Update dependencies (#1784)

2 files changed, 1051 insertions, 0 deletions

diff --git a/vendor/github.com/graph-gophers/graphql-go/internal/validation/suggestion.go b/vendor/github.com/graph-gophers/graphql-go/internal/validation/suggestion.go
new file mode 100644
index 00000000..9702b5f5
--- /dev/null
+++ b/vendor/github.com/graph-gophers/graphql-go/internal/validation/suggestion.go
@@ -0,0 +1,71 @@
+package validation
+
+import (
+	"fmt"
+	"sort"
+	"strconv"
+	"strings"
+)
+
+func makeSuggestion(prefix string, options []string, input string) string {
+	var selected []string
+	distances := make(map[string]int)
+	for _, opt := range options {
+		distance := levenshteinDistance(input, opt)
+		threshold := max(len(input)/2, max(len(opt)/2, 1))
+		if distance < threshold {
+			selected = append(selected, opt)
+			distances[opt] = distance
+		}
+	}
+
+	if len(selected) == 0 {
+		return ""
+	}
+	sort.Slice(selected, func(i, j int) bool {
+		return distances[selected[i]] < distances[selected[j]]
+	})
+
+	parts := make([]string, len(selected))
+	for i, opt := range selected {
+		parts[i] = strconv.Quote(opt)
+	}
+	if len(parts) > 1 {
+		parts[len(parts)-1] = "or " + parts[len(parts)-1]
+	}
+	return fmt.Sprintf(" %s %s?", prefix, strings.Join(parts, ", "))
+}
+
+func levenshteinDistance(s1, s2 string) int {
+	column := make([]int, len(s1)+1)
+	for y := range s1 {
+		column[y+1] = y + 1
+	}
+	for x, rx := range s2 {
+		column[0] = x + 1
+		lastdiag := x
+		for y, ry := range s1 {
+			olddiag := column[y+1]
+			if rx != ry {
+				lastdiag++
+			}
+			column[y+1] = min(column[y+1]+1, min(column[y]+1, lastdiag))
+			lastdiag = olddiag
+		}
+	}
+	return column[len(s1)]
+}
+
+func min(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}
+
+func max(a, b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}
diff --git a/vendor/github.com/graph-gophers/graphql-go/internal/validation/validation.go b/vendor/github.com/graph-gophers/graphql-go/internal/validation/validation.go
new file mode 100644
index 00000000..e3672638
--- /dev/null
+++ b/vendor/github.com/graph-gophers/graphql-go/internal/validation/validation.go
@@ -0,0 +1,980 @@
+package validation
+
+import (
+	"fmt"
+	"math"
+	"reflect"
+	"strconv"
+	"strings"
+	"text/scanner"
+
+	"github.com/graph-gophers/graphql-go/errors"
+	"github.com/graph-gophers/graphql-go/internal/common"
+	"github.com/graph-gophers/graphql-go/internal/query"
+	"github.com/graph-gophers/graphql-go/types"
+)
+
+type varSet map[*types.InputValueDefinition]struct{}
+
+type selectionPair struct{ a, b types.Selection }
+
+type nameSet map[string]errors.Location
+
+type fieldInfo struct {
+	sf     *types.FieldDefinition
+	parent types.NamedType
+}
+
+type context struct {
+	schema           *types.Schema
+	doc              *types.ExecutableDefinition
+	errs             []*errors.QueryError
+	opErrs           map[*types.OperationDefinition][]*errors.QueryError
+	usedVars         map[*types.OperationDefinition]varSet
+	fieldMap         map[*types.Field]fieldInfo
+	overlapValidated map[selectionPair]struct{}
+	maxDepth         int
+}
+
+func (c *context) addErr(loc errors.Location, rule string, format string, a ...interface{}) {
+	c.addErrMultiLoc([]errors.Location{loc}, rule, format, a...)
+}
+
+func (c *context) addErrMultiLoc(locs []errors.Location, rule string, format string, a ...interface{}) {
+	c.errs = append(c.errs, &errors.QueryError{
+		Message:   fmt.Sprintf(format, a...),
+		Locations: locs,
+		Rule:      rule,
+	})
+}
+
+type opContext struct {
+	*context
+	ops []*types.OperationDefinition
+}
+
+func newContext(s *types.Schema, doc *types.ExecutableDefinition, maxDepth int) *context {
+	return &context{
+		schema:           s,
+		doc:              doc,
+		opErrs:           make(map[*types.OperationDefinition][]*errors.QueryError),
+		usedVars:         make(map[*types.OperationDefinition]varSet),
+		fieldMap:         make(map[*types.Field]fieldInfo),
+		overlapValidated: make(map[selectionPair]struct{}),
+		maxDepth:         maxDepth,
+	}
+}
+
+func Validate(s *types.Schema, doc *types.ExecutableDefinition, variables map[string]interface{}, maxDepth int) []*errors.QueryError {
+	c := newContext(s, doc, maxDepth)
+
+	opNames := make(nameSet)
+	fragUsedBy := make(map[*types.FragmentDefinition][]*types.OperationDefinition)
+	for _, op := range doc.Operations {
+		c.usedVars[op] = make(varSet)
+		opc := &opContext{c, []*types.OperationDefinition{op}}
+
+		// Check if max depth is exceeded, if it's set. If max depth is exceeded,
+		// don't continue to validate the document and exit early.
+		if validateMaxDepth(opc, op.Selections, nil, 1) {
+			return c.errs
+		}
+
+		if op.Name.Name == "" && len(doc.Operations) != 1 {
+			c.addErr(op.Loc, "LoneAnonymousOperation", "This anonymous operation must be the only defined operation.")
+		}
+		if op.Name.Name != "" {
+			validateName(c, opNames, op.Name, "UniqueOperationNames", "operation")
+		}
+
+		validateDirectives(opc, string(op.Type), op.Directives)
+
+		varNames := make(nameSet)
+		for _, v := range op.Vars {
+			validateName(c, varNames, v.Name, "UniqueVariableNames", "variable")
+
+			t := resolveType(c, v.Type)
+			if !canBeInput(t) {
+				c.addErr(v.TypeLoc, "VariablesAreInputTypes", "Variable %q cannot be non-input type %q.", "$"+v.Name.Name, t)
+			}
+			validateValue(opc, v, variables[v.Name.Name], t)
+
+			if v.Default != nil {
+				validateLiteral(opc, v.Default)
+
+				if t != nil {
+					if nn, ok := t.(*types.NonNull); ok {
+						c.addErr(v.Default.Location(), "DefaultValuesOfCorrectType", "Variable %q of type %q is required and will not use the default value. Perhaps you meant to use type %q.", "$"+v.Name.Name, t, nn.OfType)
+					}
+
+					if ok, reason := validateValueType(opc, v.Default, t); !ok {
+						c.addErr(v.Default.Location(), "DefaultValuesOfCorrectType", "Variable %q of type %q has invalid default value %s.\n%s", "$"+v.Name.Name, t, v.Default, reason)
+					}
+				}
+			}
+		}
+
+		var entryPoint types.NamedType
+		switch op.Type {
+		case query.Query:
+			entryPoint = s.EntryPoints["query"]
+		case query.Mutation:
+			entryPoint = s.EntryPoints["mutation"]
+		case query.Subscription:
+			entryPoint = s.EntryPoints["subscription"]
+		default:
+			panic("unreachable")
+		}
+
+		validateSelectionSet(opc, op.Selections, entryPoint)
+
+		fragUsed := make(map[*types.FragmentDefinition]struct{})
+		markUsedFragments(c, op.Selections, fragUsed)
+		for frag := range fragUsed {
+			fragUsedBy[frag] = append(fragUsedBy[frag], op)
+		}
+	}
+
+	fragNames := make(nameSet)
+	fragVisited := make(map[*types.FragmentDefinition]struct{})
+	for _, frag := range doc.Fragments {
+		opc := &opContext{c, fragUsedBy[frag]}
+
+		validateName(c, fragNames, frag.Name, "UniqueFragmentNames", "fragment")
+		validateDirectives(opc, "FRAGMENT_DEFINITION", frag.Directives)
+
+		t := unwrapType(resolveType(c, &frag.On))
+		// continue even if t is nil
+		if t != nil && !canBeFragment(t) {
+			c.addErr(frag.On.Loc, "FragmentsOnCompositeTypes", "Fragment %q cannot condition on non composite type %q.", frag.Name.Name, t)
+			continue
+		}
+
+		validateSelectionSet(opc, frag.Selections, t)
+
+		if _, ok := fragVisited[frag]; !ok {
+			detectFragmentCycle(c, frag.Selections, fragVisited, nil, map[string]int{frag.Name.Name: 0})
+		}
+	}
+
+	for _, frag := range doc.Fragments {
+		if len(fragUsedBy[frag]) == 0 {
+			c.addErr(frag.Loc, "NoUnusedFragments", "Fragment %q is never used.", frag.Name.Name)
+		}
+	}
+
+	for _, op := range doc.Operations {
+		c.errs = append(c.errs, c.opErrs[op]...)
+
+		opUsedVars := c.usedVars[op]
+		for _, v := range op.Vars {
+			if _, ok := opUsedVars[v]; !ok {
+				opSuffix := ""
+				if op.Name.Name != "" {
+					opSuffix = fmt.Sprintf(" in operation %q", op.Name.Name)
+				}
+				c.addErr(v.Loc, "NoUnusedVariables", "Variable %q is never used%s.", "$"+v.Name.Name, opSuffix)
+			}
+		}
+	}
+
+	return c.errs
+}
+
+func validateValue(c *opContext, v *types.InputValueDefinition, val interface{}, t types.Type) {
+	switch t := t.(type) {
+	case *types.NonNull:
+		if val == nil {
+			c.addErr(v.Loc, "VariablesOfCorrectType", "Variable \"%s\" has invalid value null.\nExpected type \"%s\", found null.", v.Name.Name, t)
+			return
+		}
+		validateValue(c, v, val, t.OfType)
+	case *types.List:
+		if val == nil {
+			return
+		}
+		vv, ok := val.([]interface{})
+		if !ok {
+			// Input coercion rules allow single items without wrapping array
+			validateValue(c, v, val, t.OfType)
+			return
+		}
+		for _, elem := range vv {
+			validateValue(c, v, elem, t.OfType)
+		}
+	case *types.EnumTypeDefinition:
+		if val == nil {
+			return
+		}
+		e, ok := val.(string)
+		if !ok {
+			c.addErr(v.Loc, "VariablesOfCorrectType", "Variable \"%s\" has invalid type %T.\nExpected type \"%s\", found %v.", v.Name.Name, val, t, val)
+			return
+		}
+		for _, option := range t.EnumValuesDefinition {
+			if option.EnumValue == e {
+				return
+			}
+		}
+		c.addErr(v.Loc, "VariablesOfCorrectType", "Variable \"%s\" has invalid value %s.\nExpected type \"%s\", found %s.", v.Name.Name, e, t, e)
+	case *types.InputObject:
+		if val == nil {
+			return
+		}
+		in, ok := val.(map[string]interface{})
+		if !ok {
+			c.addErr(v.Loc, "VariablesOfCorrectType", "Variable \"%s\" has invalid type %T.\nExpected type \"%s\", found %s.", v.Name.Name, val, t, val)
+			return
+		}
+		for _, f := range t.Values {
+			fieldVal := in[f.Name.Name]
+			validateValue(c, f, fieldVal, f.Type)
+		}
+	}
+}
+
+// validates the query doesn't go deeper than maxDepth (if set). Returns whether
+// or not query validated max depth to avoid excessive recursion.
+//
+// The visited map is necessary to ensure that max depth validation does not get stuck in cyclical
+// fragment spreads.
+func validateMaxDepth(c *opContext, sels []types.Selection, visited map[*types.FragmentDefinition]struct{}, depth int) bool {
+	// maxDepth checking is turned off when maxDepth is 0
+	if c.maxDepth == 0 {
+		return false
+	}
+
+	exceededMaxDepth := false
+	if visited == nil {
+		visited = map[*types.FragmentDefinition]struct{}{}
+	}
+
+	for _, sel := range sels {
+		switch sel := sel.(type) {
+		case *types.Field:
+			if depth > c.maxDepth {
+				exceededMaxDepth = true
+				c.addErr(sel.Alias.Loc, "MaxDepthExceeded", "Field %q has depth %d that exceeds max depth %d", sel.Name.Name, depth, c.maxDepth)
+				continue
+			}
+			exceededMaxDepth = exceededMaxDepth || validateMaxDepth(c, sel.SelectionSet, visited, depth+1)
+
+		case *types.InlineFragment:
+			// Depth is not checked because inline fragments resolve to other fields which are checked.
+			// Depth is not incremented because inline fragments have the same depth as neighboring fields
+			exceededMaxDepth = exceededMaxDepth || validateMaxDepth(c, sel.Selections, visited, depth)
+		case *types.FragmentSpread:
+			// Depth is not checked because fragments resolve to other fields which are checked.
+			frag := c.doc.Fragments.Get(sel.Name.Name)
+			if frag == nil {
+				// In case of unknown fragment (invalid request), ignore max depth evaluation
+				c.addErr(sel.Loc, "MaxDepthEvaluationError", "Unknown fragment %q. Unable to evaluate depth.", sel.Name.Name)
+				continue
+			}
+
+			if _, ok := visited[frag]; ok {
+				// we've already seen this fragment, don't check depth again.
+				continue
+			}
+			visited[frag] = struct{}{}
+
+			// Depth is not incremented because fragments have the same depth as surrounding fields
+			exceededMaxDepth = exceededMaxDepth || validateMaxDepth(c, frag.Selections, visited, depth)
+		}
+	}
+
+	return exceededMaxDepth
+}
+
+func validateSelectionSet(c *opContext, sels []types.Selection, t types.NamedType) {
+	for _, sel := range sels {
+		validateSelection(c, sel, t)
+	}
+
+	for i, a := range sels {
+		for _, b := range sels[i+1:] {
+			c.validateOverlap(a, b, nil, nil)
+		}
+	}
+}
+
+func validateSelection(c *opContext, sel types.Selection, t types.NamedType) {
+	switch sel := sel.(type) {
+	case *types.Field:
+		validateDirectives(c, "FIELD", sel.Directives)
+
+		fieldName := sel.Name.Name
+		var f *types.FieldDefinition
+		switch fieldName {
+		case "__typename":
+			f = &types.FieldDefinition{
+				Name: "__typename",
+				Type: c.schema.Types["String"],
+			}
+		case "__schema":
+			f = &types.FieldDefinition{
+				Name: "__schema",
+				Type: c.schema.Types["__Schema"],
+			}
+		case "__type":
+			f = &types.FieldDefinition{
+				Name: "__type",
+				Arguments: types.ArgumentsDefinition{
+					&types.InputValueDefinition{
+						Name: types.Ident{Name: "name"},
+						Type: &types.NonNull{OfType: c.schema.Types["String"]},
+					},
+				},
+				Type: c.schema.Types["__Type"],
+			}
+		default:
+			f = fields(t).Get(fieldName)
+			if f == nil && t != nil {
+				suggestion := makeSuggestion("Did you mean", fields(t).Names(), fieldName)
+				c.addErr(sel.Alias.Loc, "FieldsOnCorrectType", "Cannot query field %q on type %q.%s", fieldName, t, suggestion)
+			}
+		}
+		c.fieldMap[sel] = fieldInfo{sf: f, parent: t}
+
+		validateArgumentLiterals(c, sel.Arguments)
+		if f != nil {
+			validateArgumentTypes(c, sel.Arguments, f.Arguments, sel.Alias.Loc,
+				func() string { return fmt.Sprintf("field %q of type %q", fieldName, t) },
+				func() string { return fmt.Sprintf("Field %q", fieldName) },
+			)
+		}
+
+		var ft types.Type
+		if f != nil {
+			ft = f.Type
+			sf := hasSubfields(ft)
+			if sf && sel.SelectionSet == nil {
+				c.addErr(sel.Alias.Loc, "ScalarLeafs", "Field %q of type %q must have a selection of subfields. Did you mean \"%s { ... }\"?", fieldName, ft, fieldName)
+			}
+			if !sf && sel.SelectionSet != nil {
+				c.addErr(sel.SelectionSetLoc, "ScalarLeafs", "Field %q must not have a selection since type %q has no subfields.", fieldName, ft)
+			}
+		}
+		if sel.SelectionSet != nil {
+			validateSelectionSet(c, sel.SelectionSet, unwrapType(ft))
+		}
+
+	case *types.InlineFragment:
+		validateDirectives(c, "INLINE_FRAGMENT", sel.Directives)
+		if sel.On.Name != "" {
+			fragTyp := unwrapType(resolveType(c.context, &sel.On))
+			if fragTyp != nil && !compatible(t, fragTyp) {
+				c.addErr(sel.Loc, "PossibleFragmentSpreads", "Fragment cannot be spread here as objects of type %q can never be of type %q.", t, fragTyp)
+			}
+			t = fragTyp
+			// continue even if t is nil
+		}
+		if t != nil && !canBeFragment(t) {
+			c.addErr(sel.On.Loc, "FragmentsOnCompositeTypes", "Fragment cannot condition on non composite type %q.", t)
+			return
+		}
+		validateSelectionSet(c, sel.Selections, unwrapType(t))
+
+	case *types.FragmentSpread:
+		validateDirectives(c, "FRAGMENT_SPREAD", sel.Directives)
+		frag := c.doc.Fragments.Get(sel.Name.Name)
+		if frag == nil {
+			c.addErr(sel.Name.Loc, "KnownFragmentNames", "Unknown fragment %q.", sel.Name.Name)
+			return
+		}
+		fragTyp := c.schema.Types[frag.On.Name]
+		if !compatible(t, fragTyp) {
+			c.addErr(sel.Loc, "PossibleFragmentSpreads", "Fragment %q cannot be spread here as objects of type %q can never be of type %q.", frag.Name.Name, t, fragTyp)
+		}
+
+	default:
+		panic("unreachable")
+	}
+}
+
+func compatible(a, b types.Type) bool {
+	for _, pta := range possibleTypes(a) {
+		for _, ptb := range possibleTypes(b) {
+			if pta == ptb {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+func possibleTypes(t types.Type) []*types.ObjectTypeDefinition {
+	switch t := t.(type) {
+	case *types.ObjectTypeDefinition:
+		return []*types.ObjectTypeDefinition{t}
+	case *types.InterfaceTypeDefinition:
+		return t.PossibleTypes
+	case *types.Union:
+		return t.UnionMemberTypes
+	default:
+		return nil
+	}
+}
+
+func markUsedFragments(c *context, sels []types.Selection, fragUsed map[*types.FragmentDefinition]struct{}) {
+	for _, sel := range sels {
+		switch sel := sel.(type) {
+		case *types.Field:
+			if sel.SelectionSet != nil {
+				markUsedFragments(c, sel.SelectionSet, fragUsed)
+			}
+
+		case *types.InlineFragment:
+			markUsedFragments(c, sel.Selections, fragUsed)
+
+		case *types.FragmentSpread:
+			frag := c.doc.Fragments.Get(sel.Name.Name)
+			if frag == nil {
+				return
+			}
+
+			if _, ok := fragUsed[frag]; ok {
+				continue
+			}
+
+			fragUsed[frag] = struct{}{}
+			markUsedFragments(c, frag.Selections, fragUsed)
+
+		default:
+			panic("unreachable")
+		}
+	}
+}
+
+func detectFragmentCycle(c *context, sels []types.Selection, fragVisited map[*types.FragmentDefinition]struct{}, spreadPath []*types.FragmentSpread, spreadPathIndex map[string]int) {
+	for _, sel := range sels {
+		detectFragmentCycleSel(c, sel, fragVisited, spreadPath, spreadPathIndex)
+	}
+}
+
+func detectFragmentCycleSel(c *context, sel types.Selection, fragVisited map[*types.FragmentDefinition]struct{}, spreadPath []*types.FragmentSpread, spreadPathIndex map[string]int) {
+	switch sel := sel.(type) {
+	case *types.Field:
+		if sel.SelectionSet != nil {
+			detectFragmentCycle(c, sel.SelectionSet, fragVisited, spreadPath, spreadPathIndex)
+		}
+
+	case *types.InlineFragment:
+		detectFragmentCycle(c, sel.Selections, fragVisited, spreadPath, spreadPathIndex)
+
+	case *types.FragmentSpread:
+		frag := c.doc.Fragments.Get(sel.Name.Name)
+		if frag == nil {
+			return
+		}
+
+		spreadPath = append(spreadPath, sel)
+		if i, ok := spreadPathIndex[frag.Name.Name]; ok {
+			cyclePath := spreadPath[i:]
+			via := ""
+			if len(cyclePath) > 1 {
+				names := make([]string, len(cyclePath)-1)
+				for i, frag := range cyclePath[:len(cyclePath)-1] {
+					names[i] = frag.Name.Name
+				}
+				via = " via " + strings.Join(names, ", ")
+			}
+
+			locs := make([]errors.Location, len(cyclePath))
+			for i, frag := range cyclePath {
+				locs[i] = frag.Loc
+			}
+			c.addErrMultiLoc(locs, "NoFragmentCycles", "Cannot spread fragment %q within itself%s.", frag.Name.Name, via)
+			return
+		}
+
+		if _, ok := fragVisited[frag]; ok {
+			return
+		}
+		fragVisited[frag] = struct{}{}
+
+		spreadPathIndex[frag.Name.Name] = len(spreadPath)
+		detectFragmentCycle(c, frag.Selections, fragVisited, spreadPath, spreadPathIndex)
+		delete(spreadPathIndex, frag.Name.Name)
+
+	default:
+		panic("unreachable")
+	}
+}
+
+func (c *context) validateOverlap(a, b types.Selection, reasons *[]string, locs *[]errors.Location) {
+	if a == b {
+		return
+	}
+
+	if _, ok := c.overlapValidated[selectionPair{a, b}]; ok {
+		return
+	}
+	c.overlapValidated[selectionPair{a, b}] = struct{}{}
+	c.overlapValidated[selectionPair{b, a}] = struct{}{}
+
+	switch a := a.(type) {
+	case *types.Field:
+		switch b := b.(type) {
+		case *types.Field:
+			if b.Alias.Loc.Before(a.Alias.Loc) {
+				a, b = b, a
+			}
+			if reasons2, locs2 := c.validateFieldOverlap(a, b); len(reasons2) != 0 {
+				locs2 = append(locs2, a.Alias.Loc, b.Alias.Loc)
+				if reasons == nil {
+					c.addErrMultiLoc(locs2, "OverlappingFieldsCanBeMerged", "Fields %q conflict because %s. Use different aliases on the fields to fetch both if this was intentional.", a.Alias.Name, strings.Join(reasons2, " and "))
+					return
+				}
+				for _, r := range reasons2 {
+					*reasons = append(*reasons, fmt.Sprintf("subfields %q conflict because %s", a.Alias.Name, r))
+				}
+				*locs = append(*locs, locs2...)
+			}
+
+		case *types.InlineFragment:
+			for _, sel := range b.Selections {
+				c.validateOverlap(a, sel, reasons, locs)
+			}
+
+		case *types.FragmentSpread:
+			if frag := c.doc.Fragments.Get(b.Name.Name); frag != nil {
+				for _, sel := range frag.Selections {
+					c.validateOverlap(a, sel, reasons, locs)
+				}
+			}
+
+		default:
+			panic("unreachable")
+		}
+
+	case *types.InlineFragment:
+		for _, sel := range a.Selections {
+			c.validateOverlap(sel, b, reasons, locs)
+		}
+
+	case *types.FragmentSpread:
+		if frag := c.doc.Fragments.Get(a.Name.Name); frag != nil {
+			for _, sel := range frag.Selections {
+				c.validateOverlap(sel, b, reasons, locs)
+			}
+		}
+
+	default:
+		panic("unreachable")
+	}
+}
+
+func (c *context) validateFieldOverlap(a, b *types.Field) ([]string, []errors.Location) {
+	if a.Alias.Name != b.Alias.Name {
+		return nil, nil
+	}
+
+	if asf := c.fieldMap[a].sf; asf != nil {
+		if bsf := c.fieldMap[b].sf; bsf != nil {
+			if !typesCompatible(asf.Type, bsf.Type) {
+				return []string{fmt.Sprintf("they return conflicting types %s and %s", asf.Type, bsf.Type)}, nil
+			}
+		}
+	}
+
+	at := c.fieldMap[a].parent
+	bt := c.fieldMap[b].parent
+	if at == nil || bt == nil || at == bt {
+		if a.Name.Name != b.Name.Name {
+			return []string{fmt.Sprintf("%s and %s are different fields", a.Name.Name, b.Name.Name)}, nil
+		}
+
+		if argumentsConflict(a.Arguments, b.Arguments) {
+			return []string{"they have differing arguments"}, nil
+		}
+	}
+
+	var reasons []string
+	var locs []errors.Location
+	for _, a2 := range a.SelectionSet {
+		for _, b2 := range b.SelectionSet {
+			c.validateOverlap(a2, b2, &reasons, &locs)
+		}
+	}
+	return reasons, locs
+}
+
+func argumentsConflict(a, b types.ArgumentList) bool {
+	if len(a) != len(b) {
+		return true
+	}
+	for _, argA := range a {
+		valB, ok := b.Get(argA.Name.Name)
+		if !ok || !reflect.DeepEqual(argA.Value.Deserialize(nil), valB.Deserialize(nil)) {
+			return true
+		}
+	}
+	return false
+}
+
+func fields(t types.Type) types.FieldsDefinition {
+	switch t := t.(type) {
+	case *types.ObjectTypeDefinition:
+		return t.Fields
+	case *types.InterfaceTypeDefinition:
+		return t.Fields
+	default:
+		return nil
+	}
+}
+
+func unwrapType(t types.Type) types.NamedType {
+	if t == nil {
+		return nil
+	}
+	for {
+		switch t2 := t.(type) {
+		case types.NamedType:
+			return t2
+		case *types.List:
+			t = t2.OfType
+		case *types.NonNull:
+			t = t2.OfType
+		default:
+			panic("unreachable")
+		}
+	}
+}
+
+func resolveType(c *context, t types.Type) types.Type {
+	t2, err := common.ResolveType(t, c.schema.Resolve)
+	if err != nil {
+		c.errs = append(c.errs, err)
+	}
+	return t2
+}
+
+func validateDirectives(c *opContext, loc string, directives types.DirectiveList) {
+	directiveNames := make(nameSet)
+	for _, d := range directives {
+		dirName := d.Name.Name
+		validateNameCustomMsg(c.context, directiveNames, d.Name, "UniqueDirectivesPerLocation", func() string {
+			return fmt.Sprintf("The directive %q can only be used once at this location.", dirName)
+		})
+
+		validateArgumentLiterals(c, d.Arguments)
+
+		dd, ok := c.schema.Directives[dirName]
+		if !ok {
+			c.addErr(d.Name.Loc, "KnownDirectives", "Unknown directive %q.", dirName)
+			continue
+		}
+
+		locOK := false
+		for _, allowedLoc := range dd.Locations {
+			if loc == allowedLoc {
+				locOK = true
+				break
+			}
+		}
+		if !locOK {
+			c.addErr(d.Name.Loc, "KnownDirectives", "Directive %q may not be used on %s.", dirName, loc)
+		}
+
+		validateArgumentTypes(c, d.Arguments, dd.Arguments, d.Name.Loc,
+			func() string { return fmt.Sprintf("directive %q", "@"+dirName) },
+			func() string { return fmt.Sprintf("Directive %q", "@"+dirName) },
+		)
+	}
+}
+
+func validateName(c *context, set nameSet, name types.Ident, rule string, kind string) {
+	validateNameCustomMsg(c, set, name, rule, func() string {
+		return fmt.Sprintf("There can be only one %s named %q.", kind, name.Name)
+	})
+}
+
+func validateNameCustomMsg(c *context, set nameSet, name types.Ident, rule string, msg func() string) {
+	if loc, ok := set[name.Name]; ok {
+		c.addErrMultiLoc([]errors.Location{loc, name.Loc}, rule, msg())
+		return
+	}
+	set[name.Name] = name.Loc
+}
+
+func validateArgumentTypes(c *opContext, args types.ArgumentList, argDecls types.ArgumentsDefinition, loc errors.Location, owner1, owner2 func() string) {
+	for _, selArg := range args {
+		arg := argDecls.Get(selArg.Name.Name)
+		if arg == nil {
+			c.addErr(selArg.Name.Loc, "KnownArgumentNames", "Unknown argument %q on %s.", selArg.Name.Name, owner1())
+			continue
+		}
+		value := selArg.Value
+		if ok, reason := validateValueType(c, value, arg.Type); !ok {
+			c.addErr(value.Location(), "ArgumentsOfCorrectType", "Argument %q has invalid value %s.\n%s", arg.Name.Name, value, reason)
+		}
+	}
+	for _, decl := range argDecls {
+		if _, ok := decl.Type.(*types.NonNull); ok {
+			if _, ok := args.Get(decl.Name.Name); !ok {
+				c.addErr(loc, "ProvidedNonNullArguments", "%s argument %q of type %q is required but not provided.", owner2(), decl.Name.Name, decl.Type)
+			}
+		}
+	}
+}
+
+func validateArgumentLiterals(c *opContext, args types.ArgumentList) {
+	argNames := make(nameSet)
+	for _, arg := range args {
+		validateName(c.context, argNames, arg.Name, "UniqueArgumentNames", "argument")
+		validateLiteral(c, arg.Value)
+	}
+}
+
+func validateLiteral(c *opContext, l types.Value) {
+	switch l := l.(type) {
+	case *types.ObjectValue:
+		fieldNames := make(nameSet)
+		for _, f := range l.Fields {
+			validateName(c.context, fieldNames, f.Name, "UniqueInputFieldNames", "input field")
+			validateLiteral(c, f.Value)
+		}
+	case *types.ListValue:
+		for _, entry := range l.Values {
+			validateLiteral(c, entry)
+		}
+	case *types.Variable:
+		for _, op := range c.ops {
+			v := op.Vars.Get(l.Name)
+			if v == nil {
+				byOp := ""
+				if op.Name.Name != "" {
+					byOp = fmt.Sprintf(" by operation %q", op.Name.Name)
+				}
+				c.opErrs[op] = append(c.opErrs[op], &errors.QueryError{
+					Message:   fmt.Sprintf("Variable %q is not defined%s.", "$"+l.Name, byOp),
+					Locations: []errors.Location{l.Loc, op.Loc},
+					Rule:      "NoUndefinedVariables",
+				})
+				continue
+			}
+			validateValueType(c, l, resolveType(c.context, v.Type))
+			c.usedVars[op][v] = struct{}{}
+		}
+	}
+}
+
+func validateValueType(c *opContext, v types.Value, t types.Type) (bool, string) {
+	if v, ok := v.(*types.Variable); ok {
+		for _, op := range c.ops {
+			if v2 := op.Vars.Get(v.Name); v2 != nil {
+				t2, err := common.ResolveType(v2.Type, c.schema.Resolve)
+				if _, ok := t2.(*types.NonNull); !ok && v2.Default != nil {
+					t2 = &types.NonNull{OfType: t2}
+				}
+				if err == nil && !typeCanBeUsedAs(t2, t) {
+					c.addErrMultiLoc([]errors.Location{v2.Loc, v.Loc}, "VariablesInAllowedPosition", "Variable %q of type %q used in position expecting type %q.", "$"+v.Name, t2, t)
+				}
+			}
+		}
+		return true, ""
+	}
+
+	if nn, ok := t.(*types.NonNull); ok {
+		if isNull(v) {
+			return false, fmt.Sprintf("Expected %q, found null.", t)
+		}
+		t = nn.OfType
+	}
+	if isNull(v) {
+		return true, ""
+	}
+
+	switch t := t.(type) {
+	case *types.ScalarTypeDefinition, *types.EnumTypeDefinition:
+		if lit, ok := v.(*types.PrimitiveValue); ok {
+			if validateBasicLit(lit, t) {
+				return true, ""
+			}
+			return false, fmt.Sprintf("Expected type %q, found %s.", t, v)
+		}
+		return true, ""
+
+	case *types.List:
+		list, ok := v.(*types.ListValue)
+		if !ok {
+			return validateValueType(c, v, t.OfType) // single value instead of list
+		}
+		for i, entry := range list.Values {
+			if ok, reason := validateValueType(c, entry, t.OfType); !ok {
+				return false, fmt.Sprintf("In element #%d: %s", i, reason)
+			}
+		}
+		return true, ""
+
+	case *types.InputObject:
+		v, ok := v.(*types.ObjectValue)
+		if !ok {
+			return false, fmt.Sprintf("Expected %q, found not an object.", t)
+		}
+		for _, f := range v.Fields {
+			name := f.Name.Name
+			iv := t.Values.Get(name)
+			if iv == nil {
+				return false, fmt.Sprintf("In field %q: Unknown field.", name)
+			}
+			if ok, reason := validateValueType(c, f.Value, iv.Type); !ok {
+				return false, fmt.Sprintf("In field %q: %s", name, reason)
+			}
+		}
+		for _, iv := range t.Values {
+			found := false
+			for _, f := range v.Fields {
+				if f.Name.Name == iv.Name.Name {
+					found = true
+					break
+				}
+			}
+			if !found {
+				if _, ok := iv.Type.(*types.NonNull); ok && iv.Default == nil {
+					return false, fmt.Sprintf("In field %q: Expected %q, found null.", iv.Name.Name, iv.Type)
+				}
+			}
+		}
+		return true, ""
+	}
+
+	return false, fmt.Sprintf("Expected type %q, found %s.", t, v)
+}
+
+func validateBasicLit(v *types.PrimitiveValue, t types.Type) bool {
+	switch t := t.(type) {
+	case *types.ScalarTypeDefinition:
+		switch t.Name {
+		case "Int":
+			if v.Type != scanner.Int {
+				return false
+			}
+			f, err := strconv.ParseFloat(v.Text, 64)
+			if err != nil {
+				panic(err)
+			}
+			return f >= math.MinInt32 && f <= math.MaxInt32
+		case "Float":
+			return v.Type == scanner.Int || v.Type == scanner.Float
+		case "String":
+			return v.Type == scanner.String
+		case "Boolean":
+			return v.Type == scanner.Ident && (v.Text == "true" || v.Text == "false")
+		case "ID":
+			return v.Type == scanner.Int || v.Type == scanner.String
+		default:
+			//TODO: Type-check against expected type by Unmarshalling
+			return true
+		}
+
+	case *types.EnumTypeDefinition:
+		if v.Type != scanner.Ident {
+			return false
+		}
+		for _, option := range t.EnumValuesDefinition {
+			if option.EnumValue == v.Text {
+				return true
+			}
+		}
+		return false
+	}
+
+	return false
+}
+
+func canBeFragment(t types.Type) bool {
+	switch t.(type) {
+	case *types.ObjectTypeDefinition, *types.InterfaceTypeDefinition, *types.Union:
+		return true
+	default:
+		return false
+	}
+}
+
+func canBeInput(t types.Type) bool {
+	switch t := t.(type) {
+	case *types.InputObject, *types.ScalarTypeDefinition, *types.EnumTypeDefinition:
+		return true
+	case *types.List:
+		return canBeInput(t.OfType)
+	case *types.NonNull:
+		return canBeInput(t.OfType)
+	default:
+		return false
+	}
+}
+
+func hasSubfields(t types.Type) bool {
+	switch t := t.(type) {
+	case *types.ObjectTypeDefinition, *types.InterfaceTypeDefinition, *types.Union:
+		return true
+	case *types.List:
+		return hasSubfields(t.OfType)
+	case *types.NonNull:
+		return hasSubfields(t.OfType)
+	default:
+		return false
+	}
+}
+
+func isLeaf(t types.Type) bool {
+	switch t.(type) {
+	case *types.ScalarTypeDefinition, *types.EnumTypeDefinition:
+		return true
+	default:
+		return false
+	}
+}
+
+func isNull(lit interface{}) bool {
+	_, ok := lit.(*types.NullValue)
+	return ok
+}
+
+func typesCompatible(a, b types.Type) bool {
+	al, aIsList := a.(*types.List)
+	bl, bIsList := b.(*types.List)
+	if aIsList || bIsList {
+		return aIsList && bIsList && typesCompatible(al.OfType, bl.OfType)
+	}
+
+	ann, aIsNN := a.(*types.NonNull)
+	bnn, bIsNN := b.(*types.NonNull)
+	if aIsNN || bIsNN {
+		return aIsNN && bIsNN && typesCompatible(ann.OfType, bnn.OfType)
+	}
+
+	if isLeaf(a) || isLeaf(b) {
+		return a == b
+	}
+
+	return true
+}
+
+func typeCanBeUsedAs(t, as types.Type) bool {
+	nnT, okT := t.(*types.NonNull)
+	if okT {
+		t = nnT.OfType
+	}
+
+	nnAs, okAs := as.(*types.NonNull)
+	if okAs {
+		as = nnAs.OfType
+		if !okT {
+			return false // nullable can not be used as non-null
+		}
+	}
+
+	if t == as {
+		return true
+	}
+
+	if lT, ok := t.(*types.List); ok {
+		if lAs, ok := as.(*types.List); ok {
+			return typeCanBeUsedAs(lT.OfType, lAs.OfType)
+		}
+	}
+	return false
+}