[Coverity] Fix unchecked return value, NFC

[pengfei]

@barannikov88 I still think [[nodiscard]] and (void) are a great couple for functions we care of the return value much rather than a contradication. The (void) tells compiler we are intended to do so here. This looks much better than we comment it like above everywhere.

[barannikov88]

llvm/lib/ObjectYAML/ELFEmitter.cpp

73

If viewed without a context, I would say that this should either take an action on the result of checkLimit, or the function should not me marked [[nodiscard]].
Considering the context, and the use of Error class in particular, I'm not sure this would be the correct fix.
I would suggest requesting a review from someone who is more familiar with this (not really my area).

[pengfei]

llvm/lib/ObjectYAML/ELFEmitter.cpp

73

Sure, adding @grimar to have a look.

[pengfei]

Ping @grimar

llvm/lib/ObjectYAML/ELFEmitter.cpp

 //===- yaml2elf - Convert YAML to a ELF object file -----------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 ///

 class ContiguousBlobAccumulator {
   const uint64_t InitialOffset;
   const uint64_t MaxSize;
 
   SmallVector<char, 128> Buf;
   raw_svector_ostream OS;
   Error ReachedLimitErr = Error::success();
 
-  bool checkLimit(uint64_t Size) {
+  [[nodiscard]] bool checkLimit(uint64_t Size) {
     if (!ReachedLimitErr && getOffset() + Size <= MaxSize)
       return true;
     if (!ReachedLimitErr)
       ReachedLimitErr = createStringError(errc::invalid_argument,
                                           "reached the output size limit");
     return false;
   }
 
 public:
   ContiguousBlobAccumulator(uint64_t BaseOffset, uint64_t SizeLimit)
       : InitialOffset(BaseOffset), MaxSize(SizeLimit), OS(Buf) {}
 
   uint64_t tell() const { return OS.tell(); }
   uint64_t getOffset() const { return InitialOffset + OS.tell(); }
   void writeBlobToStream(raw_ostream &Out) const { Out << OS.str(); }
 
   Error takeLimitError() {
     // Request to write 0 bytes to check we did not reach the limit.
-    checkLimit(0);
+    (void)checkLimit(0);
     return std::move(ReachedLimitErr);
   }
 
   /// \returns The new offset.
   uint64_t padToAlignment(unsigned Align) {
     uint64_t CurrentOffset = getOffset();
     if (ReachedLimitErr)
       return CurrentOffset;