Add debug mode and rewrite assertions (#52)

examples/panic.c

@@ -0,0 +1,48 @@
+#define KERNAUX_DEBUG
+#include <kernaux/assert.h>
+
+#include <assert.h>
+#include <stddef.h>
+#include <string.h>
+
+static unsigned int count = 0;
+static const char *last_file = NULL;
+static int last_line = 0;
+static const char *last_str = NULL;
+
+static void assert_cb(
+    const char *const file,
+    const int line,
+    const char *const str
+) {
+    ++count;
+    last_file = file;
+    last_line = line;
+    last_str = str;
+}
+
+int main()
+{
+    KERNAUX_PANIC("foo");
+
+    assert(count == 0);
+    assert(last_file == NULL);
+    assert(last_line == 0);
+    assert(last_str == NULL);
+
+    kernaux_assert_cb = assert_cb;
+
+    KERNAUX_PANIC("bar");
+
+    assert(count == 1);
+    assert(strcmp(last_file, __FILE__) == 0);
+    assert(last_line == __LINE__ - 4);
+    assert(strcmp(last_str, "bar") == 0);
+
+    KERNAUX_PANIC("car");
+
+    assert(count == 2);
+    assert(strcmp(last_file, __FILE__) == 0);
+    assert(last_line == __LINE__ - 4);
+    assert(strcmp(last_str, "car") == 0);
+}