Add stringintconv and ifaceassert to govet

Add new linters:
* stringintconv, enabled by default
* ifaceassert is additional linter

Move govet tests to a dedicated folder

pkg/golinters/govet.go

@@ -17,6 +17,7 @@ import (
 	"golang.org/x/tools/go/analysis/passes/errorsas"
 	"golang.org/x/tools/go/analysis/passes/findcall"
 	"golang.org/x/tools/go/analysis/passes/httpresponse"
+	"golang.org/x/tools/go/analysis/passes/ifaceassert"
 	_ "golang.org/x/tools/go/analysis/passes/inspect" // unused internal analyzer
 	"golang.org/x/tools/go/analysis/passes/loopclosure"
 	"golang.org/x/tools/go/analysis/passes/lostcancel"
@@ -28,6 +29,7 @@ import (
 	"golang.org/x/tools/go/analysis/passes/shift"
 	"golang.org/x/tools/go/analysis/passes/sortslice"
 	"golang.org/x/tools/go/analysis/passes/stdmethods"
+	"golang.org/x/tools/go/analysis/passes/stringintconv"
 	"golang.org/x/tools/go/analysis/passes/structtag"
 	"golang.org/x/tools/go/analysis/passes/testinggoroutine"
 	"golang.org/x/tools/go/analysis/passes/tests"
@@ -55,6 +57,7 @@ var (
 		errorsas.Analyzer,
 		findcall.Analyzer,
 		httpresponse.Analyzer,
+		ifaceassert.Analyzer,
 		loopclosure.Analyzer,
 		lostcancel.Analyzer,
 		nilfunc.Analyzer,
@@ -64,6 +67,7 @@ var (
 		shift.Analyzer,
 		sortslice.Analyzer,
 		stdmethods.Analyzer,
+		stringintconv.Analyzer,
 		structtag.Analyzer,
 		testinggoroutine.Analyzer,
 		tests.Analyzer,
@@ -90,6 +94,7 @@ var (
 		printf.Analyzer,
 		shift.Analyzer,
 		stdmethods.Analyzer,
+		stringintconv.Analyzer,
 		structtag.Analyzer,
 		tests.Analyzer,
 		unmarshal.Analyzer,

test/testdata/govet.go → test/testdata/govet/default.go

@@ -1,18 +1,18 @@
 //args: -Egovet
 //config: linters-settings.govet.check-shadowing=true
-package testdata
+package govet
 
 import (
 	"fmt"
 	"io"
 	"os"
 )
 
-func Govet() error {
+func Composites() error {
 	return &os.PathError{"first", "path", os.ErrNotExist} // ERROR "composites: `os.PathError` composite literal uses unkeyed fields"
 }
 
-func GovetShadow(f io.Reader, buf []byte) (err error) {
+func Shadow(f io.Reader, buf []byte) (err error) {
 	if f != nil {
 		_, err := f.Read(buf) // ERROR "shadow: declaration of .err. shadows declaration at line \d+"
 		if err != nil {
@@ -24,15 +24,20 @@ func GovetShadow(f io.Reader, buf []byte) (err error) {
 	return
 }
 
-func GovetNolintVet() error {
+func NolintVet() error {
 	return &os.PathError{"first", "path", os.ErrNotExist} //nolint:vet
 }
 
-func GovetNolintVetShadow() error {
+func NolintVetShadow() error {
 	return &os.PathError{"first", "path", os.ErrNotExist} //nolint:vetshadow
 }
 
-func GovetPrintf() {
+func Printf() {
 	x := "dummy"
 	fmt.Printf("%d", x) // ERROR "printf: Printf format %d has arg x of wrong type string"
 }
+
+func StringIntConv() {
+	i := 42
+	fmt.Println("i = " + string(i)) // ERROR "stringintconv: conversion from int to string yields a string of one rune, not a string of digits (did you mean fmt.Sprint(x)?)"
+}

test/testdata/govet/ifaceassert.go

@@ -0,0 +1,14 @@
+//args: -Egovet
+//config: linters-settings.govet.enable=["ifaceassert"]
+package govet
+
+import (
+	"io"
+)
+
+func IfaceAssert() {
+	var v interface {
+		Read()
+	}
+	_ = v.(io.Reader) // ERROR "composites: `os.PathError` composite literal uses unkeyed fields"
+}