Add lint check for bad delay locations.

src/V3Const.cpp

@@ -102,7 +102,7 @@ private:
     bool m_doShort;  // Remove expressions that short circuit
     bool m_doV;  // Verilog, not C++ conversion
     bool m_doGenerate;  // Postpone width checking inside generate
-    bool m_hasJumpGo;  // JumpGo under this while
+    bool m_hasJumpDelay;  // JumpGo or Delay under this while
     AstNodeModule* m_modp;  // Current module
     AstArraySel* m_selp;  // Current select
     AstNode* m_scopep;  // Current scope
@@ -2114,11 +2114,11 @@ private:
         iterateChildren(nodep);
     }
     virtual void visit(AstWhile* nodep) VL_OVERRIDE {
-        bool oldHasJumpGo = m_hasJumpGo;
+        bool oldHasJumpDelay = m_hasJumpDelay;
-        m_hasJumpGo = false;
+        m_hasJumpDelay = false;
         { iterateChildren(nodep); }
-        bool thisWhileHasJumpGo = m_hasJumpGo;
+        bool thisWhileHasJumpDelay = m_hasJumpDelay;
-        m_hasJumpGo = thisWhileHasJumpGo || oldHasJumpGo;
+        m_hasJumpDelay = thisWhileHasJumpDelay || oldHasJumpDelay;
         if (m_doNConst) {
             if (nodep->condp()->isZero()) {
                 UINFO(4, "WHILE(0) => nop " << nodep << endl);
@@ -2129,7 +2129,7 @@ private:
                 }
                 VL_DO_DANGLING(nodep->deleteTree(), nodep);
             } else if (nodep->condp()->isNeqZero()) {
-                if (!thisWhileHasJumpGo) {
+                if (!thisWhileHasJumpDelay) {
                     nodep->v3warn(INFINITELOOP, "Infinite loop (condition always true)");
                     nodep->fileline()->modifyWarnOff(V3ErrorCode::INFINITELOOP,
                                                      true);  // Complain just once
@@ -2161,9 +2161,13 @@ private:
     //-----
     // Jump elimination
 
+    virtual void visit(AstDelay* nodep) VL_OVERRIDE {
+        iterateChildren(nodep);
+        m_hasJumpDelay = true;
+    }
     virtual void visit(AstJumpGo* nodep) VL_OVERRIDE {
         iterateChildren(nodep);
-        m_hasJumpGo = true;
+        m_hasJumpDelay = true;
         if (m_doExpensive) {
             // If last statement in a jump label we have JumpLabel(...., JumpGo)
             // Often caused by "return" in a Verilog function.  The Go is pointless, remove.
@@ -2566,7 +2570,7 @@ public:
         m_doShort = true;  // Presently always done
         m_doV = false;
         m_doGenerate = false;  // Inside generate conditionals
-        m_hasJumpGo = false;
+        m_hasJumpDelay = false;
         m_warn = false;
         m_wremove = true;  // Overridden in visitors
         m_modp = NULL;

src/V3Width.cpp

@@ -189,8 +189,8 @@ private:
     bool m_paramsOnly;  // Computing parameter value; limit operation
     AstRange* m_cellRangep;  // Range for arrayed instantiations, NULL for normal instantiations
     AstNodeFTask* m_ftaskp;  // Current function/task
+    AstNodeProcedure* m_procedurep;  // Current final/always
     AstFunc* m_funcp;  // Current function
-    AstInitial* m_initialp;  // Current initial block
     AstAttrOf* m_attrp;  // Current attribute
     bool m_doGenerate;  // Do errors later inside generate statement
     int m_dtTables;  // Number of created data type tables
@@ -539,6 +539,17 @@ private:
         }
     }
     virtual void visit(AstDelay* nodep) VL_OVERRIDE {
+        if (VN_IS(m_procedurep, Final)) {
+            nodep->v3error("Delays are not legal in final blocks. IEEE 1800-2017 9.2.3");
+            VL_DO_DANGLING(pushDeletep(nodep->unlinkFrBack()), nodep);
+            return;
+        }
+        if (VN_IS(m_ftaskp, Func)) {
+            nodep->v3error("Delays are not legal in functions. Suggest use a task. "
+                           "IEEE 1800-2017 13.4.4");
+            VL_DO_DANGLING(pushDeletep(nodep->unlinkFrBack()), nodep);
+            return;
+        }
         nodep->v3warn(STMTDLY, "Unsupported: Ignoring delay on this delayed statement.");
         VL_DO_DANGLING(pushDeletep(nodep->unlinkFrBack()), nodep);
     }
@@ -1661,7 +1672,8 @@ private:
         // if (debug() >= 9) nodep->dumpTree(cout, "  VRout ");
         if (nodep->lvalue() && nodep->varp()->direction() == VDirection::CONSTREF) {
             nodep->v3error("Assigning to const ref variable: " << nodep->prettyNameQ());
-        } else if (nodep->lvalue() && nodep->varp()->isConst() && !m_paramsOnly && !m_initialp) {
+        } else if (nodep->lvalue() && nodep->varp()->isConst() && !m_paramsOnly
+                   && !VN_IS(m_procedurep, Initial)) {
             // Too loose, but need to allow our generated first assignment
             // Move this to a property of the AstInitial block
             nodep->v3error("Assigning to const variable: " << nodep->prettyNameQ());
@@ -3763,11 +3775,11 @@ private:
         processFTaskRefArgs(nodep);
         nodep->didWidth(true);
     }
-    virtual void visit(AstInitial* nodep) VL_OVERRIDE {
+    virtual void visit(AstNodeProcedure* nodep) VL_OVERRIDE {
         assertAtStatement(nodep);
-        m_initialp = nodep;
+        m_procedurep = nodep;
         userIterateChildren(nodep, NULL);
-        m_initialp = NULL;
+        m_procedurep = NULL;
     }
     virtual void visit(AstNetlist* nodep) VL_OVERRIDE {
         // Iterate modules backwards, in bottom-up order.  That's faster
@@ -5227,8 +5239,8 @@ public:
         m_paramsOnly = paramsOnly;
         m_cellRangep = NULL;
         m_ftaskp = NULL;
+        m_procedurep = NULL;
         m_funcp = NULL;
-        m_initialp = NULL;
         m_attrp = NULL;
         m_doGenerate = doGenerate;
         m_dtTables = 0;

test_regress/t/t_timing_func_bad.out

@@ -0,0 +1,9 @@
+%Error: t/t_timing_func_bad.v:10:8: Delays are not legal in functions. Suggest use a task. IEEE 1800-2017 13.4.4
+                                  : ... In instance t
+   10 |       #1 $stop;
+      |        ^
+%Error: t/t_timing_func_bad.v:23:8: Delays are not legal in final blocks. IEEE 1800-2017 9.2.3
+                                  : ... In instance t
+   23 |       #1;
+      |        ^
+%Error: Exiting due to

test_regress/t/t_timing_func_bad.pl

@@ -0,0 +1,20 @@
+#!/usr/bin/env perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2019 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.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+scenarios(linter => 1);
+
+compile(
+    verilator_flags2 => ['--lint-only'],
+    fails => 1,
+    expect_filename => $Self->{golden_filename},
+    );
+
+ok(1);
+1;

test_regress/t/t_timing_func_bad.v

@@ -0,0 +1,27 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2020 by Wilson Snyder.
+// SPDX-License-Identifier: CC0-1.0
+
+module t(/*AUTOARG*/);
+
+   function int f;
+      #1 $stop;
+      f = 0;
+   endfunction
+
+   int i;
+
+   initial begin
+      i = f();
+      $write("*-* All Finished *-*\n");
+      $finish;
+   end
+
+   final begin
+      #1;
+      $stop;
+   end
+
+endmodule