[OpenMP] Use an explicit copy in a range-based for

[Mordante]

Summary

The std::pair<const clang::ValueDecl *, llvm::ArrayRef<clang::OMPClauseMappableExprCommon::MappableComponent>>
type will be copied in a range-based for loop. Make the copy explicit to
avoid the -Wrange-loop-analysis warning.

This avoids new warnings due to D68912 adds -Wrange-loop-analysis to -Wall.

[ABataev]

Why do we get the warnings with references?

[Mordante]

OMPMappableExprListClause::const_component_lists_iterator::operator*() returns an object and not a reference to an object.
-Wrange-loop-analysis warns to make it more visible the object is a copy and not a reference.

[ABataev]

LG, thanks!

clang/lib/CodeGen/CGOpenMPRuntime.cpp

auto &&InfoGen = [&Info](
       Info[VD].emplace_back(L, MapType, MapModifiers, ReturnDevicePointer,
                             IsImplicit);
     };
 
     assert(CurDir.is<const OMPExecutableDirective *>() &&
            "Expect a executable directive");
     const auto *CurExecDir = CurDir.get<const OMPExecutableDirective *>();
     for (const auto *C : CurExecDir->getClausesOfKind<OMPMapClause>())
-      for (const auto &L : C->component_lists()) {
+      for (const auto L : C->component_lists()) {
         InfoGen(L.first, L.second, C->getMapType(), C->getMapTypeModifiers(),
             /*ReturnDevicePointer=*/false, C->isImplicit());
       }
     for (const auto *C : CurExecDir->getClausesOfKind<OMPToClause>())
-      for (const auto &L : C->component_lists()) {
+      for (const auto L : C->component_lists()) {
         InfoGen(L.first, L.second, OMPC_MAP_to, llvm::None,
             /*ReturnDevicePointer=*/false, C->isImplicit());
       }
     for (const auto *C : CurExecDir->getClausesOfKind<OMPFromClause>())
-      for (const auto &L : C->component_lists()) {
+      for (const auto L : C->component_lists()) {
         InfoGen(L.first, L.second, OMPC_MAP_from, llvm::None,
             /*ReturnDevicePointer=*/false, C->isImplicit());
       }
 
     // Look at the use_device_ptr clause information and mark the existing map
     // entries as such. If there is no map information for an entry in the
     // use_device_ptr list, we create one with map type 'alloc' and zero size
     // section. It is the user fault if that was not mapped before. If there is
     // no map information and the pointer is a struct member, then we defer the
     // emission of that entry until the whole struct has been processed.
     llvm::MapVector<const ValueDecl *, SmallVector<DeferredDevicePtrEntryTy, 4>>
         DeferredInfo;
 
     for (const auto *C :
          CurExecDir->getClausesOfKind<OMPUseDevicePtrClause>()) {
-      for (const auto &L : C->component_lists()) {
+      for (const auto L : C->component_lists()) {
         assert(!L.second.empty() && "Not expecting empty list of components!");
         const ValueDecl *VD = L.second.back().getAssociatedDeclaration();
         VD = cast<ValueDecl>(VD->getCanonicalDecl());
         const Expr *IE = L.second.back().getAssociatedExpression();
         // If the first component is a member expression, we have to look into
         // 'this', which maps to null in the map of map information. Otherwise
         // look directly for the information.
         auto It = Info.find(isa<MemberExpr>(IE) ? nullptr : VD);
auto &&InfoGen = [&Info](
       const ValueDecl *VD =
           D ? cast<ValueDecl>(D->getCanonicalDecl()) : nullptr;
       Info[VD].emplace_back(L, MapType, MapModifiers, ReturnDevicePointer,
                             IsImplicit);
     };
 
     for (const auto *C : CurMapperDir->clauselists()) {
       const auto *MC = cast<OMPMapClause>(C);
-      for (const auto &L : MC->component_lists()) {
+      for (const auto L : MC->component_lists()) {
         InfoGen(L.first, L.second, MC->getMapType(), MC->getMapTypeModifiers(),
                 /*ReturnDevicePointer=*/false, MC->isImplicit());
       }
     }
 
     for (const auto &M : Info) {
       // We need to know when we generate information for the first component
       // associated with a capture, because the mapping flags depend on it.
void generateInfoForCapture(const CapturedStmt::Capture *Cap,
     using MapData =
         std::tuple<OMPClauseMappableExprCommon::MappableExprComponentListRef,
                    OpenMPMapClauseKind, ArrayRef<OpenMPMapModifierKind>, bool>;
     SmallVector<MapData, 4> DeclComponentLists;
     assert(CurDir.is<const OMPExecutableDirective *>() &&
            "Expect a executable directive");
     const auto *CurExecDir = CurDir.get<const OMPExecutableDirective *>();
     for (const auto *C : CurExecDir->getClausesOfKind<OMPMapClause>()) {
-      for (const auto &L : C->decl_component_lists(VD)) {
+      for (const auto L : C->decl_component_lists(VD)) {
         assert(L.first == VD &&
                "We got information for the wrong declaration??");
         assert(!L.second.empty() &&
                "Not expecting declaration with no component lists.");
         DeclComponentLists.emplace_back(L.second, C->getMapType(),
                                         C->getMapTypeModifiers(),
                                         C->isImplicit());
       }
void generateInfoForDeclareTargetLink(MapBaseValuesArrayTy &BasePointers,
                                         MapValuesArrayTy &Sizes,
                                         MapFlagsArrayTy &Types) const {
     assert(CurDir.is<const OMPExecutableDirective *>() &&
            "Expect a executable directive");
     const auto *CurExecDir = CurDir.get<const OMPExecutableDirective *>();
     // Map other list items in the map clause which are not captured variables
     // but "declare target link" global variables.
     for (const auto *C : CurExecDir->getClausesOfKind<OMPMapClause>()) {
-      for (const auto &L : C->component_lists()) {
+      for (const auto L : C->component_lists()) {
         if (!L.first)
           continue;
         const auto *VD = dyn_cast<VarDecl>(L.first);
         if (!VD)
           continue;
         llvm::Optional<OMPDeclareTargetDeclAttr::MapTypeTy> Res =
             OMPDeclareTargetDeclAttr::isDeclareTargetDeclaration(VD);
         if (CGF.CGM.getOpenMPRuntime().hasRequiresUnifiedSharedMemory() ||