Add types.Unalias to types assertions and types switches to get an …

…underlying type instead of types.Alias (#33868)

sdks/go/pkg/beam/util/starcgenx/starcgenx.go

@@ -15,7 +15,7 @@
 
 // Package starcgenx is a Static Analysis Type Assertion shim and Registration Code Generator
 // which provides an extractor to extract types from a package, in order to generate
-// approprate shimsr a package so code can be generated for it.
+// appropriate shims for a package so code can be generated for it.
 //
 // It's written for use by the starcgen tool, but separate to permit
 // alternative "go/importer" Importers for accessing types from imported packages.
@@ -336,6 +336,7 @@ func (e *Extractor) isRequired(ident string, obj types.Object, idsRequired, idsF
 	// or it's receiver type identifier needs to be in the filtered identifiers.
 	if idsRequired[ident] {
 		idsFound[ident] = true
+		e.Printf("isRequired found: %s\n", ident)
 		return true
 	}
 	// Check if this is a function.
@@ -347,10 +348,10 @@ func (e *Extractor) isRequired(ident string, obj types.Object, idsRequired, idsF
 	if recv := sig.Recv(); recv != nil && graph.IsLifecycleMethod(ident) {
 		// We don't want to care about pointers, so dereference to value type.
 		t := recv.Type()
-		p, ok := t.(*types.Pointer)
+		p, ok := types.Unalias(t).(*types.Pointer)
 		for ok {
 			t = p.Elem()
-			p, ok = t.(*types.Pointer)
+			p, ok = types.Unalias(t).(*types.Pointer)
 		}
 		ts := types.TypeString(t, e.qualifier)
 		e.Printf("recv %v has %v, ts: %s %s--- ", recv, sig, ts, ident)
@@ -384,14 +385,16 @@ func (e *Extractor) fromObj(fset *token.FileSet, id *ast.Ident, obj types.Object
 		ident = obj.Name()
 	}
 	if !e.isRequired(ident, obj, idsRequired, idsFound) {
+		e.Printf("%s: %q with package %q is not required \n",
+			fset.Position(id.Pos()), id.Name, pkg.Name())
 		return
 	}
 
 	switch ot := obj.(type) {
 	case *types.Var:
 		// Vars are tricky since they could be anything, and anywhere (package scope, parameters, etc)
 		// eg. Flags, or Field Tags, among others.
-		// I'm increasingly convinced that we should simply igonore vars.
+		// I'm increasingly convinced that we should simply ignore vars.
 		// Do nothing for vars.
 	case *types.Func:
 		sig := obj.Type().(*types.Signature)
@@ -405,10 +408,10 @@ func (e *Extractor) fromObj(fset *token.FileSet, id *ast.Ident, obj types.Object
 			}
 			// This must be a structural DoFn! We should generate a closure wrapper for it.
 			t := recv.Type()
-			p, ok := t.(*types.Pointer)
+			p, ok := types.Unalias(t).(*types.Pointer)
 			for ok {
 				t = p.Elem()
-				p, ok = t.(*types.Pointer)
+				p, ok = types.Unalias(t).(*types.Pointer)
 			}
 			ts := types.TypeString(t, e.qualifier)
 			mthdMap := e.wraps[ts]
@@ -453,6 +456,10 @@ func (e *Extractor) extractType(ot *types.TypeName) {
 	// A single level is safe since the code we're analysing imports it,
 	// so we can assume the generated code can access it too.
 	if ot.IsAlias() {
+		if t, ok := ot.Type().(*types.Alias); ok {
+			ot = t.Obj()
+			name = types.TypeString(t, e.qualifier)
+		}
 		if t, ok := ot.Type().(*types.Named); ok {
 			ot = t.Obj()
 			name = types.TypeString(t, e.qualifier)
@@ -461,7 +468,7 @@ func (e *Extractor) extractType(ot *types.TypeName) {
 	// Only register non-universe types (eg. avoid `error` and similar)
 	if pkg := ot.Pkg(); pkg != nil {
 		path := pkg.Path()
-		e.imports[pkg.Path()] = struct{}{}
+		e.imports[path] = struct{}{}
 
 		// Do not add universal types to be registered.
 		if path == shimx.TypexImport {
@@ -484,17 +491,17 @@ func (e *Extractor) extractFromContainer(t types.Type) types.Type {
 	// Container types need to be iteratively unwrapped until we're at the base type,
 	// so we can get the import if necessary.
 	for {
-		if s, ok := t.(*types.Slice); ok {
+		if s, ok := types.Unalias(t).(*types.Slice); ok {
 			t = s.Elem()
 			continue
 		}
 
-		if p, ok := t.(*types.Pointer); ok {
+		if p, ok := types.Unalias(t).(*types.Pointer); ok {
 			t = p.Elem()
 			continue
 		}
 
-		if a, ok := t.(*types.Array); ok {
+		if a, ok := types.Unalias(t).(*types.Array); ok {
 			t = a.Elem()
 			continue
 		}
@@ -510,9 +517,17 @@ func (e *Extractor) extractFromTuple(tuple *types.Tuple) {
 		t := e.extractFromContainer(s.Type())
 
 		// Here's where we ensure we register new imports.
+		if at, ok := t.(*types.Alias); ok {
+			if pkg := at.Obj().Pkg(); pkg != nil {
+				e.imports[pkg.Path()] = struct{}{}
+			}
+		}
 		if t, ok := t.(*types.Named); ok {
 			if pkg := t.Obj().Pkg(); pkg != nil {
+				e.Printf("extractType: adding import path %q for %v\n", pkg.Path(), t)
 				e.imports[pkg.Path()] = struct{}{}
+			} else {
+				e.Printf("extractType: %v has no package to import\n", t)
 			}
 			e.extractType(t.Obj())
 		}
@@ -683,7 +698,7 @@ func (e *Extractor) makeEmitter(sig *types.Signature) (shimx.Emitter, bool) {
 
 // makeInput checks if the given signature is an iterator or not, and if so,
 // returns a shimx.Input struct for the signature for use by the code
-// generator. The canonical check for an iterater signature is in the
+// generator. The canonical check for an iterator signature is in the
 // funcx.UnfoldIter function which uses the reflect library,
 // and this logic is replicated here.
 func (e *Extractor) makeInput(sig *types.Signature) (shimx.Input, bool) {
@@ -692,13 +707,13 @@ func (e *Extractor) makeInput(sig *types.Signature) (shimx.Input, bool) {
 		return shimx.Input{}, false
 	}
 	// Iterators must return a bool.
-	if b, ok := r.At(0).Type().(*types.Basic); !ok || b.Kind() != types.Bool {
+	if b, ok := types.Unalias(r.At(0).Type()).(*types.Basic); !ok || b.Kind() != types.Bool {
 		return shimx.Input{}, false
 	}
 	p := sig.Params()
 	for i := 0; i < p.Len(); i++ {
 		// All params for iterators must be pointers.
-		if _, ok := p.At(i).Type().(*types.Pointer); !ok {
+		if _, ok := types.Unalias(p.At(i).Type()).(*types.Pointer); !ok {
 			return shimx.Input{}, false
 		}
 	}