Report error on typedef referencing self (#2539).

Changes

@@ -12,6 +12,8 @@ The contributors that suggested a given feature are shown in []. Thanks!
 
 ***   Support static methods and typedefs in classes (#2615). [Krzysztof Bieganski]
 
+****  Report error on typedef referencing self (#2539). [Cody Piersall]
+
 ****  Fix iteration over mutating list bug in VPI (#2588). [Kaleb Barrett]
 
 ****  Fix return from callValueCbs (#2589) (#2605). [Marlon James]

src/V3Width.cpp

@@ -1605,6 +1605,17 @@ private:
     }
     virtual void visit(AstTypedef* nodep) override {
         if (nodep->didWidthAndSet()) return;  // This node is a dtype & not both PRELIMed+FINALed
+        if (auto* refp = checkRefToTypedefRecurse(nodep, nodep)) {
+            nodep->v3error("Typedef has self-reference: " << nodep->prettyNameQ() << endl
+                                                          << nodep->warnContextPrimary() << endl
+                                                          << refp->warnOther()
+                                                          << "... Location of reference" << endl
+                                                          << refp->warnContextSecondary());
+            // May cause internel error but avoids infinite loop on dump
+            refp->typedefp(nullptr);
+            VL_DO_DANGLING(pushDeletep(nodep->unlinkFrBack()), nodep);
+            return;
+        }
         nodep->dtypep(iterateEditMoveDTypep(nodep, nodep->subDTypep()));
         userIterateChildren(nodep, nullptr);
     }
@@ -5808,6 +5819,20 @@ private:
         }
         return nodep;  // By default return this
     }
+    AstRefDType* checkRefToTypedefRecurse(AstNode* nodep, AstTypedef* typedefp) {
+        // Recurse all children looking for self reference
+        // This avoids iterateEditMoveDTypep going into a hard to resolve loop
+        // Only call once for any given typedef, or will become O(n^2)
+        if (VL_LIKELY(!nodep)) return nullptr;
+        if (auto* refp = VN_CAST(nodep, RefDType)) {
+            if (refp->typedefp() == typedefp) return refp;
+        }
+        if (auto* refp = checkRefToTypedefRecurse(nodep->op1p(), typedefp)) return refp;
+        if (auto* refp = checkRefToTypedefRecurse(nodep->op2p(), typedefp)) return refp;
+        if (auto* refp = checkRefToTypedefRecurse(nodep->op3p(), typedefp)) return refp;
+        if (auto* refp = checkRefToTypedefRecurse(nodep->op4p(), typedefp)) return refp;
+        return nullptr;
+    }
 
     //----------------------------------------------------------------------
     // METHODS - special iterators

test_regress/t/t_enum_bad_circdecl.out

@@ -0,0 +1,8 @@
+%Error: t/t_enum_bad_circdecl.v:11:6: Typedef has self-reference: 'bad_redecl'
+                                    : ... In instance t
+   11 |    } bad_redecl;
+      |      ^~~~~~~~~~
+        t/t_enum_bad_circdecl.v:9:17: ... Location of reference
+    9 |    typedef enum bad_redecl [2:0] {
+      |                 ^~~~~~~~~~
+%Error: Exiting due to

test_regress/t/t_enum_bad_circdecl.pl

@@ -0,0 +1,20 @@
+#!/usr/bin/env perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2003 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(linter => 1);
+
+lint(
+    verilator_flags2 => ["--lint-only -Wwarn-VARHIDDEN"],
+    fails => 1,
+    expect_filename => $Self->{golden_filename},
+    );
+
+ok(1);
+1;

test_regress/t/t_enum_bad_circdecl.v

@@ -0,0 +1,13 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2020 by Wilson Snyder.
+// SPDX-License-Identifier: CC0-1.0
+
+module t();
+
+   typedef enum bad_redecl [2:0] {
+      VALUE
+   } bad_redecl;
+
+endmodule