Fully apply David Blaikie suggestion and add comment explaining why.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@244461 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/tools/dsymutil/DwarfLinker.cpp b/tools/dsymutil/DwarfLinker.cpp
index ae2f6d3b36f1db8143ff9aa20d7e87b3e870f15a..95f4ae4dc0df3e1538a197a7d77d0bdb76ef2ef1 100644 (file)
--- a/tools/dsymutil/DwarfLinker.cpp
+++ b/tools/dsymutil/DwarfLinker.cpp
@@ -2884,8 +2884,10 @@ void DwarfLinker::patchLineTableForUnit(CompileUnit &Unit,
       if (StopAddress != -1ULL && !Seq.empty()) {
         // Insert end sequence row with the computed end address, but
         // the same line as the previous one.
+        // Do not collapse the next two statements as the push_back operation
+        // may reallocate the vector and invalidate the iterator Seq.back().
         auto NextLine = Seq.back();
-        Seq.emplace_back(NextLine);
+        Seq.push_back(NextLine);
         Seq.back().Address = StopAddress;
         Seq.back().EndSequence = 1;
         Seq.back().PrologueEnd = 0;