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Allow assigning nil to any pointer

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This commit is contained in:
Eugen Wissner 2025-02-04 13:28:09 +01:00
parent aab16e4941
commit 8abeff0095
Signed by: belka
GPG Key ID: A27FDC1E8EE902C0
2 changed files with 12 additions and 87 deletions
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82
README.md
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@ -19,83 +19,5 @@ and a possbility to compile Elna programs for different platforms.
## Grammar
```ebnf
digit = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9";
letter = "A" | "B" | … | "Z" | "a" | "b" | … | "z";
ident = letter { letter | digit | "_" };
integer = digit { digit };
float = integer "." integer;
boolean = "true" | "false";
literal = integer | float | boolean | "'" character "'" | """ { character } """;
program = [ "type" type_definitions ";" ]
[ constant_part ]
{ procedure_definition }
[ variable_part ]
"begin" [ statement_list ] "end" ".";
procedure_definition = "proc" ident formal_parameter_list ";" ( block | "extern" ) ";";
block = [ constant_part ]
[ variable_part ]
statement;
constant_part = "const" ident "=" integer { "," ident "=" integer } ";";
variable_part = "var" variable_declarations ";";
statement = ident ":=" expression
| ident actual_parameter_list
| while_do
| if_then_else;
while_do = "while" condition "do" [ statement_list ] "end";
if_then_else = "if" expression
"then" [ statement_list ]
[ else statement_list ] "end";
statement_list = statement {";" statement };
condition = "odd" expression |
expression ("="|"#"|"<"|"<="|">"|">=") expression;
comparison_operator = "=", "<>", "<", ">", "<=", ">=";
unary_prefix = "not", "@";
expression = logical_operand { ("and" | "or") logical_operand };
logical_operand = comparand { comparison_operator comparand };
comparand = summand { ("+" | "-") summand };
summand = factor { ("*" | "/") factor };
factor = pointer { unary_prefix pointer };
pointer = literal
| designator_expression { $$ = $1; }
| "(" expression ")";
designator_expression = designator_expression "[" expression "]"
| designator_expression "." ident
| designator_expression "^"
| ident;
formal_parameter_list = "(" [ variable_declarations ] ")";
actual_parameter_list = "(" [ expressions ] ")";
expressions = expression { "," expression };
variable_declarations = variable_declaration { ";" variable_declaration };
variable_declaration = ident ":" type_expression;
type_expression = "array" integer "of" type_expression
| "pointer" "to" type_expression
| "record" field_list "end"
| "union" field_list "end"
| ident;
field_list = field_declaration { ";" field_declaration };
field_declaration = ident ":" type_expression;
```
Flex and bison grammar specifications, `lexer.ll` and `parser.yy`, can be found
in the `boot/` directory.

17
gcc/elna-generic.cc
View File

@ -699,20 +699,23 @@ namespace gcc
this->current_expression = error_mark_node;
return;
}
if (TREE_TYPE(this->current_expression) != TREE_TYPE(lvalue))
if (TREE_TYPE(this->current_expression) == TREE_TYPE(lvalue)
|| (is_pointer_type(TREE_TYPE(lvalue)) && this->current_expression == null_pointer_node))
{
tree assignment = build2_loc(statement_location, MODIFY_EXPR,
void_type_node, lvalue, this->current_expression);
append_to_statement_list(assignment, &this->current_statements);
this->current_expression = NULL_TREE;
}
else
{
error_at(statement_location,
"cannot assign value of type %s to variable of type %s",
print_type(TREE_TYPE(this->current_expression)),
print_type(TREE_TYPE(lvalue)));
this->current_expression = error_mark_node;
return;
}
auto assignment = build2_loc(statement_location, MODIFY_EXPR,
void_type_node, lvalue, this->current_expression);
append_to_statement_list(assignment, &this->current_statements);
this->current_expression = NULL_TREE;
}
void generic_visitor::visit(boot::if_statement *statement)