Load modules using real names if module aliases are used

elsh · elsh · commit 55b9fa11d87f · 2021-10-05T10:55:22.000-07:00
rdar://83591943
diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
@@ -1848,12 +1848,27 @@ ASTContext::getLoadedModules() const {
 }
 
 ModuleDecl *ASTContext::getLoadedModule(Identifier ModuleName) const {
-  return getImpl().LoadedModules.lookup(ModuleName);
+  // Look up a loaded module using an actual module name (physical name
+  // on disk). If the -module-alias option is used, the module name that
+  // appears in source code will be different from the real module name
+  // on disk, otherwise the same.
+  //
+  // For example, if '-module-alias Foo=Bar' is passed in to the frontend,
+  // and a source file has 'import Foo', a module called Bar (real name)
+  // will be loaded and returned.
+  auto realName = getRealModuleName(ModuleName);
+  return getImpl().LoadedModules.lookup(realName);
 }
 
 void ASTContext::addLoadedModule(ModuleDecl *M) {
   assert(M);
-  getImpl().LoadedModules[M->getName()] = M;
+  // Add a loaded module using an actual module name (physical name
+  // on disk), in case -module-alias is used (otherwise same).
+  //
+  // For example, if '-module-alias Foo=Bar' is passed in to the frontend,
+  // and a source file has 'import Foo', a module called Bar (real name)
+  // will be loaded and added to the map.
+  getImpl().LoadedModules[M->getRealName()] = M;
 }
 
 void ASTContext::registerGenericSignatureBuilder(
diff --git a/lib/Frontend/ModuleInterfaceLoader.cpp b/lib/Frontend/ModuleInterfaceLoader.cpp
@@ -1739,7 +1739,13 @@ bool ExplicitSwiftModuleLoader::findModule(ImportPath::Element ModuleID,
            std::unique_ptr<llvm::MemoryBuffer> *ModuleDocBuffer,
            std::unique_ptr<llvm::MemoryBuffer> *ModuleSourceInfoBuffer,
            bool skipBuildingInterface, bool &IsFramework, bool &IsSystemModule) {
-  StringRef moduleName = ModuleID.Item.str();
+  // Find a module with an actual, physical name on disk, in case
+  // -module-alias is used (otherwise same).
+  //
+  // For example, if '-module-alias Foo=Bar' is passed in to the frontend, and an
+  // input file has 'import Foo', a module called Bar (real name) should be searched.
+  StringRef moduleName = Ctx.getRealModuleName(ModuleID.Item).str();
+
   auto it = Impl.ExplicitModuleMap.find(moduleName);
   // If no explicit module path is given matches the name, return with an
   // error code.
diff --git a/lib/Sema/SourceLoader.cpp b/lib/Sema/SourceLoader.cpp
@@ -34,13 +34,20 @@ using namespace swift;
 // FIXME: Basically the same as SerializedModuleLoader.
 using FileOrError = llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>;
 
-static FileOrError findModule(ASTContext &ctx, StringRef moduleID,
+static FileOrError findModule(ASTContext &ctx, Identifier moduleID,
                               SourceLoc importLoc) {
   llvm::SmallString<128> inputFilename;
+  // Find a module with an actual, physical name on disk, in case
+  // -module-alias is used (otherwise same).
+  //
+  // For example, if '-module-alias Foo=Bar' is passed in to the frontend,
+  // and a source file has 'import Foo', a module called Bar (real name)
+  // should be searched.
+  StringRef moduleNameRef = ctx.getRealModuleName(moduleID).str();
 
   for (auto Path : ctx.SearchPathOpts.ImportSearchPaths) {
     inputFilename = Path;
-    llvm::sys::path::append(inputFilename, moduleID);
+    llvm::sys::path::append(inputFilename, moduleNameRef);
     inputFilename.append(".swift");
     llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> FileBufOrErr =
       ctx.SourceMgr.getFileSystem()->getBufferForFile(inputFilename.str());
@@ -66,7 +73,7 @@ bool SourceLoader::canImportModule(ImportPath::Element ID,
                                    llvm::VersionTuple version,
                                    bool underlyingVersion) {
   // Search the memory buffers to see if we can find this file on disk.
-  FileOrError inputFileOrError = findModule(Ctx, ID.Item.str(),
+  FileOrError inputFileOrError = findModule(Ctx, ID.Item,
                                             ID.Loc);
   if (!inputFileOrError) {
     auto err = inputFileOrError.getError();
@@ -88,7 +95,7 @@ ModuleDecl *SourceLoader::loadModule(SourceLoc importLoc,
 
   auto moduleID = path[0];
 
-  FileOrError inputFileOrError = findModule(Ctx, moduleID.Item.str(),
+  FileOrError inputFileOrError = findModule(Ctx, moduleID.Item,
                                             moduleID.Loc);
   if (!inputFileOrError) {
     auto err = inputFileOrError.getError();
diff --git a/lib/Serialization/SerializedModuleLoader.cpp b/lib/Serialization/SerializedModuleLoader.cpp
@@ -533,7 +533,14 @@ SerializedModuleLoaderBase::findModule(ImportPath::Element moduleID,
            std::unique_ptr<llvm::MemoryBuffer> *moduleDocBuffer,
            std::unique_ptr<llvm::MemoryBuffer> *moduleSourceInfoBuffer,
            bool skipBuildingInterface, bool &isFramework, bool &isSystemModule) {
-  SmallString<32> moduleName(moduleID.Item.str());
+  // Find a module with an actual, physical name on disk, in case
+  // -module-alias is used (otherwise same).
+  //
+  // For example, if '-module-alias Foo=Bar' is passed in to the frontend,
+  // and a source file has 'import Foo', a module called Bar (real name)
+  // should be searched.
+  StringRef moduleNameRef = Ctx.getRealModuleName(moduleID.Item).str();
+  SmallString<32> moduleName(moduleNameRef);
   SerializedModuleBaseName genericBaseName(moduleName);
 
   auto genericModuleFileName =
@@ -1156,7 +1163,6 @@ bool MemoryBufferSerializedModuleLoader::canImportModule(
   assert(!(mIt->second.userVersion.empty()));
   return mIt->second.userVersion >= version;
 }
-
 ModuleDecl *
 SerializedModuleLoaderBase::loadModule(SourceLoc importLoc,
                                        ImportPath::Module path) {
@@ -1220,13 +1226,14 @@ MemoryBufferSerializedModuleLoader::loadModule(SourceLoc importLoc,
     return nullptr;
 
   auto moduleID = path[0];
+  auto moduleName = Ctx.getRealModuleName(moduleID.Item).str();
 
   // See if we find it in the registered memory buffers.
 
   // FIXME: Right now this works only with access paths of length 1.
   // Once submodules are designed, this needs to support suffix
   // matching and a search path.
-  auto bufIter = MemoryBuffers.find(moduleID.Item.str());
+  auto bufIter = MemoryBuffers.find(moduleName);
   if (bufIter == MemoryBuffers.end())
     return nullptr;
 
diff --git a/test/Frontend/load-module-with-alias.swift b/test/Frontend/load-module-with-alias.swift
@@ -0,0 +1,20 @@
+/// Test the -module-alias flag.
+
+// RUN: %empty-directory(%t)
+
+/// Create a module Bar
+// RUN: echo 'public func bar() {}' > %t/FileBar.swift
+// RUN: %target-swift-frontend -module-name Bar %t/FileBar.swift -emit-module -emit-module-path %t/Bar.swiftmodule
+
+/// Check if Bar.swiftmodule is created
+// RUN: test -f %t/Bar.swiftmodule
+// RUN: not test -f %t/Cat.swiftmodule
+
+/// Create a module Foo that imports Cat with -module-alias Cat=Bar
+// RUN: echo 'import Cat' > %t/FileFoo.swift
+// RUN: %target-swift-frontend -module-name Foo -module-alias Cat=Bar %t/FileFoo.swift -emit-module -emit-module-path %t/Foo.swiftmodule -I %t
+
+/// Check if Foo.swiftmodule is created without an error
+// RUN: test -f %t/Foo.swiftmodule
+// RUN: test -f %t/Bar.swiftmodule
+// RUN: not test -f %t/Cat.swiftmodule
