Enable analysis of packages using type parameters

Upstream analyzers support type parameters now, so we no longer need to skip
analysis.

PiperOrigin-RevId: 504383378

tools/checkinfo/checkinfo.go

@@ -74,12 +74,16 @@ func walkObject(pass *analysis.Pass, obj types.Object) {
 		pass.ExportObjectFact(obj, &a)
 		pass.ExportObjectFact(obj, &s)
 	case *types.TypeName:
-		// Skip if just an alias, or if not underlying type. If it is
-		// not an alias, then it must be package-local.
+		// Skip if just an alias, or if not underlying type, or if a
+		// type parameter. If it is not an alias, then it must be
+		// package-local.
 		typ := x.Type()
 		if x.IsAlias() || typ == nil || typ.Underlying() == nil {
 			break
 		}
+		if _, ok := typ.(*types.TypeParam); ok {
+			break
+		}
 		// Add basic information.
 		a := Align(pass.TypesSizes.Alignof(typ))
 		s := Size(pass.TypesSizes.Sizeof(typ))

tools/nogo/check/check.go

@@ -365,6 +365,7 @@ func (i *importer) checkPackage(path string, srcs []string) (*types.Package, Fin
 	}
 	typesInfo := &types.Info{
 		Types:      make(map[ast.Expr]types.TypeAndValue),
+		Instances:  make(map[*ast.Ident]types.Instance),
 		Uses:       make(map[*ast.Ident]types.Object),
 		Defs:       make(map[*ast.Ident]types.Object),
 		Implicits:  make(map[ast.Node]types.Object),
@@ -726,12 +727,6 @@ func SplitPackages(srcs []string, srcRootPrefix string) map[string][]string {
 			continue
 		}
 
-		// Skip unsupported packages explicitly.
-		if _, ok := usesTypeParams[pkg]; ok {
-			log.Printf("WARNING: Skipping package %q: type param analysis not yet supported.", pkg)
-			continue
-		}
-
 		// Add to the package.
 		sources[pkg] = append(sources[pkg], filename)
 	}
@@ -739,16 +734,6 @@ func SplitPackages(srcs []string, srcRootPrefix string) map[string][]string {
 	return sources
 }
 
-// Go standard library packages using Go 1.18 type parameter features.
-//
-// As of writing, analysis tooling is not updated to support type parameters
-// and will choke on these packages. We skip these packages entirely for now.
-//
-// TODO(b/201686256): remove once tooling can handle type parameters.
-var usesTypeParams = map[string]struct{}{
-	"sync/atomic": {}, // https://go.dev/issue/50860
-}
-
 // Bundle checks a bundle of files (typically the standard library).
 func Bundle(sources map[string][]string) (FindingSet, facts.Serializer, error) {
 	// Process all packages.