Fix constant function default parameters, bug1211.

Changes

@@ -14,6 +14,8 @@ The contributors that suggested a given feature are shown in []. Thanks!
 
 ****  Fix GCC noreturn compile error, bug1209. [Mike Popoloski]
 
+****  Fix constant function default parameters, bug1211. [Mike Popoloski]
+
 
 * Verilator 3.910 2017-09-07
 

src/V3Task.cpp

@@ -35,6 +35,7 @@
 #include <map>
 
 #include "V3Global.h"
+#include "V3Const.h"
 #include "V3Task.h"
 #include "V3Inst.h"
 #include "V3Ast.h"
@@ -1260,11 +1261,20 @@ V3TaskConnects V3Task::taskConnects(AstNodeFTaskRef* nodep, AstNode* taskStmtsp)
 			       <<"' in function call to "<<nodep->taskp()->prettyTypeName());
 		newvaluep = new AstConst(nodep->fileline(), AstConst::Unsized32(), 0);
 	    } else if (!portp->valuep()->castConst()) {
-		// Problem otherwise is we might have a varref, task call, or something else that only
-		// makes sense in the domain of the function, not the callee.
-		nodep->v3error("Unsupported: Non-constant default value in missing argument '"<<portp->prettyName()
-			       <<"' in function call to "<<nodep->taskp()->prettyTypeName());
-		newvaluep = new AstConst(nodep->fileline(), AstConst::Unsized32(), 0);
+		// The default value for this port might be a constant
+		// expression that hasn't been folded yet. Try folding it
+		// now; we don't have much to lose if it fails.
+		newvaluep = V3Const::constifyParamsEdit(portp->valuep());
+		if (!newvaluep->castConst()) {
+		    // Problem otherwise is we might have a varref, task call, or something else that only
+		    // makes sense in the domain of the function, not the callee.
+		    nodep->v3error("Unsupported: Non-constant default value in missing argument '"<<portp->prettyName()
+				   <<"' in function call to "<<nodep->taskp()->prettyTypeName());
+		    newvaluep = new AstConst(nodep->fileline(), AstConst::Unsized32(), 0);
+		}
+		else {
+		    newvaluep = newvaluep->cloneTree(true);
+		}
 	    } else {
 		newvaluep = portp->valuep()->cloneTree(true);
 	    }

test_regress/t/t_func_defaults.pl

@@ -0,0 +1,18 @@
+#!/usr/bin/perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2003 by Wilson Snyder. This program is free software; you can
+# redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+
+compile (
+    );
+
+execute (
+    check_finished=>1,
+    );
+
+ok(1);
+1;

test_regress/t/t_func_defaults.v

@@ -0,0 +1,33 @@
+// DESCRIPTION: Verilator: Test for warning (not error) on improperly width'ed
+// default function argument
+//
+// This file ONLY is placed into the Public Domain, for any use,
+// without warranty, 2015 by Todd Strader.
+
+parameter logic Bar = 1'b1;
+
+function automatic logic calc_y;
+   return 1'b1;
+endfunction
+
+function automatic logic [1:0] foo
+  (
+   input logic x = Bar,
+   input logic y = calc_y()
+   );
+   return x + y;
+endfunction
+
+module t (/*AUTOARG*/);
+   logic [1:0] foo_val;
+
+   initial begin
+      foo_val = foo();
+      if (foo_val != 2'b10) $stop;
+
+      $write("*-* All Finished *-*\n");
+      $finish;
+   end
+
+endmodule
+