From 90dc04cf93f09fab1f5284e27e9d457b6566ed64 Mon Sep 17 00:00:00 2001
From: Wilson Snyder <wsnyder@wsnyder.org>
Date: Sat, 20 Aug 2022 14:01:13 -0400
Subject: [PATCH] Add --future0 and --future1 options.

---
 Changes                         |  1 +
 docs/guide/exe_verilator.rst    | 24 ++++++++++++++++++++++++
 src/V3Options.cpp               | 15 +++++++++++++++
 src/V3Options.h                 |  6 ++++++
 test_regress/t/t_flag_future.pl |  2 +-
 5 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/Changes b/Changes
index 65ee0fd39..752f4c15c 100644
--- a/Changes
+++ b/Changes
@@ -13,6 +13,7 @@ Verilator 4.225 devel
 
 **Minor:**
 
+* Add --future0 and --future1 options.
 * Fix incorrect bit op tree optimization (#3470). [algrobman]
 * Fix empty string arguments to display (#3484). [Grulfen]
 * Fix table misoptimizing away display (#3488). [Stefan Post]
diff --git a/docs/guide/exe_verilator.rst b/docs/guide/exe_verilator.rst
index 5e1c6282f..0348c4db2 100644
--- a/docs/guide/exe_verilator.rst
+++ b/docs/guide/exe_verilator.rst
@@ -491,6 +491,30 @@ Summary:
    are typically used only when recommended by a maintainer to help debug
    or work around an issue.
 
+.. option:: -future0 <option>
+
+   Rarely needed.  Suppress an unknown Verilator option for an option that
+   takes no additional arguments.  This is used to allow scripts written
+   with pragmas for a later version of Verilator to run under a older
+   version.  e.g. :code:`-future0 option --option` would on older versions
+   that do not understand :code:`--option` or :code:`+option` suppress what
+   would otherwise be an invalid option error, and on newer versions that
+   implement :code:`--option`, :code:`-future0 option --option` would have
+   the :code:`-future0 option` ignored and the :code:`--option` would
+   function appropriately.
+
+.. option:: -future1 <option>
+
+   Rarely needed.  Suppress an unknown Verilator option for an option that
+   takes an additional argument.  This is used to allow scripts written
+   with pragmas for a later version of Verilator to run under a older
+   version.  e.g. :code:`-future1 option --option arg` would on older
+   versions that do not understand :code:`--option arg` or :code:`+option
+   arg` suppress what would otherwise be an invalid option error, and on
+   newer versions that implement :code:`--option arg`, :code:`-future1
+   option --option arg` would have the :code:`-future1 option` ignored and
+   the :code:`--option arg` would function appropriately.
+
 .. option:: -G<name>=<value>
 
    Overwrites the given parameter of the toplevel module. The value is
diff --git a/src/V3Options.cpp b/src/V3Options.cpp
index 8ef8038b6..6aced78e6 100644
--- a/src/V3Options.cpp
+++ b/src/V3Options.cpp
@@ -359,9 +359,17 @@ void V3Options::addCFlags(const string& filename) { m_cFlags.push_back(filename)
 void V3Options::addLdLibs(const string& filename) { m_ldLibs.push_back(filename); }
 void V3Options::addMakeFlags(const string& filename) { m_makeFlags.push_back(filename); }
 void V3Options::addFuture(const string& flag) { m_futures.insert(flag); }
+void V3Options::addFuture0(const string& flag) { m_future0s.insert(flag); }
+void V3Options::addFuture1(const string& flag) { m_future1s.insert(flag); }
 bool V3Options::isFuture(const string& flag) const {
     return m_futures.find(flag) != m_futures.end();
 }
+bool V3Options::isFuture0(const string& flag) const {
+    return m_future0s.find(flag) != m_future0s.end();
+}
+bool V3Options::isFuture1(const string& flag) const {
+    return m_future1s.find(flag) != m_future1s.end();
+}
 bool V3Options::isLibraryFile(const string& filename) const {
     return m_libraryFiles.find(filename) != m_libraryFiles.end();
 }
@@ -1083,6 +1091,8 @@ void V3Options::parseOptsList(FileLine* fl, const string& optdir, int argc, char
         parseOptsFile(fl, parseFileArg(optdir, valp), false);
     });
     DECL_OPTION("-flatten", OnOff, &m_flatten);
+    DECL_OPTION("-future0", CbVal, [this, fl, &optdir](const char* valp) { addFuture0(valp); });
+    DECL_OPTION("-future1", CbVal, [this, fl, &optdir](const char* valp) { addFuture1(valp); });
 
     DECL_OPTION("-facyc-simp", FOnOff, &m_fAcycSimp);
     DECL_OPTION("-fassemble", FOnOff, &m_fAssemble);
@@ -1512,8 +1522,13 @@ void V3Options::parseOptsList(FileLine* fl, const string& optdir, int argc, char
                 ++i;
             }
         } else if (argv[i][0] == '-' || argv[i][0] == '+') {
+            const char* argvNoDashp = (argv[i][1] == '-') ? (argv[i] + 2) : (argv[i] + 1);
             if (const int consumed = parser.parse(i, argc, argv)) {
                 i += consumed;
+            } else if (isFuture0(argvNoDashp)) {
+                ++i;
+            } else if (isFuture1(argvNoDashp)) {
+                i += 2;
             } else {
                 fl->v3fatal("Invalid option: " << argv[i] << parser.getSuggestion(argv[i]));
                 ++i;  // LCOV_EXCL_LINE
diff --git a/src/V3Options.h b/src/V3Options.h
index 4db4e9d05..8637277bb 100644
--- a/src/V3Options.h
+++ b/src/V3Options.h
@@ -199,6 +199,8 @@ private:
     V3StringList m_ldLibs;      // argument: user LDFLAGS
     V3StringList m_makeFlags;   // argument: user MAKEFLAGS
     V3StringSet m_futures;      // argument: -Wfuture- list
+    V3StringSet m_future0s;     // argument: -future list
+    V3StringSet m_future1s;     // argument: -future1 list
     V3StringSet m_libraryFiles; // argument: Verilog -v files
     V3StringSet m_clockers;     // argument: Verilog -clk signals
     V3StringSet m_noClockers;   // argument: Verilog -noclk signals
@@ -371,6 +373,8 @@ private:
     void addArg(const string& arg);
     void addDefine(const string& defline, bool allowPlus);
     void addFuture(const string& flag);
+    void addFuture0(const string& flag);
+    void addFuture1(const string& flag);
     void addIncDirUser(const string& incdir);  // User requested
     void addIncDirFallback(const string& incdir);  // Low priority if not found otherwise
     void addParameter(const string& paramline, bool allowPlus);
@@ -572,6 +576,8 @@ public:
     void checkParameters();
 
     bool isFuture(const string& flag) const;
+    bool isFuture0(const string& flag) const;
+    bool isFuture1(const string& flag) const;
     bool isLibraryFile(const string& filename) const;
     bool isClocker(const string& signame) const;
     bool isNoClocker(const string& signame) const;
diff --git a/test_regress/t/t_flag_future.pl b/test_regress/t/t_flag_future.pl
index c6b72116c..5216b1dfd 100755
--- a/test_regress/t/t_flag_future.pl
+++ b/test_regress/t/t_flag_future.pl
@@ -11,7 +11,7 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 scenarios(vlt => 1);
 
 lint(
-    verilator_flags2 => [qw(--lint-only -Wfuture-FUTURE1 -Wfuture-FUTURE2)],
+    verilator_flags2 => [qw(--lint-only --future0 thefuture --future1 thefuturei --thefuture -thefuture +thefuture --thefuturei 1 -Wfuture-FUTURE1 -Wfuture-FUTURE2)],
     );
 
 ok(1);