Test funcptr import type (#4913)

* add a test for a function pointer from js being called, when there is also a call to it that due to asm.js ffi reasons has a different type

Author: kripken

tests/core/test_funcptr_import_type.cpp

@@ -0,0 +1,26 @@
+#include <stdio.h>
+
+extern "C" {
+float floaty(float f32, int i32, double f64);
+float floatyAlone(float f32, int i32, double f64);
+}
+
+int main()
+{
+  // call it once normally. the asm.js ffi will force it to be an f64
+  printf("|%f|\n", floaty(12.34f, 1, 100.32));
+  {
+    // call it using a function pointer, which will need to be f32
+    auto* fp = floaty;
+    volatile auto vfp = fp;
+    printf("|%f|\n", vfp(12.34f, 1, 100.32));
+  }
+  {
+    // no other call for this one
+    auto* fp = floatyAlone;
+    volatile auto vfp = fp;
+    printf("|%f|\n", vfp(12.34f, 1, 100.32));
+  }
+  return 0;
+}
+

tests/core/test_funcptr_import_type.js

@@ -0,0 +1,9 @@
+mergeInto(LibraryManager.library, {
+  floaty: function(x, y, z) {
+    return -x + y;
+  },
+  floatyAlone: function(x, y, z) {
+    return x - y;
+  }
+});
+

tests/core/test_funcptr_import_type.out

@@ -0,0 +1,3 @@
+|-11.340000|
+|-11.340000|
+|11.340000|

tests/test_core.py

@@ -4768,6 +4768,10 @@ def test_unicode_js_library(self):
     self.emcc_args += ['--js-library', path_from_root('tests', 'unicode_library.js')]
     self.do_run(open(os.path.join(self.get_dir(), 'main.cpp'), 'r').read(), u'Unicode snowman \u2603 says hello!')
 
+  def test_funcptr_import_type(self):
+    self.emcc_args += ['--js-library', path_from_root('tests', 'core', 'test_funcptr_import_type.js'), '-std=c++11']
+    self.do_run_in_out_file_test('tests', 'core', 'test_funcptr_import_type')
+
   def test_constglobalunion(self):
     self.emcc_args += ['-s', 'EXPORT_ALL=1']