[Thermo] deprecate name/id support in Phase::speciesIndex

include/cantera/thermo/Phase.h

@@ -68,15 +68,11 @@ class Solution;
  * operate on a state vector, which is in general of length (2 + nSpecies()).
  * The first two entries of the state vector are temperature and density.
  *
- * A species name may be referred to via three methods:
- *
- *    -   "speciesName"
- *    -   "PhaseId:speciesName"
- *    -   "phaseName:speciesName"
- *    .
- *
- * The first two methods of naming may not yield a unique species within
- * complicated assemblies of %Cantera Phases.
+ * A species name is referred to via "speciesName", which is unique within a
+ * given phase. Note that within multiphase mixtures ("MultiPhase"), both a
+ * phase name/index as well as species name are required to access information
+ * about a species in a particular phase. For surfaces, the species names are
+ * unique among the phases.
  *
  * @todo
  *   - Make the concept of saving state vectors more general, so that it can

src/thermo/Phase.cpp

@@ -214,6 +214,11 @@ size_t Phase::speciesIndex(const std::string& nameStr) const
         std::string pn;
         std::string sn = parseSpeciesName(nameStr, pn);
         if (pn == "" || pn == m_name || pn == m_id) {
+            warn_deprecated("Phase::speciesIndex()",
+                            "Retrieval of species indices via "
+                            "'PhaseId:speciesName' or 'phaseName:"
+                            "speciesName to be removed "
+                            "after Cantera 2.5.");
             it = m_speciesIndices.find(nameStr);
             if (it != m_speciesIndices.end()) {
                 return it->second;