Suppress COMBDLY when inside always_latch, bug854.

Changes

@@ -3,6 +3,11 @@ Revision history for Verilator
 The contributors that suggested a given feature are shown in [].  [by ...]
 indicates the contributor was also the author of the fix; Thanks!
 
+* Verilator 3.869 devel
+
+****  Suppress COMBDLY when inside always_latch, bug854. [Iztok Jeras]
+
+
 * Verilator 3.868 2014-12-20
 
 **    New verilator_coverage program added to replace SystemPerl's vcoverage.

src/V3Active.cpp

@@ -163,7 +163,7 @@ public:
 
 class ActiveDlyVisitor : public ActiveBaseVisitor {
 public:
-    enum CheckType { CT_SEQ, CT_COMBO, CT_INITIAL };
+    enum CheckType { CT_SEQ, CT_COMBO, CT_INITIAL, CT_LATCH };
 private:
     CheckType 	m_check;	// Combo logic or other
     AstNode*	m_alwaysp;	// Always we're under
@@ -175,6 +175,8 @@ private:
 	    UINFO(5,"    ASSIGNDLY "<<nodep<<endl);
 	    if (m_check == CT_INITIAL) {
 		nodep->v3warn(INITIALDLY,"Delayed assignments (<=) in initial or final block; suggest blocking assignments (=).");
+	    } else if (m_check == CT_LATCH) {
+		// Suppress. Shouldn't matter that the interior of the latch races 
 	    } else {
 		nodep->v3warn(COMBDLY,"Delayed assignments (<=) in non-clocked (non flop or latch) block; suggest blocking assignments (=).");
 	    }
@@ -306,7 +308,7 @@ private:
     }
 
     // METHODS
-    void visitAlways(AstNode* nodep, AstSenTree* oldsensesp) {
+    void visitAlways(AstNode* nodep, AstSenTree* oldsensesp, VAlwaysKwd kwd) {
 	// Move always to appropriate ACTIVE based on its sense list
 	if (oldsensesp
 	    && oldsensesp->sensesp()
@@ -358,7 +360,11 @@ private:
 
 	// Warn and/or convert any delayed assignments
 	if (combo && !sequent) {
-	    ActiveDlyVisitor dlyvisitor (nodep, ActiveDlyVisitor::CT_COMBO);
+	    if (kwd == VAlwaysKwd::ALWAYS_LATCH) {
+		ActiveDlyVisitor dlyvisitor (nodep, ActiveDlyVisitor::CT_LATCH);
+	    } else {
+		ActiveDlyVisitor dlyvisitor (nodep, ActiveDlyVisitor::CT_COMBO);
+	    }
 	}
 	else if (!combo && sequent) {
 	    ActiveDlyVisitor dlyvisitor (nodep, ActiveDlyVisitor::CT_SEQ);
@@ -374,13 +380,13 @@ private:
 	    nodep->unlinkFrBack()->deleteTree(); nodep=NULL;
 	    return;
 	}
-	visitAlways(nodep, nodep->sensesp());
+	visitAlways(nodep, nodep->sensesp(), nodep->keyword());
     }
     virtual void visit(AstAlwaysPublic* nodep, AstNUser*) {
 	// Move always to appropriate ACTIVE based on its sense list
 	UINFO(4,"    ALWPub   "<<nodep<<endl);
 	//if (debug()>=9) nodep->dumpTree(cout,"  Alw: ");
-	visitAlways(nodep, nodep->sensesp());
+	visitAlways(nodep, nodep->sensesp(), VAlwaysKwd::ALWAYS);
     }
     virtual void visit(AstSenGate* nodep, AstNUser*) {
 	AstSenItem* subitemp = nodep->sensesp();

test_regress/t/t_lint_latch_bad.pl

@@ -0,0 +1,29 @@
+#!/usr/bin/perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2008 by Wilson Snyder. This program is free software; you can
+# redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+
+$Self->{vlt} or $Self->skip("Verilator only test");
+
+compile (
+    v_flags2 => ["--lint-only -Wwarn-style -Wno-DECLFILENAME"],
+    fails=>1,
+    verilator_make_gcc => 0,
+    make_top_shell => 0,
+    make_main => 0,
+    expect=>
+quotemeta(
+'%Warning-COMBDLY: t/t_lint_latch_bad.v:24: Delayed assignments (<=) in non-clocked (non flop or latch) block; suggest blocking assignments (=).
+%Warning-COMBDLY: Use "/* verilator lint_off COMBDLY */" and lint_on around source to disable this message.
+%Warning-COMBDLY: *** See the manual before disabling this,
+%Warning-COMBDLY: else you may end up with different sim results.
+%Error: Exiting due to 1 warning').'.*',
+    );
+
+ok(1);
+1;
+

test_regress/t/t_lint_latch_bad.v

@@ -0,0 +1,29 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed into the Public Domain, for any use,
+// without warranty, 2010 by Wilson Snyder.
+
+module t (/*AUTOARG*/
+   // Outputs
+   bl, cl, bc, cc,
+   // Inputs
+   a
+   );
+
+   input logic a;
+   output logic bl;
+   output logic cl;
+   always_latch begin
+      bl <= a;  // No warning
+      cl = a;
+   end
+
+   output logic bc;
+   output logic	cc;
+   always_comb begin
+      bc <= a;  // Warning
+      cc = a;
+   end
+
+
+endmodule