Add error on static access to non-static class member (#4072)

Before this patch, it was possible to access non-static class members using
static access, which resulted in C++ compilation errors. This adds
verilation-time checks for such situations.

src/V3LinkDot.cpp

@@ -2534,12 +2534,14 @@ private:
             string expectWhat;
             bool allowScope = false;
             bool allowVar = false;
+            bool staticAccess = false;
             if (m_ds.m_dotPos == DP_PACKAGE) {
                 // {package}::{a}
                 AstNodeModule* classOrPackagep = nullptr;
                 expectWhat = "scope/variable";
                 allowScope = true;
                 allowVar = true;
+                staticAccess = true;
                 UASSERT_OBJ(VN_IS(m_ds.m_dotp->lhsp(), ClassOrPackageRef), m_ds.m_dotp->lhsp(),
                             "Bad package link");
                 AstClassOrPackageRef* const cpackagerefp
@@ -2667,6 +2669,10 @@ private:
                             newp = refp;
                         }
                     } else {
+                        if (staticAccess && !varp->lifetime().isStatic() && !varp->isParam()) {
+                            nodep->v3error("Static access to non-static member variable "
+                                           << varp->prettyNameQ() << endl);
+                        }
                         AstVarRef* const refp = new AstVarRef{
                             nodep->fileline(), varp, VAccess::READ};  // lvalue'ness computed later
                         refp->classOrPackagep(foundp->classOrPackagep());
@@ -2980,6 +2986,7 @@ private:
             iterateChildren(nodep);
         }
 
+        bool staticAccess = false;
         if (m_ds.m_unresolvedClass) {
             // Unable to link before V3Param
             return;
@@ -2995,6 +3002,7 @@ private:
         } else if (m_ds.m_dotp && m_ds.m_dotPos == DP_PACKAGE) {
             UASSERT_OBJ(VN_IS(m_ds.m_dotp->lhsp(), ClassOrPackageRef), m_ds.m_dotp->lhsp(),
                         "Bad package link");
+            staticAccess = true;
             AstClassOrPackageRef* const cpackagerefp
                 = VN_AS(m_ds.m_dotp->lhsp(), ClassOrPackageRef);
             if (cpackagerefp->name() == "local") {
@@ -3066,6 +3074,10 @@ private:
             AstNodeFTask* const taskp
                 = foundp ? VN_CAST(foundp->nodep(), NodeFTask) : nullptr;  // Maybe nullptr
             if (taskp) {
+                if (staticAccess && !taskp->lifetime().isStatic()) {
+                    nodep->v3error("Static access to non-static task/function "
+                                   << taskp->prettyNameQ() << endl);
+                }
                 nodep->taskp(taskp);
                 nodep->classOrPackagep(foundp->classOrPackagep());
                 UINFO(7, "         Resolved " << nodep << endl);  // Also prints taskp

test_regress/t/t_class_fwd_cc.v

@@ -15,7 +15,7 @@ package Pkg;
       endfunction
    endclass
    class Fwd;
-      function Fwd m_uvm_get_root();
+      static function Fwd m_uvm_get_root();
          return null;
       endfunction
    endclass

test_regress/t/t_class_member_bad3.out

@@ -0,0 +1,7 @@
+%Error: t/t_class_member_bad3.v:16:12: Static access to non-static member variable 'member'
+   16 |       Foo::member = 1;
+      |            ^~~~~~
+%Error: t/t_class_member_bad3.v:17:12: Static access to non-static task/function 'method'
+   17 |       Foo::method();
+      |            ^~~~~~
+%Error: Exiting due to

test_regress/t/t_class_member_bad3.pl

@@ -0,0 +1,19 @@
+#!/usr/bin/env perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2023 by Antmicro Ltd. 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);
+
+lint(
+    fails => 1,
+    expect_filename => $Self->{golden_filename},
+    );
+
+ok(1);
+1;

test_regress/t/t_class_member_bad3.v

@@ -0,0 +1,19 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2023 by Antmicro Ltd.
+// SPDX-License-Identifier: CC0-1.0
+
+class Foo;
+   int member;
+
+   task method; endtask
+endclass
+
+module t;
+   initial begin
+      Foo foo = new;
+      Foo::member = 1;
+      Foo::method();
+   end
+endmodule