Fix lint_off disables on preprocessor warnings (#4703).

Changes

@@ -16,6 +16,7 @@ Verilator 5.021 devel
 * Add predicted stack overflow warning (#4799).
 * Remove deprecated 32-bit pointer mode (`gcc -m32`).
 * Fix delays using wrong timeunits when modules inlined (#4806). [Paul Wright]
+* Fix lint_off disables on preprocessor warnings (#4703). [Srinivasan Venkataramanan]
 
 
 Verilator 5.020 2024-01-01

src/V3PreLex.h

@@ -162,6 +162,7 @@ public:  // Used only by V3PreLex.cpp and V3PreProc.cpp
     int m_streamDepth = 0;  // Depth of stream processing
     YY_BUFFER_STATE m_bufferState;  // Flex state
     FileLine* m_tokFilelinep;  // Starting position of current token
+    std::deque<FileLine> m_lexLintState;  // Current lint state for save/restore
 
     // State to lexer
     static V3PreLex* s_currentLexp;  ///< Current lexing point
@@ -209,6 +210,9 @@ public:  // Used only by V3PreLex.cpp and V3PreProc.cpp
         }
     }
     void warnBackslashSpace();
+    void verilatorCmtLint(const char* textp, bool warnOff);
+    void verilatorCmtLintRestore();
+    void verilatorCmtLintSave();
     // Called by V3PreProc.cpp to inform lexer
     void pushStateDefArg(int level);
     void pushStateDefForm();

src/V3PreLex.l

@@ -66,7 +66,6 @@ static void appendDefValue(const char* t, size_t l) { LEXP->appendDefValue(t, l)
 %}
 
 %x ARGMODE
-%x CMTBEGM
 %x CMTMODE
 %x CMTONEM
 %x DEFCMT
@@ -420,6 +419,16 @@ bom             [\357\273\277]
 <ARGMODE>[^\/\*\n\r\\(,){}\[\]\"`]+     |
 <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"[^*]*"*/"      { 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; }
+<INITIAL>"/*"{ws}*"verilator lint_save"[^*]*"*/"     { FL_FWDC; LEXP->verilatorCmtLintSave(); return VP_COMMENT; }
+
         /* One line comments. */
 <INITIAL>"//"{ws}*{crnl} { FL_FWDC; linenoInc(); yytext=(char*)"\n"; yyleng=1; return VP_WHITE; }
 <INITIAL>"//"           { yy_push_state(CMTONEM); yymore(); }
@@ -427,16 +436,13 @@ bom             [\357\273\277]
 
         /* C-style comments. */
         /**** See also DEFCMT */
-        /* We distinguish between the start of a comment, and later, to look for prefix comments (deprecated) */
 <INITIAL>"/*"           { yy_push_state(CMTMODE); yymore(); }
-<CMTBEGM>{ws}+          { yymore(); }
-<CMTBEGM,CMTMODE>"*/"           { FL_FWDC; yy_pop_state(); return VP_COMMENT; }
-<CMTBEGM,CMTMODE>{crnl}         { linenoInc(); yymore(); }
-<CMTBEGM,CMTMODE><<EOF>>        { FL_FWDC; yyerrorf("EOF in '/* ... */' block comment\n");
+<CMTMODE>"*/"           { FL_FWDC; yy_pop_state(); return VP_COMMENT; }
+<CMTMODE>{crnl}         { linenoInc(); yymore(); }
+<CMTMODE><<EOF>>        { FL_FWDC; yyerrorf("EOF in '/* ... */' block comment\n");
                                   yyleng=0; return VP_EOF_ERROR; }
-<CMTMODE>{word}                 { yymore(); }
-<CMTBEGM>.                      { yymore(); BEGIN CMTMODE; }    /* beginning in comment */
-<CMTMODE>.                      { yymore(); }
+<CMTMODE>{word}         { yymore(); }
+<CMTMODE>.              { yymore(); }
 
         /* Define calls */
         /* symbdef prevents normal lex rules from making `\`"foo a symbol {`"foo} instead of a BACKQUOTE */
@@ -735,6 +741,33 @@ void V3PreLex::unused() {
     }  // LCOV_EXCL_STOP
 }
 
+void V3PreLex::verilatorCmtLintSave() {
+    m_lexLintState.push_back(*curFilelinep());
+}
+void V3PreLex::verilatorCmtLintRestore() {
+    // No error here on restore without save - the verilog.y parse will report as appropriate
+    if (m_lexLintState.empty()) return;
+    curFilelinep()->warnStateFrom(m_lexLintState.back());
+    m_lexLintState.pop_back();
+}
+void V3PreLex::verilatorCmtLint(const char* textp, bool warnOff) {
+    const char* sp = textp;
+    while (*sp && std::isspace(*sp)) ++sp;
+    while (*sp && !std::isspace(*sp)) ++sp;  // "verilator"
+    while (*sp && std::isspace(*sp)) ++sp;
+    while (*sp && !std::isspace(*sp)) ++sp;  // "lint_on/lint_off"
+    while (*sp && std::isspace(*sp)) ++sp;
+    string msg = sp;
+    for (auto pos = msg.begin(); pos != msg.end(); ++pos) {
+        if (std::isspace(*pos) || *pos == '*') {
+            msg.erase(pos, msg.end());
+            break;
+        }
+    }
+    // No warnings on bad warning codes - the verilog.y parse will report as appropriate
+    curFilelinep()->warnOff(msg, warnOff);
+}
+
 /*###################################################################
  * Local Variables:
  * mode: C++

test_regress/t/t_pp_dupdef_pragma_bad.out

@@ -0,0 +1,13 @@
+%Warning-REDEFMACRO: t/t_pp_dupdef_pragma_bad.v:11:19: Redefining existing define: 'DUP', with different value: 'b_bad'
+                     t/t_pp_dupdef_pragma_bad.v:11:19: ... Location of previous definition, with value: 'a'
+                     ... For warning description see https://verilator.org/warn/REDEFMACRO?v=latest
+                     ... Use "/* verilator lint_off REDEFMACRO */" and lint_on around source to disable this message.
+%Warning-REDEFMACRO: t/t_pp_dupdef_pragma_bad.v:16:19: Redefining existing define: 'DUP', with different value: 'd_bad'
+                     t/t_pp_dupdef_pragma_bad.v:16:19: ... Location of previous definition, with value: 'c_nowarn'
+%Warning-REDEFMACRO: t/t_pp_dupdef_pragma_bad.v:21:19: Redefining existing define: 'DUP', with different value: 'f_bad'
+                     t/t_pp_dupdef_pragma_bad.v:21:19: ... Location of previous definition, with value: 'e_nowarn'
+%Warning-REDEFMACRO: t/t_pp_dupdef_pragma_bad.v:26:19: Redefining existing define: 'DUP', with different value: 'k_bad'
+                     t/t_pp_dupdef_pragma_bad.v:26:19: ... Location of previous definition, with value: 'j_nowarn'
+%Warning-REDEFMACRO: t/t_pp_dupdef_pragma_bad.v:31:19: Redefining existing define: 'DUP', with different value: 'm_bad'
+                     t/t_pp_dupdef_pragma_bad.v:31:19: ... Location of previous definition, with value: 'l_nowarn'
+%Error: Exiting due to

test_regress/t/t_pp_dupdef_pragma_bad.pl

@@ -0,0 +1,19 @@
+#!/usr/bin/env perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2008 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
+
+scenarios(vlt => 1);
+
+lint(
+    fails => 1,
+    expect_filename => $Self->{golden_filename},
+    );
+
+ok(1);
+1;

test_regress/t/t_pp_dupdef_pragma_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, 2008 by Wilson Snyder.
+// SPDX-License-Identifier: CC0-1.0
+
+module t;
+
+`define DUP a
+`define DUP b_bad
+
+// verilator lint_off REDEFMACRO
+`define DUP c_nowarn
+// verilator lint_on REDEFMACRO
+`define DUP d_bad
+// verilator lint_save
+// verilator lint_off REDEFMACRO
+`define DUP e_nowarn
+// verilator lint_restore
+`define DUP f_bad
+
+/* verilator lint_off REDEFMACRO */
+`define DUP j_nowarn
+/* verilator lint_on REDEFMACRO */
+`define DUP k_bad
+/* verilator lint_save */
+/* verilator lint_off REDEFMACRO */
+`define DUP l_nowarn
+/* verilator lint_restore */
+`define DUP m_bad
+
+endmodule