Implement noreturn procedure declarations

boot/ast.cc

@@ -419,7 +419,13 @@ namespace boot
 
     procedure_definition::procedure_definition(const struct position position, const std::string& identifier,
             const bool exported, std::shared_ptr<top_type> return_type)
-        : definition(position, identifier, exported), m_return_type(return_type)
+        : definition(position, identifier, exported), m_return_type(return_type), no_return{ false }
+    {
+    }
+
+    procedure_definition::procedure_definition(const struct position position, const std::string& identifier,
+            const bool exported, no_return_t)
+        : definition(position, identifier, exported), m_return_type(nullptr), no_return{ true }
     {
     }
 

boot/lexer.ll

@@ -280,6 +280,9 @@ defer                   {
 @                       {
                             return yy::parser::make_AT(this->location);
                         }
+!                       {
+                            return yy::parser::make_EXCLAMATION(this->location);
+                        }
 .                       {
                             std::stringstream ss;
 

boot/parser.yy

@@ -85,13 +85,12 @@ along with GCC; see the file COPYING3.  If not see
 %token CONST VAR PROCEDURE TYPE RECORD UNION
 %token BEGIN_BLOCK END_BLOCK EXTERN DEFER
 %token LEFT_PAREN RIGHT_PAREN LEFT_SQUARE RIGHT_SQUARE SEMICOLON DOT COMMA
-%token AND OR NOT CAST SHIFT_LEFT SHIFT_RIGHT
+%token NOT CAST EXCLAMATION
-%token GREATER_EQUAL LESS_EQUAL LESS_THAN GREATER_THAN NOT_EQUAL EQUALS
-%token PLUS MINUS MULTIPLICATION DIVISION REMAINDER
 %token ASSIGNMENT COLON HAT AT NIL ARROW
 
 %left OR AND XOR
 %left EQUALS NOT_EQUAL LESS_THAN GREATER_THAN LESS_EQUAL GREATER_EQUAL
+%left SHIFT_LEFT SHIFT_RIGHT
 %left PLUS MINUS
 %left MULTIPLICATION DIVISION REMAINDER
 
@@ -169,6 +168,12 @@ procedure_heading:
                  $2.first, $2.second);
             std::swap($3, $$->parameters);
         }
+    | PROCEDURE identifier_definition formal_parameter_list ARROW EXCLAMATION SEMICOLON
+        {
+            $$ = new elna::boot::procedure_definition(elna::boot::make_position(@1),
+                 $2.first, $2.second, elna::boot::procedure_definition::no_return_t{});
+            std::swap($3, $$->parameters);
+        }
     | PROCEDURE identifier_definition formal_parameter_list ARROW type_expression SEMICOLON
         {
             $$ = new elna::boot::procedure_definition(elna::boot::make_position(@1),

gcc/elna-generic.cc

@@ -256,6 +256,10 @@ namespace gcc
         tree fndecl = build_fn_decl(definition->identifier.c_str(), declaration_type);
         this->symbol_map->enter(definition->identifier, fndecl);
 
+        if (definition->no_return)
+        {
+            TREE_THIS_VOLATILE(fndecl) = 1;
+        }
         if (definition->body() != nullptr)
         {
             tree resdecl = build_decl(UNKNOWN_LOCATION, RESULT_DECL, NULL_TREE, return_type);

include/elna/boot/ast.h

@@ -366,10 +366,16 @@ namespace boot
         block *m_body{ nullptr };
 
     public:
+        struct no_return_t
+        {
+        };
+        const bool no_return{ false };
         std::vector<variable_declaration *> parameters;
 
         procedure_definition(const struct position position, const std::string& identifier,
                 const bool exported, std::shared_ptr<top_type> return_type = nullptr);
+        procedure_definition(const struct position position, const std::string& identifier,
+                const bool exported, no_return_t);
         virtual void accept(parser_visitor *visitor) override;
 
         std::shared_ptr<top_type> return_type();

source.elna

@@ -60,6 +60,7 @@ const
   TOKEN_CHARACTER* = 55
   TOKEN_STRING* = 56
   TOKEN_DEFER* = 57
+  TOKEN_EXCLAMATION* = 58
 
 type
   Position* = record
@@ -134,7 +135,7 @@ proc strlen(ptr: ^Char) -> Word; extern
 proc strtol(nptr: ^Char, endptr: ^^Char, base: Int) -> Int; extern
 
 proc perror(s: ^Char); extern
-proc exit(code: Int); extern
+proc exit(code: Int) -> !; extern
 
 (*
   Standard procedures.
@@ -567,6 +568,8 @@ begin
 	  write_s("\"...\"")
 	elsif current_token^.kind = TOKEN_DEFER then
 	  write_s("DEFER")
+	elsif current_token^.kind = TOKEN_EXCLAMATION then
+	  write_c('!')
 	else
 	  write_s("UNKNOWN<")
 	  write_i(current_token^.kind)
@@ -800,6 +803,9 @@ begin
 	elsif first_char = '@' then
 	  current_token^.kind := TOKEN_AT
 	  source_code := advance_source(source_code, 1u)
+	elsif first_char = '!' then
+	  current_token^.kind := TOKEN_EXCLAMATION
+	  source_code := advance_source(source_code, 1u)
 	else
 	  current_token^.kind := 0
 	  source_code := advance_source(source_code, 1u)
@@ -818,11 +824,6 @@ begin
   return tokens
 end
 
-proc parse_literal(tokens: ^^Token, tokens_size: ^Word) -> ^Literal;
-begin
-  return cast(calloc(1u, Literal.size): ^Literal)
-end
-
 proc parse_constant_definition(tokens: ^^Token,
     tokens_size: ^Word) -> ^ConstantDefinition;
 var
@@ -839,8 +840,6 @@ begin
   write_z(result^.name)
   write_c('\n')
 
-  result^.body := parse_literal(tokens, tokens_size)
-
   tokens^ := tokens^ + 2u
   tokens_size := tokens_size - 2u