staticcheck (#313)

* CI: use staticcheck for linting

This commit switches the linter for Go code from golint to staticcheck.
Golint has been deprecated since last year and staticcheck is a
recommended replacement.

Signed-off-by: Lucas Servén Marín <lserven@gmail.com>

* revendor

Signed-off-by: Lucas Servén Marín <lserven@gmail.com>

* cmd,pkg: fix lint warnings

Signed-off-by: Lucas Servén Marín <lserven@gmail.com>

vendor/honnef.co/go/tools/unused/edge.go

@@ -0,0 +1,59 @@
+package unused
+
+//go:generate go run golang.org/x/tools/cmd/stringer@master -type edgeKind
+type edgeKind uint64
+
+func (e edgeKind) is(o edgeKind) bool {
+	return e&o != 0
+}
+
+const (
+	edgeAlias edgeKind = 1 << iota
+	edgeBlankField
+	edgeAnonymousStruct
+	edgeCgoExported
+	edgeConstGroup
+	edgeElementType
+	edgeEmbeddedInterface
+	edgeExportedConstant
+	edgeExportedField
+	edgeExportedFunction
+	edgeExportedMethod
+	edgeExportedType
+	edgeExportedVariable
+	edgeExtendsExportedFields
+	edgeExtendsExportedMethodSet
+	edgeFieldAccess
+	edgeFunctionArgument
+	edgeFunctionResult
+	edgeFunctionSignature
+	edgeImplements
+	edgeInstructionOperand
+	edgeInterfaceCall
+	edgeInterfaceMethod
+	edgeKeyType
+	edgeLinkname
+	edgeMainFunction
+	edgeNamedType
+	edgeNetRPCRegister
+	edgeNoCopySentinel
+	edgeProvidesMethod
+	edgeReceiver
+	edgeRuntimeFunction
+	edgeSignature
+	edgeStructConversion
+	edgeTestSink
+	edgeTupleElement
+	edgeType
+	edgeTypeName
+	edgeUnderlyingType
+	edgePointerType
+	edgeUnsafeConversion
+	edgeUsedConstant
+	edgeVarDecl
+	edgeIgnored
+	edgeSamePointer
+	edgeTypeParam
+	edgeTypeArg
+	edgeUnionTerm
+)

vendor/honnef.co/go/tools/unused/edgekind_string.go

@@ -0,0 +1,119 @@
+// Code generated by "stringer -type edgeKind"; DO NOT EDIT.
+
+package unused
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[edgeAlias-1]
+	_ = x[edgeBlankField-2]
+	_ = x[edgeAnonymousStruct-4]
+	_ = x[edgeCgoExported-8]
+	_ = x[edgeConstGroup-16]
+	_ = x[edgeElementType-32]
+	_ = x[edgeEmbeddedInterface-64]
+	_ = x[edgeExportedConstant-128]
+	_ = x[edgeExportedField-256]
+	_ = x[edgeExportedFunction-512]
+	_ = x[edgeExportedMethod-1024]
+	_ = x[edgeExportedType-2048]
+	_ = x[edgeExportedVariable-4096]
+	_ = x[edgeExtendsExportedFields-8192]
+	_ = x[edgeExtendsExportedMethodSet-16384]
+	_ = x[edgeFieldAccess-32768]
+	_ = x[edgeFunctionArgument-65536]
+	_ = x[edgeFunctionResult-131072]
+	_ = x[edgeFunctionSignature-262144]
+	_ = x[edgeImplements-524288]
+	_ = x[edgeInstructionOperand-1048576]
+	_ = x[edgeInterfaceCall-2097152]
+	_ = x[edgeInterfaceMethod-4194304]
+	_ = x[edgeKeyType-8388608]
+	_ = x[edgeLinkname-16777216]
+	_ = x[edgeMainFunction-33554432]
+	_ = x[edgeNamedType-67108864]
+	_ = x[edgeNetRPCRegister-134217728]
+	_ = x[edgeNoCopySentinel-268435456]
+	_ = x[edgeProvidesMethod-536870912]
+	_ = x[edgeReceiver-1073741824]
+	_ = x[edgeRuntimeFunction-2147483648]
+	_ = x[edgeSignature-4294967296]
+	_ = x[edgeStructConversion-8589934592]
+	_ = x[edgeTestSink-17179869184]
+	_ = x[edgeTupleElement-34359738368]
+	_ = x[edgeType-68719476736]
+	_ = x[edgeTypeName-137438953472]
+	_ = x[edgeUnderlyingType-274877906944]
+	_ = x[edgePointerType-549755813888]
+	_ = x[edgeUnsafeConversion-1099511627776]
+	_ = x[edgeUsedConstant-2199023255552]
+	_ = x[edgeVarDecl-4398046511104]
+	_ = x[edgeIgnored-8796093022208]
+	_ = x[edgeSamePointer-17592186044416]
+	_ = x[edgeTypeParam-35184372088832]
+	_ = x[edgeTypeArg-70368744177664]
+	_ = x[edgeUnionTerm-140737488355328]
+}
+
+const _edgeKind_name = "edgeAliasedgeBlankFieldedgeAnonymousStructedgeCgoExportededgeConstGroupedgeElementTypeedgeEmbeddedInterfaceedgeExportedConstantedgeExportedFieldedgeExportedFunctionedgeExportedMethodedgeExportedTypeedgeExportedVariableedgeExtendsExportedFieldsedgeExtendsExportedMethodSetedgeFieldAccessedgeFunctionArgumentedgeFunctionResultedgeFunctionSignatureedgeImplementsedgeInstructionOperandedgeInterfaceCalledgeInterfaceMethodedgeKeyTypeedgeLinknameedgeMainFunctionedgeNamedTypeedgeNetRPCRegisteredgeNoCopySentineledgeProvidesMethodedgeReceiveredgeRuntimeFunctionedgeSignatureedgeStructConversionedgeTestSinkedgeTupleElementedgeTypeedgeTypeNameedgeUnderlyingTypeedgePointerTypeedgeUnsafeConversionedgeUsedConstantedgeVarDecledgeIgnorededgeSamePointeredgeTypeParamedgeTypeArgedgeUnionTerm"
+
+var _edgeKind_map = map[edgeKind]string{
+	1:               _edgeKind_name[0:9],
+	2:               _edgeKind_name[9:23],
+	4:               _edgeKind_name[23:42],
+	8:               _edgeKind_name[42:57],
+	16:              _edgeKind_name[57:71],
+	32:              _edgeKind_name[71:86],
+	64:              _edgeKind_name[86:107],
+	128:             _edgeKind_name[107:127],
+	256:             _edgeKind_name[127:144],
+	512:             _edgeKind_name[144:164],
+	1024:            _edgeKind_name[164:182],
+	2048:            _edgeKind_name[182:198],
+	4096:            _edgeKind_name[198:218],
+	8192:            _edgeKind_name[218:243],
+	16384:           _edgeKind_name[243:271],
+	32768:           _edgeKind_name[271:286],
+	65536:           _edgeKind_name[286:306],
+	131072:          _edgeKind_name[306:324],
+	262144:          _edgeKind_name[324:345],
+	524288:          _edgeKind_name[345:359],
+	1048576:         _edgeKind_name[359:381],
+	2097152:         _edgeKind_name[381:398],
+	4194304:         _edgeKind_name[398:417],
+	8388608:         _edgeKind_name[417:428],
+	16777216:        _edgeKind_name[428:440],
+	33554432:        _edgeKind_name[440:456],
+	67108864:        _edgeKind_name[456:469],
+	134217728:       _edgeKind_name[469:487],
+	268435456:       _edgeKind_name[487:505],
+	536870912:       _edgeKind_name[505:523],
+	1073741824:      _edgeKind_name[523:535],
+	2147483648:      _edgeKind_name[535:554],
+	4294967296:      _edgeKind_name[554:567],
+	8589934592:      _edgeKind_name[567:587],
+	17179869184:     _edgeKind_name[587:599],
+	34359738368:     _edgeKind_name[599:615],
+	68719476736:     _edgeKind_name[615:623],
+	137438953472:    _edgeKind_name[623:635],
+	274877906944:    _edgeKind_name[635:653],
+	549755813888:    _edgeKind_name[653:668],
+	1099511627776:   _edgeKind_name[668:688],
+	2199023255552:   _edgeKind_name[688:704],
+	4398046511104:   _edgeKind_name[704:715],
+	8796093022208:   _edgeKind_name[715:726],
+	17592186044416:  _edgeKind_name[726:741],
+	35184372088832:  _edgeKind_name[741:754],
+	70368744177664:  _edgeKind_name[754:765],
+	140737488355328: _edgeKind_name[765:778],
+}
+
+func (i edgeKind) String() string {
+	if str, ok := _edgeKind_map[i]; ok {
+		return str
+	}
+	return "edgeKind(" + strconv.FormatInt(int64(i), 10) + ")"
+}

vendor/honnef.co/go/tools/unused/implements.go

@@ -0,0 +1,82 @@
+package unused
+
+import "go/types"
+
+// lookupMethod returns the index of and method with matching package and name, or (-1, nil).
+func lookupMethod(T *types.Interface, pkg *types.Package, name string) (int, *types.Func) {
+	if name != "_" {
+		for i := 0; i < T.NumMethods(); i++ {
+			m := T.Method(i)
+			if sameId(m, pkg, name) {
+				return i, m
+			}
+		}
+	}
+	return -1, nil
+}
+
+func sameId(obj types.Object, pkg *types.Package, name string) bool {
+	// spec:
+	// "Two identifiers are different if they are spelled differently,
+	// or if they appear in different packages and are not exported.
+	// Otherwise, they are the same."
+	if name != obj.Name() {
+		return false
+	}
+	// obj.Name == name
+	if obj.Exported() {
+		return true
+	}
+	// not exported, so packages must be the same (pkg == nil for
+	// fields in Universe scope; this can only happen for types
+	// introduced via Eval)
+	if pkg == nil || obj.Pkg() == nil {
+		return pkg == obj.Pkg()
+	}
+	// pkg != nil && obj.pkg != nil
+	return pkg.Path() == obj.Pkg().Path()
+}
+
+func (g *graph) implements(V types.Type, T *types.Interface, msV *types.MethodSet) ([]*types.Selection, bool) {
+	// fast path for common case
+	if T.Empty() {
+		return nil, true
+	}
+
+	if ityp, _ := V.Underlying().(*types.Interface); ityp != nil {
+		// TODO(dh): is this code reachable?
+		for i := 0; i < T.NumMethods(); i++ {
+			m := T.Method(i)
+			_, obj := lookupMethod(ityp, m.Pkg(), m.Name())
+			switch {
+			case obj == nil:
+				return nil, false
+			case !types.Identical(obj.Type(), m.Type()):
+				return nil, false
+			}
+		}
+		return nil, true
+	}
+
+	// A concrete type implements T if it implements all methods of T.
+	var sels []*types.Selection
+	for i := 0; i < T.NumMethods(); i++ {
+		m := T.Method(i)
+		sel := msV.Lookup(m.Pkg(), m.Name())
+		if sel == nil {
+			return nil, false
+		}
+
+		f, _ := sel.Obj().(*types.Func)
+		if f == nil {
+			return nil, false
+		}
+
+		if !types.Identical(f.Type(), m.Type()) {
+			return nil, false
+		}
+
+		sels = append(sels, sel)
+	}
+	return sels, true
+}