Merge pull request #78869 from artemcm/61_NoPackageOnlyImportOnImplicitBuild

[6.1 🍒][ModuleInterface] Determine package-only resolution need based on input mode

Author: artemcm

lib/Frontend/CompilerInvocation.cpp

@@ -2297,9 +2297,10 @@ static bool ParseSearchPathArgs(SearchPathOptions &Opts, ArgList &Args,
   Opts.ScannerModuleValidation |= Args.hasFlag(OPT_scanner_module_validation,
                                                OPT_no_scanner_module_validation,
                                                CASOpts.EnableCaching);
+
   bool buildingFromInterface =
-      FrontendOptions::doesActionBuildModuleFromInterface(
-          FrontendOpts.RequestedAction);
+      FrontendOpts.InputMode ==
+      FrontendOptions::ParseInputMode::SwiftModuleInterface;
   auto firstInputPath =
       FrontendOpts.InputsAndOutputs.hasInputs()
           ? FrontendOpts.InputsAndOutputs.getFilenameOfFirstInput()

test/ModuleInterface/no-package-dependencies-on-non-package-interface-implicit.swift

@@ -0,0 +1,35 @@
+// RUN: %empty-directory(%t)
+// RUN: %empty-directory(%t/module-cache)
+// RUN: %empty-directory(%t/Swift)
+// RUN: %empty-directory(%t/OtherSwift)
+// RUN: split-file %s %t
+
+// Build in-package ModuleC
+// RUN: %target-swift-frontend -emit-module -emit-module-path %t/OtherSwift/ModuleC.swiftmodule -module-name ModuleC -package-name TestPak %t/C.swift
+
+// Build in-package ModuleB
+// RUN: %target-swift-frontend -emit-module -emit-module-path %t/Swift/ModuleB.swiftmodule -enable-library-evolution -emit-module-interface-path %t/Swift/ModuleB.swiftinterface  -module-name ModuleB -package-name TestPak %t/B.swift -I%t/OtherSwift
+
+// Build in-package ModuleA
+// RUN: %target-swift-frontend -emit-module -emit-module-path %t/Swift/ModuleA.swiftmodule -enable-library-evolution -emit-module-interface-path %t/Swift/ModuleA.swiftinterface -module-name ModuleA -package-name TestPak %t/A.swift -I%t/Swift -I%t/OtherSwift
+
+// Remove binary module for A to make sure an implicit interface compile gets triggered
+// RUN: rm %t/Swift/ModuleA.swiftmodule
+// Remove in-package-only dependency of B to ensure that if the compiler looks for it, compilation will fail
+// RUN: rm %t/OtherSwift/ModuleC.swiftmodule
+
+// Build out-of-package client source
+// RUN: %target-swift-frontend -emit-module -emit-module-path %t/Swift/Client.swiftmodule -module-name Client %t/Client.swift -I%t/Swift
+
+//--- C.swift
+public func c() {}
+
+//--- B.swift
+package import ModuleC
+
+//--- A.swift
+@_exported public import ModuleB
+
+//--- Client.swift
+import ModuleA
+