Merge pull request #239 from CatalaLang/fix_237

Nice error messages for empty structs and enums

compiler/surface/name_resolution.ml

@@ -377,6 +377,12 @@ let process_struct_decl (ctxt : context) (sdecl : Ast.struct_decl) : context =
   let s_uid =
     Desugared.Ast.IdentMap.find (fst sdecl.struct_decl_name) ctxt.struct_idmap
   in
+  if List.length sdecl.struct_decl_fields = 0 then
+    Errors.raise_spanned_error
+      (Pos.get_position sdecl.struct_decl_name)
+      "The struct %s does not have any fields; give it some for Catala to be \
+       able to accept it."
+      (Pos.unmark sdecl.struct_decl_name);
   List.fold_left
     (fun ctxt (fdecl, _) ->
       let f_uid =
@@ -420,6 +426,12 @@ let process_enum_decl (ctxt : context) (edecl : Ast.enum_decl) : context =
   let e_uid =
     Desugared.Ast.IdentMap.find (fst edecl.enum_decl_name) ctxt.enum_idmap
   in
+  if List.length edecl.enum_decl_cases = 0 then
+    Errors.raise_spanned_error
+      (Pos.get_position edecl.enum_decl_name)
+      "The enum %s does not have any cases; give it some for Catala to be able \
+       to accept it."
+      (Pos.unmark edecl.enum_decl_name);
   List.fold_left
     (fun ctxt (cdecl, cdecl_pos) ->
       let c_uid =

compiler/surface/parser.messages

@@ -2,8 +2,7 @@ source_file: BEGIN_CODE DECLARATION ENUM CONSTRUCTOR COLON ALT CONSTRUCTOR CONTE
 ##
 ## Ends in an error in state: 358.
 ##
-## nonempty_list(enum_decl_line) -> enum_decl_line . [ SCOPE END_CODE DECLARATION ]
+## list(enum_decl_line) -> enum_decl_line . list(enum_decl_line) [ SCOPE END_CODE DECLARATION ]
-## nonempty_list(enum_decl_line) -> enum_decl_line . nonempty_list(enum_decl_line) [ SCOPE END_CODE DECLARATION ]
 ##
 ## The known suffix of the stack is as follows:
 ## enum_decl_line
@@ -51,7 +50,7 @@ source_file: BEGIN_CODE DECLARATION ENUM CONSTRUCTOR COLON YEAR
 ##
 ## Ends in an error in state: 350.
 ##
-## code_item -> DECLARATION ENUM constructor COLON . nonempty_list(enum_decl_line) [ SCOPE END_CODE DECLARATION ]
+## code_item -> DECLARATION ENUM constructor COLON . list(enum_decl_line) [ SCOPE END_CODE DECLARATION ]
 ##
 ## The known suffix of the stack is as follows:
 ## DECLARATION ENUM constructor COLON
@@ -63,7 +62,7 @@ source_file: BEGIN_CODE DECLARATION ENUM CONSTRUCTOR YEAR
 ##
 ## Ends in an error in state: 349.
 ##
-## code_item -> DECLARATION ENUM constructor . COLON nonempty_list(enum_decl_line) [ SCOPE END_CODE DECLARATION ]
+## code_item -> DECLARATION ENUM constructor . COLON list(enum_decl_line) [ SCOPE END_CODE DECLARATION ]
 ##
 ## The known suffix of the stack is as follows:
 ## DECLARATION ENUM constructor
@@ -75,7 +74,7 @@ source_file: BEGIN_CODE DECLARATION ENUM YEAR
 ##
 ## Ends in an error in state: 348.
 ##
-## code_item -> DECLARATION ENUM . constructor COLON nonempty_list(enum_decl_line) [ SCOPE END_CODE DECLARATION ]
+## code_item -> DECLARATION ENUM . constructor COLON list(enum_decl_line) [ SCOPE END_CODE DECLARATION ]
 ##
 ## The known suffix of the stack is as follows:
 ## DECLARATION ENUM
@@ -264,7 +263,7 @@ source_file: BEGIN_CODE DECLARATION YEAR
 ##
 ## code_item -> DECLARATION . STRUCT constructor COLON list(struct_scope) [ SCOPE END_CODE DECLARATION ]
 ## code_item -> DECLARATION . SCOPE constructor COLON nonempty_list(scope_decl_item) [ SCOPE END_CODE DECLARATION ]
-## code_item -> DECLARATION . ENUM constructor COLON nonempty_list(enum_decl_line) [ SCOPE END_CODE DECLARATION ]
+## code_item -> DECLARATION . ENUM constructor COLON list(enum_decl_line) [ SCOPE END_CODE DECLARATION ]
 ##
 ## The known suffix of the stack is as follows:
 ## DECLARATION

compiler/surface/parser.mly

@@ -617,7 +617,7 @@ code_item:
     scope_decl_context = context;
   }, Pos.from_lpos $sloc)
 }
-| DECLARATION ENUM c = constructor COLON cases = nonempty_list(enum_decl_line) {
+| DECLARATION ENUM c = constructor COLON cases = list(enum_decl_line) {
   (EnumDecl {
     enum_decl_name = c;
     enum_decl_cases = cases;

tests/test_enum/bad/empty.catala_en

@@ -0,0 +1,8 @@
+## Test
+
+```catala
+declaration enumeration Foo:
+
+declaration scope Bar:
+  internal foo content Foo
+```

tests/test_enum/bad/output/empty.catala_en.Typecheck

@@ -0,0 +1,7 @@
+[ERROR] The enum Foo does not have any cases; give it some for Catala to be able to accept it.
+
+ --> tests/test_enum/bad/empty.catala_en
+  |
+4 | declaration enumeration Foo:
+  |                         ^^^
+  + Test

tests/test_struct/bad/empty_struct.catala_en

@@ -0,0 +1,8 @@
+## Test
+
+```catala
+declaration structure Foo:
+
+declaration scope Bar:
+  internal foo content Foo
+```

tests/test_struct/bad/output/empty_struct.catala_en.Typecheck

@@ -0,0 +1,7 @@
+[ERROR] The struct Foo does not have any fields; give it some for Catala to be able to accept it.
+
+ --> tests/test_struct/bad/empty_struct.catala_en
+  |
+4 | declaration structure Foo:
+  |                       ^^^
+  + Test