[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, 35 insertions, 39 deletions

diff --git a/llvm/tools/llvm-nm/llvm-nm.cpp b/llvm/tools/llvm-nm/llvm-nm.cpp
index 2cd0ede4a53..9b2f5220bad 100644
--- a/llvm/tools/llvm-nm/llvm-nm.cpp
+++ b/llvm/tools/llvm-nm/llvm-nm.cpp
@@ -1109,30 +1109,31 @@ static void dumpSymbolNamesFromFile(std::string &Filename) {
       }
     }
 
-    for (Archive::child_iterator I = A->child_begin(), E = A->child_end();
-         I != E; ++I) {
-      if (error(I->getError()))
-        return;
-      auto &C = I->get();
-      Expected<std::unique_ptr<Binary>> ChildOrErr = C.getAsBinary(&Context);
-      if (!ChildOrErr) {
-        if (auto E = isNotObjectErrorInvalidFileType(ChildOrErr.takeError()))
-          error(std::move(E), Filename, C);
-        continue;
-      }
-      if (SymbolicFile *O = dyn_cast<SymbolicFile>(&*ChildOrErr.get())) {
-        if (!checkMachOAndArchFlags(O, Filename))
-          return;
-        if (!PrintFileName) {
-          outs() << "\n";
-          if (isa<MachOObjectFile>(O)) {
-            outs() << Filename << "(" << O->getFileName() << ")";
-          } else
-            outs() << O->getFileName();
-          outs() << ":\n";
+    {
+      Error Err;
+      for (auto &C : A->children(Err)) {
+        Expected<std::unique_ptr<Binary>> ChildOrErr = C.getAsBinary(&Context);
+        if (!ChildOrErr) {
+          if (auto E = isNotObjectErrorInvalidFileType(ChildOrErr.takeError()))
+            error(std::move(E), Filename, C);
+          continue;
+        }
+        if (SymbolicFile *O = dyn_cast<SymbolicFile>(&*ChildOrErr.get())) {
+          if (!checkMachOAndArchFlags(O, Filename))
+            return;
+          if (!PrintFileName) {
+            outs() << "\n";
+            if (isa<MachOObjectFile>(O)) {
+              outs() << Filename << "(" << O->getFileName() << ")";
+            } else
+              outs() << O->getFileName();
+            outs() << ":\n";
+          }
+          dumpSymbolNamesFromObject(*O, false, Filename);
         }
-        dumpSymbolNamesFromObject(*O, false, Filename);
       }
+      if (Err)
+        error(std::move(Err), A->getFileName());
     }
     return;
   }
@@ -1174,12 +1175,8 @@ static void dumpSymbolNamesFromFile(std::string &Filename) {
             } else if (Expected<std::unique_ptr<Archive>> AOrErr =
                            I->getAsArchive()) {
               std::unique_ptr<Archive> &A = *AOrErr;
-              for (Archive::child_iterator AI = A->child_begin(),
-                                           AE = A->child_end();
-                   AI != AE; ++AI) {
-                if (error(AI->getError()))
-                  return;
-                auto &C = AI->get();
+              Error Err;
+              for (auto &C : A->children(Err)) {
                 Expected<std::unique_ptr<Binary>> ChildOrErr =
                     C.getAsBinary(&Context);
                 if (!ChildOrErr) {
@@ -1209,6 +1206,8 @@ static void dumpSymbolNamesFromFile(std::string &Filename) {
                                             ArchitectureName);
                 }
               }
+              if (Err)
+                error(std::move(Err), A->getFileName());
             } else {
               consumeError(AOrErr.takeError());
               error(Filename + " for architecture " +
@@ -1247,12 +1246,8 @@ static void dumpSymbolNamesFromFile(std::string &Filename) {
           } else if (Expected<std::unique_ptr<Archive>> AOrErr =
                          I->getAsArchive()) {
             std::unique_ptr<Archive> &A = *AOrErr;
-            for (Archive::child_iterator AI = A->child_begin(),
-                                         AE = A->child_end();
-                 AI != AE; ++AI) {
-              if (error(AI->getError()))
-                return;
-              auto &C = AI->get();
+            Error Err;
+            for (auto &C : A->children(Err)) {
               Expected<std::unique_ptr<Binary>> ChildOrErr =
                   C.getAsBinary(&Context);
               if (!ChildOrErr) {
@@ -1272,6 +1267,8 @@ static void dumpSymbolNamesFromFile(std::string &Filename) {
                 dumpSymbolNamesFromObject(*O, false, ArchiveName);
               }
             }
+            if (Err)
+              error(std::move(Err), A->getFileName());
           } else {
             consumeError(AOrErr.takeError());
             error(Filename + " for architecture " +
@@ -1316,11 +1313,8 @@ static void dumpSymbolNamesFromFile(std::string &Filename) {
       } else if (Expected<std::unique_ptr<Archive>> AOrErr =
                   I->getAsArchive()) {
         std::unique_ptr<Archive> &A = *AOrErr;
-        for (Archive::child_iterator AI = A->child_begin(), AE = A->child_end();
-             AI != AE; ++AI) {
-          if (error(AI->getError()))
-            return;
-          auto &C = AI->get();
+        Error Err;
+        for (auto &C : A->children(Err)) {
           Expected<std::unique_ptr<Binary>> ChildOrErr =
             C.getAsBinary(&Context);
           if (!ChildOrErr) {
@@ -1349,6 +1343,8 @@ static void dumpSymbolNamesFromFile(std::string &Filename) {
             dumpSymbolNamesFromObject(*O, false, ArchiveName, ArchitectureName);
           }
         }
+        if (Err)
+          error(std::move(Err), A->getFileName());
       } else {
         consumeError(AOrErr.takeError());
         error(Filename + " for architecture " +