Make MCAsmParserSemaCallback::LookupInlineAsmLabel a pure virtual function

[• ehsan]

Summary

r218229 made this function return a dummy nullptr in order to avoid
API breakage between clang/llvm.

[rnk]

lgtm

Thanks, feel free to commit these kinds of improvements without pre-commit review at your discretion.

[• ehsan]

Closed by commit rL218266 (authored by @ehsan).

[• ehsan]

In D5432#4, @rnk wrote:

Thanks, feel free to commit these kinds of improvements without pre-commit review at your discretion.

Will do, thanks!

llvm/trunk/include/llvm/MC/MCParser/MCAsmParser.h

 /// MCAsmParserSemaCallback - Generic Sema callback for assembly parser.
 class MCAsmParserSemaCallback {
 public:
   virtual ~MCAsmParserSemaCallback();
   virtual void *LookupInlineAsmIdentifier(StringRef &LineBuf,
                                           InlineAsmIdentifierInfo &Info,
                                           bool IsUnevaluatedContext) = 0;
   virtual StringRef LookupInlineAsmLabel(StringRef Identifier, SourceMgr &SM,
-                                         SMLoc Location, bool Create)
-  { return nullptr; }
+                                         SMLoc Location, bool Create) = 0;
 
   virtual bool LookupInlineAsmField(StringRef Base, StringRef Member,
                                     unsigned &Offset) = 0;
 };
 
 /// MCAsmParser - Generic assembler parser interface, for use by target specific
 /// assembly parsers.
 class MCAsmParser {