I learned about extern C

bindings/node.js/binding.gyp

@@ -7,7 +7,9 @@
         'ckzg_wrap.cxx',
       ],
       'include_dirs': ['../../inc', '../../src'],
-      'libraries': ['/Users/coffman@coinbase.com/src/c-kzg/bindings/node.js/libckzg.a'],
+      'libraries': [
+        '/Users/coffman@coinbase.com/src/c-kzg/bindings/node.js/c_kzg_4844.o'
+      ],
     }
   ]
 }

bindings/node.js/ckzg.cxx

@@ -3,7 +3,9 @@
 #include <stdlib.h>
 #include "ckzg.h"
 
-void testFunction() {}
+void testFunction() {
+  return test_function();
+}
 
 KZGSettings* loadTrustSetup(const char* file) {
   KZGSettings* out = (KZGSettings*)malloc(sizeof(KZGSettings));

bindings/node.js/ckzg.swg

@@ -1,6 +1,8 @@
 /* File : ckzg.swg */
 %module ckzg
 
+%include <typemaps.i>
+
 %{
 #include "ckzg.h"
 %}

bindings/node.js/runnable.js

@@ -8,4 +8,5 @@ console.log(kzg);
 
 console.log('Invoking function...', kzg.testFunction());
 
-console.log('Invoking freeTrustedSetup...', kzg.freeTrustedSetup(null));
+let config = {};
+console.log('Invoking freeTrustedSetup...', kzg.freeTrustedSetup(config));

src/Makefile

@@ -2,4 +2,8 @@ INCLUDE_DIRS = ../inc
 CFLAGS += -O2
 
 c_kzg_4844.o: c_kzg_4844.c Makefile
-	clang -Wall -I$(INCLUDE_DIRS) $(CFLAGS) -c $<
+	clang -Wall -I$(INCLUDE_DIRS) $(CFLAGS) -mmacosx-version-min=10.15 -c $<
+
+lib: c_kzg_4844.c Makefile
+	clang -Wall -I$(INCLUDE_DIRS) $(CFLAGS) -mmacosx-version-min=10.15 -c c_kzg_4844.c
+	mv c_kzg_4844.o ../bindings/node.js

src/c_kzg_4844.c

@@ -20,6 +20,9 @@
 #include <stdlib.h>
 #include <string.h>
 
+void test_function() {}
+
+
 /**
  * Wrapped `malloc()` that reports failures to allocate.
  *

src/c_kzg_4844.h

@@ -54,6 +54,12 @@ typedef enum {
     C_KZG_MALLOC,  /**< Could not allocate memory */
 } C_KZG_RET;
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void test_function();
+
 /**
  * KZGCommitment and KZGProof can be recovered as 48 bytes
  */
@@ -118,4 +124,8 @@ C_KZG_RET verify_kzg_proof(bool *out,
     const KZGProof *kzg_proof,
     const KZGSettings *s);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif // C_KZG_4844_H