Improve `lint_off` to allow multiple messages and comments (#2755 partial).

Changes

@@ -33,6 +33,7 @@ Verilator 5.041 devel
 * Support digits in `$sscanf` field width formats (#6083). [Iztok Jeras]
 * Support pure functions in sensitivity lists (#6393). [Krzysztof Bieganski, Antmicro Ltd.]
 * Support simple alias statements (#6339) (#6501). [Ryszard Rozak, Antmicro Ltd.]
+* Improve `lint_off` to allow multiple messages and comments (#2755).
 * Improve automatic selection of logic for DFG synthesis (#6370). [Geza Lore]
 * Improve `covergroup with function sample` handling  (#6387). [Jakub Wasilewski]
 * Improve DFG type system (#6390). [Geza Lore]

docs/guide/extensions.rst

@@ -362,15 +362,20 @@ or "`ifdef`"'s may break other tools.
 
    Same as :option:`isolate_assignments` control file option.
 
-.. option:: /*verilator&32;lint_off <msg>*/
+.. option:: /*verilator&32;lint_off <msgs>*/
 
-   Disable the specified warning message for any warnings following the
-   comment.
+   Disable the specified warning message(s) for any warnings following the
+   comment.  Multiple messages may be specified, separated with commas.
 
-.. option:: /*verilator&32;lint_on <msg>*/
+   If a one-line slash-slash-format comment is used, then the metacomment
+   ends at the newline or at an earlier next slash-slash. This allow
+   commenting the reason for the disable, e.g. :code:`// verilator lint_off
+   MSG // Because...`.
 
-   Re-enable the specified warning message for any warnings following the
-   comment.
+.. option:: /*verilator&32;lint_on <msgs>*/
+
+   Re-enable the specified warning message(s) for any warnings following
+   the comment.  Multiple messages may be specified, separated with commas.
 
 .. option:: /*verilator&32;lint_restore*/
 

src/V3FileLine.cpp

@@ -368,23 +368,29 @@ std::ostream& operator<<(std::ostream& os, FileLine* fileline) {
     return (os);
 }
 
-bool FileLine::warnOff(const string& msg, bool flag) {
-    const char* cmsg = msg.c_str();
-    // Backward compatibility with msg="UNUSED"
-    if (V3ErrorCode::unusedMsg(cmsg)) {
-        warnOff(V3ErrorCode::UNUSEDGENVAR, flag);
-        warnOff(V3ErrorCode::UNUSEDLOOP, flag);
-        warnOff(V3ErrorCode::UNUSEDPARAM, flag);
-        warnOff(V3ErrorCode::UNUSEDSIGNAL, flag);
-        return true;
-    }
-    const V3ErrorCode code{cmsg};
-    if (code.hardError()) {
-        return false;
-    } else {
-        warnOff(code, flag);
-        return true;
+string FileLine::warnOffParse(const string& msgs, bool flag) {
+    string result;
+    for (const string& msg : VString::split(msgs, ',')) {
+        const char* cmsg = msg.c_str();
+        // Backward compatibility with msg="UNUSED"
+        if (V3ErrorCode::unusedMsg(cmsg)) {
+            warnOff(V3ErrorCode::UNUSEDGENVAR, flag);
+            warnOff(V3ErrorCode::UNUSEDLOOP, flag);
+            warnOff(V3ErrorCode::UNUSEDPARAM, flag);
+            warnOff(V3ErrorCode::UNUSEDSIGNAL, flag);
+            continue;
+        }
+
+        const V3ErrorCode code{cmsg};
+        if (!code.hardError()) {
+            warnOff(code, flag);
+            continue;
+        }
+
+        // Error if not suppressed
+        if (!v3Global.opt.isFuture(msg)) result = VString::dot(result, ",", cmsg);
     }
+    return result;
 }
 
 void FileLine::warnLintOff(bool flag) {

src/V3FileLine.h

@@ -322,7 +322,7 @@ public:
         m_msgEnIdx = singleton().msgEnSetBit(m_msgEnIdx, code, flag);
     }
     void warnOff(V3ErrorCode code, bool flag) { warnOn(code, !flag); }
-    bool warnOff(const string& msg, bool flag);  // Returns 1 if ok
+    string warnOffParse(const string& msgs, bool flag);  // Returns "" if ok
     bool warnIsOff(V3ErrorCode code) const VL_MT_SAFE;
     void warnLintOff(bool flag);
     void warnStyleOff(bool flag);
@@ -350,8 +350,8 @@ public:
     static void globalWarnOff(V3ErrorCode code, bool flag) {
         defaultFileLine().warnOff(code, flag);
     }
-    static bool globalWarnOff(const string& code, bool flag) {
-        return defaultFileLine().warnOff(code, flag);
+    static string globalWarnOffParse(const string& msgs, bool flag) {
+        return defaultFileLine().warnOffParse(msgs, flag);
     }
     static void fileNameNumMapDumpXml(std::ostream& os) { singleton().fileNameNumMapDumpXml(os); }
     static void fileNameNumMapDumpJson(std::ostream& os) {

src/V3Options.cpp

@@ -1807,7 +1807,8 @@ void V3Options::parseOptsList(FileLine* fl, const string& optdir, int argc,
         addFuture(optp);
     });
     DECL_OPTION("-Wno-", CbPartialMatch, [fl, &parser](const char* optp) VL_MT_DISABLED {
-        if (!FileLine::globalWarnOff(optp, true)) {
+        const string err = FileLine::globalWarnOffParse(optp, true);
+        if (!err.empty()) {
             const string fullopt = "-Wno-"s + optp;
             fl->v3fatal("Unknown warning specified: " << fullopt
                                                       << parser.getSuggestion(fullopt.c_str()));

src/V3ParseImp.cpp

@@ -171,12 +171,9 @@ void V3ParseImp::lexVerilatorCmtLint(FileLine* fl, const char* textp, bool warnO
     string::size_type pos;
     if ((pos = msg.find('*')) != string::npos) msg.erase(pos);
     // Use parsep()->lexFileline() as want to affect later FileLine's warnings
-    if (!(parsep()->lexFileline()->warnOff(msg, warnOff))) {
-        if (!v3Global.opt.isFuture(msg)) {
-            fl->v3error("Unknown verilator lint message code: '" << msg << "', in '" << textp
-                                                                 << "'");
-        }
-    }
+    const string err = parsep()->lexFileline()->warnOffParse(msg, warnOff);
+    if (!err.empty())
+        fl->v3error("Unknown verilator lint message code: '" << err << "', in '" << textp << "'");
 }
 
 void V3ParseImp::lexVerilatorCmtBad(FileLine* fl, const char* textp) {

src/V3PreLex.l

@@ -438,10 +438,10 @@ bom             [\357\273\277]
 <ARGMODE>.              { FL_FWDC; appendDefValue(yytext, yyleng); FL_BRK; }
 
         /* Pragma comments. */
-<INITIAL>"//"{ws}*"verilator lint_off"[^\n\r]*       { FL_FWDC; LEXP->verilatorCmtLint(yytext + 2, true); return VP_COMMENT; }
-<INITIAL>"//"{ws}*"verilator lint_on"[^\n\r]*        { FL_FWDC; LEXP->verilatorCmtLint(yytext + 2, false); return VP_COMMENT; }
-<INITIAL>"//"{ws}*"verilator lint_restore"[^\n\r]*   { FL_FWDC; LEXP->verilatorCmtLintRestore(); return VP_COMMENT; }
-<INITIAL>"//"{ws}*"verilator lint_save"[^\n\r]*      { FL_FWDC; LEXP->verilatorCmtLintSave(); return VP_COMMENT; }
+<INITIAL>"//"{ws}*"verilator lint_off"[^\n\r/]*      { FL_FWDC; LEXP->verilatorCmtLint(yytext + 2, true); return VP_COMMENT; }
+<INITIAL>"//"{ws}*"verilator lint_on"[^\n\r/]*       { FL_FWDC; LEXP->verilatorCmtLint(yytext + 2, false); return VP_COMMENT; }
+<INITIAL>"//"{ws}*"verilator lint_restore"[^\n\r/]*  { FL_FWDC; LEXP->verilatorCmtLintRestore(); return VP_COMMENT; }
+<INITIAL>"//"{ws}*"verilator lint_save"[^\n\r/]*     { FL_FWDC; LEXP->verilatorCmtLintSave(); return VP_COMMENT; }
 <INITIAL>"/*"{ws}*"verilator lint_off"[^*]*"*/"      { FL_FWDC; LEXP->verilatorCmtLint(yytext + 2, true); return VP_COMMENT; }
 <INITIAL>"/*"{ws}*"verilator lint_on"[^*]*"*/"       { FL_FWDC; LEXP->verilatorCmtLint(yytext + 2, false); return VP_COMMENT; }
 <INITIAL>"/*"{ws}*"verilator lint_restore"[^*]*"*/"  { FL_FWDC; LEXP->verilatorCmtLintRestore(); return VP_COMMENT; }
@@ -788,7 +788,7 @@ void V3PreLex::verilatorCmtLint(const char* textp, bool warnOff) {
         }
     }
     // No warnings on bad warning codes - the verilog.y parse will report as appropriate
-    curFilelinep()->warnOff(msg, warnOff);
+    curFilelinep()->warnOffParse(msg, warnOff);
 }
 
 /*###################################################################

src/V3String.cpp

@@ -327,6 +327,14 @@ string VString::replaceWord(const string& str, const string& from, const string&
     return result;
 }
 
+std::deque<string> VString::split(const string& str, char delimiter) {
+    std::deque<std::string> results;
+    std::istringstream is{str};
+    std::string token;
+    while (std::getline(is, token, delimiter)) results.push_back(token);
+    return results;
+}
+
 bool VString::endsWith(const string& str, const string& suffix) {
     if (str.length() < suffix.length()) return false;
     return str.compare(str.length() - suffix.length(), suffix.length(), suffix) == 0;

src/V3String.h

@@ -22,6 +22,7 @@
 
 // No V3 headers here - this is a base class for Vlc etc
 
+#include <deque>
 #include <iomanip>
 #include <map>
 #include <set>
@@ -138,6 +139,8 @@ public:
     // to be a consecutive sequence of the characters [a-zA-Z0-9_]. Sub-words are not replaced.
     // e.g.: replaceWords("one apple bad_apple", "apple", "banana") -> "one banana bad_apple"
     static string replaceWord(const string& str, const string& from, const string& to);
+    // Return deque of strings split by the given delimiter
+    static std::deque<string> split(const string& str, char delimiter = ',');
     // Predicate to check if 'str' starts with 'prefix'
     static bool startsWith(const string& str, const char* prefixp) {
         return !str.rfind(prefixp, 0);  // Faster than .find(_) == 0

test_regress/t/t_altera_lpm.v

@@ -46,12 +46,7 @@
 //END_MODULE_NAME--------------------------------------------------------------
 
 //See also: https://github.com/twosigma/verilator_support
-// verilator lint_off COMBDLY
-// verilator lint_off INITIALDLY
-// verilator lint_off MULTIDRIVEN
-// verilator lint_off UNSIGNED
-// verilator lint_off WIDTH
-// verilator lint_off LATCH
+// verilator lint_off COMBDLY,INITIALDLY,LATCH,MULTIDRIVEN,UNSIGNED,WIDTH
 
 // BEGINNING OF MODULE
 `timescale 1 ps / 1 ps

test_regress/t/t_lib_prot.v

@@ -154,11 +154,9 @@ module t #(parameter GATED_CLK = 0) (/*AUTOARG*/
          logic possibly_gated_clk;
          if (GATED_CLK != 0) begin: yes_gated_clock
             logic clk_en_latch;
-            /* verilator lint_off COMBDLY */
-            /* verilator lint_off LATCH */
+            // verilator lint_off COMBDLY,LATCH
             always_comb if (clk == '0) clk_en_latch <= clk_en;
-            /* verilator lint_on LATCH */
-            /* verilator lint_on COMBDLY */
+            // verilator lint_on COMBDLY,LATCH
             assign possibly_gated_clk = clk & clk_en_latch;
          end else begin: no_gated_clock
             assign possibly_gated_clk = clk;

test_regress/t/t_lint_multiple_msgs.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.lint()
+
+test.passes()

test_regress/t/t_lint_multiple_msgs.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 Wilson Snyder.
+// SPDX-License-Identifier: CC0-1.0
+
+module t (
+    input [3:1] i3,
+    input [4:1] i4,
+    output [3:1] o3,
+    output [4:1] o4
+);
+
+  // verilator lint_off WIDTHTRUNC,WIDTHEXPAND  // after slashes ignored
+  assign o3 = i4;
+  assign o4 = i3;
+
+endmodule