Fix toggle coverage dataDeclp error on multi-edge driven signals.

src/V3AstNodeOther.h

@@ -2653,7 +2653,7 @@ public:
     const char* broken() const override {
         if (m_dataDeclp
             && (m_dataDeclp == this || m_dataDeclp->m_dataDeclp)) {  // Avoid O(n^2) accessing
-            v3fatalSrc("dataDeclp should point to real data, not be a list");
+            v3fatalSrc("dataDeclp should point to real data, not be a list: " << cvtToHex(this));
         }
         return nullptr;
     }

src/V3CoverageJoin.cpp

@@ -48,6 +48,8 @@ class CoverageJoinVisitor final : public VNVisitor {
         V3DupFinder dupFinder;  // Duplicate code detection
         // Hash all of the original signals we toggle cover
         for (AstCoverToggle* nodep : m_toggleps) dupFinder.insert(nodep->origp());
+        if (dumpLevel() || debug() >= 9)
+            dupFinder.dumpFile(v3Global.debugFilename("coveragejoin") + ".hash", false);
         // Find if there are any duplicates
         for (AstCoverToggle* nodep : m_toggleps) {
             // nodep->backp() is null if we already detected it's a duplicate and unlinked earlier
@@ -85,7 +87,8 @@ class CoverageJoinVisitor final : public VNVisitor {
     }
 
     // VISITORS
-    void visit(AstNetlist* nodep) override {
+    void visit(AstActive* nodep) override {
+        m_toggleps.clear();
         // Find all Coverage's
         iterateChildren(nodep);
         // Simplify

src/V3DupFinder.cpp

@@ -53,6 +53,7 @@ V3DupFinder::iterator V3DupFinder::findDuplicate(AstNode* nodep, V3DupFinderUser
 }
 
 void V3DupFinder::dumpFile(const string& filename, bool tree) {
+    UINFO(2, "Dumping " << filename << endl);
     const std::unique_ptr<std::ofstream> logp{V3File::new_ofstream(filename)};
     if (logp->fail()) v3fatal("Can't write " << filename);