Make goto-cc fail when warnings are emitted and -Werror and -Wextra are set

For goto-cl, goto-armcc, etc the equivalent options enable fail-on-warnings
mode. Do not fail with -Werror -Wall (but not -Wextra) as that breaks too
many builds as we don't have an equivalent of -Wno-...

Author: tautschnig

src/goto-cc/armcc_mode.cpp

@@ -46,7 +46,7 @@ int armcc_modet::doit()
 
   unsigned int verbosity=1;
 
-  compilet compiler(cmdline);
+  compilet compiler(cmdline, cmdline.isset("diag_error="));
 
   #if 0
   bool act_as_ld=

src/goto-cc/as_mode.cpp

@@ -159,7 +159,7 @@ int as_modet::doit()
   config.set(cmdline);
 
   // determine actions to be undertaken
-  compilet compiler(cmdline);
+  compilet compiler(cmdline, cmdline.isset("fatal-warnings"));
   compiler.ui_message_handler.set_verbosity(verbosity);
 
   if(cmdline.isset('b')) // as86 only

src/goto-cc/compile.cpp

@@ -121,6 +121,9 @@ bool compilet::doit()
     return true;
   }
 
+  const unsigned warnings_before=
+    get_message_handler().get_message_count(messaget::M_WARNING);
+
   if(source_files.size()>0)
     if(compile())
       return true;
@@ -133,7 +136,10 @@ bool compilet::doit()
       return true;
   }
 
-  return false;
+  return
+    warning_is_fatal &&
+    get_message_handler().get_message_count(messaget::M_WARNING)!=
+    warnings_before;
 }
 
 /*******************************************************************\
@@ -156,8 +162,8 @@ bool compilet::add_input_file(const std::string &file_name)
     std::ifstream in(file_name);
     if(!in)
     {
-      error() << "failed to open file `" << file_name << "'" << eom;
-      return false; // generously ignore
+      warning() << "failed to open file `" << file_name << "'" << eom;
+      return warning_is_fatal; // generously ignore unless -Werror
     }
   }
 
@@ -168,7 +174,7 @@ bool compilet::add_input_file(const std::string &file_name)
     // a file without extension; will ignore
     warning() << "input file `" << file_name
               << "' has no extension, not considered" << eom;
-    return false;
+    return warning_is_fatal;
   }
 
   std::string ext = file_name.substr(r+1, file_name.length());
@@ -329,7 +335,7 @@ bool compilet::find_library(const std::string &name)
       else if(is_elf_file(libname))
       {
         warning() << "Warning: Cannot read ELF library " << libname << eom;
-        return false;
+        return warning_is_fatal;
       }
     }
   }
@@ -752,11 +758,12 @@ Function: compilet::compilet
 
 \*******************************************************************/
 
-compilet::compilet(cmdlinet &_cmdline):
+compilet::compilet(cmdlinet &_cmdline, bool Werror):
   language_uit(_cmdline, ui_message_handler),
   ui_message_handler(_cmdline, "goto-cc " CBMC_VERSION),
   ns(symbol_table),
-  cmdline(_cmdline)
+  cmdline(_cmdline),
+  warning_is_fatal(Werror)
 {
   mode=COMPILE_LINK_EXECUTABLE;
   echo_file_name=false;

src/goto-cc/compile.h

@@ -45,7 +45,7 @@ class compilet:public language_uit
   std::string object_file_extension;
   std::string output_file_object, output_file_executable;
 
-  explicit compilet(cmdlinet &_cmdline);
+  compilet(cmdlinet &_cmdline, bool Werror);
 
   ~compilet();
 
@@ -72,6 +72,7 @@ class compilet:public language_uit
 
 protected:
   cmdlinet &cmdline;
+  bool warning_is_fatal;
 
   unsigned function_body_count(const goto_functionst &);
 

src/goto-cc/cw_mode.cpp

@@ -46,7 +46,7 @@ int cw_modet::doit()
 
   unsigned int verbosity=1;
 
-  compilet compiler(cmdline);
+  compilet compiler(cmdline, cmdline.isset("Werror"));
 
   #if 0
   bool act_as_ld=

src/goto-cc/gcc_mode.cpp

@@ -218,7 +218,7 @@ int gcc_modet::doit()
     return EX_OK;
   }
 
-  if(cmdline.isset("Wall"))
+  if(cmdline.isset("Wall") || cmdline.isset("Wextra"))
     verbosity=2;
 
   if(cmdline.isset("verbosity"))
@@ -303,7 +303,10 @@ int gcc_modet::doit()
     config.ansi_c.double_width=config.ansi_c.single_width;
 
   // determine actions to be undertaken
-  compilet compiler(cmdline);
+  compilet compiler(cmdline,
+                    cmdline.isset("Werror") &&
+                    cmdline.isset("Wextra") &&
+                    !cmdline.isset("Wno-error"));
   compiler.set_message_handler(get_message_handler());
 
   if(act_as_ld)

src/goto-cc/ms_cl_mode.cpp

@@ -59,7 +59,7 @@ int ms_cl_modet::doit()
 
   unsigned int verbosity=1;
 
-  compilet compiler(cmdline);
+  compilet compiler(cmdline, cmdline.isset("WX"));
 
   #if 0
   bool act_as_ld=