GCC and CL message handler: print warnings as errors

We already treated warnings as errors (if requested via command-line
options), but we should also mimic the output presented by CL/GCC with
those command-line options set.

src/goto-cc/armcc_mode.cpp

@@ -49,6 +49,7 @@ int armcc_modet::doit()
     cmdline.isset("diag_warning=") ? messaget::M_WARNING : messaget::M_ERROR;
   const auto verbosity = messaget::eval_verbosity(
     cmdline.get_value("verbosity"), default_verbosity, message_handler);
+  message_handler.print_warnings_as_errors(cmdline.isset("diag_error="));
 
   messaget log{message_handler};
   log.debug() << "ARM mode" << messaget::eom;

src/goto-cc/as_mode.cpp

@@ -110,6 +110,7 @@ int as_modet::doit()
     messaget::M_WARNING : messaget::M_ERROR;
   messaget::eval_verbosity(
     cmdline.get_value("verbosity"), default_verbosity, message_handler);
+  message_handler.print_warnings_as_errors(cmdline.isset("fatal-warnings"));
 
   if(act_as_as86)
   {

src/goto-cc/cl_message_handler.cpp

@@ -25,6 +25,9 @@ void cl_message_handlert::print(
 
   std::ostringstream formatted_message;
 
+  if(level == messaget::M_WARNING && warnings_are_errors)
+    formatted_message << "error: warning treated as error\n";
+
   const irep_idt file = location.get_file();
   const std::string &line = id2string(location.get_line());
   formatted_message << file << '(' << line << "): ";

src/goto-cc/cl_message_handler.h

@@ -29,6 +29,16 @@ class cl_message_handlert : public console_message_handlert
     const source_locationt &location) override;
 
   using console_message_handlert::print;
+
+  /// With \p yes set to \c true, prefix warnings with an error message.
+  /// \param yes: Whether or not to prefix warnings.
+  void print_warnings_as_errors(bool yes)
+  {
+    warnings_are_errors = yes;
+  }
+
+private:
+  bool warnings_are_errors = false;
 };
 
 #endif // CPROVER_GOTO_CC_CL_MESSAGE_HANDLER_H

src/goto-cc/gcc_message_handler.cpp

@@ -53,8 +53,12 @@ void gcc_message_handlert::print(
       else
         out << column << ": ";
 
-      if(level == messaget::M_ERROR)
+      if(
+        level == messaget::M_ERROR ||
+        (level == messaget::M_WARNING && warnings_are_errors))
+      {
         out << string(messaget::red) << "error: ";
+      }
       else if(level == messaget::M_WARNING)
         out << string(messaget::bright_magenta) << "warning: ";
 

src/goto-cc/gcc_message_handler.h

@@ -30,7 +30,17 @@ class gcc_message_handlert : public console_message_handlert
     const std::string &message,
     const source_locationt &location) override;
 
+  /// With \p yes set to \c true, prefix warnings with "error:" instead of
+  /// "warning:".
+  /// \param yes: Whether or not to prefix warnings with "error:".
+  void print_warnings_as_errors(bool yes)
+  {
+    warnings_are_errors = yes;
+  }
+
 private:
+  bool warnings_are_errors = false;
+
   /// feed a command into a string
   std::string string(const messaget::commandt &c) const
   {

src/goto-cc/gcc_mode.cpp

@@ -315,6 +315,8 @@ int gcc_modet::doit()
     messaget::M_WARNING : messaget::M_ERROR;
   messaget::eval_verbosity(
     cmdline.get_value("verbosity"), default_verbosity, gcc_message_handler);
+  gcc_message_handler.print_warnings_as_errors(
+    cmdline.isset("Werror") && !cmdline.isset("Wno-error"));
 
   bool act_as_bcc=
     base_name=="bcc" ||

src/goto-cc/ld_mode.cpp

@@ -77,6 +77,8 @@ int ld_modet::doit()
 
   messaget::eval_verbosity(
     cmdline.get_value("verbosity"), messaget::M_ERROR, gcc_message_handler);
+  gcc_message_handler.print_warnings_as_errors(
+    cmdline.isset("fatal-warnings") && !cmdline.isset("no-fatal-warnings"));
 
   compilet compiler(
     cmdline,

src/goto-cc/ms_cl_mode.cpp

@@ -61,6 +61,7 @@ int ms_cl_modet::doit()
                                    : messaget::M_ERROR;
   const auto verbosity = messaget::eval_verbosity(
     cmdline.get_value("verbosity"), default_verbosity, message_handler);
+  message_handler.print_warnings_as_errors(cmdline.isset("WX"));
 
   ms_cl_versiont ms_cl_version;
   ms_cl_version.get("cl.exe");

src/goto-cc/ms_link_mode.cpp

@@ -35,6 +35,7 @@ int ms_link_modet::doit()
 
   messaget::eval_verbosity(
     cmdline.get_value("verbosity"), messaget::M_ERROR, message_handler);
+  message_handler.print_warnings_as_errors(cmdline.isset("WX"));
 
   compilet compiler(cmdline, message_handler, cmdline.isset("WX"));