[lld-link] better error message when failing to open archive members

Summary:
The message "could not get the buffer for the member defining symbol"
now also contains the name of the archive and the name of the archive
member that we tried to open.

Reviewers: ruiu

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D57974

llvm-svn: 353572

Author: inglorion

lld/COFF/Driver.cpp

@@ -224,23 +224,33 @@ void LinkerDriver::addArchiveBuffer(MemoryBufferRef MB, StringRef SymName,
 void LinkerDriver::enqueueArchiveMember(const Archive::Child &C,
                                         StringRef SymName,
                                         StringRef ParentName) {
+
+  auto ReportBufferError = [=](Error &&E,
+                              StringRef ChildName) {
+    fatal("could not get the buffer for the member defining symbol " +
+          SymName + ": " + ParentName + "(" + ChildName + "): " +
+          toString(std::move(E)));
+  };
+
   if (!C.getParent()->isThin()) {
-    MemoryBufferRef MB = CHECK(
-        C.getMemoryBufferRef(),
-        "could not get the buffer for the member defining symbol " + SymName);
+    Expected<MemoryBufferRef> MBOrErr = C.getMemoryBufferRef();
+    if (!MBOrErr)
+      ReportBufferError(MBOrErr.takeError(), check(C.getFullName()));
+    MemoryBufferRef MB = MBOrErr.get();
     enqueueTask([=]() { Driver->addArchiveBuffer(MB, SymName, ParentName); });
     return;
   }
 
-  auto Future = std::make_shared<std::future<MBErrPair>>(createFutureForFile(
-      CHECK(C.getFullName(),
-            "could not get the filename for the member defining symbol " +
-                SymName)));
+  std::string ChildName = CHECK(
+      C.getFullName(),
+      "could not get the filename for the member defining symbol " +
+      SymName);
+  auto Future = std::make_shared<std::future<MBErrPair>>(
+      createFutureForFile(ChildName));
   enqueueTask([=]() {
     auto MBOrErr = Future->get();
     if (MBOrErr.second)
-      fatal("could not get the buffer for the member defining " + SymName +
-            ": " + MBOrErr.second.message());
+      ReportBufferError(errorCodeToError(MBOrErr.second), ChildName);
     Driver->addArchiveBuffer(takeBuffer(std::move(MBOrErr.first)), SymName,
                              ParentName);
   });