nogo: instantiate type info for generic type info when running under …

…Go >=1.18

This mirrors what golang.org/x/tools/go/packages does when loading packages.

Should fix bazel-contrib#3211 (and probably bazel-contrib#3164 as well).

go/tools/builders/BUILD.bazel

@@ -81,6 +81,8 @@ go_source(
         "env.go",
         "flags.go",
         "nogo_main.go",
+        "nogo_typeparams_go118.go",
+        "nogo_typeparams_go117.go",
         "pack.go",
     ],
     # //go/tools/builders:nogo_srcs is considered a different target by

go/tools/builders/nogo_main.go

@@ -335,6 +335,9 @@ func load(packagePath string, imp *importer, filenames []string) (*goPackage, er
 		Scopes:     make(map[ast.Node]*types.Scope),
 		Selections: make(map[*ast.SelectorExpr]*types.Selection),
 	}
+
+	initInstanceInfo(info)
+
 	types, err := config.Check(packagePath, pkg.fset, syntax, info)
 	if err != nil {
 		pkg.illTyped, pkg.typeCheckError = true, err

go/tools/builders/nogo_typeparams_go117.go

@@ -0,0 +1,23 @@
+/* Copyright 2022 The Bazel Authors. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+//go:build !go1.18
+// +build !go1.18
+
+package main
+
+import "go/types"
+
+func initInstanceInfo(*types.Info) {}

go/tools/builders/nogo_typeparams_go118.go

@@ -0,0 +1,28 @@
+/* Copyright 2022 The Bazel Authors. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+//go:build go1.18
+// +build go1.18
+
+package main
+
+import (
+	"go/ast"
+	"go/types"
+)
+
+func initInstanceInfo(info *types.Info) {
+	info.Instances = make(map[*ast.Ident]types.Instance)
+}