Create a new AST node for iftype clauses.

This creates a new scope with both the constraint and the body of the
iftype, but without the else clause.

src/libponyc/ast/frame.c

@@ -264,7 +264,7 @@ bool frame_push(typecheck_t* t, ast_t* ast)
           break;
         }
 
-        case TK_IFTYPE:
+        case TK_IFTYPE_CLAUSE:
         {
           AST_GET_CHILDREN(parent, l_type, r_type, body);
 

src/libponyc/ast/parser.c

@@ -738,31 +738,34 @@ DEF(ifdef);
   REORDER(0, 2, 3, 1);
   DONE();
 
-// ELSEIF [annotations] type <: type THEN seq [elseiftype | (ELSE seq)]
-DEF(elseiftype);
-  AST_NODE(TK_IFTYPE);
+// type <: type THEN seq
+DEF(iftypeclause);
+  AST_NODE(TK_IFTYPE_CLAUSE);
   SCOPE();
-  SKIP(NULL, TK_ELSEIF);
-  ANNOTATE(annotations);
   RULE("type", type);
   SKIP(NULL, TK_SUBTYPE);
   RULE("type", type);
   SKIP(NULL, TK_THEN);
   RULE("then value", seq);
+  DONE();
+
+// ELSEIF [annotations] iftypeclause [elseiftype | (ELSE seq)]
+DEF(elseiftype);
+  AST_NODE(TK_IFTYPE);
+  SKIP(NULL, TK_ELSEIF);
+  ANNOTATE(annotations);
+  SCOPE();
+  RULE("iftype clause", iftypeclause);
   OPT RULE("else clause", elseiftype, elseclause);
   DONE();
 
-// IFTYPE [annotations] type <: type THEN seq [elseiftype | (ELSE seq)] END
+// IFTYPE [annotations] iftypeclause [elseiftype | (ELSE seq)] END
 DEF(iftype);
   PRINT_INLINE();
   TOKEN(NULL, TK_IFTYPE);
-  ANNOTATE(annotations);
   SCOPE();
-  RULE("type", type);
-  SKIP(NULL, TK_SUBTYPE);
-  RULE("type", type);
-  SKIP(NULL, TK_THEN);
-  RULE("then value", seq);
+  ANNOTATE(annotations);
+  RULE("iftype clause", iftypeclause);
   OPT RULE("else clause", elseiftype, elseclause);
   TERMINATE("iftype expression", TK_END);
   DONE();

src/libponyc/ast/token.h

@@ -148,6 +148,7 @@ typedef enum token_id
   TK_IF,
   TK_IFDEF,
   TK_IFTYPE,
+  TK_IFTYPE_CLAUSE,
   TK_THEN,
   TK_ELSE,
   TK_ELSEIF,

src/libponyc/codegen/gencontrol.c

@@ -156,7 +156,8 @@ LLVMValueRef gen_if(compile_t* c, ast_t* ast)
 
 LLVMValueRef gen_iftype(compile_t* c, ast_t* ast)
 {
-  AST_GET_CHILDREN(ast, subtype, supertype, left, right);
+  AST_GET_CHILDREN(ast, left_clause, right);
+  AST_GET_CHILDREN(left_clause, subtype, supertype, left);
 
   if(is_subtype_constraint(subtype, supertype, NULL, c->opt))
     return gen_expr(c, left);

src/libponyc/expr/control.c

@@ -137,7 +137,8 @@ bool expr_if(pass_opt_t* opt, ast_t* ast)
 bool expr_iftype(pass_opt_t* opt, ast_t* ast)
 {
   pony_assert(ast_id(ast) == TK_IFTYPE);
-  AST_GET_CHILDREN(ast, sub, super, left, right);
+  AST_GET_CHILDREN(ast, left_control, right);
+  AST_GET_CHILDREN(left_control, sub, super, left);
 
   ast_t* type = NULL;
 

src/libponyc/pass/expr.c

@@ -56,8 +56,8 @@ bool is_result_needed(ast_t* ast)
 
       return is_result_needed(parent);
 
-    case TK_IFTYPE:
-      // Sub/supertype not needed, body/else needed only if parent needed.
+    case TK_IFTYPE_CLAUSE:
+      // Sub/supertype not needed, body needed only if parent needed.
       if((ast_child(parent) == ast) || (ast_childidx(parent, 1) == ast))
         return false;
 
@@ -78,6 +78,7 @@ bool is_result_needed(ast_t* ast)
       return is_result_needed(parent);
 
     case TK_CASES:
+    case TK_IFTYPE:
     case TK_TRY:
     case TK_TRY_NO_CHECK:
     case TK_RECOVER:
@@ -135,7 +136,7 @@ bool is_method_result(typecheck_t* t, ast_t* ast)
         return false;
       break;
 
-    case TK_IFTYPE:
+    case TK_IFTYPE_CLAUSE:
       // The subtype and the supertype are not the result.
       if((ast_child(parent) == ast) || (ast_childidx(parent, 1) == ast))
         return false;
@@ -154,6 +155,7 @@ bool is_method_result(typecheck_t* t, ast_t* ast)
       break;
 
     case TK_CASES:
+    case TK_IFTYPE:
     case TK_RECOVER:
       // These can be results.
       break;

src/libponyc/pass/refer.c

@@ -936,7 +936,9 @@ static bool refer_iftype(pass_opt_t* opt, ast_t* ast)
 {
   (void)opt;
   pony_assert(ast_id(ast) == TK_IFTYPE);
-  AST_GET_CHILDREN(ast, sub, super, left, right);
+
+  AST_GET_CHILDREN(ast, left_clause, right);
+  AST_GET_CHILDREN(left_clause, sub, super, left);
 
   size_t branch_count = 0;
 

src/libponyc/pass/scope.c

@@ -199,25 +199,26 @@ static ast_t* make_iftype_typeparam(pass_opt_t* opt, ast_t* subtype,
   return typeparam;
 }
 
-static ast_result_t scope_iftype(pass_opt_t* opt, ast_t* ast)
+static ast_result_t scope_iftype_clause(pass_opt_t* opt, ast_t* ast)
 {
-  AST_GET_CHILDREN(ast, subtype, supertype, then_clause);
+  pony_assert(ast_id(ast) == TK_IFTYPE_CLAUSE);
+
+  AST_GET_CHILDREN(ast, subtype, supertype, body);
 
   ast_t* typeparams = ast_from(ast, TK_TYPEPARAMS);
 
   switch(ast_id(subtype))
   {
     case TK_NOMINAL:
     {
-      ast_t* typeparam = make_iftype_typeparam(opt, subtype, supertype,
-        then_clause);
+      ast_t* typeparam = make_iftype_typeparam(opt, subtype, supertype, body);
       if(typeparam == NULL)
       {
         ast_free_unattached(typeparams);
         return AST_ERROR;
       }
 
-      if(!set_scope(opt, then_clause, ast_child(typeparam), typeparam, true))
+      if(!set_scope(opt, body, ast_child(typeparam), typeparam, true))
       {
         ast_free_unattached(typeparams);
         return AST_ERROR;
@@ -252,14 +253,14 @@ static ast_result_t scope_iftype(pass_opt_t* opt, ast_t* ast)
       while(sub_child != NULL)
       {
         ast_t* typeparam = make_iftype_typeparam(opt, sub_child, super_child,
-          then_clause);
+          body);
         if(typeparam == NULL)
         {
           ast_free_unattached(typeparams);
           return AST_ERROR;
         }
 
-        if(!set_scope(opt, then_clause, ast_child(typeparam), typeparam, true))
+        if(!set_scope(opt, body, ast_child(typeparam), typeparam, true))
         {
           ast_free_unattached(typeparams);
           return AST_ERROR;
@@ -322,8 +323,8 @@ ast_result_t pass_scope(ast_t** astp, pass_opt_t* options)
       ast_setdata(ast, ast);
       break;
 
-    case TK_IFTYPE:
-      return scope_iftype(options, ast);
+    case TK_IFTYPE_CLAUSE:
+      return scope_iftype_clause(options, ast);
 
     default: {}
   }

src/libponyc/pass/sugar.c

@@ -1267,7 +1267,7 @@ ast_result_t pass_sugar(ast_t** astp, pass_opt_t* options)
     case TK_IF:
     case TK_WHILE:
     case TK_REPEAT:           return sugar_else(ast, 2);
-    case TK_IFTYPE:           return sugar_else(ast, 3);
+    case TK_IFTYPE:           return sugar_else(ast, 1);
     case TK_TRY:              return sugar_try(ast);
     case TK_FOR:              return sugar_for(options, astp);
     case TK_WITH:             return sugar_with(options, astp);

src/libponyc/reach/reach.c

@@ -1242,7 +1242,8 @@ static void reachable_expr(reach_t* r, ast_t* ast, pass_opt_t* opt)
 
     case TK_IFTYPE:
     {
-      AST_GET_CHILDREN(ast, sub, super, left, right);
+      AST_GET_CHILDREN(ast, left_clause, right);
+      AST_GET_CHILDREN(left_clause, sub, super, left);
 
       ast_t* type = ast_type(ast);