goto-cc: also use the linker when processing multiple source files

The linker is able to do some type sanitisation across translation units, and
there is no reason behaviour should be different whether we link previously
compiled object files or a set of source files.

Author: tautschnig

regression/ansi-c/linking_conflicts1/test.desc

@@ -3,7 +3,6 @@ main.c
 other.c
 ^EXIT=(64|1)$
 ^SIGNAL=0$
-^CONVERSION ERROR$
 error: conflicting function declarations `bar'
 error: conflicting function declarations `bar2'
 --

src/goto-cc/compile.cpp

@@ -34,6 +34,7 @@ Date: June 2006
 
 #include <goto-programs/goto_convert.h>
 #include <goto-programs/goto_convert_functions.h>
+#include <goto-programs/link_goto_model.h>
 #include <goto-programs/read_goto_binary.h>
 #include <goto-programs/write_goto_binary.h>
 
@@ -359,9 +360,9 @@ bool compilet::compile()
     if(echo_file_name)
       std::cout << get_base_name(file_name, false) << '\n' << std::flush;
 
-    bool r=parse_source(file_name); // don't break the program!
+    auto file_goto_model = parse_source(file_name);
 
-    if(r)
+    if(!file_goto_model.has_value())
     {
       const std::string &debug_outfile=
         cmdline.get_value("print-rejected-preprocessed-source");
@@ -381,7 +382,7 @@ bool compilet::compile()
       // output an object file for every source file
 
       // "compile" functions
-      convert_symbols(goto_model.goto_functions);
+      convert_symbols(file_goto_model->goto_functions);
 
       std::string cfn;
 
@@ -398,13 +399,22 @@ bool compilet::compile()
       else
         cfn = output_file_object;
 
-      if(write_bin_object_file(cfn, goto_model))
+      if(write_bin_object_file(cfn, *file_goto_model))
         return true;
 
-      if(add_written_cprover_symbols(goto_model.symbol_table))
+      if(add_written_cprover_symbols(file_goto_model->symbol_table))
         return true;
-
-      goto_model.clear(); // clean symbol table for next source file.
+    }
+    else
+    {
+      try
+      {
+        link_goto_model(goto_model, *file_goto_model, get_message_handler());
+      }
+      catch(...)
+      {
+        return true;
+      }
     }
   }
 
@@ -579,30 +589,31 @@ bool compilet::write_bin_object_file(
   return false;
 }
 
-/// parses a source file
-/// \return true on error, false otherwise
-bool compilet::parse_source(const std::string &file_name)
+/// Parses and type checks a source file located at \p file_name.
+/// \return A goto model if, and only if, parsing and type checking succeeded.
+optionalt<goto_modelt> compilet::parse_source(const std::string &file_name)
 {
   language_filest language_files;
   language_files.set_message_handler(get_message_handler());
 
   if(parse(file_name, language_files))
-    return true;
+    return {};
 
   // we just typecheck one file here
-  if(language_files.typecheck(goto_model.symbol_table))
+  goto_modelt file_goto_model;
+  if(language_files.typecheck(file_goto_model.symbol_table))
   {
     error() << "CONVERSION ERROR" << eom;
-    return true;
+    return {};
   }
 
-  if(language_files.final(goto_model.symbol_table))
+  if(language_files.final(file_goto_model.symbol_table))
   {
     error() << "CONVERSION ERROR" << eom;
-    return true;
+    return {};
   }
 
-  return false;
+  return std::move(file_goto_model);
 }
 
 /// constructor

src/goto-cc/compile.h

@@ -71,7 +71,7 @@ class compilet : public messaget
   bool compile();
   bool link();
 
-  bool parse_source(const std::string &);
+  optionalt<goto_modelt> parse_source(const std::string &);
 
   bool write_bin_object_file(const std::string &, const goto_modelt &);