From 982db0281cf6ac3f9c52dbb4238b9ed3f06a01df Mon Sep 17 00:00:00 2001
From: Syrus <me@syrusakbary.com>
Date: Sat, 15 Dec 2018 22:43:10 -0800
Subject: [PATCH] Added support for 0 or 2 params in main emscripten function

---
 emtests/printf.c       |   2 +-
 emtests/printf.wasm    | Bin 46714 -> 46706 bytes
 rustfmt.toml           |   1 +
 src/webassembly/mod.rs |  26 +++++++++++++++++++++-----
 4 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/emtests/printf.c b/emtests/printf.c
index 3f2ad8b71..55abc0ad5 100644
--- a/emtests/printf.c
+++ b/emtests/printf.c
@@ -8,7 +8,7 @@
 #include <stdio.h>
 #include <math.h>
 
-int main( int argc, char * argv [] ) {
+int main() {
   int x;
   printf("ab%gc%nd\n", 1.23f, &x);
   printf("n=%d\n", x);
diff --git a/emtests/printf.wasm b/emtests/printf.wasm
index 0d4197a24a39c24322e8b7a0bf5e4adfb76a4b39..bd5c1ebf4b04041778c8b30ee9b84665fa0e8a9a 100644
GIT binary patch
delta 1000
zcmZ9KyK59-6vgMYkC}bVK9X!Unc4GYH`&c=ldz&#nJXzQM6~jMn99~_7A#b>5YkxM
ziA_+_Xd`Q71Pif{AP5F5L?ei4B#qv?GdqN>&fat8ckaix-|4aO=h%3D-O!Ew8^!}&
zf4%#~ycxdB=;y+gqxvm}o)|&fX*sRjHEWv(*UX_$_l!VQSqH2Y*1vk7T-HO@66;IW
zBI{$;0_%WPxZhf!9M-R_HtPr0Eb9SlhIPoALfEHnpe&vds4`1EP<a+NP-*m)$v+?R
zVx2Ul!Q9a_ZBW}gxpdLwiL!yJp$7fDq0xZ{)7@@B?;4sikcJ`dM-ORs>Ci)7(lQ-s
z?6X>dn!*%?Z)B#=9?Fti^r|GeCHXX_>CvZ7H1n<*%v{c2;LVmCuZ}ud!v6AL37d-9
zl(4gyrMI^vzUw0;aVCy45;xF@;*g&C$Vi@z^Q`1^n2U0@dGkExlQbVF4_;jU-bYqo
zJC1FEefTkK3*1CANf`zZ!#{o4q0mm8J3=d{n0AC-z(SHT-9js-cbjko&e6BgmF5I)
zqn(TlFJdtn8D7FtGV%>}(4lYy)3Ax0lofWKe!tTDr|fO{hYNCmF1iyYqsv&HF!|lA
zVCAeyKbj~=X>sfhrL-uet5}W9P}#A|t!r4D_>^1Mv3}O1`#@1zOJjF*)RMIJ&>Neh
z(vrNB4Q!0f_)9L`#Aak(jrP+Epd_s>rR2T2a+zD$B1fLk5#UN#p;O3w0#szK(&+Kt
OQK-t;-`BIZ_x=M2{o6eN

delta 1004
zcmZ9KyKmEA6vb^PX&mSMPSZL$U!6ATD}6U&A{TXFs1Qv24<0K114m*21OrkQMmEG!
zfx5sJ7RbN=45&gvqKE-Ok$^6!3*4JH5z6%QJ;&!<>+|>f)Hpvio?JEb;L$bXuCBlA
zehggq-iGyE&#_d?vFM@U)-1<zqE~`#9#VlQT6EiRRgu|Y7MOo@SLK+;%q;U6GsAqq
zOfx&oB=e`{ss!^BGtPX&j4}I6>FqHi@LJSxmB}+)m1mS(m13k^Wuc|Q{CJNShe%Tf
zG!=lZf(Y+vn%2o3o?W~U&=4lmRV9=V+BG!l+X$!HWrP}rrlw$FO4N5YELQ2*MoQc~
zooK8hzfVC|O=Fr~$V?w><i$7Xc~X2+>@v!9|9yQp^R5}pT#B`LvniiBi&+Xv_J`g5
z70P-xY<hJ=gj*Fvq%7)}MWw8Qif=!zAS!muw_{>gQ61VW^C|#iH|8n@<%eHa5R-7+
zx8o9?!yI{o-K=xkfit!_T|>=Jf3F}e>4a}5Bt4ILe|18_3s@Mt9Im78hr3lIB%Gu#
zgELG@xPiuS^jPQgA{NIsr<bra9{J3cu{<29S4C3F(tD4-UT*$Xk+%HOv{bBMWkTfS
zDpn^%zA#NR$D+r1`c_3+S~DZLC#@N2UBlXh$gS&GpAflq0~`N~bO*>tX?COzJ~b<)
zo7fzQ-e6T$ZpIe2MymfRw{By5B+8rg6v#?zj^z3>_%L^{Lzdj26CfvMfzBcG8Bmb9
bNQ2vYQ=uqht7egwjD9}Q`{q&5JUILZQDon`

diff --git a/rustfmt.toml b/rustfmt.toml
index dc26521c0..4a3e0232a 100644
--- a/rustfmt.toml
+++ b/rustfmt.toml
@@ -1,3 +1,4 @@
 ignore = [
     "src/spectests",
+    "src/emtests",
 ]
diff --git a/src/webassembly/mod.rs b/src/webassembly/mod.rs
index 5c679ba48..d91ac003f 100644
--- a/src/webassembly/mod.rs
+++ b/src/webassembly/mod.rs
@@ -11,6 +11,7 @@ use cranelift_codegen::{
     isa,
     settings::{self, Configurable},
 };
+use cranelift_wasm::ModuleEnvironment;
 use std::panic;
 use std::str::FromStr;
 use target_lexicon;
@@ -226,11 +227,26 @@ pub fn start_instance(
             _ => panic!("_main emscripten function not found"),
         };
 
-        let main: extern "C" fn(u32, u32, &Instance) = get_instance_function!(instance, func_index);
-
-        let (argc, argv) = store_module_arguments(path, args, instance);
-
-        call_protected!(main(argc, argv, &instance)).map_err(|err| format!("{}", err))
+        let sig_index = module.get_func_type(func_index);
+        let signature = module.get_signature(sig_index);
+        let num_params = signature.params.len();
+        match num_params {
+            2 => {
+                let main: extern "C" fn(u32, u32, &Instance) =
+                    get_instance_function!(instance, func_index);
+                let (argc, argv) = store_module_arguments(path, args, instance);
+                call_protected!(main(argc, argv, &instance))
+            }
+            0 => {
+                let main: extern "C" fn(&Instance) = get_instance_function!(instance, func_index);
+                call_protected!(main(&instance))
+            }
+            _ => panic!(
+                "The emscripten main function has received an incorrect number of params {}",
+                num_params
+            ),
+        }
+        .map_err(|err| format!("{}", err))
     // TODO: We should implement emscripten __ATEXIT__
     } else {
         let func_index =