Add more tests for weak linking

Author: sbc100

tests/core/test_dylink_weak_main.c

@@ -1,13 +1,33 @@
 #include <stdio.h>
+#include <assert.h>
 
-void side();
+void side_print_foo();
+int side_get_foo();
+void* side_get_foo_addr();
+
+int side_get_bar();
+void* side_get_bar_addr();
 
 __attribute__((weak)) int foo() {
   return 42;
 }
 
+__attribute__((weak)) int bar = 43;
+
 int main(int argc, char const *argv[]) {
   printf("main foo() -> %d\n", foo());
-  side();
+  side_print_foo();
+
+  // Check that addresses match
+  assert(&foo == side_get_foo_addr());
+  assert(&bar == side_get_bar_addr());
+
+  // Check that main-moduled defined symbols take precedence.
+  assert(bar == 43);
+  assert(side_get_bar() == 43);
+
+  assert(foo() == 42);
+  assert(side_get_foo() == 42);
+
   return 0;
 }

tests/core/test_dylink_weak_side.c

@@ -1,11 +1,30 @@
 #include <stdio.h>
 
 extern int foo();
+extern int bar;
 
 __attribute__((weak)) int foo() {
   return 99;
 }
 
-void side() {
+__attribute__((weak)) int bar = 100;
+
+void side_print_foo() {
   printf("side foo() -> %d\n", foo());
 }
+
+int side_get_foo() {
+  return foo();
+}
+
+void* side_get_foo_addr() {
+  return &foo;
+}
+
+int side_get_bar() {
+  return bar;
+}
+
+void* side_get_bar_addr() {
+  return &bar;
+}

tests/test_core.py

@@ -3780,7 +3780,7 @@ def test_dylink_static_funcpointer_float(self):
       header='typedef float (*floatfunc)(float);', force_c=True)
 
   @needs_dylink
-  def test_missing_signatures(self):
+  def test_dylink_missing_signatures(self):
     create_file('test_sig.c', r'''#include <emscripten.h>
                                        int main() {
                                          return 0 == ( (long)&emscripten_run_script_string +
@@ -4567,7 +4567,6 @@ def test_dylink_argv_argc(self):
       expected='3 hello world!',
       need_reverse=False)
 
-  @disabled('https://github.com/emscripten-core/emscripten/issues/13773')
   def test_dylink_weak(self):
     # Verify that weakly symbols can be defined in both side module and main
     # module