Produce an error for an invalid use of .symver.

llvm-svn: 117462

llvm/lib/MC/ELFObjectWriter.cpp

@@ -468,6 +468,11 @@ void ELFObjectWriterImpl::ExecutePostLayoutBinding(MCAssembler &Asm) {
     if (!Symbol.isUndefined() && !Rest.startswith("@@@"))
       continue;
 
+    // FIXME: produce a better error message.
+    if (Symbol.isUndefined() && Rest.startswith("@@") &&
+        !Rest.startswith("@@@"))
+      report_fatal_error("A @@ version cannot be undefined");
+
     std::pair<const MCSymbol *, const MCSymbol *> t(&Symbol, &Alias);
     Renames.insert(t);
   }

llvm/test/MC/ELF/invalid-symver.s

@@ -0,0 +1,7 @@
+// RUN: not llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o %t 2> %t.out
+// RUN: FileCheck --input-file=%t.out %s
+
+// CHECK: A @@ version cannot be undefined
+
+        .symver undefined, foo@@bar
+        .long undefined