Fix the warnings on unused variables (NFC)

clang-tools-extra/clangd/AST.cpp

@@ -116,6 +116,7 @@ getQualification(ASTContext &Context, const DeclContext *DestContext,
     if (auto *TD = llvm::dyn_cast<TagDecl>(CurContext)) {
       // There can't be any more tag parents after hitting a namespace.
       assert(!ReachedNS);
+      (void)ReachedNS;
       NNS = NestedNameSpecifier::Create(Context, nullptr, false,
                                         TD->getTypeForDecl());
     } else {

lld/MachO/InputSection.cpp

@@ -50,7 +50,7 @@ void InputSection::writeTo(uint8_t *buf) {
         // relative to the start of the thread-local data memory area, which
         // is initialized via copying all the TLV data sections (which are all
         // contiguous).
-        if (auto *defined = dyn_cast<Defined>(referentSym))
+        if (isa<Defined>(referentSym))
           referentVA -= firstTLVDataSection->addr;
       }
     } else if (auto *referentIsec = r.referent.dyn_cast<InputSection *>()) {

llvm/lib/Transforms/Coroutines/CoroFrame.cpp

@@ -1538,6 +1538,7 @@ static void rewritePHIs(BasicBlock &BB) {
         // CleanupPad with a CatchSwitch predecessor: therefore this is an
         // unwind destination that needs to be handle specially.
         assert(CS->getUnwindDest() == &BB);
+        (void)CS;
         rewritePHIsForCleanupPad(&BB, CleanupPad);
         return;
       }