Removal of contructors for interface classes

Signed-off-by: Igor Zaworski <izaworski@internships.antmicro.com>

src/V3CCtors.cpp

@@ -149,6 +149,10 @@ class CCtorsVisitor final : public VNVisitor {
 
     // VISITORS
     void visit(AstNodeModule* nodep) override {
+        if (const AstClass* const classp = VN_CAST(nodep, Class)) {
+            // Interface class may only have pure virtuals and params which do not need cctor reset
+            if (classp->isInterfaceClass()) return;
+        }
         VL_RESTORER(m_modp);
         VL_RESTORER(m_varResetp);
         m_modp = nodep;

src/V3EmitCBase.cpp

@@ -143,11 +143,12 @@ void EmitCBaseVisitorConst::emitCFuncHeader(const AstCFunc* funcp, const AstNode
     if (funcp->isConstructor()) {
         if (!withScope) putns(funcp, funcNameProtect(funcp, modp));
         if (!withScope) {
-            puts("() = default;\n");
+            puts("() = default");
             if (const AstClass* const classp = VN_CAST(modp, Class)) {
-                if (classp->isInterfaceClass()) puts("bool __VvirtClassInitialized = false;\n");
+                // Interfaces classes do not need a constructor
+                if (classp->isInterfaceClass()) return;
             }
-            puts("void ");
+            puts(";\nvoid ");
         }
         puts("init");
     } else {
@@ -168,7 +169,9 @@ void EmitCBaseVisitorConst::emitCFuncDecl(const AstCFunc* funcp, const AstNodeMo
         putns(funcp, "virtual ");
     }
     emitCFuncHeader(funcp, modp, /* withScope: */ false);
-    if (funcp->emptyBody() && !funcp->isLoose() && !cLinkage) {
+    const AstClass* const classp = VN_CAST(modp, Class);
+    if (funcp->emptyBody() && !funcp->isLoose() && !cLinkage
+        && !(funcp->isConstructor() && classp && classp->isInterfaceClass())) {
         putns(funcp, " {}\n");
     } else {
         putns(funcp, ";\n");

src/V3EmitCFunc.h

@@ -335,6 +335,7 @@ public:
         std::unordered_set<AstClass*> doneClasses;
         collectVirtualBasesRecursep(classp, virtualBases);
         for (AstClass* vbase : virtualBases) {
+            if (vbase->isInterfaceClass()) continue;
             if (doneClasses.count(vbase)) continue;
             doneClasses.emplace(vbase);
             puts(EmitCUtil::prefixNameProtect(vbase));
@@ -350,6 +351,7 @@ public:
         // Direct non-virtual bases in declaration order
         for (const AstClassExtends* extp = classp->extendsp(); extp;
              extp = VN_AS(extp->nextp(), ClassExtends)) {
+            if (extp->classp()->isInterfaceClass()) continue;
             if (extp->classp()->useVirtualPublic()) continue;
             if (doneClasses.count(extp->classp())) continue;
             doneClasses.emplace(extp->classp());
@@ -406,13 +408,7 @@ public:
         puts(" {\n");
         if (nodep->isConstructor()) {
             const AstClass* const classp = VN_CAST(nodep->scopep()->modp(), Class);
-            if (classp && classp->extendsp()) {
-                if (classp->isInterfaceClass()) {
-                    puts("if (__VvirtClassInitialized) return;\n");
-                    puts("__VvirtClassInitialized = true;\n");
-                }
-                putConstructorSubinit(classp, nodep);
-            }
+            if (classp && classp->extendsp()) putConstructorSubinit(classp, nodep);
         }
 
         // "+" in the debug indicates a print from the model

src/V3LinkDot.cpp

@@ -5288,7 +5288,10 @@ class LinkDotResolveVisitor final : public VNVisitor {
                         << classExtendsp->argsp()->warnContextSecondary());
                 }
                 if (classExtendsp && classExtendsp->classOrNullp()) {
-                    if (!m_explicitSuperNewp && m_statep->forParamed()) {
+                    if (!m_explicitSuperNewp && m_statep->forParamed()
+                        && !VN_AS(classExtendsp->childDTypep()->skipRefp(), ClassRefDType)
+                                ->classp()
+                                ->isInterfaceClass()) {
                         AstNodeStmt* const superNewp
                             = addImplicitSuperNewCall(VN_AS(nodep, Func), classExtendsp);
                         UINFO(9, "created super new " << superNewp);

src/V3Task.cpp

@@ -1310,9 +1310,15 @@ class TaskVisitor final : public VNVisitor {
 
         if (!nodep->dpiImport() && !nodep->taskPublic()) {
             // Need symbol table
-            if (cfuncp->name() == "new") {
-                const string stmt = VIdProtect::protect("_ctor_var_reset") + "(vlSymsp);";
-                cfuncp->addStmtsp(new AstCStmt{nodep->fileline(), stmt});
+            if (cfuncp->isConstructor()) {
+                bool isInterfaceClass = false;
+                if (const AstClass* const classp = VN_CAST(m_modp, Class)) {
+                    isInterfaceClass = classp->isInterfaceClass();
+                }
+                if (!isInterfaceClass) {
+                    const string stmt = VIdProtect::protect("_ctor_var_reset") + "(vlSymsp);";
+                    cfuncp->addStmtsp(new AstCStmt{nodep->fileline(), stmt});
+                }
             }
         }
         if (nodep->dpiContext()) {