add assert_always() macro for release build assertions

src/mbgl/util/assert.hpp

@@ -0,0 +1,13 @@
+#ifndef MBGL_UTIL_ASSERT
+#define MBGL_UTIL_ASSERT
+
+#include <cassert>
+
+// Based on FreeBSD's src/include/assert.h
+// Licensed under the original BSD license
+#define assert_always(expr)                                                                        \
+    ((void)((expr) ? ((void)0) : ((void)fprintf(stderr, "%s:%u: failed assertion `%s'\n",          \
+                                                __FILE__, __LINE__, #expr),                        \
+                                  abort())))
+
+#endif

test/miscellaneous/assert.cpp

@@ -0,0 +1,9 @@
+#include "../fixtures/util.hpp"
+
+#include <mbgl/util/assert.hpp>
+
+using namespace mbgl;
+
+TEST(Assert, Always) {
+    EXPECT_DEATH(assert_always(true == false), "failed assertion `true == false'");
+}

test/test.gypi

@@ -41,6 +41,7 @@
 
         'headless/headless.cpp',
 
+        'miscellaneous/assert.cpp',
         'miscellaneous/clip_ids.cpp',
         'miscellaneous/binpack.cpp',
         'miscellaneous/bilinear.cpp',