[NFC][clang] Fix Coverity static analyzer tool concerns about auto_causes_copy

[Manna]

Summary

Reported by Coverity:

AUTO_CAUSES_COPY
Unnecessary object copies can affect performance

1. Inside FrontendActions.cpp file,

In clang::​DumpModuleInfoAction::​ExecuteAction(): Using the auto keyword without an & causes the copy of an object of type pair.

2. Inside ComputeDependence.cpp file,

In clang::​computeDependence(clang::​OverloadExpr *, bool, bool, bool): Using the auto keyword without an & causes the copy of an object of type TemplateArgumentLoc.

[erichkeane]

Previous comments on this were here: https://reviews.llvm.org/D147552. I've copy/pasted them into here to keep history at least somewhat reasonable.

This LGTM.

clang/lib/AST/ComputeDependence.cpp

753

Ends up being pretty sizable, TemplateArgumentLoc has a TemplateArgument (which we typically pass around by value), but it also has a TemplateArgumentLocInfo, which is a pair of pointers + a pair of source locations.

clang/lib/Frontend/FrontendActions.cpp

885

A pair of a string and the other type, definitely worth saving the copies.

[Manna]

Thanks @erichkeane.

Is this known failure?

Failed Tests (1):

Clang :: SemaCXX/warn-unsafe-buffer-usage-fixits-addressof-arraysubscript.cpp

https://buildkite.com/llvm-project/premerge-checks/builds/145026#01874e21-00e2-47a9-9bc4-975357d197ef

[erichkeane]

In D147574#4245877, @Manna wrote:

Thanks @erichkeane.

Is this known failure?

Failed Tests (1):

Clang :: SemaCXX/warn-unsafe-buffer-usage-fixits-addressof-arraysubscript.cpp

https://buildkite.com/llvm-project/premerge-checks/builds/145026#01874e21-00e2-47a9-9bc4-975357d197ef

Looks like the commit that added that test got reverted here d5c428356f6ee107a97977eb9ef1aa4d5fa0c378 because it caused the test to fail, so it looks like the answer is 'yes'.

[Manna]

In D147574#4245881, @erichkeane wrote:

In D147574#4245877, @Manna wrote:

Thanks @erichkeane.

Is this known failure?

Failed Tests (1):

Clang :: SemaCXX/warn-unsafe-buffer-usage-fixits-addressof-arraysubscript.cpp

https://buildkite.com/llvm-project/premerge-checks/builds/145026#01874e21-00e2-47a9-9bc4-975357d197ef

Looks like the commit that added that test got reverted here d5c428356f6ee107a97977eb9ef1aa4d5fa0c378 because it caused the test to fail, so it looks like the answer is 'yes'.

Thanks @erichkeane for confirming!

[aaron.ballman]

LGTM

[Manna]

In D147574#4246004, @aaron.ballman wrote:

LGTM

Thank you @aaron.ballman

[Manna]

I have committed the patch here: https://reviews.llvm.org/rG59cb47015a18

[Manna]

I am closing this revision since it's already been pushed: https://reviews.llvm.org/rG59cb47015a18

clang/lib/AST/ComputeDependence.cpp

clang::computeDependence(OverloadExpr *E, bool KnownDependent,
   for (auto *D : E->decls()) {
     if (D->getDeclContext()->isDependentContext() ||
         isa<UnresolvedUsingValueDecl>(D))
       Deps |= ExprDependence::TypeValueInstantiation;
   }
   // If we have explicit template arguments, check for dependent
   // template arguments and whether they contain any unexpanded pack
   // expansions.
-  for (auto A : E->template_arguments())
+  for (const auto &A : E->template_arguments())
     Deps |= toExprDependence(A.getArgument().getDependence());
   return Deps;
 }
 
 ExprDependence clang::computeDependence(DependentScopeDeclRefExpr *E) {
   auto D = ExprDependence::TypeValue;
   D |= getDependenceInExpr(E->getNameInfo());
   if (auto *Q = E->getQualifier())

clang/lib/Frontend/FrontendActions.cpp

if (auto FilteredMacros = llvm::make_filter_range(
         !FilteredMacros.empty()) {
       Out << "   Macro Definitions:\n";
       for (/*<IdentifierInfo *, MacroState> pair*/ const auto &Macro :
            FilteredMacros)
         Out << "     " << Macro.first->getName() << "\n";
     }
 
     // Now let's print out any modules we did not see as part of the Primary.
-    for (auto SM : SubModMap) {
+    for (const auto &SM : SubModMap) {
       if (!SM.second.Seen && SM.second.Mod) {
         Out << "  " << ModuleKindName(SM.second.Kind) << " '" << SM.first
             << "' at index #" << SM.second.Idx
             << " has no direct reference in the Primary\n";
       }
     }
     Out << "  ====== ======\n";
   }