Fix configure over-disabling warnings.

configure.ac

@@ -419,6 +419,7 @@ AC_LINK_IFELSE(
 CFG_WITH_THREADED=$_my_result
 AC_SUBST(CFG_WITH_THREADED)
 AC_MSG_RESULT($CFG_WITH_THREADED)
+CXXFLAGS="$ACO_SAVE_CXXFLAGS"
 
 # Check compiler flag
 if test "$CFG_WITH_THREADED" = "no" ; then

src/V3CCtors.cpp

@@ -146,13 +146,11 @@ void V3CCtors::cctorsAll() {
          modp = VN_CAST(modp->nextp(), NodeModule)) {
         // Process each module in turn
         {
-            AstCFunc* varResetFuncp;
             V3CCtorsVisitor var_reset(
                 modp, "_ctor_var_reset",
                 (VN_IS(modp, Class) ? EmitCBaseVisitor::symClassVar() : ""),
                 (VN_IS(modp, Class) ? "vlSymsp" : ""),
                 (VN_IS(modp, Class) ? "if (false && vlSymsp) {}  // Prevent unused\n" : ""));
-            varResetFuncp = var_reset.builtFuncp();
 
             for (AstNode* np = modp->stmtsp(); np; np = np->nextp()) {
                 if (AstVar* varp = VN_CAST(np, Var)) {

src/V3EmitC.cpp

@@ -1655,7 +1655,7 @@ class EmitCImp : EmitCStmts {
             string cvtarray = (adtypep->subDTypep()->isWide() ? ".data()" : "");
             return emitVarResetRecurse(varp, adtypep->subDTypep(), depth + 1,
                                        ".atDefault()" + cvtarray);
-        } else if (AstClassRefDType* adtypep = VN_CAST(dtypep, ClassRefDType)) {
+        } else if (VN_IS(dtypep, ClassRefDType)) {
             return "";  // Constructor does it
         } else if (AstDynArrayDType* adtypep = VN_CAST(dtypep, DynArrayDType)) {
             // Access std::array as C array