Factor out ModuleDecl overload of import resolution

This resolves imports for the entire module.

Author: hamishknight

include/swift/Subsystems.h

@@ -117,6 +117,9 @@ namespace swift {
                               bool TokenizeInterpolatedString = true,
                               ArrayRef<Token> SplitTokens = ArrayRef<Token>());
 
+  /// Perform import resolution for the module.
+  void performImportResolution(ModuleDecl *M);
+
   /// This walks the AST to resolve imports.
   void performImportResolution(SourceFile &SF);
 

lib/Frontend/Frontend.cpp

@@ -1552,19 +1552,8 @@ bool CompilerInstance::performParseAndResolveImportsOnly() {
     }
   }
 
-  // Resolve imports for all the source files.
-  for (auto *file : mainModule->getFiles()) {
-    if (auto *SF = dyn_cast<SourceFile>(file))
-      performImportResolution(*SF);
-  }
-
-  assert(llvm::all_of(mainModule->getFiles(), [](const FileUnit *File) -> bool {
-    auto *SF = dyn_cast<SourceFile>(File);
-    if (!SF)
-      return true;
-    return SF->ASTStage >= SourceFile::ImportsResolved;
-  }) && "some files have not yet had their imports resolved");
-  mainModule->setHasResolvedImports();
+  // Resolve imports for all the source files in the module.
+  performImportResolution(mainModule);
 
   bindExtensions(*mainModule);
   return Context->hadError();

lib/Sema/ImportResolution.cpp

@@ -266,6 +266,19 @@ class ImportResolver final : public DeclVisitor<ImportResolver> {
 // MARK: performImportResolution
 //===----------------------------------------------------------------------===//
 
+void swift::performImportResolution(ModuleDecl *M) {
+  for (auto *file : M->getFiles()) {
+    auto *SF = dyn_cast<SourceFile>(file);
+    if (!SF)
+      continue;
+
+    performImportResolution(*SF);
+    assert(SF->ASTStage >= SourceFile::ImportsResolved &&
+           "file has not had its imports resolved");
+  }
+  M->setHasResolvedImports();
+}
+
 /// performImportResolution - This walks the AST to resolve imports.
 ///
 /// Before we can type-check a source file, we need to make declarations

lib/Sema/SourceLoader.cpp

@@ -142,8 +142,7 @@ ModuleDecl *SourceLoader::loadModule(SourceLoc importLoc,
       new (Ctx) SourceFile(*importMod, SourceFileKind::Library, bufferID,
                            SourceFile::getDefaultParsingOptions(Ctx.LangOpts));
   importMod->addFile(*importFile);
-  performImportResolution(*importFile);
-  importMod->setHasResolvedImports();
+  performImportResolution(importMod);
   bindExtensions(*importMod);
   return importMod;
 }