Merging r323390:

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r323390 | ericwf | 2018-01-24 16:02:48 -0800 (Wed, 24 Jan 2018) | 9 lines

Fix PR35564 - std::list splice/erase incorrectly throw in debug mode.

There was a bug in the implementation of splice where the container
sizes were updated before decrementing one of the iterators. Afterwards,
the result of decrementing the iterator was flagged as UB by the debug
implementation because the container was reported to be empty.

This patch fixes that bug by delaying the updating of the container
sizes until after the iterators have been correctly constructed.
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llvm-svn: 334621

1 files changed, 57 insertions, 0 deletions

diff --git a/libcxx/test/libcxx/debug/containers/db_sequence_container_iterators.pass.cpp b/libcxx/test/libcxx/debug/containers/db_sequence_container_iterators.pass.cpp
index 3ae009a8e96c..57d16c2723f7 100644
--- a/libcxx/test/libcxx/debug/containers/db_sequence_container_iterators.pass.cpp
+++ b/libcxx/test/libcxx/debug/containers/db_sequence_container_iterators.pass.cpp
@@ -42,6 +42,7 @@ public:
     Base::run();
     try {
       FrontOnEmptyContainer();
+
       if constexpr (CT != CT_ForwardList) {
         AssignInvalidates();
         BackOnEmptyContainer();
@@ -50,6 +51,8 @@ public:
         InsertIterIterIter();
         EmplaceIterValue();
         EraseIterIter();
+      } else {
+        SpliceFirstElemAfter();
       }
       if constexpr (CT == CT_Vector || CT == CT_Deque || CT == CT_List) {
         PopBack();
@@ -57,12 +60,66 @@ public:
       if constexpr (CT == CT_List || CT == CT_Deque) {
         PopFront(); // FIXME: Run with forward list as well
       }
+      if constexpr (CT == CT_List || CT == CT_ForwardList) {
+        RemoveFirstElem();
+      }
+      if constexpr (CT == CT_List) {
+        SpliceFirstElem();
+      }
     } catch (...) {
       assert(false && "uncaught debug exception");
     }
   }
 
 private:
+  static void RemoveFirstElem() {
+    // See llvm.org/PR35564
+    CHECKPOINT("remove(<first-elem>)");
+    {
+      Container C = makeContainer(1);
+      auto FirstVal = *(C.begin());
+      C.remove(FirstVal);
+      assert(C.empty());
+    }
+    {
+      Container C = {1, 1, 1, 1};
+      auto FirstVal = *(C.begin());
+      C.remove(FirstVal);
+      assert(C.empty());
+    }
+  }
+
+  static void SpliceFirstElem() {
+    // See llvm.org/PR35564
+    CHECKPOINT("splice(<first-elem>)");
+    {
+      Container C = makeContainer(1);
+      Container C2;
+      C2.splice(C2.end(), C, C.begin(), ++C.begin());
+    }
+    {
+      Container C = makeContainer(1);
+      Container C2;
+      C2.splice(C2.end(), C, C.begin());
+    }
+  }
+
+
+  static void SpliceFirstElemAfter() {
+    // See llvm.org/PR35564
+    CHECKPOINT("splice(<first-elem>)");
+    {
+      Container C = makeContainer(1);
+      Container C2;
+      C2.splice_after(C2.begin(), C, C.begin(), ++C.begin());
+    }
+    {
+      Container C = makeContainer(1);
+      Container C2;
+      C2.splice_after(C2.begin(), C, C.begin());
+    }
+  }
+
   static void AssignInvalidates() {
     CHECKPOINT("assign(Size, Value)");
     Container C(allocator_type{});