Render symbol graphs for cross-import overlay modules, if present

lib/SymbolGraphGen/FormatVersion.h

@@ -15,6 +15,6 @@
 
 #define SWIFT_SYMBOLGRAPH_FORMAT_MAJOR 0
 #define SWIFT_SYMBOLGRAPH_FORMAT_MINOR 5
-#define SWIFT_SYMBOLGRAPH_FORMAT_PATCH 0
+#define SWIFT_SYMBOLGRAPH_FORMAT_PATCH 1
 
 #endif // SWIFT_SYMBOLGRAPHGEN_FORMATVERSION_H

lib/SymbolGraphGen/SymbolGraph.cpp

@@ -39,7 +39,15 @@ SymbolGraph::SymbolGraph(SymbolGraphASTWalker &Walker,
   M(M),
   ExtendedModule(ExtendedModule),
   Ctx(Ctx),
-  ModuleVersion(ModuleVersion) {}
+  ModuleVersion(ModuleVersion) {
+    if (auto *DM = M.getDeclaringModuleIfCrossImportOverlay()) {
+      DeclaringModule = DM;
+      SmallVector<Identifier, 1> Bystanders;
+      if (M.getRequiredBystandersIfCrossImportOverlay(DM, Bystanders)) {
+        BystanderModules = Bystanders;
+      }
+    }
+  }
 
 // MARK: - Utilities
 
@@ -499,7 +507,17 @@ void SymbolGraph::serialize(llvm::json::OStream &OS) {
     }); // end metadata:
 
     OS.attributeObject("module", [&](){
-      OS.attribute("name", M.getNameStr());
+      if (DeclaringModule) {
+        // A cross-import overlay can be considered part of its declaring module
+        OS.attribute("name", (*DeclaringModule)->getNameStr());
+        std::vector<StringRef> B;
+        for (auto BModule : BystanderModules) {
+          B.push_back(BModule.str());
+        }
+        OS.attribute("bystanders", B);
+      } else {
+        OS.attribute("name", M.getNameStr());
+      }
       AttributeRAII Platform("platform", OS);
 
       auto *MainFile = M.getFiles().front();

lib/SymbolGraphGen/SymbolGraph.h

@@ -42,6 +42,16 @@ struct SymbolGraph {
    The module whose types were extended in `M`.
    */
   Optional<ModuleDecl *> ExtendedModule;
+
+  /**
+   The module declaring `M`, if `M` is a cross-import overlay.
+   */
+  Optional<ModuleDecl *> DeclaringModule;
+
+  /**
+   The modules that must be imported alongside `DeclaringModule` for `M` to be imported, if `M` is a cross-import overlay.
+   */
+  SmallVector<Identifier, 1> BystanderModules;
 
   /**
    A context for allocations.

lib/SymbolGraphGen/SymbolGraphGen.cpp

@@ -22,10 +22,27 @@ using namespace symbolgraphgen;
 namespace {
 int serializeSymbolGraph(SymbolGraph &SG,
                          const SymbolGraphOptions &Options) {
-  SmallString<256> FileName(SG.M.getNameStr());
-  if (SG.ExtendedModule.hasValue()) {
+  SmallString<256> FileName;
+  if (SG.DeclaringModule.hasValue()) {
+    // Save a cross-import overlay symbol graph as `MainModule@BystandingModule[@BystandingModule...]@OverlayModule.symbols.json`
+    //
+    // The overlay module's name is added as a disambiguator in case an overlay
+    // declares multiple modules for the same set of imports.
+    FileName.append(SG.DeclaringModule.getValue()->getNameStr());
+    for (auto BystanderModule : SG.BystanderModules) {
+      FileName.push_back('@');
+      FileName.append(BystanderModule.str());
+    }
+
     FileName.push_back('@');
-    FileName.append(SG.ExtendedModule.getValue()->getNameStr());
+    FileName.append(SG.M.getNameStr());
+  } else {
+    FileName.append(SG.M.getNameStr());
+
+    if (SG.ExtendedModule.hasValue()) {
+      FileName.push_back('@');
+      FileName.append(SG.ExtendedModule.getValue()->getNameStr());
+    }
   }
   FileName.append(".symbols.json");
 

test/SymbolGraph/Module/CrossImport.swift

@@ -0,0 +1,21 @@
+// RUN: %empty-directory(%t)
+// RUN: %target-build-swift %S/Inputs/CrossImport/A.swift -I %t -module-name A -emit-module -emit-module-path %t/
+// RUN: %target-build-swift %S/Inputs/CrossImport/B.swift -I %t -module-name B -emit-module -emit-module-path %t/
+// RUN: %target-build-swift %s -module-name _A_B -I %t -emit-module -emit-module-path %t/
+// RUN: cp -r %S/Inputs/CrossImport/A.swiftcrossimport %t/
+// RUN: %target-swift-symbolgraph-extract -module-name A -I %t -pretty-print -output-dir %t
+// RUN: %FileCheck %s --input-file %t/A@B@_A_B.symbols.json
+
+@_exported import A
+import B
+
+extension A {
+    public func transmogrify() -> B {
+        return B(y: self.x);
+    }
+}
+
+// CHECK: module
+// CHECK-NEXT: "name": "A"
+// CHECK-NEXT: bystanders
+// CHECK-NEXT:   B

test/SymbolGraph/Module/Inputs/CrossImport/A.swift

@@ -0,0 +1,3 @@
+public struct A {
+    public var x: Int
+}

test/SymbolGraph/Module/Inputs/CrossImport/A.swiftcrossimport/B.swiftoverlay

@@ -0,0 +1,5 @@
+%YAML 1.2
+---
+version: 1
+modules:
+  - name: _A_B

test/SymbolGraph/Module/Inputs/CrossImport/B.swift

@@ -0,0 +1,7 @@
+public struct B {
+    public var y: Int
+
+    public init(y: Int) {
+        self.y = y
+    }
+}

tools/driver/swift_symbolgraph_extract_main.cpp

@@ -217,12 +217,12 @@ int swift_symbolgraph_extract_main(ArrayRef<const char *> Args, const char *Argv
   }
 
   auto M = CI.getASTContext().getModuleByName(options::ModuleName);
+  SmallVector<Identifier, 32> VisibleModuleNames;
+  CI.getASTContext().getVisibleTopLevelModuleNames(VisibleModuleNames);
   if (!M) {
     llvm::errs()
       << "Couldn't load module '" << options::ModuleName << '\''
       << " in the current SDK and search paths.\n";
-    SmallVector<Identifier, 32> VisibleModuleNames;
-    CI.getASTContext().getVisibleTopLevelModuleNames(VisibleModuleNames);
 
     if (VisibleModuleNames.empty()) {
       llvm::errs() << "Could not find any modules.\n";
@@ -241,7 +241,29 @@ int swift_symbolgraph_extract_main(ArrayRef<const char *> Args, const char *Argv
 
   const auto &MainFile = M->getMainFile(FileUnitKind::SerializedAST);
   llvm::errs() << "Emitting symbol graph for module file: " << MainFile.getModuleDefiningPath() << '\n';
+
+  int Success = symbolgraphgen::emitSymbolGraphForModule(M, Options);
+
+  // Look for cross-import overlays that the given module imports.
+
+  // Clear out the diagnostic printer before looking for cross-import overlay modules,
+  // since some SDK modules can cause errors in the getModuleByName() call. The call
+  // itself will properly return nullptr after this failure, so for our purposes we
+  // don't need to print these errors.
+  CI.removeDiagnosticConsumer(&DiagPrinter);
+
+  for (const auto &ModuleName : VisibleModuleNames) {
+    if (ModuleName.str().startswith("_")) {
+      auto CIM = CI.getASTContext().getModuleByName(ModuleName.str());
+      if (CIM && CIM->isCrossImportOverlayOf(M)) {
+        const auto &CIMainFile = CIM->getMainFile(FileUnitKind::SerializedAST);
+        llvm::errs() << "Emitting symbol graph for cross-import overlay module file: "
+          << CIMainFile.getModuleDefiningPath() << '\n';
+
+        Success |= symbolgraphgen::emitSymbolGraphForModule(CIM, Options);
+      }
+    }
+  }
 
-  return symbolgraphgen::emitSymbolGraphForModule(M,
-    Options);
+  return Success;
 }