Revert "Append new attributes to the end of an AttributeList."

This reverts commit r335084 as requested by David Jones and
Eric Christopher because of differences of emitted warnings.

llvm-svn: 335516

1 files changed, 22 insertions, 11 deletions

diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index 0daf1b3bdb7..a1ce26d27ca 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -2804,25 +2804,36 @@ static bool hasSameOverloadableAttrs(const FunctionDecl *A,
   // Note that pass_object_size attributes are represented in the function's
   // ExtParameterInfo, so we don't need to check them here.
 
-  // Return false if any of the enable_if expressions of A and B are different.
+  SmallVector<const EnableIfAttr *, 4> AEnableIfs;
+  // Since this is an equality check, we can ignore that enable_if attrs show up
+  // in reverse order.
+  for (const auto *EIA : A->specific_attrs<EnableIfAttr>())
+    AEnableIfs.push_back(EIA);
+
+  SmallVector<const EnableIfAttr *, 4> BEnableIfs;
+  for (const auto *EIA : B->specific_attrs<EnableIfAttr>())
+    BEnableIfs.push_back(EIA);
+
+  // Two very common cases: either we have 0 enable_if attrs, or we have an
+  // unequal number of enable_if attrs.
+  if (AEnableIfs.empty() && BEnableIfs.empty())
+    return true;
+
+  if (AEnableIfs.size() != BEnableIfs.size())
+    return false;
+
   llvm::FoldingSetNodeID Cand1ID, Cand2ID;
-  auto AEnableIfAttrs = A->specific_attrs<EnableIfAttr>();
-  auto BEnableIfAttrs = B->specific_attrs<EnableIfAttr>();
-  auto AEnableIf = AEnableIfAttrs.begin();
-  auto BEnableIf = BEnableIfAttrs.begin();
-  for (; AEnableIf != AEnableIfAttrs.end() && BEnableIf != BEnableIfAttrs.end();
-       ++BEnableIf, ++AEnableIf) {
+  for (unsigned I = 0, E = AEnableIfs.size(); I != E; ++I) {
     Cand1ID.clear();
     Cand2ID.clear();
 
-    AEnableIf->getCond()->Profile(Cand1ID, A->getASTContext(), true);
-    BEnableIf->getCond()->Profile(Cand2ID, B->getASTContext(), true);
+    AEnableIfs[I]->getCond()->Profile(Cand1ID, A->getASTContext(), true);
+    BEnableIfs[I]->getCond()->Profile(Cand2ID, B->getASTContext(), true);
     if (Cand1ID != Cand2ID)
       return false;
   }
 
-  // Return false if the number of enable_if attributes was different.
-  return AEnableIf == AEnableIfAttrs.end() && BEnableIf == BEnableIfAttrs.end();
+  return true;
 }
 
 /// Determine whether the two declarations refer to the same entity.