Fix omitting error when assigning to an input (#6169)

docs/CONTRIBUTORS

@@ -24,6 +24,7 @@ Anthony Donlon
 Anthony Moore
 Arkadiusz Kozdra
 Arthur Rosa
+Artur Bieniek
 Aylon Chaim Porat
 Bartłomiej Chmiel
 Brian Li

src/V3Width.cpp

@@ -2461,11 +2461,11 @@ class WidthVisitor final : public VNVisitor {
         // if (debug() >= 9) nodep->dumpTree("-  VRout: ");
         if (nodep->access().isWriteOrRW() && nodep->varp()->direction() == VDirection::CONSTREF) {
             nodep->v3error("Assigning to const ref variable: " << nodep->prettyNameQ());
-        } else if (!nodep->varp()->isForced() && nodep->access().isWriteOrRW()
-                   && nodep->varp()->isInput() && !nodep->varp()->isFuncLocal()
-                   && nodep->varp()->isReadOnly() && (!m_ftaskp || !m_ftaskp->isConstructor())
-                   && !VN_IS(m_procedurep, InitialAutomatic)
-                   && !VN_IS(m_procedurep, InitialStatic)) {
+        } else if (nodep->access().isWriteOrRW() && nodep->varp()->isInput()
+                   && !nodep->varp()->isFuncLocal() && nodep->varp()->isReadOnly()
+                   && (!m_ftaskp || !m_ftaskp->isConstructor())
+                   && !VN_IS(m_procedurep, InitialAutomatic) && !VN_IS(m_procedurep, InitialStatic)
+                   && !VN_IS(nodep->abovep(), AssignForce) && !VN_IS(nodep->abovep(), Release)) {
             nodep->v3warn(ASSIGNIN, "Assigning to input/const variable: " << nodep->prettyNameQ());
         } else if (nodep->access().isWriteOrRW() && nodep->varp()->isConst() && !m_paramsOnly
                    && (!m_ftaskp || !m_ftaskp->isConstructor())

test_regress/t/t_force_input_assign_bad.out

@@ -0,0 +1,14 @@
+%Error-ASSIGNIN: t/t_force_input_assign_bad.v:18:10: Assigning to input/const variable: 'i'
+                                                   : ... note: In instance 't'
+   18 |       s1.i = 2;
+      |          ^
+                 ... For error description see https://verilator.org/warn/ASSIGNIN?v=latest
+%Error-ASSIGNIN: t/t_force_input_assign_bad.v:21:10: Assigning to input/const variable: 'i'
+                                                   : ... note: In instance 't'
+   21 |       s2.i = 2;
+      |          ^
+%Error-ASSIGNIN: t/t_force_input_assign_bad.v:25:17: Assigning to input/const variable: 'i'
+                                                   : ... note: In instance 't'
+   25 |       assign s3.i = 2;
+      |                 ^
+%Error: Exiting due to

test_regress/t/t_force_input_assign_bad.py

@@ -0,0 +1,18 @@
+#!/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.lint(expect_filename=test.golden_filename,
+          verilator_flags2=['--error-limit 1000'],
+          fails=True)
+
+test.passes()

test_regress/t/t_force_input_assign_bad.v

@@ -0,0 +1,32 @@
+// 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
+
+module sub(input [1:0] i);
+endmodule
+
+module t;
+  sub s1(1);
+  sub s2(1);
+  sub s3(1);
+  sub s4(1);
+  sub s5(1);
+  initial begin
+      // these should fail
+      s1.i = 2;
+      force s1.i = '1;
+
+      s2.i = 2;
+      release s2.i;
+
+      force s3.i = '1;
+      assign s3.i = 2;
+
+      // these should not
+      force s4.i = '1;
+
+      release s5.i;
+  end
+endmodule