refactor how error output is created and only print input and parsed line if they differ in text

src/error.cpp

@@ -121,16 +121,9 @@ void Error::all(const std::string &file, int line, int failed, const std::string
   std::string lastcmd = "(unknown)";
   std::string mesg = "ERROR: " + str + fmt::format(" ({}:{})\n",  truncpath(file), line);
 
-  if (input && input->line) lastcmd = input->line;
+  // add text about the input following the error message
 
-  if (failed > NOLASTLINE) {
-    try {
-      mesg += fmt::format("Last input line: {}\n", lastcmd);
-      if (failed > NOPOINTER) mesg += utils::point_to_error(input, failed);
-    } catch (fmt::format_error &) {
-      ; // do nothing
-    }
-  }
+  if (failed > NOLASTLINE) mesg += utils::point_to_error(input, failed);
   if (comm->me == 0) utils::logmesg(lmp,mesg);
 
   // allow commands if an exception was caught in a run
@@ -153,23 +146,11 @@ void Error::all(const std::string &file, int line, int failed, const std::string
 
 void Error::one(const std::string &file, int line, int failed, const std::string &str)
 {
-  int me;
   std::string lastcmd = "(unknown)";
-  MPI_Comm_rank(world,&me);
 
-  if (input && input->line) lastcmd = input->line;
-  std::string mesg;
-  try {
-    if (failed == NOLASTLINE) {
-      mesg = fmt::format("ERROR on proc {}: {} ({}:{})\n", me, str, truncpath(file), line);
-    } else {
-      mesg = fmt::format("ERROR on proc {}: {} ({}:{})\nLast input line: {}\n",
-                         me, str, truncpath(file), line, lastcmd);
-    }
+  std::string mesg = fmt::format("ERROR on proc {}: {} ({}:{})\n", comm->me, str,
+                                 truncpath(file), line);
   if (failed > NOPOINTER) mesg += utils::point_to_error(input, failed);
-  } catch (fmt::format_error &) {
-    ; // do nothing
-  }
   utils::logmesg(lmp,mesg);
 
   if (universe->nworlds > 1)

src/fix_ave_time.cpp

@@ -1075,7 +1075,7 @@ void FixAveTime::options(int iarg, int narg, char **arg)
       if (iarg+2 > narg) utils::missing_cmd_args(FLERR, "fix ave/time mode", error);
       if (strcmp(arg[iarg+1],"scalar") == 0) mode = SCALAR;
       else if (strcmp(arg[iarg+1],"vector") == 0) mode = VECTOR;
-      else error->all(FLERR,"Unknown fix ave/time mode {}", arg[iarg+1]);
+      else error->all(FLERR,iarg+1,"Unknown fix ave/time mode {}", arg[iarg+1]);
       iarg += 2;
     } else if (strcmp(arg[iarg],"off") == 0) {
       if (iarg+2 > narg) utils::missing_cmd_args(FLERR, "fix ave/time off", error);

src/input.h

@@ -26,6 +26,7 @@ class Input : protected Pointers {
   friend class Error;
   friend class Deprecated;
   friend class SimpleCommandsTest_Echo_Test;
+  friend std::string utils::point_to_error(Input *input, int failed);
 
  public:
   char *command;               // ptr to current command

src/utils.cpp

@@ -158,39 +158,65 @@ void utils::missing_cmd_args(const std::string &file, int line, const std::strin
 std::string utils::point_to_error(Input *input, int failed)
 {
   if (input) {
-    std::string cmdline = "--> parsed line: ";
-    int indicator = cmdline.size();    // error indicator points to command by default
-    cmdline += input->command;
-    cmdline += ' ';
+    std::string lastline = input->line;
+    std::string lastargs = input->command;
+    std::string cmdline = "Last input line: ";
+
+    // extended output
+    if (failed > Error::NOPOINTER) {
+
+      // indicator points to command by default
+      int indicator = 0;
+      int quoted = 0;
+      lastargs += ' ';
 
       // assemble pre-processed command line and update error indicator position, if needed.
       for (int i = 0; i < input->narg; ++i) {
         std::string inputarg = input->arg[i];
-      if (i == failed) indicator = cmdline.size();
+        if (i == failed) indicator = lastargs.size();
 
         // argument contains whitespace. add quotes. check which type of quotes, too
         if (inputarg.find_first_of(" \t\n") != std::string::npos) {
+          if (i == failed) quoted = 2;
           if (inputarg.find_first_of('"') != std::string::npos) {
-          cmdline += "'";
-          cmdline += inputarg;
-          cmdline += "'";
+            lastargs += "'";
+            lastargs += inputarg;
+            lastargs += "'";
           } else {
-          cmdline += '"';
-          cmdline += inputarg;
-          cmdline += '"';
+            lastargs += '"';
+            lastargs += inputarg;
+            lastargs += '"';
           }
         } else
-        cmdline += inputarg;
-      cmdline += ' ';
+          lastargs += inputarg;
+        lastargs += ' ';
       }
+
+      indicator += cmdline.size();
+      // the string is unchanged by substitution (ignoring whitespace), print output only once
+      if (utils::strsame(lastline, lastargs)) {
+        cmdline += lastargs;
+      } else {
+        cmdline += lastline;
+        cmdline += '\n';
+        // must have the same number of chars as "Last input line: " used in the previous line
+        cmdline += "--> parsed line: ";
+        cmdline += lastargs;
+      }
+
       // construct and append error indicator line
       cmdline += '\n';
       cmdline += std::string(indicator, ' ');
-    cmdline += std::string(strlen(input->arg[failed]), '^');
+      cmdline += std::string(strlen(input->arg[failed]) + quoted, '^');
       cmdline += '\n';
+
+    } else {
+      cmdline += input->line;
+      cmdline += '\n';
+    }
     return cmdline;
   } else
-    return std::string("(Failed command line text not available)");
+    return std::string("(Failed input line text not available)");
 }
 
 /* specialization for the case of just a single string argument */

src/utils.h

@@ -68,7 +68,7 @@ namespace utils {
 
   void missing_cmd_args(const std::string &file, int line, const std::string &cmd, Error *error);
 
-  /*! Create string with last command after pre-processing and pointing to arg with error
+  /*! Create string with last command and optionally pointing to arg with error
    *
    * This function is a helper function for error messages.  It creates
    *