**Fix:** Resolve build errors on modern GCC (13+) by fixing C linker and C++ header issues.

build_state

@@ -0,0 +1 @@
+,,,cc,,

glava/glava.h

@@ -14,8 +14,8 @@ struct glava_renderer;
 /* External API */
 
 typedef struct glava_renderer* volatile glava_handle;
-__attribute__((noreturn, visibility("default"))) void (*glava_abort)            (void);
-__attribute__((noreturn, visibility("default"))) void (*glava_return)           (void);
+extern __attribute__((noreturn, visibility("default"))) void (*glava_abort)            (void);
+extern __attribute__((noreturn, visibility("default"))) void (*glava_return)           (void);
 __attribute__((visibility("default")))           void glava_assign_external_ctx (void* ctx);
 __attribute__((visibility("default")))           void glava_entry               (int argc, char** argv, glava_handle* ret);
 __attribute__((visibility("default")))           void glava_terminate           (glava_handle* ref);

glfft/glfft_gl_interface.cpp

@@ -24,6 +24,10 @@
 #include <cstring>
 #include <vector>
 
+#include <cstdio>  // for stdout, stderr, vfprintf, fprintf, vsnprintf
+#include <cerrno>  // for errno
+#include <cstring> // for strerror
+
 using namespace GLFFT;
 using namespace std;
 

glfft/glfft_gl_interface.hpp

@@ -23,6 +23,10 @@
 
 #include "glfft_gl_api_headers.hpp"
 
+#include <cstdio>  // for stdout, stderr, vfprintf, fprintf, vsnprintf
+#include <cerrno>  // for errno
+#include <cstring> // for strerror
+
 /* GLava additions (POSIX) */
 extern "C" {
     #include <time.h>

glfft/glfft_wisdom.cpp

@@ -21,6 +21,8 @@
 #include "glfft.hpp"
 #include <utility>
 
+#include <stdexcept> // for std::logic_error
+
 /* GLAVA NOTICE: automatic wisdom serialization support may be added at a late date */
 #ifdef GLFFT_SERIALIZATION
 #include "rapidjson/reader.h"