Fix postincrement in truncating and counting iterators

include/fmt/format.h

@@ -840,7 +840,11 @@ class counting_iterator {
     return *this;
   }
 
-  counting_iterator operator++(int) { return ++*this; }
+  counting_iterator operator++(int) {
+    auto it = *this;
+    ++*this;
+    return it;
+  }
 
   T &operator*() const { return blackhole_; }
 };
@@ -877,7 +881,11 @@ class truncating_iterator {
     return *this;
   }
 
-  truncating_iterator operator++(int) { return ++*this; }
+  truncating_iterator operator++(int) {
+    auto it = *this;
+    ++*this;
+    return it;
+  }
 
   reference operator*() const { return count_ < limit_ ? *out_ : blackhole_; }
 };

test/format-test.cc

@@ -14,16 +14,11 @@
 #include <memory>
 #include <stdint.h>
 
-#include "gmock.h"
-
-// Test that the library compiles if None is defined to 0 as done by xlib.h.
-#define None 0
-
 #include "fmt/format.h"
-
-#include "util.h"
-#include "mock-allocator.h"
+#include "gmock.h"
 #include "gtest-extra.h"
+#include "mock-allocator.h"
+#include "util.h"
 
 #undef min
 #undef max
@@ -1528,9 +1523,6 @@ TEST(FormatTest, FormatToN) {
   EXPECT_EQ(6u, result.size);
   EXPECT_EQ(buffer + 3, result.out);
   EXPECT_EQ("foox", fmt::string_view(buffer, 4));
-
-  // Workaround for potentially unused macro
-  static_cast<void>(None);
 }
 
 #if FMT_USE_CONSTEXPR

test/util-test.cc

@@ -931,3 +931,18 @@ TEST(FPTest, GetCachedPower) {
     EXPECT_DOUBLE_EQ(pow(10, dec_exp), ldexp(fp.f, fp.e));
   }
 }
+
+TEST(IteratorTest, CountingIterator) {
+  fmt::internal::counting_iterator<char> it;
+  auto prev = it++;
+  EXPECT_EQ(prev.count(), 0);
+  EXPECT_EQ(it.count(), 1);
+}
+
+TEST(IteratorTest, TruncatingIterator) {
+  char *p = FMT_NULL;
+  fmt::internal::truncating_iterator<char*> it(p, 3);
+  auto prev = it++;
+  EXPECT_EQ(prev.base(), p);
+  EXPECT_EQ(it.base(), p + 1);
+}