Add compilation message to user facing FlatZinc files

changes.rst

@@ -24,7 +24,9 @@ Changes:
    previous behaviour) you can use ``--solver default``.
 -  Add the ``--fzn-format`` flag to influence whether the generated FlatZinc from
    ``--compile`` or ``--fzn`` is given in the traditional FlatZinc format or the
-   new JSON-based format.
+   new JSON-based format. (:bugref:`868`)
+-  Comments regarding the compilation invocation are now included in user-facing
+   FlatZinc (``.fzn``) files, created by the ``--compile`` or ``--fzn`` flags.
 
 Bug fixes:
 ^^^^^^^^^^

include/minizinc/flattener.hh

@@ -72,6 +72,7 @@ public:
   void setFlagOutputJSON(bool f) {
     _flags.fznFormat = f ? FlattenerFlags::FF_JSON : FlattenerFlags::FF_FZN;
   }
+  void setCmdLineStr(std::string&& cmdline) { _cmdlineStr = std::move(cmdline); }
   Env* getEnv() const {
     assert(_pEnv.get());
     return _pEnv.get();
@@ -133,6 +134,7 @@ private:
 
   std::string _stdLibDir;
   std::string _globalsDir;
+  std::string _cmdlineStr;
 
   std::string _flagOutputBase;
   std::string _flagOutputFzn;

lib/flattener.cpp

@@ -135,7 +135,9 @@ void Flattener::printHelp(ostream& os) const {
              ? "  -o <file>, --fzn <file>, --output-to-file <file>, --output-fzn-to-file <file>\n"
              : "  --fzn <file>, --output-fzn-to-file <file>\n")
      << "    Filename for generated FlatZinc output" << std::endl
-     << "  --fzn-format <fzn|json>\n    Whether the FlatZinc generated for the user is formatted traditionally or as JSON.\n    (Does not affect the FlatZinc directly passed to the solver.)"
+     << "  --fzn-format <fzn|json>\n    Whether the FlatZinc generated for the user is formatted "
+        "traditionally or as JSON.\n    (Does not affect the FlatZinc directly passed to the "
+        "solver.)"
      << std::endl
      << "  --ozn, --output-ozn-to-file <file>\n    Filename for model output specification "
         "(--ozn- "
@@ -207,13 +209,13 @@ bool Flattener::processOption(int& i, std::vector<std::string>& argv,
                            &buffer)) {
     _flagOutputFzn = FileUtils::file_path(buffer, workingDir);
   } else if (cop.getOption("--fzn-format", &buffer)) {
-	  if (buffer == "fzn") {
-			_flags.fznFormat = FlattenerFlags::FF_FZN;
-		} else if (buffer == "json") {
-			_flags.fznFormat = FlattenerFlags::FF_JSON;
-		} else {
-			return false;
-		}
+    if (buffer == "fzn") {
+      _flags.fznFormat = FlattenerFlags::FF_FZN;
+    } else if (buffer == "json") {
+      _flags.fznFormat = FlattenerFlags::FF_JSON;
+    } else {
+      return false;
+    }
   } else if (cop.getOption("--output-paths")) {
     _fopts.collectMznPaths = true;
   } else if (cop.getOption("--output-paths-to-file", &buffer)) {
@@ -995,6 +997,10 @@ void Flattener::flatten(const std::string& modelString, const std::string& model
           check_io_status(ofs.good(), " I/O error: cannot open fzn output file. ");
           switch (_flags.fznFormat) {
             case FlattenerFlags::FF_FZN: {
+              ofs << "% Generated by MiniZinc " << MZN_VERSION_MAJOR << "." << MZN_VERSION_MINOR
+                  << "." << MZN_VERSION_PATCH << std::endl;
+              ofs << "% Solver library: " << _globalsDir << std::endl;
+              ofs << "% Command line invocation: " << _cmdlineStr << std::endl << std::endl;
               Printer p(ofs, 0, true, &env->envi());
               p.print(env->flat());
             } break;

lib/solver.cpp

@@ -34,6 +34,7 @@
 #include <iomanip>
 #include <iostream>
 #include <ratio>
+#include <sstream>
 
 #ifdef HAS_OSICBC
 #include <minizinc/solvers/MIP/MIP_osicbc_solverfactory.hh>
@@ -65,13 +66,13 @@
 #ifdef HAS_HIGHS
 #include <minizinc/solvers/MIP/MIP_highs_solverfactory.hh>
 #endif
+#include <minizinc/exception.hh>
 #include <minizinc/solvers/fzn_solverfactory.hh>
 #include <minizinc/solvers/fzn_solverinstance.hh>
 #include <minizinc/solvers/mzn_solverfactory.hh>
 #include <minizinc/solvers/mzn_solverinstance.hh>
 #include <minizinc/solvers/nl/nl_solverfactory.hh>
 #include <minizinc/solvers/nl/nl_solverinstance.hh>
-#include <minizinc/exception.hh>
 
 using namespace std;
 using namespace MiniZinc;
@@ -257,7 +258,8 @@ void MznSolver::printHelp(std::ostream& os, const std::string& selectedSolver) {
      << "  --solvers\n    Print list of available solvers." << std::endl
      << "  --time-limit <ms>\n    Stop after <ms> milliseconds (includes compilation and solving)."
      << std::endl
-     << "  --solver <solver id>, --solver <solver config file>.msc, --solver default\n    Select solver to use, or explicitly specify using the default solver."
+     << "  --solver <solver id>, --solver <solver config file>.msc, --solver default\n    Select "
+        "solver to use, or explicitly specify using the default solver."
      << std::endl
      << "  --help <solver id>\n    Print help for a particular solver." << std::endl
      << "  -v, -l, --verbose\n    Print progress/log statements. Note that some solvers may log "
@@ -349,6 +351,11 @@ void add_flags(const std::string& sep, const std::vector<std::string>& in_args,
 }
 
 MznSolver::OptionStatus MznSolver::processOptions(std::vector<std::string>& argv) {
+  std::ostringstream cmdline_ss;
+  for (const auto& arg : argv) {
+    cmdline_ss << arg << " ";
+  }
+
   _executableName = argv[0];
   _executableName = _executableName.substr(_executableName.find_last_of("/\\") + 1);
   size_t lastdot = _executableName.find_last_of('.');
@@ -658,7 +665,9 @@ MznSolver::OptionStatus MznSolver::processOptions(std::vector<std::string>& argv
   if (ifMzn2Fzn()) {
     _flt.setFlagOutputByDefault(true);
     if (solver.empty()) {
-    	throw BadOption("Using the --compile (or -c) flag requires that a solver is selected explicitly using the --solver flag");
+      throw BadOption(
+          "Using the --compile (or -c) flag requires that a solver is selected explicitly using "
+          "the --solver flag");
     }
   }
 
@@ -928,6 +937,10 @@ MznSolver::OptionStatus MznSolver::processOptions(std::vector<std::string>& argv
         throw BadOption(ss.str());
       }
     }
+
+    /// Set the command line string for printing user FlatZinc
+    _flt.setCmdLineStr(std::move(cmdline_ss.str()));
+
     return OPTION_OK;
   }
   for (i = 1; i < argc; ++i) {

lib/solver_config.cpp

@@ -380,8 +380,9 @@ SolverConfig SolverConfig::load(const string& filename) {
             sc._needsPathsFile = get_bool(ai);
           } else if (ai->id() == "tags") {
             std::vector<std::string> loaded = get_string_list(ai);
-          	std::vector<std::string> tags;
-           	std::copy_if (loaded.begin(), loaded.end(), std::back_inserter(tags), [](std::string s){return s != "default";} );
+            std::vector<std::string> tags;
+            std::copy_if(loaded.begin(), loaded.end(), std::back_inserter(tags),
+                         [](std::string s) { return s != "default"; });
             sc._tags = tags;
           } else if (ai->id() == "stdFlags") {
             sc._stdFlags = get_string_list(ai);
@@ -582,8 +583,8 @@ void SolverConfigs::addConfig(const MiniZinc::SolverConfig& sc) {
   // Add default tag if the solver is marked as the overall default
   DefaultMap::const_iterator def_it = _tagDefault.find("");
   if (def_it != _tagDefault.end() && def_it->second == id) {
-		sc_tags.emplace_back("default");
-	}
+    sc_tags.emplace_back("default");
+  }
 
   for (const auto& t : sc_tags) {
     auto it = _tags.find(t);

tests/minizinc_testing/spec.py

@@ -326,7 +326,7 @@ def normalized(self):
                 count=1,
             )
             for line in fzn.split("\n")
-            if len(line.strip()) > 0
+            if len(line.strip()) > 0 and not line.strip().startswith("%")
         ]
         return "\n".join(sorted(lines))  # Sort the FlatZinc lines
 

tests/spec/unit/driver/test_model_interface_only.py

@@ -7,7 +7,7 @@
 def test_model_interface_only_1():
     assert isinstance(default_driver, Driver)
     p = subprocess.Popen(
-        [default_driver._executable, "-", "--model-interface-only", "-c"],
+        [default_driver._executable, "-", "--model-interface-only",],
         stdin=subprocess.PIPE,
         stdout=subprocess.PIPE,
         stderr=subprocess.PIPE,
@@ -31,7 +31,7 @@ def test_model_interface_only_1():
 def test_model_interface_only_2():
     assert isinstance(default_driver, Driver)
     p = subprocess.Popen(
-        [default_driver._executable, "-", "--model-interface-only", "-c"],
+        [default_driver._executable, "-", "--model-interface-only"],
         stdin=subprocess.PIPE,
         stdout=subprocess.PIPE,
         stderr=subprocess.PIPE,
@@ -53,7 +53,7 @@ def test_model_interface_only_2():
 def test_model_interface_only_3():
     assert isinstance(default_driver, Driver)
     p = subprocess.Popen(
-        [default_driver._executable, "-", "--model-interface-only", "-c"],
+        [default_driver._executable, "-", "--model-interface-only"],
         stdin=subprocess.PIPE,
         stdout=subprocess.PIPE,
         stderr=subprocess.PIPE,