1 files changed, 115 insertions, 0 deletions
diff --git a/src/cmd/vendor/golang.org/x/tools/internal/typeparams/typeparams.go b/src/cmd/vendor/golang.org/x/tools/internal/typeparams/typeparams.go
new file mode 100644
index 0000000000..be6b0525f6
--- /dev/null
+++ b/src/cmd/vendor/golang.org/x/tools/internal/typeparams/typeparams.go
@@ -0,0 +1,115 @@
+// Copyright 2021 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.
+
+//go:build typeparams && go1.18
+// +build typeparams,go1.18
+
+package typeparams
+
+import (
+	"go/ast"
+	"go/types"
+)
+
+// NOTE: doc comments must be kept in sync with notypeparams.go.
+
+// Enabled reports whether type parameters are enabled in the current build
+// environment.
+const Enabled = true
+
+// GetIndexExprData extracts data from AST nodes that represent index
+// expressions.
+//
+// For an ast.IndexExpr, the resulting IndexExprData will have exactly one
+// index expression. For an ast.MultiIndexExpr (go1.18+), it may have a
+// variable number of index expressions.
+//
+// For nodes that don't represent index expressions, GetIndexExprData returns
+// nil.
+func GetIndexExprData(n ast.Node) *IndexExprData {
+	switch e := n.(type) {
+	case *ast.IndexExpr:
+		return &IndexExprData{
+			X:       e.X,
+			Lbrack:  e.Lbrack,
+			Indices: []ast.Expr{e.Index},
+			Rbrack:  e.Rbrack,
+		}
+	case *ast.MultiIndexExpr:
+		return (*IndexExprData)(e)
+	}
+	return nil
+}
+
+// ForTypeDecl extracts the (possibly nil) type parameter node list from n.
+func ForTypeDecl(n *ast.TypeSpec) *ast.FieldList {
+	return n.TParams
+}
+
+// ForFuncDecl extracts the (possibly nil) type parameter node list from n.
+func ForFuncDecl(n *ast.FuncDecl) *ast.FieldList {
+	if n.Type != nil {
+		return n.Type.TParams
+	}
+	return nil
+}
+
+// ForSignature extracts the (possibly empty) type parameter object list from
+// sig.
+func ForSignature(sig *types.Signature) []*types.TypeName {
+	return tparamsSlice(sig.TParams())
+}
+
+// IsComparable reports if iface is the comparable interface.
+func IsComparable(iface *types.Interface) bool {
+	return iface.IsComparable()
+}
+
+// IsConstraint reports whether iface may only be used as a type parameter
+// constraint (i.e. has a type set or is the comparable interface).
+func IsConstraint(iface *types.Interface) bool {
+	return iface.IsConstraint()
+}
+
+// ForNamed extracts the (possibly empty) type parameter object list from
+// named.
+func ForNamed(named *types.Named) []*types.TypeName {
+	return tparamsSlice(named.TParams())
+}
+
+func tparamsSlice(tparams *types.TypeParams) []*types.TypeName {
+	if tparams.Len() == 0 {
+		return nil
+	}
+	result := make([]*types.TypeName, tparams.Len())
+	for i := 0; i < tparams.Len(); i++ {
+		result[i] = tparams.At(i)
+	}
+	return result
+}
+
+// NamedTArgs extracts the (possibly empty) type argument list from named.
+func NamedTArgs(named *types.Named) []types.Type {
+	return named.TArgs()
+}
+
+// InitInferred initializes info to record inferred type information.
+func InitInferred(info *types.Info) {
+	info.Inferred = make(map[ast.Expr]types.Inferred)
+}
+
+// GetInferred extracts inferred type information from info for e.
+//
+// The expression e may have an inferred type if it is an *ast.IndexExpr
+// representing partial instantiation of a generic function type for which type
+// arguments have been inferred using constraint type inference, or if it is an
+// *ast.CallExpr for which type type arguments have be inferred using both
+// constraint type inference and function argument inference.
+func GetInferred(info *types.Info, e ast.Expr) ([]types.Type, *types.Signature) {
+	if info.Inferred == nil {
+		return nil, nil
+	}
+	inf := info.Inferred[e]
+	return inf.TArgs, inf.Sig
+}