From f0c569ab0da8b13b220455c60407dadcc47e3d41 Mon Sep 17 00:00:00 2001
From: Wilson Snyder <wsnyder@wsnyder.org>
Date: Sat, 23 May 2026 19:56:28 -0400
Subject: [PATCH] Fix CASEINCOMPLETE to not warn on `unique0 case` (#7647).

Fixes #7647.
---
 Changes                                    |  1 +
 docs/guide/warnings.rst                    |  3 +++
 src/V3Case.cpp                             | 13 ++++++++-----
 test_regress/t/t_lint_caseincomplete_bad.v |  5 +++++
 4 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/Changes b/Changes
index 8007838b5..cd6e5d4c8 100644
--- a/Changes
+++ b/Changes
@@ -83,6 +83,7 @@ Verilator 5.049 devel
 * Fix force determinism (#7620) (#7637). [Artur Bieniek, Antmicro Ltd.]
 * Fix reference counting for modport task references (#7628). [Nick Brereton]
 * Fix implicit conversions of VlWide (#7642). [Geza Lore, Testorrent USA, Inc.]
+* Fix CASEINCOMPLETE to not warn on `unique0 case` (#7647).
 
 
 Verilator 5.048 2026-04-26
diff --git a/docs/guide/warnings.rst b/docs/guide/warnings.rst
index 4ce0a8cee..0ed315330 100644
--- a/docs/guide/warnings.rst
+++ b/docs/guide/warnings.rst
@@ -382,6 +382,9 @@ List Of Warnings
    non-enumerated values (IEEE 1800-2023 12.5.3). Verilator checks that
    illegal values are not hit, unless :vlopt:`--no-assert-case` was used.
 
+   Unique0 case statements will never cause this warning. (Although unique0
+   should be avoided in synthesizable code as may result in latch behavior.)
+
    Ignoring this warning will only suppress the lint check; it will
    simulate correctly.
 
diff --git a/src/V3Case.cpp b/src/V3Case.cpp
index e2baca0a5..4eca73e01 100644
--- a/src/V3Case.cpp
+++ b/src/V3Case.cpp
@@ -178,8 +178,10 @@ class CaseVisitor final : public VNVisitor {
             for (uint32_t i = 0; i < numCases; ++i) {
                 if ((i & mask) == val) {
                     if (!m_valueItem[i]) {
-                        nodep->v3warn(CASEINCOMPLETE, "Enum item " << itemp->prettyNameQ()
-                                                                   << " not covered by case\n");
+                        if (!nodep->unique0Pragma())
+                            nodep->v3warn(CASEINCOMPLETE, "Enum item "
+                                                              << itemp->prettyNameQ()
+                                                              << " not covered by case\n");
                         m_caseIncomplete = true;
                         return false;  // enum has uncovered value by case items
                     }
@@ -310,9 +312,10 @@ class CaseVisitor final : public VNVisitor {
             } else {
                 for (uint32_t i = 0; i < numCases; ++i) {
                     if (!m_valueItem[i]) {  // has uncovered case
-                        nodep->v3warn(CASEINCOMPLETE, "Case values incompletely covered "
-                                                      "(example pattern 0x"
-                                                          << std::hex << i << ")");
+                        if (!nodep->unique0Pragma())
+                            nodep->v3warn(CASEINCOMPLETE, "Case values incompletely covered "
+                                                          "(example pattern 0x"
+                                                              << std::hex << i << ")");
                         m_caseIncomplete = true;
                         m_caseNoOverlapsAllCovered = false;
                         return false;
diff --git a/test_regress/t/t_lint_caseincomplete_bad.v b/test_regress/t/t_lint_caseincomplete_bad.v
index 81678a474..2a8bf8edf 100644
--- a/test_regress/t/t_lint_caseincomplete_bad.v
+++ b/test_regress/t/t_lint_caseincomplete_bad.v
@@ -14,5 +14,10 @@ module t (
       2'b10: ;
       2'b11: ;
     endcase
+
+    unique0 case (i)  // No warning
+      2'b00: ;
+    endcase
   end
+
 endmodule