Squash a few more unused warnings (#17743)

Author: airspeedswift

lib/Basic/Mangler.cpp

@@ -144,7 +144,7 @@ void Mangler::finalize(llvm::raw_ostream &stream) {
   stream.write(result.data(), result.size());
 }
 
-
+LLVM_ATTRIBUTE_UNUSED
 static bool treeContains(Demangle::NodePointer Nd, Demangle::Node::Kind Kind) {
   if (Nd->getKind() == Kind)
     return true;

lib/ClangImporter/IAMInference.cpp

@@ -690,6 +690,7 @@ IAMResult IAMInference::inferVar(const clang::VarDecl *varDecl) {
   auto fail = [varDecl]() -> IAMResult {
     DEBUG(llvm::dbgs() << "failed to infer variable: ");
     DEBUG(varDecl->print(llvm::dbgs()));
+    (void)varDecl;
     DEBUG(llvm::dbgs() << "\n");
     ++FailInferVar;
     return {};
@@ -733,6 +734,7 @@ IAMResult IAMInference::infer(const clang::NamedDecl *clangDecl) {
   auto fail = [funcDecl]() -> IAMResult {
     DEBUG(llvm::dbgs() << "failed to infer function: ");
     DEBUG(funcDecl->print(llvm::dbgs()));
+    (void)funcDecl;
     DEBUG(llvm::dbgs() << "\n");
     ++FailInferFunction;
     return {};

lib/IRGen/GenOpaque.cpp

@@ -482,6 +482,7 @@ void IRGenFunction::emitDeallocateDynamicAlloca(StackAddress address) {
   if (isCoroutine()) {
     auto allocToken = address.getExtraInfo();
     assert(allocToken && "dynamic alloca in coroutine without alloc token?");
+    (void)allocToken;
     auto freeFn = llvm::Intrinsic::getDeclaration(
         &IGM.Module, llvm::Intrinsic::ID::coro_alloca_free);
     Builder.CreateCall(freeFn, address.getAddressPointer());

lib/SILGen/RValue.cpp

@@ -377,6 +377,7 @@ static void copyOrInitValuesInto(Initialization *init,
   init->finishInitialization(SGF);
 }
 
+LLVM_ATTRIBUTE_UNUSED
 static unsigned
 expectedExplosionSize(CanType type) {
   auto tuple = dyn_cast<TupleType>(type);

lib/Sema/TypeCheckDeclOverride.cpp

@@ -660,6 +660,8 @@ SmallVector<OverrideMatch, 2> OverrideMatcher::match(
     auto parentMethod = dyn_cast<AbstractFunctionDecl>(parentDecl);
     auto parentStorage = dyn_cast<AbstractStorageDecl>(parentDecl);
     assert(parentMethod || parentStorage);
+    (void)parentMethod;
+    (void)parentStorage;
 
     // Check whether the types are identical.
     auto parentDeclTy = getMemberTypeForComparison(ctx, parentDecl, decl);