Correcting replace_string_methods to not overwrite the map we iterate on

The previous implementation was writing in the map while iterating on
it which could cause some bugs. The new implementation does this in
two steps to avoid the problem.

Author: romainbrenguier

src/java_bytecode/java_bytecode_language.cpp

@@ -812,17 +812,24 @@ Function: java_bytecode_languaget::replace_string_methods
 void java_bytecode_languaget::replace_string_methods(
   symbol_tablet &context)
 {
-  for(auto &id_symbol_pair : context.symbols)
+  // Symbols that have code type are potentialy to be replaced
+  std::list<symbolt> code_symbols;
+  forall_symbols(symbol, context.symbols)
   {
-    const irep_idt &id=id_symbol_pair.first;
-    symbolt &symbol=id_symbol_pair.second;
-    if(symbol.type.id()==ID_code)
+    if(symbol->second.type.id()==ID_code)
+      code_symbols.push_back(symbol->second);
+  }
+
+  for(const auto &symbol : code_symbols)
+  {
+    const irep_idt &id=symbol.name;
+    exprt generated_code=string_preprocess.code_for_function(
+      id, to_code_type(symbol.type), symbol.location, context);
+    if(generated_code.is_not_nil())
     {
-      exprt generated_code=string_preprocess.code_for_function(
-         id, to_code_type(symbol.type), symbol.location, context);
-      if(generated_code.is_not_nil())
-        // Replace body of the function by code generated by string preprocess
-        symbol.value=generated_code;
+      // Replace body of the function by code generated by string preprocess
+      symbolt &symbol=context.lookup(id);
+      symbol.value=generated_code;
     }
   }
 }