[Object] Change Archive::child_iterator for better interop with Error/Expected.

See http://reviews.llvm.org/D22079

Changes the Archive::child_begin and Archive::children to require a reference
to an Error. If iterator increment fails (because the archive header is
damaged) the iterator will be set to 'end()', and the error stored in the
given Error&. The Error value should be checked by the user immediately after
the loop. E.g.:

Error Err;
for (auto &C : A->children(Err)) {
  // Do something with archive child C.
}
// Check the error immediately after the loop.
if (Err)
  return Err;

Failure to check the Error will result in an abort() when the Error goes out of
scope (as guaranteed by the Error class).

llvm-svn: 275316

1 files changed, 5 insertions, 4 deletions

diff --git a/llvm/lib/ExecutionEngine/Orc/OrcMCJITReplacement.h b/llvm/lib/ExecutionEngine/Orc/OrcMCJITReplacement.h
index 5ab47b97dbd..2fde56447fc 100644
--- a/llvm/lib/ExecutionEngine/Orc/OrcMCJITReplacement.h
+++ b/llvm/lib/ExecutionEngine/Orc/OrcMCJITReplacement.h
@@ -258,13 +258,14 @@ private:
     for (object::OwningBinary<object::Archive> &OB : Archives) {
       object::Archive *A = OB.getBinary();
       // Look for our symbols in each Archive
-      object::Archive::child_iterator ChildIt = A->findSym(Name);
-      if (std::error_code EC = ChildIt->getError())
-        report_fatal_error(EC.message());
+      Error Err;
+      object::Archive::child_iterator ChildIt = A->findSym(Err, Name);
+      if (Err)
+        report_fatal_error(std::move(Err));
       if (ChildIt != A->child_end()) {
         // FIXME: Support nested archives?
         Expected<std::unique_ptr<object::Binary>> ChildBinOrErr =
-            (*ChildIt)->getAsBinary();
+            ChildIt->getAsBinary();
         if (!ChildBinOrErr) {
           // TODO: Actually report errors helpfully.
           consumeError(ChildBinOrErr.takeError());