Correct naming of unnamed generate blocks.

This patch causes unnamed generate blocks to be automatically named
using the naming scheme defined in the Verilog-2005 standard. This
is a fix for the problem discussed in pr1821610.

elaborate.cc

@@ -3553,6 +3553,17 @@ bool PGenerate::elaborate(Design*des, NetScope*container) const
 	    if (scope->parent() != container)
 		  continue;
 
+	      // If this was an unnamed generate block, replace its
+	      // temporary name with a name generated using the naming
+	      // scheme defined in the Verilog-2005 standard.
+	    const char*name = scope_name.str();
+	    if (name[0] == '$') {
+		  if (!scope->auto_name("genblk", '0', name + 4)) {
+			cerr << get_line() << ": warning: Couldn't build"
+			     << " unique name for unnamed generate block"
+			     << " - using internal name " << name << endl;
+		  }
+	    }
 	    if (debug_elaborate)
 		  cerr << get_line() << ": debug: Elaborate in "
 		       << "scope " << scope_path(scope) << endl;

net_scope.cc

@@ -90,6 +90,24 @@ NetExpr* NetScope::set_parameter(perm_string key, NetExpr*expr,
       return res;
 }
 
+bool NetScope::auto_name(const char*prefix, char pad, const char* suffix)
+{
+      char tmp[32];
+      int pad_pos = strlen(prefix);
+      int max_pos = sizeof(tmp) - strlen(suffix) - 1;
+      strncpy(tmp, prefix, sizeof(tmp));
+      while (pad_pos <= max_pos) {
+	    strcat(tmp + pad_pos, suffix);
+	    hname_t new_name(lex_strings.make(tmp));
+	    if (!up_->child(new_name)) {
+		  name_ = new_name;
+		  return true;
+	    }
+	    tmp[pad_pos++] = pad;
+      }
+      return false;
+}
+
 /*
  * Return false if this creates a new parameter.
  */

netlist.h

@@ -3189,6 +3189,12 @@ class NetScope : public Attrib {
       NetScope(NetScope*up, const hname_t&name, TYPE t);
       ~NetScope();
 
+	/* Rename the scope using the name generated by inserting as
+	   many pad characters as required between prefix and suffix
+	   to make the name unique in the parent scope. Return false
+	   if a unique name couldn't be generated. */
+      bool auto_name(const char* prefix, char pad, const char* suffix);
+
 	/* Parameters exist within a scope, and these methods allow
 	   one to manipulate the set. In these cases, the name is the
 	   *simple* name of the parameter, the hierarchy is implicit in

pform.cc

@@ -417,8 +417,11 @@ void pform_endgenerate()
       assert(pform_cur_generate != 0);
       assert(pform_cur_module);
 
-	// If there is no explicit block name, then use a default
-	// internal name.
+	// If there is no explicit block name then generate a temporary
+	// name. This will be replaced by the correct name later, once
+	// we know all the explicit names in the surrounding scope. If
+	// the naming scheme used here is changed, PGenerate::elaborate
+	// must be changed to match.
       if (pform_cur_generate->scope_name == 0) {
 	    char tmp[16];
 	    snprintf(tmp, sizeof tmp, "$gen%d", pform_cur_generate->id_number);