Merge branch 'fix-reasonligo-wrongfunctionarguments-error' into 'dev'

Correct wrong function arguments error message

See merge request ligolang/ligo!375

src/bin/expect_tests/syntax_error_tests.ml

@@ -15,3 +15,22 @@ let%expect_test _ =
     * Open a gitlab issue: https://gitlab.com/ligolang/ligo/issues/new
     * Check the changelog by running 'ligo changelog' |} ] ;
 
+  run_ligo_bad [ "compile-contract" ; "../../test/contracts/negative/error_function_arguments.religo" ; "main" ] ;
+  [%expect {|
+    ligo: in file "error_function_arguments.religo", line 1, characters 14-27. : It looks like you are defining a function, however we do not
+          understand the parameters declaration.
+          Examples of valid functions:
+          let x = (a: string, b: int) : int => 3;
+          let tuple = ((a, b): (int, int)) => a + b; 
+          let x = (a: string) : string => "Hello, " ++ a;
+           {"location":"in file \"error_function_arguments.religo\", line 1, characters 14-27"}
+      
+
+     If you're not sure how to fix this error, you can
+     do one of the following:
+
+    * Visit our documentation: https://ligolang.org/docs/intro/what-and-why/
+    * Ask a question on our Discord: https://discord.gg/9rhYaEt
+    * Open a gitlab issue: https://gitlab.com/ligolang/ligo/issues/new
+    * Check the changelog by running 'ligo changelog' |} ] ;
+

src/passes/1-parser/reasonligo.ml

@@ -55,7 +55,14 @@ module Errors =
 
     let wrong_function_arguments (expr: AST.expr) =
       let title () = "" in
-      let message () = "Wrong function arguments.\n" in
+      let message () = "It looks like you are defining a function, \
+               however we do not\n\
+               understand the parameters declaration.\n\
+               Examples of valid functions:\n\
+               let x = (a: string, b: int) : int => 3;\n\
+               let tuple = ((a, b): (int, int)) => a + b; \n\
+               let x = (a: string) : string => \"Hello, \" ++ a;\n" 
+      in
       let expression_loc = AST.expr_to_region expr in
       let data = [
         ("location",

src/test/contracts/negative/error_function_arguments.religo

@@ -0,0 +1,2 @@
+let div = (a, b : nat * nat) : option (nat) =>
+  if (b == 0n) { None; } else { Some (a/b); }