COFF: Preserve original spelling of DLL file name.

This patch fixes a subtle incompatibility with MSVC linker.
MSVC linker preserves the original spelling of a DLL in the
import descriptor table. LLD previously converted all
characters to lowercase. Usually this difference is benign,
but if a program explicitly checks for DLL file names, the
program could fail.

llvm-svn: 246620

1 files changed, 4 insertions, 4 deletions

diff --git a/lld/COFF/DLL.cpp b/lld/COFF/DLL.cpp
index 5da0fca3c71..79e201a9af1 100644
--- a/lld/COFF/DLL.cpp
+++ b/lld/COFF/DLL.cpp
@@ -128,13 +128,13 @@ static std::vector<std::vector<DefinedImportData *>>
 binImports(const std::vector<DefinedImportData *> &Imports) {
   // Group DLL-imported symbols by DLL name because that's how
   // symbols are layed out in the import descriptor table.
-  auto Less = [](StringRef A, StringRef B) {
+  auto Less = [](const std::string &A, const std::string &B) {
     return Config->DLLOrder[A] < Config->DLLOrder[B];
   };
-  std::map<StringRef, std::vector<DefinedImportData *>,
-           bool(*)(StringRef, StringRef)> M(Less);
+  std::map<std::string, std::vector<DefinedImportData *>,
+           bool(*)(const std::string &, const std::string &)> M(Less);
   for (DefinedImportData *Sym : Imports)
-    M[Sym->getDLLName()].push_back(Sym);
+    M[Sym->getDLLName().lower()].push_back(Sym);
 
   std::vector<std::vector<DefinedImportData *>> V;
   for (auto &P : M) {