Unify package and archive modes - step 2

Author: podtserkovskiy

CHANGELOG.md

@@ -4,7 +4,10 @@ All notable changes to this project will be documented in this file.
 This project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
 ## Unreleased
-- No changes yet.
+- [#273][]: Archive mode: supports same capabilities as "package" mode, including:
+  erroring out on type constraints and handling type aliases explicitly
+
+[#273]: https://github.com/uber-go/mock/pull/273
 
 ## 0.6.0 (18 Aug 2025)
 ### Added

mockgen/archive.go

@@ -11,7 +11,7 @@ import (
 	"golang.org/x/tools/go/gcexportdata"
 )
 
-func archiveMode(importPath string, symbols []string, archive string) (*model.Package, error) {
+func parseExportFile(importPath string, symbols []string, archive string) (*model.Package, error) {
 	f, err := os.Open(archive)
 	if err != nil {
 		return nil, err

mockgen/mockgen.go

@@ -100,7 +100,7 @@ func main() {
 		checkArgs()
 		packageName = flag.Arg(0)
 		interfaces := strings.Split(flag.Arg(1), ",")
-		pkg, err = archiveMode(packageName, interfaces, *archive)
+		pkg, err = parseExportFile(packageName, interfaces, *archive)
 
 	default: // package mode
 		checkArgs()

mockgen/package_mode.go

@@ -15,28 +15,20 @@ var (
 	buildFlags = flag.String("build_flags", "", "(package mode) Additional flags for go build.")
 )
 
-type packageModeParser struct {
-	pkgName string
-}
+type packageModeParser struct{}
 
 func (p *packageModeParser) parsePackage(packageName string, ifaces []string) (*model.Package, error) {
-	p.pkgName = packageName
-
 	pkg, err := p.loadPackage(packageName)
 	if err != nil {
 		return nil, fmt.Errorf("load package: %w", err)
 	}
 
-	interfaces, err := extractInterfacesFromPackageTypes(pkg.Types, ifaces)
+	modelPackage, err := parseExportFile(packageName, ifaces, pkg.ExportFile)
 	if err != nil {
 		return nil, fmt.Errorf("extract interfaces from package: %w", err)
 	}
 
-	return &model.Package{
-		Name:       pkg.Types.Name(),
-		PkgPath:    packageName,
-		Interfaces: interfaces,
-	}, nil
+	return modelPackage, nil
 }
 
 func (p *packageModeParser) loadPackage(packageName string) (*packages.Package, error) {
@@ -46,7 +38,7 @@ func (p *packageModeParser) loadPackage(packageName string) (*packages.Package,
 	}
 
 	cfg := &packages.Config{
-		Mode:       packages.NeedDeps | packages.NeedImports | packages.NeedTypes | packages.NeedTypesInfo | packages.NeedEmbedFiles | packages.LoadSyntax,
+		Mode:       packages.NeedExportFile,
 		BuildFlags: buildFlagsSet,
 	}
 	pkgs, err := packages.Load(cfg, packageName)