cmd/vet: include the errors.As check from upstream x/tools

This change revendors golang.org/x/tools to include the check and
modifies cmd/vet to add it to the command.

CL 179977 will enable the check by default for 'go test'.

Commands run (starting in GOROOT/src):
	cd cmd
	emacs vet/main.go
	go get -u=patch golang.org/x/tools/go/analysis/passes/errorsas@latest
	go mod tidy
	go mod vendor
	cd ..
	./make.bash
	go test all

Updates #31213

Change-Id: Ic2ba9bd2d31c4c5fd9e7c42ca14e8dc38520c93b
Reviewed-on: https://go-review.googlesource.com/c/go/+/181717
Reviewed-by: Jonathan Amsterdam <jba@google.com>

diff --git a/src/cmd/go.mod b/src/cmd/go.mod
index 86e32814963dffe918c36ea2e6f7d1631fdf2532..3d9b4a8d244fc548023ec47e312ac6f63806b313 100644 (file)
--- a/src/cmd/go.mod
+++ b/src/cmd/go.mod
@@ -8,5 +8,5 @@ require (
        golang.org/x/arch v0.0.0-20181203225421-5a4828bb7045
        golang.org/x/crypto v0.0.0-20190325154230-a5d413f7728c
        golang.org/x/sys v0.0.0-20190502175342-a43fa875dd82 // indirect
-       golang.org/x/tools v0.0.0-20190602112858-2de7f9bf822c
+       golang.org/x/tools v0.0.0-20190611154301-25a4f137592f
 )

diff --git a/src/cmd/go.sum b/src/cmd/go.sum
index 9cb4e8630ca6b530c55b894b40b9a0fa0e17a9f2..6ca1dee5ed6a2359f476b5c9c9264e20fc9c9544 100644 (file)
--- a/src/cmd/go.sum
+++ b/src/cmd/go.sum
@@ -13,5 +13,5 @@ golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5h
 golang.org/x/sys v0.0.0-20190502175342-a43fa875dd82 h1:vsphBvatvfbhlb4PO1BYSr9dzugGxJ/SQHoNufZJq1w=
 golang.org/x/sys v0.0.0-20190502175342-a43fa875dd82/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
-golang.org/x/tools v0.0.0-20190602112858-2de7f9bf822c h1:8QARbM77BTyoVvSaGaoQPCYgZlVROYX1uKApKK98b+8=
-golang.org/x/tools v0.0.0-20190602112858-2de7f9bf822c/go.mod h1:/rFqwRUd4F7ZHNgwSSTFct+R/Kf4OFW1sUzUTQQTgfc=
+golang.org/x/tools v0.0.0-20190611154301-25a4f137592f h1:6awn5JC4pwVI5HiBqs7MDtRxnwV9PpO5iSA9v6P09pA=
+golang.org/x/tools v0.0.0-20190611154301-25a4f137592f/go.mod h1:/rFqwRUd4F7ZHNgwSSTFct+R/Kf4OFW1sUzUTQQTgfc=

diff --git a/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/errorsas/errorsas.go b/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/errorsas/errorsas.go
new file mode 100644 (file)
index 0000000..c411466
--- /dev/null
+++ b/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/errorsas/errorsas.go
@@ -0,0 +1,75 @@
+// Copyright 2018 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.
+
+// The errorsas package defines an Analyzer that checks that the second arugment to
+// errors.As is a pointer to a type implementing error.
+package errorsas
+
+import (
+       "go/ast"
+       "go/types"
+
+       "golang.org/x/tools/go/analysis"
+       "golang.org/x/tools/go/analysis/passes/inspect"
+       "golang.org/x/tools/go/ast/inspector"
+       "golang.org/x/tools/go/types/typeutil"
+)
+
+const doc = `report passing non-pointer or non-error values to errors.As
+
+The errorsas analysis reports calls to errors.As where the type
+of the second argument is not a pointer to a type implementing error.`
+
+var Analyzer = &analysis.Analyzer{
+       Name:     "errorsas",
+       Doc:      doc,
+       Requires: []*analysis.Analyzer{inspect.Analyzer},
+       Run:      run,
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+       switch pass.Pkg.Path() {
+       case "errors", "errors_test":
+               // These packages know how to use their own APIs.
+               // Sometimes they are testing what happens to incorrect programs.
+               return nil, nil
+       }
+
+       inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+
+       nodeFilter := []ast.Node{
+               (*ast.CallExpr)(nil),
+       }
+       inspect.Preorder(nodeFilter, func(n ast.Node) {
+               call := n.(*ast.CallExpr)
+               fn := typeutil.StaticCallee(pass.TypesInfo, call)
+               if fn == nil {
+                       return // not a static call
+               }
+               if len(call.Args) < 2 {
+                       return // not enough arguments, e.g. called with return values of another function
+               }
+               if fn.FullName() == "errors.As" && !pointerToInterfaceOrError(pass, call.Args[1]) {
+                       pass.Reportf(call.Pos(), "second argument to errors.As must be a pointer to an interface or a type implementing error")
+               }
+       })
+       return nil, nil
+}
+
+var errorType = types.Universe.Lookup("error").Type().Underlying().(*types.Interface)
+
+// pointerToInterfaceOrError reports whether the type of e is a pointer to an interface or a type implementing error,
+// or is the empty interface.
+func pointerToInterfaceOrError(pass *analysis.Pass, e ast.Expr) bool {
+       t := pass.TypesInfo.Types[e].Type
+       if it, ok := t.Underlying().(*types.Interface); ok && it.NumMethods() == 0 {
+               return true
+       }
+       pt, ok := t.Underlying().(*types.Pointer)
+       if !ok {
+               return false
+       }
+       _, ok = pt.Elem().Underlying().(*types.Interface)
+       return ok || types.Implements(pt.Elem(), errorType)
+}

diff --git a/src/cmd/vendor/modules.txt b/src/cmd/vendor/modules.txt
index 8889b907e26c84dcc7e875eec9ff334d401714cb..caf340a7528bdd533cc0e03c8422dd997dbfdd29 100644 (file)
--- a/src/cmd/vendor/modules.txt
+++ b/src/cmd/vendor/modules.txt
@@ -26,7 +26,7 @@ golang.org/x/crypto/ssh/terminal
 # golang.org/x/sys v0.0.0-20190502175342-a43fa875dd82
 golang.org/x/sys/unix
 golang.org/x/sys/windows
-# golang.org/x/tools v0.0.0-20190602112858-2de7f9bf822c
+# golang.org/x/tools v0.0.0-20190611154301-25a4f137592f
 golang.org/x/tools/go/analysis
 golang.org/x/tools/go/analysis/internal/analysisflags
 golang.org/x/tools/go/analysis/internal/facts
@@ -39,6 +39,7 @@ golang.org/x/tools/go/analysis/passes/cgocall
 golang.org/x/tools/go/analysis/passes/composite
 golang.org/x/tools/go/analysis/passes/copylock
 golang.org/x/tools/go/analysis/passes/ctrlflow
+golang.org/x/tools/go/analysis/passes/errorsas
 golang.org/x/tools/go/analysis/passes/httpresponse
 golang.org/x/tools/go/analysis/passes/inspect
 golang.org/x/tools/go/analysis/passes/internal/analysisutil

diff --git a/src/cmd/vet/main.go b/src/cmd/vet/main.go
index b845d95040c993355ca1877984733dedbcf3ae69..2a4f929d6090e0d1ebca3dc3c22ac1e597b39bff 100644 (file)
--- a/src/cmd/vet/main.go
+++ b/src/cmd/vet/main.go
@@ -13,6 +13,7 @@ import (
        "golang.org/x/tools/go/analysis/passes/cgocall"
        "golang.org/x/tools/go/analysis/passes/composite"
        "golang.org/x/tools/go/analysis/passes/copylock"
+       "golang.org/x/tools/go/analysis/passes/errorsas"
        "golang.org/x/tools/go/analysis/passes/httpresponse"
        "golang.org/x/tools/go/analysis/passes/loopclosure"
        "golang.org/x/tools/go/analysis/passes/lostcancel"
@@ -40,6 +41,7 @@ func main() {
                cgocall.Analyzer,
                composite.Analyzer,
                copylock.Analyzer,
+               errorsas.Analyzer,
                httpresponse.Analyzer,
                loopclosure.Analyzer,
                lostcancel.Analyzer,