fix #642, complain when -bs-main have an empty queue

jscomp/common/bs_exception.ml

@@ -28,6 +28,8 @@ type error =
   | Bs_cyclic_depends of string  list
   | Bs_duplicated_module of string * string
   | Bs_package_not_found of string                            
+  | Bs_main_not_exist of string 
+
 exception Error of error
 
 let error err = raise (Error err)
@@ -44,6 +46,10 @@ let report_error ppf = function
   | Bs_duplicated_module (a,b)
     ->
     Format.fprintf ppf "The build system does not support two files with same names yet %s, %s" a b
+  | Bs_main_not_exist main
+    ->
+    Format.fprintf ppf "File %s not found " main
+
   | Bs_package_not_found package
     ->
     Format.fprintf ppf "Pacage %s not found or %s/lib/ocaml does not exist"

jscomp/common/bs_exception.mli

@@ -27,4 +27,6 @@ type error =
   | Bs_cyclic_depends of string  list
   | Bs_duplicated_module of string * string
   | Bs_package_not_found of string                                                        
+  | Bs_main_not_exist of string 
+
 val error : error -> 'a 

jscomp/ocaml_batch_compile.ml

@@ -67,6 +67,9 @@ let batch_compile ppf files main_file =
         Ocaml_parse.lazy_parse_implementation
         Ocaml_parse.lazy_parse_interface         
         main_file in
+    if Queue.is_empty result then 
+      Bs_exception.error (Bs_main_not_exist main_file)
+    ;
     process_result ppf main_file ast_table result     
   else 0
 

jscomp/runtime/Makefile

@@ -32,7 +32,7 @@ else
 BS_FLAGS=  $(BS_COMMON_FLAGS) -bs-package-output lib/js 
 endif
 
-COMPFLAGS += $(BS_FLAGS) -I ../stdlib -nostdlib -nopervasives -open Pervasives -unsafe -w -40
+COMPFLAGS += $(BS_FLAGS) -I ../stdlib -nostdlib -nopervasives -open Pervasives -unsafe -w -40-49