COMP: avoid ambiguous construction from tmp

src/combustionModels/singleStepCombustion/singleStepCombustion.C

@@ -118,7 +118,7 @@ singleStepCombustion<CombThermoType, ThermoType>::R
     if (semiImplicit_)
     {
         const label fNorm = singleMixturePtr_->specieProd()[specieI];
-        const volScalarField fres = singleMixturePtr_->fres(specieI);
+        const volScalarField fres(singleMixturePtr_->fres(specieI));
         wSpecie /= max(fNorm*(Y - fres), 1e-2);
 
         return -fNorm*wSpecie*fres + fNorm*fvm::Sp(wSpecie, Y);