[Explicit Module Build] Execute module interface verification in a sub-invocation context

Otherwise, with `-explicit-interface-module-build` they do not read out/inherit compiler flags written in the interface itself.

Resolves rdar://122418125

Author: artemcm

Diff for: lib/Frontend/ModuleInterfaceLoader.cpp

@@ -1768,6 +1768,10 @@ InterfaceSubContextDelegateImpl::InterfaceSubContextDelegateImpl(
   if (LoaderOpts.disableImplicitSwiftModule) {
     genericSubInvocation.getFrontendOptions().DisableImplicitModules = true;
     GenericArgs.push_back("-disable-implicit-swift-modules");
+    GenericArgs.push_back("-Xcc");
+    GenericArgs.push_back("-fno-implicit-modules");
+    GenericArgs.push_back("-Xcc");
+    GenericArgs.push_back("-fno-implicit-module-maps");
   }
   // If building an application extension, make sure API use
   // is restricted accordingly in downstream dependnecies.
@@ -1780,7 +1784,6 @@ InterfaceSubContextDelegateImpl::InterfaceSubContextDelegateImpl(
   ParentInvocationTarget = langOpts.Target;
 
   // Pass down -explicit-swift-module-map-file
-  // FIXME: we shouldn't need this. Remove it?
   StringRef explicitSwiftModuleMap = searchPathOpts.ExplicitSwiftModuleMap;
   genericSubInvocation.getSearchPathOptions().ExplicitSwiftModuleMap =
     explicitSwiftModuleMap.str();

Diff for: lib/FrontendTool/FrontendTool.cpp

@@ -413,7 +413,13 @@ static bool buildModuleFromInterface(CompilerInstance &Instance) {
   // If an explicit interface build was requested, bypass the creation of a new
   // sub-instance from the interface which will build it in a separate thread,
   // and isntead directly use the current \c Instance for compilation.
-  if (FEOpts.ExplicitInterfaceBuild)
+  //
+  // FIXME: -typecheck-module-from-interface is the exception here because
+  // currently we need to ensure it still reads the flags written out
+  // in the .swiftinterface file itself. Instead, creation of that
+  // job should incorporate those flags.
+  if (FEOpts.ExplicitInterfaceBuild &&
+      !(FEOpts.isTypeCheckAction() && !FEOpts.EnableCaching))
     return ModuleInterfaceLoader::buildExplicitSwiftModuleFromSwiftInterface(
         Instance, Invocation.getClangModuleCachePath(),
         FEOpts.BackupModuleInterfaceDir, PrebuiltCachePath, ABIPath, InputPath,

Diff for: test/ScanDependencies/explicit-module-map-typecheck-module-from-interface.swift renamed to test/ScanDependencies/explicit-typecheck-from-interface.swift

@@ -1,9 +1,12 @@
+// REQUIRES: objc_interop, OS=macosx
 // RUN: %empty-directory(%t)
 // RUN: mkdir -p %t/clang-module-cache
 // RUN: mkdir -p %t/inputs
 // RUN: echo "/// Some cool comments" > %t/foo.swift
 // RUN: echo "public func foo() {}" >> %t/foo.swift
-// RUN: %target-swift-frontend -emit-module -emit-module-path %t/inputs/Foo.swiftmodule -emit-module-interface-path %t/Foo.swiftinterface \
+// RUN: %target-swift-emit-pcm -module-name SwiftShims %swift-lib-dir/swift/shims/module.modulemap -o %t/inputs/SwiftShims.pcm
+// RUN: %target-swift-emit-pcm -module-name _SwiftConcurrencyShims %swift-lib-dir/swift/shims/module.modulemap -o %t/inputs/_SwiftConcurrencyShims.pcm
+// RUN: %target-swift-frontend -emit-module -emit-module-path %t/inputs/Foo.swiftmodule -emit-module-interface-path %t/Foo.swiftinterface -alias-module-names-in-module-interface \
 // RUN:   -swift-version 5 -enable-library-evolution -module-cache-path %t.module-cache %t/foo.swift -module-name Foo
 
 // RUN: echo "[{" > %/t/inputs/map.json
@@ -29,14 +32,22 @@
 // RUN: echo "\"isFramework\": false" >> %/t/inputs/map.json
 // RUN: echo "}," >> %/t/inputs/map.json
 // RUN: echo "{" >> %/t/inputs/map.json
+// RUN: echo "\"moduleName\": \"SwiftShims\"," >> %/t/inputs/map.json
+// RUN: echo "\"isFramework\": false," >> %/t/inputs/map.json
+// RUN: echo "\"clangModuleMapPath\": \"%swift-lib-dir/swift/shims/module.modulemap\"," >> %/t/inputs/map.json
+// RUN: echo "\"clangModulePath\": \"%t/inputs/SwiftShims.pcm\"" >> %/t/inputs/map.json
+// RUN: echo "}," >> %/t/inputs/map.json
+// RUN: echo "{" >> %/t/inputs/map.json
+// RUN: echo "\"moduleName\": \"_SwiftConcurrencyShims\"," >> %/t/inputs/map.json
+// RUN: echo "\"isFramework\": false," >> %/t/inputs/map.json
+// RUN: echo "\"clangModuleMapPath\": \"%swift-lib-dir/swift/shims/module.modulemap\"," >> %/t/inputs/map.json
+// RUN: echo "\"clangModulePath\": \"%t/inputs/_SwiftConcurrencyShims.pcm\"" >> %/t/inputs/map.json
+// RUN: echo "}," >> %/t/inputs/map.json
+// RUN: echo "{" >> %/t/inputs/map.json
 // RUN: echo "\"moduleName\": \"_StringProcessing\"," >> %/t/inputs/map.json
 // RUN: echo "\"modulePath\": \"%/string_processing_module\"," >> %/t/inputs/map.json
 // RUN: echo "\"isFramework\": false" >> %/t/inputs/map.json
 // RUN: echo "}]" >> %/t/inputs/map.json
 
 // RUN: %target-swift-frontend -typecheck-module-from-interface %t/Foo.swiftinterface -module-cache-path %t.module-cache \
-// RUN:   -explicit-interface-module-build -explicit-swift-module-map-file %t/inputs/map.json -Rmodule-loading -Xcc -Rmodule-import 2>&1 | %FileCheck %s
-
-// CHECK-DAG: loaded module 'Swift'
-// CHECK-DAG: loaded module '_StringProcessing'
-// CHECK-DAG: loaded module '_Concurrency'
+// RUN:   -explicit-interface-module-build -explicit-swift-module-map-file %t/inputs/map.json -disable-implicit-swift-modules -verify