[llvm] Remove uses of deprecated `std::iterator`

std::iterator has been deprecated in C++17 and some standard library implementations such as MS STL or libc++ emit deperecation messages when using the class.
Since LLVM has now switched to C++17 these will emit warnings on these implementations, or worse, errors in build configurations using -Werror.

This patch fixes these issues by replacing them with LLVMs own llvm::iterator_facade_base which offers a superset of functionality of std::iterator.

Differential Revision: https://reviews.llvm.org/D131320

3 files changed, 12 insertions, 16 deletions

diff --git a/llvm/include/llvm/Transforms/IPO/SampleContextTracker.h b/llvm/include/llvm/Transforms/IPO/SampleContextTracker.h
index a97d5ee3d710..1b1d2ce818f0 100644
--- a/llvm/include/llvm/Transforms/IPO/SampleContextTracker.h
+++ b/llvm/include/llvm/Transforms/IPO/SampleContextTracker.h
@@ -17,6 +17,7 @@
 
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/iterator.h"
 #include "llvm/ProfileData/SampleProf.h"
 #include <map>
 #include <queue>
@@ -143,8 +144,9 @@ public:
     return FuncToCtxtProfiles;
   }
 
-  class Iterator : public std::iterator<std::forward_iterator_tag,
-                                        const ContextTrieNode *> {
+  class Iterator : public llvm::iterator_facade_base<
+                       Iterator, std::forward_iterator_tag, ContextTrieNode *,
+                       std::ptrdiff_t, ContextTrieNode **, ContextTrieNode *> {
     std::queue<ContextTrieNode *> NodeQueue;
 
   public:
@@ -159,12 +161,6 @@ public:
       return *this;
     }
 
-    Iterator operator++(int) {
-      assert(!NodeQueue.empty() && "Iterator already at the end");
-      Iterator Ret = *this;
-      ++(*this);
-      return Ret;
-    }
     bool operator==(const Iterator &Other) const {
       if (NodeQueue.empty() && Other.NodeQueue.empty())
         return true;
@@ -172,7 +168,7 @@ public:
         return false;
       return NodeQueue.front() == Other.NodeQueue.front();
     }
-    bool operator!=(const Iterator &Other) const { return !(*this == Other); }
+
     ContextTrieNode *operator*() const {
       assert(!NodeQueue.empty() && "Invalid access to end iterator");
       return NodeQueue.front();
diff --git a/llvm/lib/Target/Hexagon/MCTargetDesc/HexagonMCInstrInfo.h b/llvm/lib/Target/Hexagon/MCTargetDesc/HexagonMCInstrInfo.h
index f0c4a86fde78..ccd2482c3fd7 100644
--- a/llvm/lib/Target/Hexagon/MCTargetDesc/HexagonMCInstrInfo.h
+++ b/llvm/lib/Target/Hexagon/MCTargetDesc/HexagonMCInstrInfo.h
@@ -15,6 +15,7 @@
 
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/iterator.h"
 #include "llvm/ADT/iterator_range.h"
 #include "llvm/MC/MCInst.h"
 #include "llvm/Support/MathExtras.h"
@@ -41,8 +42,9 @@ public:
 
 namespace Hexagon {
 
-class PacketIterator : public std::iterator<std::forward_iterator_tag,
-    PacketIterator> {
+class PacketIterator
+    : public llvm::iterator_facade_base<
+          PacketIterator, std::forward_iterator_tag, const MCInst> {
   MCInstrInfo const &MCII;
   MCInst::const_iterator BundleCurrent;
   MCInst::const_iterator BundleEnd;
@@ -56,9 +58,6 @@ public:
   PacketIterator &operator++();
   MCInst const &operator*() const;
   bool operator==(PacketIterator const &Other) const;
-  bool operator!=(PacketIterator const &Other) const {
-    return !(*this == Other);
-  }
 };
 
 } // end namespace Hexagon
diff --git a/llvm/unittests/ADT/IteratorTest.cpp b/llvm/unittests/ADT/IteratorTest.cpp
index ba92d00d7d3d..7269bfc4b6fb 100644
--- a/llvm/unittests/ADT/IteratorTest.cpp
+++ b/llvm/unittests/ADT/IteratorTest.cpp
@@ -19,8 +19,9 @@ namespace {
 
 template <int> struct Shadow;
 
-struct WeirdIter : std::iterator<std::input_iterator_tag, Shadow<0>, Shadow<1>,
-                                 Shadow<2>, Shadow<3>> {};
+struct WeirdIter
+    : llvm::iterator_facade_base<WeirdIter, std::input_iterator_tag, Shadow<0>,
+                                 Shadow<1>, Shadow<2>, Shadow<3>> {};
 
 struct AdaptedIter : iterator_adaptor_base<AdaptedIter, WeirdIter> {};