Improve `covergroup with function sample` handling (#6387)

docs/CONTRIBUTORS

@@ -94,6 +94,7 @@ Iru Cai
 Ivan Vnučec
 Iztok Jeras
 Jake Merdich
+Jakub Wasilewski
 James Bailey
 James Hanlon
 James Hutchinson

src/verilog.y

@@ -147,19 +147,28 @@ public:
         nodep->trace(GRAMMARP->allTracingOn(fileline));
         return nodep;
     }
-    void createCoverGroupMethods(AstClass* nodep) {
+    void createCoverGroupMethods(AstClass* nodep, AstNode* sampleArgs) {
         // Hidden static to take unspecified reference argument results
         AstVar* const defaultVarp
             = new AstVar{nodep->fileline(), VVarType::MEMBER, "__Vint", nodep->findIntDType()};
         defaultVarp->lifetime(VLifetime::STATIC);
         nodep->addStmtsp(defaultVarp);
-        // IEEE: function void sample(), void start(), void stop()
+
-        for (const string& name : {"sample"s, "start"s, "stop"s}) {
+        // IEEE: function void sample()
+        AstFunc* const funcp = new AstFunc{nodep->fileline(), "sample", nullptr, nullptr};
+        funcp->addStmtsp(sampleArgs);
+        funcp->classMethod(true);
+        funcp->dtypep(funcp->findVoidDType());
+        nodep->addMembersp(funcp);
+
+        // IEEE: function void start(), void stop()
+        for (const string& name : {"start"s, "stop"s}) {
             AstFunc* const funcp = new AstFunc{nodep->fileline(), name, nullptr, nullptr};
             funcp->classMethod(true);
             funcp->dtypep(funcp->findVoidDType());
             nodep->addMembersp(funcp);
         }
+
         // IEEE: static function real get_coverage(optional ref int, optional ref int)
         // IEEE: function real get_inst_coverage(optional ref int, optional ref int)
         for (const string& name : {"get_coverage"s, "get_inst_coverage"s}) {
@@ -6944,36 +6953,43 @@ boolean_abbrev<nodeExprp>:  // ==IEEE: boolean_abbrev
 // Covergroup
 
 covergroup_declaration<nodep>:  // ==IEEE: covergroup_declaration
-                covergroup_declarationFront coverage_eventE ';'
+                 yCOVERGROUP idAny cgPortListE coverage_eventE ';'
         /*cont*/    coverage_spec_or_optionListE
-        /*cont*/    yENDGROUP endLabelE
+        /*cont*/ yENDGROUP endLabelE
-                        { $$ = $1;
+                        { AstClass *cgClassp = new AstClass{$<fl>2, *$2, PARSEP->libname()};
-                          GRAMMARP->endLabel($<fl>6, $1, $6); }
+                          AstFunc* const newp = new AstFunc{$<fl>1, "new", nullptr, nullptr};
-        |       covergroup_declarationFront '(' tf_port_listE ')'
-        /*cont*/    coverage_eventE ';' coverage_spec_or_optionListE
-        /*cont*/    yENDGROUP endLabelE
-                        { AstFunc* const newp = new AstFunc{$<fl>1, "new", nullptr, nullptr};
                           newp->classMethod(true);
                           newp->isConstructor(true);
-                          newp->dtypep($1->dtypep());
+                          newp->dtypep(cgClassp->dtypep());
                           newp->addStmtsp($3);
-                          $1->addMembersp(newp);
+                          cgClassp->addMembersp(newp);
-                          $$ = $1;
+                          GRAMMARP->createCoverGroupMethods(cgClassp, $4);
-                          GRAMMARP->endLabel($<fl>9, $1, $9); }
-        ;
 
-covergroup_extendsE<fl>:  // IEEE: Part of covergroup_declaration
+                          $$ = cgClassp;
-                /* empty */                             { $$ = nullptr; }
+                          GRAMMARP->endLabel($<fl>8, $$, $8);
-        |       yEXTENDS                                { $$ = $1; }
-        ;
-
-covergroup_declarationFront<classp>:  // IEEE: part of covergroup_declaration
-                yCOVERGROUP covergroup_extendsE idAny
-                        {
                           BBCOVERIGN($<fl>1, "Ignoring unsupported: covergroup");
-                          $$ = new AstClass{$<fl>3, *$3, PARSEP->libname()};
+                        }
-                          GRAMMARP->createCoverGroupMethods($$); }
+        |        yCOVERGROUP yEXTENDS idAny ';'
-                ;
+        /*cont*/     coverage_spec_or_optionListE
+        /*cont*/ yENDGROUP endLabelE
+                        { AstClass *cgClassp = new AstClass{$<fl>3, *$3, PARSEP->libname()};
+                          AstFunc* const newp = new AstFunc{$<fl>1, "new", nullptr, nullptr};
+                          newp->classMethod(true);
+                          newp->isConstructor(true);
+                          newp->dtypep(cgClassp->dtypep());
+                          cgClassp->addMembersp(newp);
+                          GRAMMARP->createCoverGroupMethods(cgClassp, nullptr);
+
+                          $$ = cgClassp;
+                          GRAMMARP->endLabel($<fl>7, $$, $7);
+                          BBCOVERIGN($<fl>1, "Ignoring unsupported: covergroup");
+                        }
+        ;
+
+cgPortListE<nodep>:
+                /*empty*/                               { $$ = nullptr; }
+        |       '(' tf_port_listE ')'                   { $$ = $2; }
+        ;
 
 cgexpr<nodeExprp>:  // IEEE-2012: covergroup_expression, before that just expression
                 expr                                    { $$ = $1; }
@@ -7224,7 +7240,13 @@ coverage_eventE<nodep>:  // IEEE: [ coverage_event ]
         |       clocking_event
                         { $$ = nullptr; BBCOVERIGN($<fl>1, "Ignoring unsupported: coverage clocking event"); }
         |       yWITH__ETC yFUNCTION idAny/*"sample"*/ '(' tf_port_listE ')'
-                        { $$ = nullptr; BBCOVERIGN($<fl>1, "Ignoring unsupported: coverage 'with' 'function'"); }
+                        { if (*$3 != "sample") {
+                            $<fl>3->v3error("Coverage sampling function must be named 'sample'");
+                            $$ = nullptr;
+                          } else {
+                            $$ = $5;
+                          }
+                        }
         |       yP_ATAT '(' block_event_expression ')'
                         { $$ = nullptr; BBCOVERIGN($<fl>1, "Ignoring unsupported: coverage '@@' events"); }
         ;

test_regress/t/t_covergroup_coverpoints_unsup.out

@@ -1,11 +1,8 @@
-%Warning-COVERIGN: t/t_covergroup_coverpoints_unsup.v:21:5: Ignoring unsupported: covergroup
-   21 |     covergroup cg @(posedge clk);
-      |     ^~~~~~~~~~
-                   ... For warning description see https://verilator.org/warn/COVERIGN?v=latest
-                   ... Use "/* verilator lint_off COVERIGN */" and lint_on around source to disable this message.
 %Warning-COVERIGN: t/t_covergroup_coverpoints_unsup.v:21:19: Ignoring unsupported: coverage clocking event
    21 |     covergroup cg @(posedge clk);
       |                   ^
+                   ... For warning description see https://verilator.org/warn/COVERIGN?v=latest
+                   ... Use "/* verilator lint_off COVERIGN */" and lint_on around source to disable this message.
 %Warning-COVERIGN: t/t_covergroup_coverpoints_unsup.v:22:9: Ignoring unsupported: coverpoint
    22 |         coverpoint a;
       |         ^~~~~~~~~~
@@ -15,6 +12,9 @@
 %Warning-COVERIGN: t/t_covergroup_coverpoints_unsup.v:23:9: Ignoring unsupported: coverpoint
    23 |         coverpoint b {
       |         ^~~~~~~~~~
+%Warning-COVERIGN: t/t_covergroup_coverpoints_unsup.v:21:5: Ignoring unsupported: covergroup
+   21 |     covergroup cg @(posedge clk);
+      |     ^~~~~~~~~~
 %Error: t/t_covergroup_coverpoints_unsup.v:35:48: Member 'a' not found in class 'cg'
                                                 : ... note: In instance 't'
    35 |             $display("coverage a = %f", the_cg.a.get_inst_coverage());

test_regress/t/t_covergroup_in_class_with_sample.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python3
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2025 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
+
+import vltest_bootstrap
+
+test.scenarios('vlt')
+
+test.compile()
+
+test.passes()

test_regress/t/t_covergroup_in_class_with_sample.v

@@ -0,0 +1,15 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2025 by Antmicro.
+// SPDX-License-Identifier: CC0-1.0
+
+/* verilator lint_off COVERIGN */
+class C;
+  covergroup embedded(int x) with function sample (int a, bit b);
+  endgroup
+  function new();
+    embedded = new(1);
+    embedded.sample(2, 1'b0);
+  endfunction
+endclass

test_regress/t/t_covergroup_unsup.out

@@ -3,9 +3,6 @@
       |    ^~~~~~~~~~
                    ... For warning description see https://verilator.org/warn/COVERIGN?v=latest
                    ... Use "/* verilator lint_off COVERIGN */" and lint_on around source to disable this message.
-%Warning-COVERIGN: t/t_covergroup_unsup.v:28:4: Ignoring unsupported: covergroup
-   28 |    covergroup cg_opt;
-      |    ^~~~~~~~~~
 %Warning-COVERIGN: t/t_covergroup_unsup.v:29:7: Ignoring unsupported: coverage option
    29 |       type_option.weight = 1;   
       |       ^~~~~~~~~~~
@@ -54,41 +51,38 @@
 %Warning-COVERIGN: t/t_covergroup_unsup.v:44:7: Ignoring unsupported: coverage option
    44 |       option.get_inst_coverage = 1;   
       |       ^~~~~~
-%Warning-COVERIGN: t/t_covergroup_unsup.v:47:4: Ignoring unsupported: covergroup
+%Warning-COVERIGN: t/t_covergroup_unsup.v:28:4: Ignoring unsupported: covergroup
-   47 |    covergroup cg_clockingevent() @(posedge clk);
+   28 |    covergroup cg_opt;
       |    ^~~~~~~~~~
 %Warning-COVERIGN: t/t_covergroup_unsup.v:47:34: Ignoring unsupported: coverage clocking event
    47 |    covergroup cg_clockingevent() @(posedge clk);
       |                                  ^
+%Warning-COVERIGN: t/t_covergroup_unsup.v:47:4: Ignoring unsupported: covergroup
+   47 |    covergroup cg_clockingevent() @(posedge clk);
+      |    ^~~~~~~~~~
 %Warning-COVERIGN: t/t_covergroup_unsup.v:49:4: Ignoring unsupported: covergroup
    49 |    covergroup cg_withfunction() with function sample (a);
       |    ^~~~~~~~~~
-%Warning-COVERIGN: t/t_covergroup_unsup.v:49:33: Ignoring unsupported: coverage 'with' 'function'
-   49 |    covergroup cg_withfunction() with function sample (a);
-      |                                 ^~~~
-%Warning-COVERIGN: t/t_covergroup_unsup.v:51:4: Ignoring unsupported: covergroup
-   51 |    covergroup cg_atat() @@ (begin funca or end funcb);
-      |    ^~~~~~~~~~
 %Warning-COVERIGN: t/t_covergroup_unsup.v:51:25: Ignoring unsupported: coverage '@@' events
    51 |    covergroup cg_atat() @@ (begin funca or end funcb);
       |                         ^~
+%Warning-COVERIGN: t/t_covergroup_unsup.v:51:4: Ignoring unsupported: covergroup
+   51 |    covergroup cg_atat() @@ (begin funca or end funcb);
+      |    ^~~~~~~~~~
 %Warning-COVERIGN: t/t_covergroup_unsup.v:53:4: Ignoring unsupported: covergroup
    53 |    covergroup cg_bracket;
       |    ^~~~~~~~~~
-%Warning-COVERIGN: t/t_covergroup_unsup.v:56:4: Ignoring unsupported: covergroup
-   56 |    covergroup cg_bracket2;
-      |    ^~~~~~~~~~
 %Warning-COVERIGN: t/t_covergroup_unsup.v:57:9: Ignoring unsupported: coverage option
    57 |       { option.name = "option"; }
       |         ^~~~~~
-%Warning-COVERIGN: t/t_covergroup_unsup.v:59:4: Ignoring unsupported: covergroup
+%Warning-COVERIGN: t/t_covergroup_unsup.v:56:4: Ignoring unsupported: covergroup
-   59 |    covergroup cg_cp;
+   56 |    covergroup cg_bracket2;
       |    ^~~~~~~~~~
 %Warning-COVERIGN: t/t_covergroup_unsup.v:60:7: Ignoring unsupported: coverpoint
    60 |       coverpoint a;
       |       ^~~~~~~~~~
-%Warning-COVERIGN: t/t_covergroup_unsup.v:62:4: Ignoring unsupported: covergroup
+%Warning-COVERIGN: t/t_covergroup_unsup.v:59:4: Ignoring unsupported: covergroup
-   62 |    covergroup cg_cp_iff;
+   59 |    covergroup cg_cp;
       |    ^~~~~~~~~~
 %Warning-COVERIGN: t/t_covergroup_unsup.v:63:20: Ignoring unsupported: cover 'iff'
    63 |       coverpoint a iff (b);
@@ -96,8 +90,8 @@
 %Warning-COVERIGN: t/t_covergroup_unsup.v:63:7: Ignoring unsupported: coverpoint
    63 |       coverpoint a iff (b);
       |       ^~~~~~~~~~
-%Warning-COVERIGN: t/t_covergroup_unsup.v:65:4: Ignoring unsupported: covergroup
+%Warning-COVERIGN: t/t_covergroup_unsup.v:62:4: Ignoring unsupported: covergroup
-   65 |    covergroup cg_id_cp_iff;
+   62 |    covergroup cg_cp_iff;
       |    ^~~~~~~~~~
 %Warning-COVERIGN: t/t_covergroup_unsup.v:66:24: Ignoring unsupported: cover 'iff'
    66 |       id: coverpoint a iff (b);
@@ -105,8 +99,8 @@
 %Warning-COVERIGN: t/t_covergroup_unsup.v:66:11: Ignoring unsupported: coverpoint
    66 |       id: coverpoint a iff (b);
       |           ^~~~~~~~~~
-%Warning-COVERIGN: t/t_covergroup_unsup.v:68:4: Ignoring unsupported: covergroup
+%Warning-COVERIGN: t/t_covergroup_unsup.v:65:4: Ignoring unsupported: covergroup
-   68 |    covergroup cg_id_cp_id1;
+   65 |    covergroup cg_id_cp_iff;
       |    ^~~~~~~~~~
 %Warning-COVERIGN: t/t_covergroup_unsup.v:69:28: Ignoring unsupported: cover 'iff'
    69 |       int id: coverpoint a iff (b);
@@ -114,8 +108,8 @@
 %Warning-COVERIGN: t/t_covergroup_unsup.v:69:15: Ignoring unsupported: coverpoint
    69 |       int id: coverpoint a iff (b);
       |               ^~~~~~~~~~
-%Warning-COVERIGN: t/t_covergroup_unsup.v:71:4: Ignoring unsupported: covergroup
+%Warning-COVERIGN: t/t_covergroup_unsup.v:68:4: Ignoring unsupported: covergroup
-   71 |    covergroup cg_id_cp_id2;
+   68 |    covergroup cg_id_cp_id1;
       |    ^~~~~~~~~~
 %Warning-COVERIGN: t/t_covergroup_unsup.v:72:32: Ignoring unsupported: cover 'iff'
    72 |       var int id: coverpoint a iff (b);
@@ -123,8 +117,8 @@
 %Warning-COVERIGN: t/t_covergroup_unsup.v:72:19: Ignoring unsupported: coverpoint
    72 |       var int id: coverpoint a iff (b);
       |                   ^~~~~~~~~~
-%Warning-COVERIGN: t/t_covergroup_unsup.v:74:4: Ignoring unsupported: covergroup
+%Warning-COVERIGN: t/t_covergroup_unsup.v:71:4: Ignoring unsupported: covergroup
-   74 |    covergroup cg_id_cp_id3;
+   71 |    covergroup cg_id_cp_id2;
       |    ^~~~~~~~~~
 %Warning-COVERIGN: t/t_covergroup_unsup.v:75:34: Ignoring unsupported: cover 'iff'
    75 |       var [3:0] id: coverpoint a iff (b);
@@ -132,8 +126,8 @@
 %Warning-COVERIGN: t/t_covergroup_unsup.v:75:21: Ignoring unsupported: coverpoint
    75 |       var [3:0] id: coverpoint a iff (b);
       |                     ^~~~~~~~~~
-%Warning-COVERIGN: t/t_covergroup_unsup.v:77:4: Ignoring unsupported: covergroup
+%Warning-COVERIGN: t/t_covergroup_unsup.v:74:4: Ignoring unsupported: covergroup
-   77 |    covergroup cg_id_cp_id4;
+   74 |    covergroup cg_id_cp_id3;
       |    ^~~~~~~~~~
 %Warning-COVERIGN: t/t_covergroup_unsup.v:78:30: Ignoring unsupported: cover 'iff'
    78 |       [3:0] id: coverpoint a iff (b);
@@ -141,8 +135,8 @@
 %Warning-COVERIGN: t/t_covergroup_unsup.v:78:17: Ignoring unsupported: coverpoint
    78 |       [3:0] id: coverpoint a iff (b);
       |                 ^~~~~~~~~~
-%Warning-COVERIGN: t/t_covergroup_unsup.v:80:4: Ignoring unsupported: covergroup
+%Warning-COVERIGN: t/t_covergroup_unsup.v:77:4: Ignoring unsupported: covergroup
-   80 |    covergroup cg_id_cp_id5;
+   77 |    covergroup cg_id_cp_id4;
       |    ^~~~~~~~~~
 %Warning-COVERIGN: t/t_covergroup_unsup.v:81:31: Ignoring unsupported: cover 'iff'
    81 |       signed id: coverpoint a iff (b);
@@ -150,8 +144,8 @@
 %Warning-COVERIGN: t/t_covergroup_unsup.v:81:18: Ignoring unsupported: coverpoint
    81 |       signed id: coverpoint a iff (b);
       |                  ^~~~~~~~~~
-%Warning-COVERIGN: t/t_covergroup_unsup.v:84:4: Ignoring unsupported: covergroup
+%Warning-COVERIGN: t/t_covergroup_unsup.v:80:4: Ignoring unsupported: covergroup
-   84 |    covergroup cg_cross;
+   80 |    covergroup cg_id_cp_id5;
       |    ^~~~~~~~~~
 %Warning-COVERIGN: t/t_covergroup_unsup.v:85:18: Ignoring unsupported: cover 'iff'
    85 |       cross a, b iff (!rst);
@@ -159,8 +153,8 @@
 %Warning-COVERIGN: t/t_covergroup_unsup.v:85:7: Ignoring unsupported: cover cross
    85 |       cross a, b iff (!rst);
       |       ^~~~~
-%Warning-COVERIGN: t/t_covergroup_unsup.v:87:4: Ignoring unsupported: covergroup
+%Warning-COVERIGN: t/t_covergroup_unsup.v:84:4: Ignoring unsupported: covergroup
-   87 |    covergroup cg_cross2;
+   84 |    covergroup cg_cross;
       |    ^~~~~~~~~~
 %Warning-COVERIGN: t/t_covergroup_unsup.v:88:18: Ignoring unsupported: cover 'iff'
    88 |       cross a, b iff (!rst) {}
@@ -168,8 +162,8 @@
 %Warning-COVERIGN: t/t_covergroup_unsup.v:88:7: Ignoring unsupported: cover cross
    88 |       cross a, b iff (!rst) {}
       |       ^~~~~
-%Warning-COVERIGN: t/t_covergroup_unsup.v:90:4: Ignoring unsupported: covergroup
+%Warning-COVERIGN: t/t_covergroup_unsup.v:87:4: Ignoring unsupported: covergroup
-   90 |    covergroup cg_cross3;
+   87 |    covergroup cg_cross2;
       |    ^~~~~~~~~~
 %Warning-COVERIGN: t/t_covergroup_unsup.v:91:20: Ignoring unsupported: coverage option
    91 |       cross a, b { option.comment = "cross"; option.weight = 12; }
@@ -180,8 +174,8 @@
 %Warning-COVERIGN: t/t_covergroup_unsup.v:91:7: Ignoring unsupported: cover cross
    91 |       cross a, b { option.comment = "cross"; option.weight = 12; }
       |       ^~~~~
-%Warning-COVERIGN: t/t_covergroup_unsup.v:93:4: Ignoring unsupported: covergroup
+%Warning-COVERIGN: t/t_covergroup_unsup.v:90:4: Ignoring unsupported: covergroup
-   93 |    covergroup cg_cross4;
+   90 |    covergroup cg_cross3;
       |    ^~~~~~~~~~
 %Warning-COVERIGN: t/t_covergroup_unsup.v:95:24: Ignoring unsupported: coverage cross 'function' declaration
    95 |          function void crossfunc; endfunction
@@ -195,8 +189,8 @@
 %Warning-COVERIGN: t/t_covergroup_unsup.v:94:7: Ignoring unsupported: cover cross
    94 |       cross a, b {
       |       ^~~~~
-%Warning-COVERIGN: t/t_covergroup_unsup.v:99:4: Ignoring unsupported: covergroup
+%Warning-COVERIGN: t/t_covergroup_unsup.v:93:4: Ignoring unsupported: covergroup
-   99 |    covergroup cg_cross_id;
+   93 |    covergroup cg_cross4;
       |    ^~~~~~~~~~
 %Warning-COVERIGN: t/t_covergroup_unsup.v:100:28: Ignoring unsupported: cover 'iff'
   100 |       my_cg_id: cross a, b iff (!rst);
@@ -204,8 +198,8 @@
 %Warning-COVERIGN: t/t_covergroup_unsup.v:100:17: Ignoring unsupported: cover cross
   100 |       my_cg_id: cross a, b iff (!rst);
       |                 ^~~~~
-%Warning-COVERIGN: t/t_covergroup_unsup.v:103:4: Ignoring unsupported: covergroup
+%Warning-COVERIGN: t/t_covergroup_unsup.v:99:4: Ignoring unsupported: covergroup
-  103 |    covergroup cg_binsoroptions_bk1;
+   99 |    covergroup cg_cross_id;
       |    ^~~~~~~~~~
 %Warning-COVERIGN: t/t_covergroup_unsup.v:105:17: Ignoring unsupported: cover bin specification
   105 |       { bins ba = {a}; }
@@ -297,8 +291,8 @@
 %Warning-COVERIGN: t/t_covergroup_unsup.v:131:19: Ignoring unsupported: cover bin trans list
   131 |       { bins bts2 = ( 3 [=5:6] ) ; }
       |                   ^
-%Warning-COVERIGN: t/t_covergroup_unsup.v:135:4: Ignoring unsupported: covergroup
+%Warning-COVERIGN: t/t_covergroup_unsup.v:103:4: Ignoring unsupported: covergroup
-  135 |    covergroup cg_cross_bins;
+  103 |    covergroup cg_binsoroptions_bk1;
       |    ^~~~~~~~~~
 %Warning-COVERIGN: t/t_covergroup_unsup.v:137:23: Ignoring unsupported: coverage select expression 'binsof'
   137 |          bins bin_a = binsof(a);
@@ -384,12 +378,12 @@
 %Warning-COVERIGN: t/t_covergroup_unsup.v:136:7: Ignoring unsupported: cover cross
   136 |       cross a, b {
       |       ^~~~~
+%Warning-COVERIGN: t/t_covergroup_unsup.v:135:4: Ignoring unsupported: covergroup
+  135 |    covergroup cg_cross_bins;
+      |    ^~~~~~~~~~
 %Warning-COVERIGN: t/t_covergroup_unsup.v:154:4: Ignoring unsupported: covergroup
   154 |    covergroup cgArgs(int cg_lim);
       |    ^~~~~~~~~~
-%Warning-COVERIGN: t/t_covergroup_unsup.v:161:7: Ignoring unsupported: covergroup
-  161 |       covergroup cov1 @m_z;
-      |       ^~~~~~~~~~
 %Warning-COVERIGN: t/t_covergroup_unsup.v:161:23: Ignoring unsupported: coverage clocking event
   161 |       covergroup cov1 @m_z;
       |                       ^
@@ -399,6 +393,9 @@
 %Warning-COVERIGN: t/t_covergroup_unsup.v:163:10: Ignoring unsupported: coverpoint
   163 |          coverpoint m_y;
       |          ^~~~~~~~~~
+%Warning-COVERIGN: t/t_covergroup_unsup.v:161:7: Ignoring unsupported: covergroup
+  161 |       covergroup cov1 @m_z;
+      |       ^~~~~~~~~~
 %Warning-COVERIGN: t/t_covergroup_unsup.v:171:7: Ignoring unsupported: covergroup
   171 |       covergroup extends cg_empty;
       |       ^~~~~~~~~~

test_regress/t/t_covergroup_with_function_foo_bad.out

@@ -0,0 +1,5 @@
+%Error: t/t_covergroup_with_function_foo_bad.v:9:35: Coverage sampling function must be named 'sample'
+    9 |   covergroup cg_bad with function foo(int x);
+      |                                   ^~~
+        ... See the manual at https://verilator.org/verilator_doc.html?v=latest for more assistance.
+%Error: Exiting due to

test_regress/t/t_covergroup_with_function_foo_bad.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python3
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2025 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
+
+import vltest_bootstrap
+
+test.scenarios('simulator')
+
+test.compile(fails=True, expect_filename=test.golden_filename)
+
+test.passes()

test_regress/t/t_covergroup_with_function_foo_bad.v

@@ -0,0 +1,12 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2025 by Antmicro.
+// SPDX-License-Identifier: CC0-1.0
+
+/* verilator lint_off COVERIGN */
+module t;
+  covergroup cg_bad with function foo(int x);
+  endgroup
+  cg_bad cov = new();
+endmodule

test_regress/t/t_covergroup_with_sample_args.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python3
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2025 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
+
+import vltest_bootstrap
+
+test.scenarios('vlt')
+
+test.compile()
+
+test.passes()

test_regress/t/t_covergroup_with_sample_args.v

@@ -0,0 +1,17 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2025 by Antmicro.
+// SPDX-License-Identifier: CC0-1.0
+
+/* verilator lint_off COVERIGN */
+module t;
+  covergroup cg_with_sample(int init_val) with function sample (int addr, bit is_read);
+  endgroup
+
+  cg_with_sample cov1 = new(42);
+
+  function void run();
+    cov1.sample(16, 1'b1);
+  endfunction
+endmodule

test_regress/t/t_covergroup_with_sample_args_default.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python3
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2025 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
+
+import vltest_bootstrap
+
+test.scenarios('vlt')
+
+test.compile()
+
+test.passes()

test_regress/t/t_covergroup_with_sample_args_default.v

@@ -0,0 +1,18 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2025 by Antmicro.
+// SPDX-License-Identifier: CC0-1.0
+
+/* verilator lint_off COVERIGN */
+module t;
+  covergroup cg_with_sample(int init) with function sample (int addr, bit is_read = 1'b0);
+  endgroup
+
+  cg_with_sample cov1 = new(7);
+
+  function void run();
+    cov1.sample(5);
+    cov1.sample(6, 1'b1);
+  endfunction
+endmodule

test_regress/t/t_covergroup_with_sample_args_too_few_bad.out

@@ -0,0 +1,6 @@
+%Error: t/t_covergroup_with_sample_args_too_few_bad.v:16:10: Missing argument on non-defaulted argument 'is_read' in function call to FUNC 'sample'
+                                                           : ... note: In instance 't'
+   16 |     cov1.sample(1);
+      |          ^~~~~~
+        ... See the manual at https://verilator.org/verilator_doc.html?v=latest for more assistance.
+%Error: Exiting due to

test_regress/t/t_covergroup_with_sample_args_too_few_bad.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python3
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2025 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
+
+import vltest_bootstrap
+
+test.scenarios('simulator')
+
+test.compile(fails=True, expect_filename=test.golden_filename)
+
+test.passes()

test_regress/t/t_covergroup_with_sample_args_too_few_bad.v

@@ -0,0 +1,18 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2025 by Antmicro.
+// SPDX-License-Identifier: CC0-1.0
+
+/* verilator lint_off COVERIGN */
+module t;
+  covergroup cg_with_sample(int init) with function sample (int addr, bit is_read);
+  endgroup
+
+  cg_with_sample cov1 = new(0);
+
+  function void run();
+    // Too few arguments (1 instead of 2)
+    cov1.sample(1);
+  endfunction
+endmodule

test_regress/t/t_covergroup_with_sample_args_too_many_bad.out

@@ -0,0 +1,6 @@
+%Error: t/t_covergroup_with_sample_args_too_many_bad.v:15:26: Too many arguments in function call to FUNC 'sample'
+                                                            : ... note: In instance 't'
+   15 |     cov1.sample(5, 1'b0, 42);   
+      |                          ^~
+        ... See the manual at https://verilator.org/verilator_doc.html?v=latest for more assistance.
+%Error: Exiting due to

test_regress/t/t_covergroup_with_sample_args_too_many_bad.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python3
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2025 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
+
+import vltest_bootstrap
+
+test.scenarios('simulator')
+
+test.compile(fails=True, expect_filename=test.golden_filename)
+
+test.passes()

test_regress/t/t_covergroup_with_sample_args_too_many_bad.v

@@ -0,0 +1,17 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2025 by Antmicro.
+// SPDX-License-Identifier: CC0-1.0
+
+/* verilator lint_off COVERIGN */
+module t;
+  covergroup cg_with_sample(int init) with function sample (int addr, bit is_read = 1'b0);
+  endgroup
+
+  cg_with_sample cov1 = new(7);
+
+  function void run();
+    cov1.sample(5, 1'b0, 42);  // Too many arguments
+  endfunction
+endmodule

test_regress/t/t_covergroup_with_sample_namedargs.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python3
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2025 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
+
+import vltest_bootstrap
+
+test.scenarios('vlt')
+
+test.compile()
+
+test.passes()

test_regress/t/t_covergroup_with_sample_namedargs.v

@@ -0,0 +1,15 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2025 by Antmicro.
+// SPDX-License-Identifier: CC0-1.0
+
+/* verilator lint_off COVERIGN */
+module t;
+  covergroup cgN with function sample (int addr, bit is_read);
+  endgroup
+  cgN cov = new();
+  function void run();
+    cov.sample(.addr(11), .is_read(1'b1));
+  endfunction
+endmodule

test_regress/t/t_covergroup_with_sample_zeroargs.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python3
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2025 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
+
+import vltest_bootstrap
+
+test.scenarios('vlt')
+
+test.compile()
+
+test.passes()

test_regress/t/t_covergroup_with_sample_zeroargs.v

@@ -0,0 +1,15 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2025 by Antmicro.
+// SPDX-License-Identifier: CC0-1.0
+
+/* verilator lint_off COVERIGN */
+module t;
+  covergroup cg0 with function sample ();
+  endgroup
+  cg0 cov = new();
+  function void run();
+    cov.sample();
+  endfunction
+endmodule