Fixes #362.

Fix comparing iterators from a different container.

include/cxxopts.hpp

@@ -1549,17 +1549,37 @@ class ParseResult
     Iterator() = default;
     Iterator(const Iterator&) = default;
 
+// GCC complains about m_iter not being initialised in the member
+// initializer list 
+CXXOPTS_IGNORE_WARNING("-Weffc++")
     Iterator(const ParseResult *pr, bool end=false)
     : m_pr(pr)
-    , m_iter(end? pr->m_defaults.end(): pr->m_sequential.begin())
     {
+      if (end)
+      {
+        m_sequential = false;
+        m_iter = m_pr->m_defaults.end();
+      }
+      else
+      {
+        m_sequential = true;
+        m_iter = m_pr->m_sequential.begin();
+
+        if (m_iter == m_pr->m_sequential.end())
+        {
+          m_sequential = false;
+          m_iter = m_pr->m_defaults.begin();
+        }
+      }
     }
+CXXOPTS_DIAGNOSTIC_POP
 
     Iterator& operator++()
     {
       ++m_iter;
-      if(m_iter == m_pr->m_sequential.end())
+      if(m_sequential && m_iter == m_pr->m_sequential.end())
       {
+        m_sequential = false;
         m_iter = m_pr->m_defaults.begin();
         return *this;
       }
@@ -1575,7 +1595,7 @@ class ParseResult
 
     bool operator==(const Iterator& other) const
     {
-      return m_iter == other.m_iter;
+      return (m_sequential == other.m_sequential) && (m_iter == other.m_iter);
     }
 
     bool operator!=(const Iterator& other) const
@@ -1596,6 +1616,7 @@ class ParseResult
     private:
     const ParseResult* m_pr;
     std::vector<KeyValue>::const_iterator m_iter;
+    bool m_sequential = true;
   };
 
   ParseResult() = default;

test/options.cpp

@@ -1,4 +1,5 @@
 #include "catch.hpp"
+#include <iostream>
 
 #include <initializer_list>
 
@@ -923,6 +924,35 @@ TEST_CASE("Iterator", "[iterator]") {
   REQUIRE(++iter == result.end());
 }
 
+TEST_CASE("Iterator no args", "[iterator]") {
+  cxxopts::Options options("tester", " - test iterating over parse result");
+
+  options.add_options()
+    ("value", "an option with a value", cxxopts::value<std::string>())
+    ("default", "an option with default value", cxxopts::value<int>()->default_value("42"))
+    ("nothing", "won't exist", cxxopts::value<std::string>())
+    ;
+
+  Argv argv({
+    "tester",
+  });
+
+  auto** actual_argv = argv.argv();
+  auto argc = argv.argc();
+
+  auto result = options.parse(argc, actual_argv);
+
+  auto iter = result.begin();
+
+  REQUIRE(iter != result.end());
+  CHECK(iter->key() == "default");
+  CHECK(iter->value() == "42");
+  
+  ++iter;
+  CHECK(iter == result.end());
+}
+
+
 TEST_CASE("No Options help", "[options]")
 {
   std::vector<std::string> positional;