Don't crash on files with no symbol table.

Thanks to Roman Divacky for the test.

llvm-svn: 249066

lld/ELF/InputFiles.cpp

@@ -78,6 +78,8 @@ ELFData<ELFT>::getSymbolsHelper(bool Local) {
 }
 
 template <class ELFT> void ELFData<ELFT>::initStringTable() {
+  if (!Symtab)
+    return;
   ErrorOr<StringRef> StringTableOrErr = ELFObj.getStringTableForSymtab(*Symtab);
   error(StringTableOrErr.getError());
   StringTable = *StringTableOrErr;

lld/test/elf2/no-symtab.s

@@ -0,0 +1,4 @@
+// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
+// RUN: lld -flavor gnu2 %t.o %p/Inputs/no-symtab.o -o %t
+.global _start
+_start: