[lld] r240183 - COFF: Take reference to argument vector using std::vector::data() instead of operator[](0).

[Peter Collingbourne]

Author: pcc
Date: Fri Jun 19 17:40:05 2015
New Revision: 240183

URL: http://llvm.org/viewvc/llvm-project?rev=240183&view=rev
Log:
COFF: Take reference to argument vector using std::vector::data() instead of operator[](0).

This avoids undefined behaviour caused by an out-of-range access if the
vector is empty, which can happen if an object file's directive section
contains only whitespace.

Modified:
    lld/trunk/COFF/DriverUtils.cpp

Modified: lld/trunk/COFF/DriverUtils.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/DriverUtils.cpp?rev=240183&r1=240182&r2=240183&view=diff
==============================================================================
--- lld/trunk/COFF/DriverUtils.cpp (original)
+++ lld/trunk/COFF/DriverUtils.cpp Fri Jun 19 17:40:05 2015
@@ -557,7 +557,7 @@ ArgParser::parse(std::vector<const char
   unsigned MissingIndex;
   unsigned MissingCount;
   std::unique_ptr<llvm::opt::InputArgList> Args(Table.ParseArgs(
-      &Argv[0], &Argv[0] + Argv.size(), MissingIndex, MissingCount));
+      Argv.data(), Argv.data() + Argv.size(), MissingIndex, MissingCount));
   if (MissingCount) {
     llvm::errs() << "missing arg value for \""
                  << Args->getArgString(MissingIndex)
@@ -587,7 +587,7 @@ std::vector<const char *> ArgParser::tok
 // character. '@<filename>' is replaced by the file's contents.
 ErrorOr<std::vector<const char *>>
 ArgParser::replaceResponseFiles(std::vector<const char *> Argv) {
-  SmallVector<const char *, 256> Tokens(&Argv[0], &Argv[0] + Argv.size());
+  SmallVector<const char *, 256> Tokens(Argv.data(), Argv.data() + Argv.size());
   BumpPtrStringSaver Saver(AllocAux);
   ExpandResponseFiles(Saver, TokenizeWindowsCommandLine, Tokens);
   return std::vector<const char *>(Tokens.begin(), Tokens.end());