Fix FunC UB (#656)

* Fix UB in func

* Improve optimizing int consts and unused variables in FunC

* Bump funC version to 0.4.3

* Fix analyzing repeat loop

---------

Co-authored-by: SpyCheese <mikle98@yandex.ru>

crypto/func/abscode.cpp

@@ -179,7 +179,7 @@ void VarDescr::set_const_nan() {
 
 void VarDescr::operator|=(const VarDescr& y) {
   val &= y.val;
-  if (is_int_const() && cmp(int_const, y.int_const) != 0) {
+  if (is_int_const() && y.is_int_const() && cmp(int_const, y.int_const) != 0) {
     val &= ~_Const;
   }
   if (!(val & _Const)) {

crypto/func/analyzer.cpp

@@ -388,7 +388,7 @@ bool Op::compute_used_vars(const CodeBlob& code, bool edit) {
       for (; l_it < left.cend(); ++l_it, ++r_it) {
         if (std::find(l_it + 1, left.cend(), *l_it) == left.cend()) {
           auto p = next_var_info[*l_it];
-          new_var_info.add_var(*r_it, !p || p->is_unused());
+          new_var_info.add_var(*r_it, edit && (!p || p->is_unused()));
           new_left.push_back(*l_it);
           new_right.push_back(*r_it);
         }
@@ -500,7 +500,12 @@ bool Op::compute_used_vars(const CodeBlob& code, bool edit) {
         }
         changes = (new_var_info.size() == n);
       } while (changes <= edit);
+      assert(left.size() == 1);
+      bool last = new_var_info.count_used(left) == 0;
       new_var_info += left;
+      if (last) {
+        new_var_info[left[0]]->flags |= VarDescr::_Last;
+      }
       return set_var_info(std::move(new_var_info));
     }
     case _Again: {

crypto/func/builtins.cpp

@@ -29,8 +29,12 @@ using namespace std::literals::string_literals;
 
 int glob_func_cnt, undef_func_cnt, glob_var_cnt, const_cnt;
 std::vector<SymDef*> glob_func, glob_vars;
+std::set<std::string> prohibited_var_names;
 
 SymDef* predefine_builtin_func(std::string name, TypeExpr* func_type) {
+  if (name.back() == '_') {
+    prohibited_var_names.insert(name);
+  }
   sym_idx_t name_idx = sym::symbols.lookup(name, 1);
   if (sym::symbols.is_keyword(name_idx)) {
     std::cerr << "fatal: global function `" << name << "` already defined as a keyword" << std::endl;

crypto/func/func.h

@@ -19,6 +19,7 @@
 #pragma once
 #include <vector>
 #include <string>
+#include <set>
 #include <stack>
 #include <utility>
 #include <algorithm>
@@ -40,7 +41,7 @@ extern std::string generated_from;
 
 constexpr int optimize_depth = 20;
 
-const std::string func_version{"0.4.2"};
+const std::string func_version{"0.4.3"};
 
 enum Keyword {
   _Eof = -1,
@@ -839,6 +840,7 @@ struct SymValConst : sym::SymValBase {
 
 extern int glob_func_cnt, undef_func_cnt, glob_var_cnt;
 extern std::vector<SymDef*> glob_func, glob_vars;
+extern std::set<std::string> prohibited_var_names;
 
 /*
  * 

crypto/func/gen-abscode.cpp

@@ -205,6 +205,10 @@ int Expr::predefine_vars() {
     case _Var:
       if (!sym) {
         assert(val < 0 && here.defined());
+        if (prohibited_var_names.count(sym::symbols.get_name(~val))) {
+          throw src::ParseError{
+              here, PSTRING() << "symbol `" << sym::symbols.get_name(~val) << "` cannot be redefined as a variable"};
+        }
         sym = sym::define_symbol(~val, false, here);
         // std::cerr << "predefining variable " << sym::symbols.get_name(~val) << std::endl;
         if (!sym) {

crypto/func/parse-func.cpp

@@ -172,6 +172,10 @@ FormalArg parse_formal_arg(Lexer& lex, int fa_idx) {
     lex.expect(_Ident, "formal parameter name");
   }
   loc = lex.cur().loc;
+  if (prohibited_var_names.count(sym::symbols.get_name(lex.cur().val))) {
+    throw src::ParseError{
+        loc, PSTRING() << "symbol `" << sym::symbols.get_name(lex.cur().val) << "` cannot be redefined as a variable"};
+  }
   SymDef* new_sym_def = sym::define_symbol(lex.cur().val, true, loc);
   if (!new_sym_def) {
     lex.cur().error_at("cannot define symbol `", "`");
@@ -397,7 +401,7 @@ bool check_global_func(const Lexem& cur, sym_idx_t func_name = 0) {
     def = sym::define_global_symbol(func_name, 0, cur.loc);
     assert(def && "cannot define global function");
     ++undef_func_cnt;
-    make_new_glob_func(def, TypeExpr::new_hole());  // was: ... ::new_func()
+    make_new_glob_func(def, TypeExpr::new_func());  // was: ... ::new_func()
     return true;
   }
   SymVal* val = dynamic_cast<SymVal*>(def->value);
@@ -1369,6 +1373,10 @@ std::vector<TypeExpr*> parse_type_var_list(Lexer& lex) {
       throw src::ParseError{lex.cur().loc, "free type identifier expected"};
     }
     auto loc = lex.cur().loc;
+    if (prohibited_var_names.count(sym::symbols.get_name(lex.cur().val))) {
+      throw src::ParseError{loc, PSTRING() << "symbol `" << sym::symbols.get_name(lex.cur().val)
+                                           << "` cannot be redefined as a variable"};
+    }
     SymDef* new_sym_def = sym::define_symbol(lex.cur().val, true, loc);
     if (!new_sym_def || new_sym_def->value) {
       lex.cur().error_at("redefined type variable `", "`");

crypto/parser/symtable.cpp

@@ -32,8 +32,8 @@ int scope_level;
 
 SymTable<100003> symbols;
 
-SymDef* sym_def[symbols.hprime];
+SymDef* sym_def[symbols.hprime + 1];
-SymDef* global_sym_def[symbols.hprime];
+SymDef* global_sym_def[symbols.hprime + 1];
 std::vector<std::pair<int, SymDef>> symbol_stack;
 std::vector<src::SrcLocation> scope_opened_at;
 

crypto/parser/symtable.h

@@ -161,8 +161,8 @@ struct SymDef {
   }
 };
 
-extern SymDef* sym_def[symbols.hprime];
+extern SymDef* sym_def[symbols.hprime + 1];
-extern SymDef* global_sym_def[symbols.hprime];
+extern SymDef* global_sym_def[symbols.hprime + 1];
 extern std::vector<std::pair<int, SymDef>> symbol_stack;
 extern std::vector<src::SrcLocation> scope_opened_at;