
GitHub-Pull-Request: #108
Reviewed-on: https://go-review.googlesource.com/c/tools/+/179880
Run-TryBot: Rebecca Stambler <[email protected]>
Reviewed-by: Rebecca Stambler <[email protected]>

Author: Jan Steinke

go.mod

@@ -5,4 +5,5 @@ go 1.11
 require (
 	golang.org/x/net v0.0.0-20190620200207-3b0461eec859
 	golang.org/x/sync v0.0.0-20190423024810-112230192c58
+	golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7
 )

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 v0.0.0-20190717185122-a985d3407aa7 h1:9zdDQZ7Thm29KFXgAX/+yaf3eVbP7djjWp/dXAppNCc=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

internal/lsp/cache/check.go

@@ -6,7 +6,6 @@ package cache
 
 import (
 	"context"
-	"fmt"
 	"go/ast"
 	"go/scanner"
 	"go/token"
@@ -20,6 +19,7 @@ import (
 	"golang.org/x/tools/internal/lsp/telemetry/log"
 	"golang.org/x/tools/internal/lsp/telemetry/trace"
 	"golang.org/x/tools/internal/span"
+	errors "golang.org/x/xerrors"
 )
 
 type importer struct {
@@ -40,7 +40,7 @@ func (imp *importer) Import(pkgPath string) (*types.Package, error) {
 	ctx := imp.ctx
 	id, ok := imp.view.mcache.ids[packagePath(pkgPath)]
 	if !ok {
-		return nil, fmt.Errorf("no known ID for %s", pkgPath)
+		return nil, errors.Errorf("no known ID for %s", pkgPath)
 	}
 	pkg, err := imp.getPkg(ctx, id)
 	if err != nil {
@@ -51,7 +51,7 @@ func (imp *importer) Import(pkgPath string) (*types.Package, error) {
 
 func (imp *importer) getPkg(ctx context.Context, id packageID) (*pkg, error) {
 	if _, ok := imp.seen[id]; ok {
-		return nil, fmt.Errorf("circular import detected")
+		return nil, errors.Errorf("circular import detected")
 	}
 	imp.view.pcache.mu.Lock()
 	e, ok := imp.view.pcache.packages[id]
@@ -99,7 +99,7 @@ func (imp *importer) typeCheck(ctx context.Context, id packageID) (*pkg, error)
 	defer done()
 	meta, ok := imp.view.mcache.packages[id]
 	if !ok {
-		return nil, fmt.Errorf("no metadata for %v", id)
+		return nil, errors.Errorf("no metadata for %v", id)
 	}
 	pkg := &pkg{
 		id:         meta.id,
@@ -123,9 +123,9 @@ func (imp *importer) typeCheck(ctx context.Context, id packageID) (*pkg, error)
 		mode = source.ParseExported
 	}
 	var (
-		files  = make([]*ast.File, len(meta.files))
-		errors = make([]error, len(meta.files))
-		wg     sync.WaitGroup
+		files       = make([]*ast.File, len(meta.files))
+		parseErrors = make([]error, len(meta.files))
+		wg          sync.WaitGroup
 	)
 	for _, filename := range meta.files {
 		uri := span.FileURI(filename)
@@ -141,7 +141,7 @@ func (imp *importer) typeCheck(ctx context.Context, id packageID) (*pkg, error)
 		go func(i int, ph source.ParseGoHandle) {
 			defer wg.Done()
 
-			files[i], errors[i] = ph.Parse(ctx)
+			files[i], parseErrors[i] = ph.Parse(ctx)
 		}(i, ph)
 	}
 	wg.Wait()
@@ -153,7 +153,7 @@ func (imp *importer) typeCheck(ctx context.Context, id packageID) (*pkg, error)
 			i++
 		}
 	}
-	for _, err := range errors {
+	for _, err := range parseErrors {
 		if err == context.Canceled {
 			return nil, err
 		}
@@ -166,7 +166,7 @@ func (imp *importer) typeCheck(ctx context.Context, id packageID) (*pkg, error)
 	if meta.pkgPath == "unsafe" {
 		pkg.types = types.Unsafe
 	} else if len(files) == 0 { // not the unsafe package, no parsed files
-		return nil, fmt.Errorf("no parsed files for package %s", pkg.pkgPath)
+		return nil, errors.Errorf("no parsed files for package %s", pkg.pkgPath)
 	} else {
 		pkg.types = types.NewPackage(string(meta.pkgPath), meta.name)
 	}
@@ -209,14 +209,14 @@ func (imp *importer) cachePackage(ctx context.Context, pkg *pkg, meta *metadata,
 		uri := ph.File().Identity().URI
 		f, err := imp.view.getFile(ctx, uri)
 		if err != nil {
-			return fmt.Errorf("no such file %s: %v", uri, err)
+			return errors.Errorf("no such file %s: %v", uri, err)
 		}
 		gof, ok := f.(*goFile)
 		if !ok {
-			return fmt.Errorf("non Go file %s", uri)
+			return errors.Errorf("non Go file %s", uri)
 		}
 		if err := imp.cachePerFile(gof, ph, pkg); err != nil {
-			return fmt.Errorf("failed to cache file %s: %v", gof.URI(), err)
+			return errors.Errorf("failed to cache file %s: %v", gof.URI(), err)
 		}
 	}
 
@@ -246,7 +246,7 @@ func (imp *importer) cachePerFile(gof *goFile, ph source.ParseGoHandle, p *pkg)
 
 	file, err := ph.Parse(imp.ctx)
 	if file == nil {
-		return fmt.Errorf("no AST for %s: %v", ph.File().Identity().URI, err)
+		return errors.Errorf("no AST for %s: %v", ph.File().Identity().URI, err)
 	}
 	gof.imports = file.Imports
 	return nil

internal/lsp/cache/gofile.go

@@ -6,7 +6,6 @@ package cache
 
 import (
 	"context"
-	"fmt"
 	"go/ast"
 	"go/token"
 	"sync"
@@ -15,6 +14,7 @@ import (
 	"golang.org/x/tools/internal/lsp/telemetry"
 	"golang.org/x/tools/internal/lsp/telemetry/log"
 	"golang.org/x/tools/internal/span"
+	errors "golang.org/x/xerrors"
 )
 
 // goFile holds all of the information we know about a Go file.
@@ -55,7 +55,7 @@ func (f *goFile) GetToken(ctx context.Context) (*token.File, error) {
 	}
 	tok := f.view.session.cache.fset.File(file.Pos())
 	if tok == nil {
-		return nil, fmt.Errorf("no token.File for %s", f.URI())
+		return nil, errors.Errorf("no token.File for %s", f.URI())
 	}
 	return tok, nil
 }
@@ -67,7 +67,7 @@ func (f *goFile) GetAST(ctx context.Context, mode source.ParseMode) (*ast.File,
 
 	if f.isDirty(ctx) || f.wrongParseMode(ctx, mode) {
 		if _, err := f.view.loadParseTypecheck(ctx, f); err != nil {
-			return nil, fmt.Errorf("GetAST: unable to check package for %s: %v", f.URI(), err)
+			return nil, errors.Errorf("GetAST: unable to check package for %s: %v", f.URI(), err)
 		}
 	}
 	fh := f.Handle(ctx)

internal/lsp/cache/load.go

@@ -15,6 +15,7 @@ import (
 	"golang.org/x/tools/internal/lsp/telemetry/tag"
 	"golang.org/x/tools/internal/lsp/telemetry/trace"
 	"golang.org/x/tools/internal/span"
+	errors "golang.org/x/xerrors"
 )
 
 func (v *view) loadParseTypecheck(ctx context.Context, f *goFile) ([]packages.Error, error) {
@@ -55,11 +56,11 @@ func (v *view) loadParseTypecheck(ctx context.Context, f *goFile) ([]packages.Er
 			return nil, err
 		}
 		if pkg == nil || pkg.IsIllTyped() {
-			return nil, fmt.Errorf("loadParseTypecheck: %s is ill typed", m.pkgPath)
+			return nil, errors.Errorf("loadParseTypecheck: %s is ill typed", m.pkgPath)
 		}
 	}
 	if len(f.pkgs) == 0 {
-		return nil, fmt.Errorf("no packages found for %s", f.URI())
+		return nil, errors.Errorf("no packages found for %s", f.URI())
 	}
 	return nil, nil
 }
@@ -93,7 +94,7 @@ func (v *view) checkMetadata(ctx context.Context, f *goFile) (map[packageID]*met
 	pkgs, err := packages.Load(v.Config(ctx), fmt.Sprintf("file=%s", f.filename()))
 	if len(pkgs) == 0 {
 		if err == nil {
-			err = fmt.Errorf("go/packages.Load: no packages found for %s", f.filename())
+			err = errors.Errorf("go/packages.Load: no packages found for %s", f.filename())
 		}
 		// Return this error as a diagnostic to the user.
 		return nil, []packages.Error{
@@ -112,7 +113,7 @@ func (v *view) checkMetadata(ctx context.Context, f *goFile) (map[packageID]*met
 		// If the package comes back with errors from `go list`,
 		// don't bother type-checking it.
 		if len(pkg.Errors) > 0 {
-			return nil, pkg.Errors, fmt.Errorf("package %s has errors, skipping type-checking", pkg.PkgPath)
+			return nil, pkg.Errors, errors.Errorf("package %s has errors, skipping type-checking", pkg.PkgPath)
 		}
 		// Build the import graph for this package.
 		if err := v.link(ctx, packagePath(pkg.PkgPath), pkg, nil, missingImports); err != nil {
@@ -132,7 +133,7 @@ func validateMetadata(ctx context.Context, missingImports map[packagePath]struct
 
 	// If `go list` failed to get data for the file in question (this should never happen).
 	if len(f.meta) == 0 {
-		return nil, fmt.Errorf("loadParseTypecheck: no metadata found for %v", f.filename())
+		return nil, errors.Errorf("loadParseTypecheck: no metadata found for %v", f.filename())
 	}
 
 	// If we have already seen these missing imports before, and we have type information,
@@ -254,7 +255,7 @@ func (v *view) link(ctx context.Context, pkgPath packagePath, pkg *packages.Pack
 	for importPath, importPkg := range pkg.Imports {
 		importPkgPath := packagePath(importPath)
 		if importPkgPath == pkgPath {
-			return fmt.Errorf("cycle detected in %s", importPath)
+			return errors.Errorf("cycle detected in %s", importPath)
 		}
 		// Don't remember any imports with significant errors.
 		if importPkgPath != "unsafe" && len(pkg.CompiledGoFiles) == 0 {

internal/lsp/cache/modfile.go

@@ -6,8 +6,9 @@ package cache
 
 import (
 	"context"
-	"fmt"
 	"go/token"
+
+	errors "golang.org/x/xerrors"
 )
 
 // modFile holds all of the information we know about a mod file.
@@ -16,7 +17,7 @@ type modFile struct {
 }
 
 func (*modFile) GetToken(context.Context) (*token.File, error) {
-	return nil, fmt.Errorf("GetToken: not implemented")
+	return nil, errors.Errorf("GetToken: not implemented")
 }
 
 func (*modFile) setContent(content []byte) {}

internal/lsp/cache/parse.go

@@ -6,7 +6,6 @@ package cache
 
 import (
 	"context"
-	"fmt"
 	"go/ast"
 	"go/parser"
 	"go/scanner"
@@ -16,6 +15,7 @@ import (
 	"golang.org/x/tools/internal/lsp/telemetry"
 	"golang.org/x/tools/internal/lsp/telemetry/trace"
 	"golang.org/x/tools/internal/memoize"
+	errors "golang.org/x/xerrors"
 )
 
 // Limits the number of parallel parser calls per process.
@@ -154,7 +154,7 @@ func fix(ctx context.Context, file *ast.File, tok *token.File, src []byte) error
 		case *ast.BadStmt:
 			err = parseDeferOrGoStmt(n, parent, tok, src) // don't shadow err
 			if err != nil {
-				err = fmt.Errorf("unable to parse defer or go from *ast.BadStmt: %v", err)
+				err = errors.Errorf("unable to parse defer or go from *ast.BadStmt: %v", err)
 			}
 			return false
 		default:
@@ -182,7 +182,7 @@ func parseDeferOrGoStmt(bad *ast.BadStmt, parent ast.Node, tok *token.File, src
 	var lit string
 	for {
 		if tkn == token.EOF {
-			return fmt.Errorf("reached the end of the file")
+			return errors.Errorf("reached the end of the file")
 		}
 		if pos >= bad.From {
 			break
@@ -200,7 +200,7 @@ func parseDeferOrGoStmt(bad *ast.BadStmt, parent ast.Node, tok *token.File, src
 			Go: pos,
 		}
 	default:
-		return fmt.Errorf("no defer or go statement found")
+		return errors.Errorf("no defer or go statement found")
 	}
 
 	// The expression after the "defer" or "go" starts at this position.
@@ -225,15 +225,15 @@ FindTo:
 		to = curr
 	}
 	if !from.IsValid() || tok.Offset(from) >= len(src) {
-		return fmt.Errorf("invalid from position")
+		return errors.Errorf("invalid from position")
 	}
 	if !to.IsValid() || tok.Offset(to)+1 >= len(src) {
-		return fmt.Errorf("invalid to position")
+		return errors.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 errors.Errorf("no expr in %s: %v", exprstr, err)
 	}
 	// parser.ParseExpr returns undefined positions.
 	// Adjust them for the current file.

internal/lsp/cache/session.go

@@ -6,7 +6,6 @@ package cache
 
 import (
 	"context"
-	"fmt"
 	"os"
 	"sort"
 	"strconv"
@@ -21,6 +20,7 @@ import (
 	"golang.org/x/tools/internal/lsp/telemetry/trace"
 	"golang.org/x/tools/internal/span"
 	"golang.org/x/tools/internal/xcontext"
+	errors "golang.org/x/xerrors"
 )
 
 type session struct {
@@ -178,7 +178,7 @@ 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 errors.Errorf("view %s for %v not found", view.Name(), view.Folder())
 }
 
 // TODO: Propagate the language ID through to the view.

internal/lsp/cache/sumfile.go

@@ -6,8 +6,9 @@ package cache
 
 import (
 	"context"
-	"fmt"
 	"go/token"
+
+	errors "golang.org/x/xerrors"
 )
 
 // sumFile holds all of the information we know about a sum file.
@@ -16,7 +17,7 @@ type sumFile struct {
 }
 
 func (*sumFile) GetToken(context.Context) (*token.File, error) {
-	return nil, fmt.Errorf("GetToken: not implemented")
+	return nil, errors.Errorf("GetToken: not implemented")
 }
 
 func (*sumFile) setContent(content []byte) {}

internal/lsp/cache/token.go

@@ -6,11 +6,11 @@ package cache
 
 import (
 	"context"
-	"fmt"
 	"go/token"
 
 	"golang.org/x/tools/internal/lsp/source"
 	"golang.org/x/tools/internal/memoize"
+	errors "golang.org/x/xerrors"
 )
 
 type tokenKey struct {
@@ -87,7 +87,7 @@ func tokenFile(ctx context.Context, c *cache, fh source.FileHandle) (*token.File
 	}
 	tok := c.FileSet().AddFile(fh.Identity().URI.Filename(), -1, len(buf))
 	if tok == nil {
-		return nil, fmt.Errorf("no token.File for %s", fh.Identity().URI)
+		return nil, errors.Errorf("no token.File for %s", fh.Identity().URI)
 	}
 	tok.SetLinesForContent(buf)
 	return tok, nil

internal/lsp/cmd/check.go

@@ -11,6 +11,7 @@ import (
 	"time"
 
 	"golang.org/x/tools/internal/span"
+	errors "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.After(30 * time.Second):
-			return fmt.Errorf("timed out waiting for results from %v", file.uri)
+			return errors.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 errors.Errorf("Could not convert position %v for %q", d.Range, d.Message)
 			}
 			fmt.Printf("%v: %v\n", spn, d.Message)
 		}