Fix `foreach` with mid-index empty commas (#6910).

Fixes #6910.

Changes

@@ -33,6 +33,7 @@ Verilator 5.045 devel
 * Fix segfault in V3Slice (#6899). [Pawel Kojma, Antmicro Ltd.]
 * Fix signedness of packed array (#6901) (#6902). [Yutetsu TAKATSUKASA]
 * Fix assignment of queue from unpacked array (#6906).
+* Fix `foreach` with mid-index empty commas (#6910).
 
 
 Verilator 5.044 2026-01-01

src/verilog.y

@@ -4053,10 +4053,13 @@ for_step_assignment<nodep>:     // ==IEEE: for_step_assignment
         ;
 
 loop_variables<nodep>:          // IEEE: loop_variables
-                parseRefBase                            { $$ = $1; }
-        |       loop_variables ',' parseRefBase         { $$ = $1->addNext($3); }
-        |       ',' parseRefBase                        { $$ = new AstEmpty{$1}; $$->addNext($2); }
-        |       ','                                     { $$ = new AstEmpty{$1}; }
+                loop_variableE                          { $$ = $1; }
+        |       loop_variables ',' loop_variableE       { $$ = $1->addNext($3); }
+        ;
+
+loop_variableE<nodep>:          // IEEE: part of loop_variables
+                /* empty */                             { $$ = new AstEmpty{CRELINE()}; }
+        |       parseRefBase                            { $$ = $1; }
         ;
 
 //************************************************

test_regress/t/t_foreach_noivar.v

@@ -7,12 +7,15 @@
 // verilog_format: off
 `define stop $stop
 `define checkh(gotv,expv) do if ((gotv) !== (expv)) begin $write("%%Error: %s:%0d:  got='h%x exp='h%x\n", `__FILE__,`__LINE__, (gotv), (expv)); `stop; end while(0);
+`define checks(gotv,expv) do if ((gotv) != (expv)) begin $write("%%Error: %s:%0d:  got='%s' exp='%s'\n", `__FILE__,`__LINE__, (gotv), (expv)); `stop; end while(0);
 // verilog_format: on
 
 module t;
 
   reg [63:0] sum;  // Checked not in objects
   reg [2:1][4:3] array[5:6][7:8];
+  bit [3:2][2:1] array2[5:4][2];
+  string did;
 
   initial begin
     sum = 0;
@@ -27,6 +30,12 @@ module t;
     end
     `checkh(sum, 0);
 
+    foreach (array2[i, j,, l]) begin
+      did = {did, $sformatf("; %0d,%0d,,%0d", i, j, l)};
+    end
+    `checks(did, "; 5,0,,2; 5,0,,1; 5,1,,2; 5,1,,1; 4,0,,2; 4,0,,1; 4,1,,2; 4,1,,1");
+    $finish;
+
     $write("*-* All Finished *-*\n");
     $finish;
   end

test_regress/t/t_foreach_noivar_bad.out

@@ -1,11 +1,11 @@
-%Warning-NOEFFECT: t/t_foreach_noivar.v:19:5: foreach with no loop variable has no effect
+%Warning-NOEFFECT: t/t_foreach_noivar.v:22:5: foreach with no loop variable has no effect
                                             : ... note: In instance 't'
-   19 |     foreach (array[]) begin   
+   22 |     foreach (array[]) begin   
       |     ^~~~~~~
                    ... For warning description see https://verilator.org/warn/NOEFFECT?v=latest
                    ... Use "/* verilator lint_off NOEFFECT */" and lint_on around source to disable this message.
-%Warning-NOEFFECT: t/t_foreach_noivar.v:25:5: foreach with no loop variable has no effect
+%Warning-NOEFFECT: t/t_foreach_noivar.v:28:5: foreach with no loop variable has no effect
                                             : ... note: In instance 't'
-   25 |     foreach (array[,,]) begin   
+   28 |     foreach (array[,,]) begin   
       |     ^~~~~~~
 %Error: Exiting due to