`function(num1 + num2, num3)` seems to run as if it is `function(num1, num2 + num3)`

[kubo]

I inserted the following three lines here and ran tests.

  CHECK(env.render("{{ multiply(3, 3) }}", data) == "9.0");
  CHECK(env.render("{{ multiply(3, 1 + 2) }}", data) == "9.0");
  CHECK(env.render("{{ multiply(1 + 2, 3) }}", data) == "9.0");

The first two lines passed tests as expected. However, the last one failed as follows.

$ make test
Running tests...
Test project /home/kubo/inja/build
    Start 1: inja_test
1/2 Test #1: inja_test ........................***Failed    0.02 sec
    Start 2: single_inja_test
2/2 Test #2: single_inja_test .................***Failed    0.02 sec

0% tests passed, 2 tests failed out of 2

Total Test time (real) =   0.04 sec

The following tests FAILED:
	  1 - inja_test (Failed)
	  2 - single_inja_test (Failed)
Errors while running CTest
make: *** [Makefile:85: test] Error  8
$ ./inja_test 
[doctest] doctest version is "2.4.6"
[doctest] run with "--help" for options
===============================================================================
/home/kubo/inja/test/test-functions.cpp:218:
TEST CASE:  callbacks

/home/kubo/inja/test/test-functions.cpp:273: ERROR: CHECK( env.render("{{ multiply(1 + 2, 3) }}", data) == "9.0" ) is NOT correct!
  values: CHECK( 5.0 == 9.0 )

===============================================================================
[doctest] test cases:  15 |  14 passed | 1 failed | 0 skipped
[doctest] assertions: 246 | 245 passed | 1 failed |
[doctest] Status: FAILURE!

The result of multiply(1 + 2, 3) is 5.0. It seems the result of multiply(1, 2 + 3).

[kubo]

@pantor Are you going to fix this issue? If no, may I do it?

[pantor]

Please go ahead!

[terrakuh]

Thanks @kubo for the patch! Can this please be merged into the main repository @pantor ?