suppress warnings and errors when lookup succeeds on a subsequent try

bindings/pyroot/cppyy/CPyCppyy/src/Cppyy.h

@@ -231,8 +231,8 @@ namespace Cppyy {
  CPPYY_IMPORT
  bool IsMethodTemplate(TCppScope_t scope, TCppIndex_t imeth);
  CPPYY_IMPORT
- TCppMethod_t
- GetMethodTemplate(TCppScope_t scope, const std::string &name, const std::string &proto, std::ostream &diagnostics);
+ TCppMethod_t GetMethodTemplate(TCppScope_t scope, const std::string &name, const std::string &proto,
+  std::ostringstream &diagnostics);
 
  CPPYY_IMPORT
  TCppIndex_t GetGlobalOperator(

bindings/pyroot/cppyy/CPyCppyy/src/TemplateProxy.cxx

@@ -218,12 +218,14 @@ PyObject* TemplateProxy::Instantiate(const std::string& fname,
  pos = proto.find("initializer_list", pos + 6);
  }
 
- Cppyy::TCppMethod_t m2 = Cppyy::GetMethodTemplate(scope, fname, proto, diagnostics);
+ std::ostringstream diagnostics2;
+ Cppyy::TCppMethod_t m2 = Cppyy::GetMethodTemplate(scope, fname, proto, diagnostics2);
  if (m2 && m2 != cppmeth) {
  // replace if the new method with vector was found; otherwise just continue
  // with the previously found method with initializer_list.
  cppmeth = m2;
  resname = Cppyy::GetMethodFullName(cppmeth);
+ diagnostics = std::move(diagnostics2);
  }
  }
 
@@ -241,6 +243,10 @@ PyObject* TemplateProxy::Instantiate(const std::string& fname,
  Py_DECREF(pyol);
  Py_DECREF(pycachename);
  Py_DECREF(dct);
+
+ PyErr_Format(PyExc_TypeError, "Failed to instantiate \"%s(%s)\"\n%s", fname.c_str(), proto.c_str(),
+ diagnostics.str().c_str());
+
  return nullptr;
  }
 

bindings/pyroot/cppyy/cppyy-backend/clingwrapper/src/clingwrapper.cxx

@@ -1837,7 +1837,7 @@ bool Cppyy::IsMethodTemplate(TCppScope_t scope, TCppIndex_t idx)
 static std::map<TDictionary::DeclId_t, CallWrapper*> gMethodTemplates;
 
 Cppyy::TCppMethod_t Cppyy::GetMethodTemplate(TCppScope_t scope, const std::string &name, const std::string &proto,
- std::ostream &diagnostics)
+ std::ostringstream &diagnostics)
 {
 // There is currently no clean way of extracting a templated method out of ROOT/meta
 // for a variety of reasons, none of them fundamental. The game played below is to
@@ -1854,6 +1854,7 @@ Cppyy::TCppMethod_t Cppyy::GetMethodTemplate(TCppScope_t scope, const std::strin
 // redirect diagnostics, taking the lock to make sure no other calls pollute the results
 R__WRITE_LOCKGUARD(ROOT::gCoreMutex);
 
+const std::string diagnosticsold = diagnostics.str();
 TInterpreter::RedirectDiagnostics redirectRAII(gInterpreter, diagnostics, /*enableColors*/ true, /*indent*/ 4);
 
 TFunction *func = nullptr;
@@ -1885,15 +1886,25 @@ if (scope == (cppyy_scope_t)GLOBAL_HANDLE) {
 
  if (!func && name.back() == '>' && (cl || scope == (cppyy_scope_t)GLOBAL_HANDLE)) {
  // try again, ignoring proto in case full name is complete template
- auto declid = gInterpreter->GetFunction(cl, name.c_str());
- if (declid) {
- auto existing = gMethodTemplates.find(declid);
- if (existing == gMethodTemplates.end()) {
- auto cw = new_CallWrapper(declid, name);
- existing = gMethodTemplates.insert(std::make_pair(declid, cw)).first;
- }
- return (TCppMethod_t)existing->second;
+ std::ostringstream diagnostics2;
+ TInterpreter::RedirectDiagnostics redirectRAII2(gInterpreter, diagnostics2, /*enableColors*/ true, /*indent*/ 4);
+
+ auto declid = gInterpreter->GetFunction(cl, name.c_str());
+ if (declid) {
+ auto existing = gMethodTemplates.find(declid);
+ if (existing == gMethodTemplates.end()) {
+ auto cw = new_CallWrapper(declid, name);
+ existing = gMethodTemplates.insert(std::make_pair(declid, cw)).first;
+ }
+ // replace diagnostics to suppress spurious errors or warnings from the previous
+ // failed lookup
+ diagnostics = std::ostringstream();
+ diagnostics << diagnosticsold;
+ diagnostics << diagnostics2.str();
+
+ return (TCppMethod_t)existing->second;
  }
+ diagnostics << diagnostics2.str();
  }
 
  if (func) {
@@ -1909,16 +1920,24 @@ if (scope == (cppyy_scope_t)GLOBAL_HANDLE) {
  if (name.back() == '>') {
  auto pos = name.find('<');
  if (pos != std::string::npos) {
- TCppMethod_t cppmeth = GetMethodTemplate(scope, name.substr(0, pos), proto, diagnostics);
+ std::ostringstream diagnostics2;
+ TCppMethod_t cppmeth = GetMethodTemplate(scope, name.substr(0, pos), proto, diagnostics2);
  if (cppmeth) {
  // allow if requested template names match up to the result
  const std::string &alt = GetMethodFullName(cppmeth);
  if (name.size() < alt.size() && alt.find('<') == pos) {
  const std::string &partial = name.substr(pos, name.size() - 1 - pos);
- if (strncmp(partial.c_str(), alt.substr(pos, alt.size() - 1 - pos).c_str(), partial.size()) == 0)
+ if (strncmp(partial.c_str(), alt.substr(pos, alt.size() - 1 - pos).c_str(), partial.size()) == 0) {
+ // replace diagnostics to suppress spurious errors or warnings
+ // from the previous failed lookup
+ diagnostics = std::ostringstream();
+ diagnostics << diagnosticsold;
+ diagnostics << diagnostics2.str();
  return cppmeth;
+ }
  }
  }
+ diagnostics << diagnostics2.str();
  }
  }
 

bindings/pyroot/cppyy/cppyy-backend/clingwrapper/src/cpp_cppyy.h

@@ -207,8 +207,8 @@ namespace Cppyy {
  RPY_EXPORTED
  bool IsMethodTemplate(TCppScope_t scope, TCppIndex_t imeth);
  RPY_EXPORTED
- TCppMethod_t
- GetMethodTemplate(TCppScope_t scope, const std::string &name, const std::string &proto, std::ostream &diagnostics);
+ TCppMethod_t GetMethodTemplate(TCppScope_t scope, const std::string &name, const std::string &proto,
+  std::ostringstream &diagnostics);
 
  RPY_EXPORTED
  TCppIndex_t GetGlobalOperator(