Add loop-contract symbols into symbol table during typecheck

Author: qinheping

src/linking/remove_internal_symbols.cpp

@@ -23,6 +23,10 @@ Author: Daniel Kroening
 
 #include "static_lifetime_init.h"
 
+static std::unordered_set<irep_idt> loop_contracts_subs{
+  ID_C_spec_loop_invariant,
+  ID_C_spec_decreases};
+
 static void get_symbols(
   const namespacet &ns,
   const symbolt &in_symbol,
@@ -43,8 +47,8 @@ static void get_symbols(
 
     find_symbols_sett new_symbols;
 
-    find_type_and_expr_symbols(symbol.type, new_symbols);
-    find_type_and_expr_symbols(symbol.value, new_symbols);
+    find_type_and_expr_symbols(symbol.type, new_symbols, loop_contracts_subs);
+    find_type_and_expr_symbols(symbol.value, new_symbols, loop_contracts_subs);
 
     for(const auto &s : new_symbols)
       working_set.push_back(&ns.lookup(s));