Front-end: pass down main executable path to the sub-ASTContext for building module interfaces. NFC

include/swift/Frontend/FrontendOptions.h

@@ -250,6 +250,9 @@ class FrontendOptions {
   /// Should we enable the dependency verifier for all primary files known to this frontend?
   bool EnableIncrementalDependencyVerifier = false;
 
+  /// The path of the swift-frontend executable.
+  std::string MainExecutablePath;
+
   /// The directory path we should use when print #include for the bridging header.
   /// By default, we include ImplicitObjCHeaderPath directly.
   llvm::Optional<std::string> BridgingHeaderDirForPrint;

include/swift/Frontend/ModuleInterfaceLoader.h

@@ -266,10 +266,12 @@ struct ModuleInterfaceLoaderOptions {
   bool remarkOnRebuildFromInterface = false;
   bool disableInterfaceLock = false;
   bool disableImplicitSwiftModule = false;
+  std::string mainExecutablePath;
   ModuleInterfaceLoaderOptions(const FrontendOptions &Opts):
     remarkOnRebuildFromInterface(Opts.RemarkOnRebuildFromModuleInterface),
     disableInterfaceLock(Opts.DisableInterfaceFileLock),
-    disableImplicitSwiftModule(Opts.DisableImplicitModules) {}
+    disableImplicitSwiftModule(Opts.DisableImplicitModules),
+    mainExecutablePath(Opts.MainExecutablePath) {}
   ModuleInterfaceLoaderOptions() = default;
 };
 

lib/Frontend/CompilerInvocation.cpp

@@ -52,6 +52,7 @@ void CompilerInvocation::computeRuntimeResourcePathFromExecutablePath(
 }
 
 void CompilerInvocation::setMainExecutablePath(StringRef Path) {
+  FrontendOpts.MainExecutablePath = Path.str();
   llvm::SmallString<128> LibPath;
   computeRuntimeResourcePathFromExecutablePath(Path, LibPath);
   setRuntimeResourcePath(LibPath.str());

lib/Frontend/ModuleInterfaceLoader.cpp

@@ -1268,6 +1268,7 @@ InterfaceSubContextDelegateImpl::InterfaceSubContextDelegateImpl(
     StringRef prebuiltCachePath,
     bool serializeDependencyHashes,
     bool trackSystemDependencies): SM(SM), Diags(Diags), ArgSaver(Allocator) {
+  subInvocation.setMainExecutablePath(LoaderOpts.mainExecutablePath);
   inheritOptionsForBuildingInterface(searchPathOpts, langOpts);
   // Configure front-end input.
   auto &SubFEOpts = subInvocation.getFrontendOptions();