[clang-tools-extra] Fix switch coverage warning

[echristo]

Summary

... I think this is right?

Add support in the switch statement for addr spaces. I couldn't get a magical API combination to get just the address space off the top of my head, but wanted to get this out.

[merge_guards_bot]

Unit tests: pass. 60867 tests passed, 0 failed and 726 were skipped.

clang-format: pass.

Build artifacts: console-log.txt, CMakeCache.txt, test-results.xml, diff.json

[sammccall]

It should be possible to test this by adapting a test case from the original ed8dadb, but I'm not certain...

clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.cpp

525

Not very familiar with this code, but it looks like this is feeding the arg back into a builder, and ed8dadb added support for sending LangAS itself to the builder.

So I don't think we should stringify it, but just send the LangAS

526

I think the stored thing is a LangAS (an enum), rather than a pointer to one.

[echristo]

Fix for some slightly better API uses.

[merge_guards_bot]

clang-format: pass.

Build artifacts: console-log.txt, diff.json

[xbolva00]

In D71486#1784079, @sammccall wrote:

It should be possible to test this by adapting a test case from the original ed8dadb, but I'm not certain...

This concern was not addressed/answered.

The commit https://reviews.llvm.org/rG5623bd52acd34db2e9cfc11d1510407610a14db0 claims that this was reviewed by rsmith, but I don't see rsmith's LGTM here..

clang-tools-extra/clang-tidy/ClangTidyDiagnosticConsumer.cpp

case clang::DiagnosticsEngine::ak_declcontext:
       Builder << reinterpret_cast<DeclContext *>(Info.getRawArg(Index));
       break;
     case clang::DiagnosticsEngine::ak_qualtype_pair:
       assert(false); // This one is not passed around.
       break;
     case clang::DiagnosticsEngine::ak_attr:
       Builder << reinterpret_cast<Attr *>(Info.getRawArg(Index));
       break;
+    case clang::DiagnosticsEngine::ak_addrspace:
+      Builder << static_cast<LangAS>(Info.getRawArg(Index));
+      break;
     }
   }
 }
 
 void ClangTidyDiagnosticConsumer::checkFilters(SourceLocation Location,
                                                const SourceManager &Sources) {
   // Invalid location may mean a diagnostic in a command line, don't skip these.
   if (!Location.isValid()) {