Fix dangling else problem in FMT_ASSERT

include/fmt/core.h

@@ -231,8 +231,9 @@ void assert_fail(const char* file, int line, const char* message);
 #    define FMT_ASSERT(condition, message)
 #  else
 #    define FMT_ASSERT(condition, message) \
-      if (!(condition))                    \
-      fmt::internal::assert_fail(__FILE__, __LINE__, (message))
+      ((condition)                         \
+           ? void()                        \
+           : fmt::internal::assert_fail(__FILE__, __LINE__, (message)))
 #  endif
 #endif
 

test/assert-test.cc

@@ -20,3 +20,14 @@ TEST(AssertTest, Fail) {
   EXPECT_DEBUG_DEATH_IF_SUPPORTED(FMT_ASSERT(false, "don't panic!"),
                                   "don't panic!");
 }
+
+bool test_condition = false;
+
+TEST(AssertTest, DanglingElse) {
+  bool executed_else = false;
+  if (test_condition)
+    FMT_ASSERT(true, "");
+  else
+    executed_else = true;
+  EXPECT_TRUE(executed_else);
+}