Merge pull request #32991 from nkcsgexi/explicit-module-map-forwarding-module

ExplicitModuleLoader: teach the module loader to accept forwarding modules

Author: nkcsgexi

lib/Frontend/ModuleInterfaceLoader.cpp

@@ -1654,6 +1654,31 @@ std::error_code ExplicitSwiftModuleLoader::findModuleFilesInDirectory(
                        moduleInfo.modulePath);
     return moduleBuf.getError();
   }
+
+  assert(moduleBuf);
+  const bool isForwardingModule = !serialization::isSerializedAST(moduleBuf
+    .get()->getBuffer());
+  // If the module is a forwarding module, read the actual content from the path
+  // encoded in the forwarding module as the actual module content.
+  if (isForwardingModule) {
+    auto forwardingModule = ForwardingModule::load(*moduleBuf.get());
+    if (forwardingModule) {
+      moduleBuf = fs.getBufferForFile(forwardingModule->underlyingModulePath);
+      if (!moduleBuf) {
+        // We cannot read the module content, diagnose.
+        Ctx.Diags.diagnose(SourceLoc(), diag::error_opening_explicit_module_file,
+                           moduleInfo.modulePath);
+        return moduleBuf.getError();
+      }
+    } else {
+      // We cannot read the module content, diagnose.
+      Ctx.Diags.diagnose(SourceLoc(), diag::error_opening_explicit_module_file,
+                         moduleInfo.modulePath);
+      return forwardingModule.getError();
+    }
+  }
+  assert(moduleBuf);
+  // Move the opened module buffer to the caller.
   *ModuleBuffer = std::move(moduleBuf.get());
 
   // Open .swiftdoc file

test/ScanDependencies/explicit-module-map-forwarding-module.swift

@@ -0,0 +1,26 @@
+// 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
+
+// Step 1: build .swiftmodule and .swiftinterface adjacent to each other from foo.swift
+// RUN: %target-swift-frontend -emit-module -emit-module-path %t/inputs/Foo.swiftmodule -emit-module-doc-path %t/inputs/Foo.swiftdoc -emit-module-source-info -emit-module-source-info-path %t/inputs/Foo.swiftsourceinfo -emit-module-interface-path %t/inputs/Foo.swiftinterface -module-cache-path %t.module-cache %t/foo.swift -module-name Foo
+
+// Step 2: build .swiftmodule from .swiftinterface and give the adjacent .swiftmodule as a candidate compiled module.
+// RUN: %target-swift-frontend -compile-module-from-interface %t/inputs/Foo.swiftinterface -o %t/inputs/Foo-from-interface.swiftmodule -module-name Foo -candidate-module-file %t/inputs/Foo.swiftmodule
+
+// Step 3: the new .swiftmodule should be a fowarding module.
+// RUN: %{python} %S/../ModuleInterface/ModuleCache/Inputs/check-is-forwarding-module.py %t/inputs/Foo-from-interface.swiftmodule
+
+// Step 4: using the forwarding module in explicit module map should be OK.
+// RUN: echo "[{" > %/t/inputs/map.json
+// RUN: echo "\"moduleName\": \"Foo\"," >> %/t/inputs/map.json
+// RUN: echo "\"modulePath\": \"%/t/inputs/Foo-from-interface.swiftmodule\"," >> %/t/inputs/map.json
+// RUN: echo "\"docPath\": \"%/t/inputs/Foo.swiftdoc\"," >> %/t/inputs/map.json
+// RUN: echo "\"sourceInfoPath\": \"%/t/inputs/Foo.swiftsourceinfo\"" >> %/t/inputs/map.json
+// RUN: echo "}]" >> %/t/inputs/map.json
+
+// RUN: %target-swift-ide-test -print-module-comments -module-to-print=Foo -enable-swiftsourceinfo -source-filename %s -explicit-swift-module-map-file %t/inputs/map.json | %FileCheck %s
+
+// CHECK: foo.swift:2:13: Func/foo RawComment=[/// Some cool comments