[clang][deps] NFC: Stop using moved-from object

[jansvoboda11]

Summary

The dependency scanning worker uses std::move to "reset" DependencyOutputOptions in the CompilerInstance that performs the implicit build. It's probably preferable to replace the object with value-initialized instance, rather than depending on the behavior of a moved-from object.

[dexonsmith]

LGTM.

clang/lib/Tooling/DependencyScanning/DependencyScanningWorker.cpp

bool runInvocation(std::shared_ptr<CompilerInvocation> Invocation,
 
     // Create the dependency collector that will collect the produced
     // dependencies.
     //
     // This also moves the existing dependency output options from the
     // invocation to the collector. The options in the invocation are reset,
     // which ensures that the compiler won't create new dependency collectors,
     // and thus won't write out the extra '.d' files to disk.
-    auto Opts = std::make_unique<DependencyOutputOptions>(
-        std::move(Compiler.getInvocation().getDependencyOutputOpts()));
+    auto Opts = std::make_unique<DependencyOutputOptions>();
+    std::swap(*Opts, Compiler.getInvocation().getDependencyOutputOpts());
     // We need at least one -MT equivalent for the generator of make dependency
     // files to work.
     if (Opts->Targets.empty())
       Opts->Targets = {deduceDepTarget(Compiler.getFrontendOpts().OutputFile,
                                        Compiler.getFrontendOpts().Inputs)};
     Opts->IncludeSystemHeaders = true;
 
     switch (Format) {