[Thermo] Revert to previous state after error setting thermo state

This prevents ThermoPhase objects from ending up in broken states
where they can't be set to a new state because of a partially-applied
invalid state, for example caused by an out-of-range temperature.

src/thermo/Phase.cpp

@@ -397,8 +397,15 @@ void Phase::setMassFractionsByName(const string& y)
 
 void Phase::setState_TD(double t, double rho)
 {
-    setTemperature(t);
-    setDensity(rho);
+    vector<double> state(partialStateSize());
+    savePartialState(state.size(), state.data());
+    try {
+        setTemperature(t);
+        setDensity(rho);
+    } catch (std::exception&) {
+        restorePartialState(state.size(), state.data());
+        throw;
+    }
 }
 
 double Phase::molecularWeight(size_t k) const

src/thermo/ThermoPhase.cpp

@@ -120,26 +120,40 @@ void ThermoPhase::setState_TPY(double t, double p, const string& y)
 
 void ThermoPhase::setState_TP(double t, double p)
 {
-    double tsave = temperature();
-    double dsave = density();
+    vector<double> state(partialStateSize());
+    savePartialState(state.size(), state.data());
     try {
         setTemperature(t);
         setPressure(p);
-    } catch (CanteraError&) {
-        setState_TD(tsave, dsave);
+    } catch (std::exception&) {
+        restorePartialState(state.size(), state.data());
         throw;
     }
 }
 
 void ThermoPhase::setState_HP(double Htarget, double p, double rtol)
 {
-    setState_HPorUV(Htarget, p, rtol, false);
+    vector<double> state(partialStateSize());
+    savePartialState(state.size(), state.data());
+    try {
+        setState_HPorUV(Htarget, p, rtol, false);
+    } catch (std::exception&) {
+        restorePartialState(state.size(), state.data());
+        throw;
+    }
 }
 
 void ThermoPhase::setState_UV(double u, double v, double rtol)
 {
     assertCompressible("setState_UV");
-    setState_HPorUV(u, v, rtol, true);
+    vector<double> state(partialStateSize());
+    savePartialState(state.size(), state.data());
+    try {
+        setState_HPorUV(u, v, rtol, true);
+    } catch (std::exception&) {
+        restorePartialState(state.size(), state.data());
+        throw;
+    }
 }
 
 void ThermoPhase::setState(const AnyMap& input_state)
@@ -452,13 +466,27 @@ void ThermoPhase::setState_HPorUV(double Htarget, double p,
 
 void ThermoPhase::setState_SP(double Starget, double p, double rtol)
 {
-    setState_SPorSV(Starget, p, rtol, false);
+    vector<double> state(partialStateSize());
+    savePartialState(state.size(), state.data());
+    try {
+        setState_SPorSV(Starget, p, rtol, false);
+    } catch (std::exception&) {
+        restorePartialState(state.size(), state.data());
+        throw;
+    }
 }
 
 void ThermoPhase::setState_SV(double Starget, double v, double rtol)
 {
     assertCompressible("setState_SV");
-    setState_SPorSV(Starget, v, rtol, true);
+    vector<double> state(partialStateSize());
+    savePartialState(state.size(), state.data());
+    try {
+        setState_SPorSV(Starget, v, rtol, true);
+    } catch (std::exception&) {
+        restorePartialState(state.size(), state.data());
+        throw;
+    }
 }
 
 void ThermoPhase::setState_SPorSV(double Starget, double p,

test/thermo/ThermoPhase_Test.cpp

@@ -302,4 +302,61 @@ TEST_F(EquilRatio_MixFrac_Test, EquilRatio_MixFrac_StoichMix_Mass)
     test_stoich_mixture(ThermoBasis::mass, 0.050011556441079318, 18.995378491732041);
 }
 
+struct SetStateRecovery : public testing::Test
+{
+    SetStateRecovery() {
+        auto soln = newSolution("debye-huckel-all.yaml", "debye-huckel-B-dot-ak-IAPWS");
+        thermo = soln->thermo();
+        T1 = thermo->temperature();
+        P1 = thermo->pressure();
+        h1 = thermo->enthalpy_mass();
+        cp1 = thermo->cp_mass();
+        s1 = thermo->entropy_mass();
+    }
+
+    shared_ptr<ThermoPhase> thermo;
+    double T1, P1, h1, cp1, s1;
+};
+
+TEST_F(SetStateRecovery, HP)
+{
+    double h2 = h1 + cp1 * (600 - T1); // Water state is invalid at 600 K
+    EXPECT_THROW(thermo->setState_HP(h2, P1), CanteraError);
+    EXPECT_DOUBLE_EQ(thermo->temperature(), T1);
+    EXPECT_DOUBLE_EQ(thermo->pressure(), P1);
+    double h3 = h1 + cp1 * (350 - T1);
+    thermo->setState_HP(h3, P1);
+    EXPECT_NEAR(thermo->temperature(), 350, 1.0);
+}
+
+TEST_F(SetStateRecovery, SP)
+{
+    double T3 = T1 + 0.5 * (600 - T1);
+    thermo->setState_TP(T3, P1);
+    double s3 = thermo->entropy_mass();
+    double s2 = s1 + 2.0 * (s3 - s1);
+    thermo->setState_TP(T1, P1);
+    EXPECT_THROW(thermo->setState_SP(s2, P1), CanteraError);
+    EXPECT_DOUBLE_EQ(thermo->temperature(), T1);
+    EXPECT_DOUBLE_EQ(thermo->pressure(), P1);
+    thermo->setState_SP(s3, P1);
+    EXPECT_NEAR(thermo->temperature(), T3, 1e-2);
+}
+
+TEST_F(SetStateRecovery, TD)
+{
+    EXPECT_THROW(thermo->setState_TD(400, -1), CanteraError);
+    EXPECT_DOUBLE_EQ(thermo->temperature(), T1);
+    EXPECT_DOUBLE_EQ(thermo->pressure(), P1);
+    thermo->setState_TP(500, 2 * P1);
+}
+
+TEST_F(SetStateRecovery, TP)
+{
+    EXPECT_THROW(thermo->setState_TP(400, -1), CanteraError);
+    EXPECT_DOUBLE_EQ(thermo->temperature(), T1);
+    EXPECT_DOUBLE_EQ(thermo->pressure(), P1);
+    thermo->setState_TP(500, 2 * P1);
+}
+
 }