[ParseableInterface] Don't serialize deps for explicit builds

If the frontend is invoked with
-build-module-from-parseable-interface, we might be trying to persist
and distribute the swiftmodule that gets built. In that case, any
dependencies we list might not be relevant.

This probably isn't really the final answer here; what we want is some
way to say /which/ dependencies are relevant, and how they're related
to how the swiftmodule that gets used. Most likely the right answer
here is to limit this to dependencies within the SDK or something.

Author: jrose-apple

include/swift/Frontend/ParseableInterfaceSupport.h

@@ -82,7 +82,8 @@ class ParseableInterfaceModuleLoader : public SerializedModuleLoaderBase {
   static bool buildSwiftModuleFromSwiftInterface(
     clang::vfs::FileSystem &FS, DiagnosticEngine &Diags, SourceLoc DiagLoc,
     CompilerInvocation &SubInvocation, StringRef InPath, StringRef OutPath,
-    StringRef ModuleCachePath, DependencyTracker *OuterTracker);
+    StringRef ModuleCachePath, DependencyTracker *OuterTracker,
+    bool ShouldSerializeDeps);
 
   std::error_code findModuleFilesInDirectory(
       AccessPathElem ModuleID, StringRef DirPath, StringRef ModuleFilename,

lib/Frontend/ParseableInterfaceSupport.cpp

@@ -307,7 +307,8 @@ collectDepsForSerialization(clang::vfs::FileSystem &FS,
 bool ParseableInterfaceModuleLoader::buildSwiftModuleFromSwiftInterface(
     clang::vfs::FileSystem &FS, DiagnosticEngine &Diags, SourceLoc DiagLoc,
     CompilerInvocation &SubInvocation, StringRef InPath, StringRef OutPath,
-    StringRef ModuleCachePath, DependencyTracker *OuterTracker) {
+    StringRef ModuleCachePath, DependencyTracker *OuterTracker,
+    bool ShouldSerializeDeps) {
   bool SubError = false;
   bool RunSuccess = llvm::CrashRecoveryContext().RunSafelyOnThread([&] {
     // Note that we don't assume ModuleCachePath is the same as the Clang
@@ -411,7 +412,8 @@ bool ParseableInterfaceModuleLoader::buildSwiftModuleFromSwiftInterface(
       SubError = true;
       return;
     }
-    SerializationOpts.Dependencies = Deps;
+    if (ShouldSerializeDeps)
+      SerializationOpts.Dependencies = Deps;
     SILMod->setSerializeSILAction([&]() {
       serialize(Mod, SerializationOpts, SILMod.get());
     });
@@ -525,7 +527,8 @@ std::error_code ParseableInterfaceModuleLoader::findModuleFilesInDirectory(
                                dependencyTracker)) {
       if (buildSwiftModuleFromSwiftInterface(FS, Diags, ModuleID.second,
                                              SubInvocation, InPath, OutPath,
-                                             CacheDir, dependencyTracker))
+                                             CacheDir, dependencyTracker,
+                                             /*ShouldSerializeDeps*/true))
         return std::make_error_code(std::errc::invalid_argument);
     }
   }
@@ -557,10 +560,15 @@ ParseableInterfaceModuleLoader::buildSwiftModuleFromSwiftInterface(
 
   auto &FS = *Ctx.SourceMgr.getFileSystem();
   auto &Diags = Ctx.Diags;
+  // FIXME: We don't really want to ignore dependencies here, but we have to
+  // identify which ones are important, and make them relocatable
+  // (SDK-relative) if we want to ship the built swiftmodules to another
+  // machine. Just leave them out for now.
   return buildSwiftModuleFromSwiftInterface(FS, Diags, /*DiagLoc*/SourceLoc(),
                                             SubInvocation, InPath, OutPath,
                                             /*CachePath*/"",
-                                            /*OuterTracker*/nullptr);
+                                            /*OuterTracker*/nullptr,
+                                            /*ShouldSerializeDeps*/false);
 }
 
 /// Diagnose any scoped imports in \p imports, i.e. those with a non-empty

test/ParseableInterface/SmokeTest.swiftinterface

@@ -14,6 +14,7 @@
 // RUN: %target-swift-ide-test -print-module -module-to-print SmokeTest -I %t -source-filename x -print-interface > %t/SmokeTest.txt
 // RUN: %FileCheck %s < %t/SmokeTest.txt
 // RUN: %FileCheck -check-prefix NEGATIVE %s < %t/SmokeTest.txt
+// RUN: llvm-bcanalyzer -dump %t/SmokeTest.swiftmodule | not grep FILE_DEPENDENCY
 
 // CHECK-LABEL: public class TestClass
 public class TestClass {