[Serialization] Test loading package dependencies

Author: xymus

test/Serialization/package-dependencies.swift

@@ -0,0 +1,47 @@
+// RUN: %empty-directory(%t)
+// RUN: split-file %s %t
+
+/// Prepare the module imported as package, and two middle modules.
+// RUN: %target-swift-frontend -emit-module %t/PackageDep.swift -o %t
+// RUN: %target-swift-frontend -emit-module %t/ResilientDep.swift -o %t \
+// RUN:   -package-name MyPackage -I %t \
+// RUN:   -enable-library-evolution \
+// RUN:   -enable-experimental-feature AccessLevelOnImport
+// RUN: %target-swift-frontend -emit-module %t/NonResilientDep.swift -o %t \
+// RUN:   -package-name MyPackage -I %t \
+// RUN:   -enable-experimental-feature AccessLevelOnImport
+
+//--- PackageDep.swift
+
+//--- ResilientDep.swift
+package import PackageDep
+
+//--- NonResilientDep.swift
+package import PackageDep
+
+/// When the middle module is library-evolution enabled, the package import
+/// is only visible to modules from the same package.
+// RUN: %target-swift-frontend -typecheck %t/ResilientClient.swift \
+// RUN:   -package-name MyPackage -I %t \
+// RUN:   -enable-experimental-feature AccessLevelOnImport \
+// RUN:   -Rmodule-loading 2>&1 | %FileCheck -check-prefix=VISIBLE-PACKAGE-DEP %s
+// VISIBLE-PACKAGE-DEP: source: '{{.*}}PackageDep.swiftmodule'
+
+// RUN: %target-swift-frontend -typecheck %t/ResilientClient.swift \
+// RUN:   -package-name NotMyPackage -I %t \
+// RUN:   -enable-experimental-feature AccessLevelOnImport \
+// RUN:   -Rmodule-loading 2>&1 | %FileCheck -check-prefix=HIDDEN-PACKAGE-DEP %s
+// HIDDEN-PACKAGE-DEP-NOT: PackageDep
+
+//--- ResilientClient.swift
+import ResilientDep
+
+/// When the middle module isn't library-evolution enabled, all clients
+/// see the package dependency.
+// RUN: %target-swift-frontend -typecheck %t/NonResilientClient.swift \
+// RUN:   -package-name NotMyPackage -I %t \
+// RUN:   -enable-experimental-feature AccessLevelOnImport \
+// RUN:   -Rmodule-loading 2>&1 | %FileCheck -check-prefix=VISIBLE-PACKAGE-DEP %s
+
+//--- NonResilientClient.swift
+import NonResilientDep