EM_ASM_ variants that return a value but receive no inputs; fixes #2070

2 files changed, 8 insertions, 1 deletions

diff --git a/system/include/emscripten/emscripten.h b/system/include/emscripten/emscripten.h
index fb456d67..2fc82f50 100644
--- a/system/include/emscripten/emscripten.h
+++ b/system/include/emscripten/emscripten.h
@@ -50,10 +50,14 @@ extern "C" {
  *      return $0 + $1;
  *    }, calc(), otherCalc());
  *
- * Note the {,}
+ * Note the { and }. If you just want to receive an output value
+ * (int or double) but *not* to pass any values, you can use
+ * EM_ASM_INT_V and EM_ASM_DOUBLE_V respectively.
  */
 #define EM_ASM_INT(code, ...) emscripten_asm_const_int(#code, __VA_ARGS__)
 #define EM_ASM_DOUBLE(code, ...) emscripten_asm_const_double(#code, __VA_ARGS__)
+#define EM_ASM_INT_V(code) emscripten_asm_const_int(#code)
+#define EM_ASM_DOUBLE_V(code) emscripten_asm_const_double(#code)
 
 /*
  * Forces LLVM to not dead-code-eliminate a function. Note that
diff --git a/tests/core/test_inlinejs3.in b/tests/core/test_inlinejs3.in
index e21ed041..9ddd5907 100644
--- a/tests/core/test_inlinejs3.in
+++ b/tests/core/test_inlinejs3.in
@@ -15,6 +15,9 @@ int main(int argc, char **argv) {
                       },
                       i, double(i) / 12);
   }
+  EM_ASM_INT({ globalVar = $0 }, sum); // no outputs, just input
+  sum = 0;
+  sum = EM_ASM_INT_V({ return globalVar }); // no inputs, just output
   printf("sum: %d\n", sum);
   return 0;
 }