[llvm-bcanalyzer] Fixed error 'Expected<T> must be checked before access or destruction'

[dendibakh]

Summary

After rL365286 I had failing test:

LLVM :: tools/gold/X86/v1.12/thinlto_emit_linked_objects.ll

It was failing with the output:

$ llvm-bcanalyzer --dump llvm/test/tools/gold/X86/v1.12/Output/thinlto_emit_linked_objects.ll.tmp3.o.thinlto.bc
Expected<T> must be checked before access or destruction.
Unchecked Expected<T> contained error:
Unexpected end of file reading 0 of 0 bytesStack dump:

[thegameg]

LGTM, thanks! Not sure how I missed this test.

[dendibakh]

In D64887#1590334, @thegameg wrote:

LGTM, thanks! Not sure how I missed this test.

Can you please double check on your side that it fails without this change?

[thegameg]

In D64887#1590340, @dendibakh wrote:

In D64887#1590334, @thegameg wrote:

LGTM, thanks! Not sure how I missed this test.

Can you please double check on your side that it fails without this change?

I don't have a setup where this test is supported, but the error and the fix look pretty obvious to me.

What I meant was that I'm not sure how I missed the bots failing.

[dendibakh]

Closed by rL366387

llvm/lib/Bitcode/Reader/BitcodeAnalyzer.cpp

 
 Error BitcodeAnalyzer::analyze(Optional<BCDumpOptions> O,
                                Optional<StringRef> CheckHash) {
-  if (Expected<CurStreamTypeType> H = analyzeHeader(O, Stream))
-    CurStreamType = *H;
+  Expected<CurStreamTypeType> MaybeType = analyzeHeader(O, Stream);
+  if (!MaybeType)
+    return MaybeType.takeError();
+  else
+    CurStreamType = *MaybeType;
 
   Stream.setBlockInfo(&BlockInfo);