Make linker-script processing failures non-fatal

The current parsing code is not yet tested on a sufficient variety of scripts.
Failing to process linker scripts is as good as the previous state where they
had been ignored completely.

Author: tautschnig

src/goto-cc/gcc_mode.cpp

@@ -935,12 +935,7 @@ int gcc_modet::gcc_hybrid_binary(compilet &compiler)
   {
     linker_script_merget ls_merge(
         compiler, output_files, goto_binaries, cmdline, gcc_message_handler);
-    const int fail=ls_merge.add_linker_script_definitions();
-    if(fail!=0)
-    {
-      error() << "Unable to merge linker script symbols" << eom;
-      return fail;
-    }
+    result=ls_merge.add_linker_script_definitions();
   }
 
   // merge output from gcc with goto-binaries

src/goto-cc/linker_script_merge.cpp

@@ -38,12 +38,25 @@ int linker_script_merget::add_linker_script_definitions()
   const std::string &elf_file=*elf_binaries.begin();
   const std::string &goto_file=*goto_binaries.begin();
 
-  jsont data;
+  temporary_filet linker_def_outfile("goto-cc-linker-info", ".json");
   std::list<irep_idt> linker_defined_symbols;
-  int fail=get_linker_script_data(
-      data, linker_defined_symbols, compiler.symbol_table, elf_file);
+  int fail=
+    get_linker_script_data(
+      linker_defined_symbols,
+      compiler.symbol_table,
+      elf_file,
+      linker_def_outfile());
+  // ignore linker script parsing failures until the code is tested more widely
+  if(fail!=0)
+    return 0;
+
+  jsont data;
+  fail=parse_json(linker_def_outfile(), get_message_handler(), data);
   if(fail!=0)
+  {
+    error() << "Problem parsing linker script JSON data" << eom;
     return fail;
+  }
 
   fail=linker_data_is_malformed(data);
   if(fail!=0)
@@ -625,23 +638,24 @@ int linker_script_merget::ls_data2instructions(
 #endif
 
 int linker_script_merget::get_linker_script_data(
-    jsont &linker_data,
     std::list<irep_idt> &linker_defined_symbols,
     const symbol_tablet &symbol_table,
-    const std::string &out_file)
+    const std::string &out_file,
+    const std::string &def_out_file)
 {
   for(auto const &pair : symbol_table.symbols)
-    if(pair.second.is_extern && pair.second.value.is_nil()
-    && pair.second.name!="__CPROVER_memory")
+    if(pair.second.is_extern && pair.second.value.is_nil() &&
+       pair.second.name!="__CPROVER_memory")
       linker_defined_symbols.push_back(pair.second.name);
 
   std::ostringstream linker_def_str;
-  std::copy(linker_defined_symbols.begin(), linker_defined_symbols.end(),
-      std::ostream_iterator<irep_idt>(linker_def_str, "\n"));
+  std::copy(
+    linker_defined_symbols.begin(),
+    linker_defined_symbols.end(),
+    std::ostream_iterator<irep_idt>(linker_def_str, "\n"));
   debug() << "Linker-defined symbols: [" << linker_def_str.str() << "]\n"
           << eom;
 
-  temporary_filet linker_def_outfile("goto-cc-linker-info", ".json");
   temporary_filet linker_def_infile("goto-cc-linker-defs", "");
   std::ofstream linker_def_file(linker_def_infile());
   linker_def_file << linker_def_str.str();
@@ -653,29 +667,24 @@ int linker_script_merget::get_linker_script_data(
     "--script",   cmdline.get_value('T'),
     "--object",   out_file,
     "--sym-file", linker_def_infile(),
-    "--out-file", linker_def_outfile()
+    "--out-file", def_out_file
   };
-  if(cmdline.isset("verbosity"))
-  {
-    unsigned verb=safe_string2unsigned(cmdline.get_value("verbosity"));
-    if(verb>9)
-      argv.push_back("--very-verbose");
-    else if(verb>4)
-      argv.push_back("--verbose");
-  }
 
-  int rc=run(argv[0], argv, linker_def_infile(), linker_def_outfile());
+  if(get_message_handler().get_verbosity()>9)
+    argv.push_back("--very-verbose");
+  else if(get_message_handler().get_verbosity()>4)
+    argv.push_back("--verbose");
+
+  debug() << "RUN:";
+  for(std::size_t i=0; i<argv.size(); i++)
+    debug() << " " << argv[i];
+  debug() << eom;
+
+  int rc=run(argv[0], argv, linker_def_infile(), def_out_file);
   if(rc!=0)
-  {
-    error() << "Problem parsing linker script" << eom;
-    return rc;
-  }
+    warning() << "Problem parsing linker script" << eom;
 
-  int fail=parse_json(linker_def_outfile(), get_message_handler(),
-      linker_data);
-  if(fail!=0)
-    error() << "Problem parsing linker script JSON data" << eom;
-  return fail;
+  return rc;
 }
 
 int linker_script_merget::goto_and_object_mismatch(

src/goto-cc/linker_script_merge.h

@@ -105,10 +105,10 @@ class linker_script_merget:public messaget
 
   /// \brief Write linker script definitions to `linker_data`.
   int get_linker_script_data(
-      jsont &linker_data,
       std::list<irep_idt> &linker_defined_symbols,
       const symbol_tablet &symbol_table,
-      const std::string &out_file);
+      const std::string &out_file,
+      const std::string &def_out_file);
 
   /// \brief Write a list of definitions derived from `data` into gp's
   ///        `instructions` member.