Fix `new this` (#5909).

Changes

@@ -62,6 +62,7 @@ Verilator 5.035 devel
 * Fix process comparisons (#5896).
 * Fix ccache with clang (#5899). [Geza Lore]
 * Fix delayed assignment malformed LHS assertion (#5904).
+* Fix `new this` (#5909).
 
 
 Verilator 5.034 2025-02-24

src/V3AstNodeDType.h

@@ -120,15 +120,7 @@ public:
     // Iff has second dtype, set as generic node function
     virtual void virtRefDType2p(AstNodeDType* nodep) {}
     // Assignable equivalence.  Calls skipRefToNonRefp() during comparisons.
-    bool similarDType(const AstNodeDType* samep) const {
-        const AstNodeDType* nodep = this;
-        nodep = nodep->skipRefToNonRefp();
-        samep = samep->skipRefToNonRefp();
-        if (nodep == samep) return true;
-        if (nodep->type() != samep->type()) return false;
-        return nodep->similarDTypeNode(samep);
-    }
-
+    bool similarDType(const AstNodeDType* samep) const;
     // Iff has a non-null subDTypep(), as generic node function
     virtual AstNodeDType* subDTypep() const VL_MT_STABLE { return nullptr; }
     virtual bool isFourstate() const;
@@ -581,7 +573,11 @@ public:
         const AstClassRefDType* const asamep = VN_DBG_AS(samep, ClassRefDType);
         return (m_classp == asamep->m_classp && m_classOrPackagep == asamep->m_classOrPackagep);
     }
-    bool similarDTypeNode(const AstNodeDType* samep) const override { return sameNode(samep); }
+    bool similarDTypeNode(const AstNodeDType* samep) const override {
+        // Doesn't need to compare m_classOrPackagep
+        const AstClassRefDType* const asamep = VN_DBG_AS(samep, ClassRefDType);
+        return m_classp == asamep->m_classp;
+    }
     void dump(std::ostream& str = std::cout) const override;
     void dumpJson(std::ostream& str = std::cout) const override;
     void dumpSmall(std::ostream& str) const override;

src/V3AstNodes.cpp

@@ -848,6 +848,15 @@ const AstNodeDType* AstNodeDType::skipRefIterp(bool skipConst, bool skipEnum,
     }
 }
 
+bool AstNodeDType::similarDType(const AstNodeDType* samep) const {
+    const AstNodeDType* nodep = this;
+    nodep = nodep->skipRefToNonRefp();
+    samep = samep->skipRefToNonRefp();
+    if (nodep == samep) return true;
+    if (nodep->type() != samep->type()) return false;
+    return nodep->similarDTypeNode(samep);
+}
+
 bool AstNodeDType::isFourstate() const { return basicp() && basicp()->isFourstate(); }
 
 class AstNodeDType::CTypeRecursed final {

test_regress/t/t_class_new_this.v

@@ -21,16 +21,26 @@ class Testcase implements ICls;
    virtual function string get();
       return "In ICls";
    endfunction
+   function Testcase clone();
+      Testcase a = new this;
+      return a;
+   endfunction
 endclass
 
 module t(/*AUTOARG*/);
 
    initial begin
       Testcase test;
+      Testcase cloned;
       test = new;
       if (test.cls.name != "test_class") $stop;
       if (test.cls.icls.get() != "In ICls") $stop;
+
+      cloned = test.clone();
+      if (cloned.cls.name != "test_class") $stop;
+
       test.cls.icls = null; // Prevent leak
+
       $write("*-* All Finished *-*\n");
       $finish;
    end