Add template to VPSet for cfi files

The ParameterSetDescription passed to the declaration of a VPSet in fillDescriptions will be used to generate the value passed as `template` to the VPSet.

Author: Dr15Jones

FWCore/Integration/test/unit_test_outputs/testProducerWithPsetDesc_cfi.py

@@ -187,10 +187,25 @@
     ouDrinks = cms.untracked.uint32(5)
   ),
   test104 = cms.untracked.VPSet(
-    cms.PSet()
+    cms.PSet(),
+    template = cms.PSetTemplate(
+        Drinks = cms.uint32(5),
+        ndoDrinks = cms.optional.uint32,
+        ndouDrinks = cms.optional.untracked.uint32,
+        oDrinks = cms.uint32(5),
+        ouDrinks = cms.untracked.uint32(5),
+        uDrinks = cms.untracked.uint32(5)
+    )
   ),
   test105 = cms.untracked.VPSet(
-  ),
+    template = cms.PSetTemplate(
+        Drinks = cms.uint32(5),
+        ndoDrinks = cms.optional.uint32,
+        ndouDrinks = cms.optional.untracked.uint32,
+        oDrinks = cms.uint32(5),
+        ouDrinks = cms.untracked.uint32(5),
+        uDrinks = cms.untracked.uint32(5)
+    )  ),
   test1 = cms.double(0.1),
   test2 = cms.double(0.2),
   testA = cms.string('fooA'),
@@ -228,6 +243,35 @@
           xvalue = cms.int32(17)
         )
       )
+    ),
+    template = cms.PSetTemplate(
+        Drinks = cms.uint32(5),
+        anotherVPSet = cms.VPSet(
+            cms.PSet(),
+            cms.PSet(
+                xvalue = cms.int32(100)
+            ),
+            template = cms.PSetTemplate(
+                xvalue = cms.int32(7)
+            )
+        ),
+        ndoDrinks = cms.optional.uint32,
+        ndouDrinks = cms.optional.untracked.uint32,
+        oDrinks = cms.uint32(5),
+        ouDrinks = cms.untracked.uint32(5),
+        testDeeplyNested = cms.PSet(
+            bswitch = cms.bool(False),
+            bvalue1 = cms.double(101),
+            bvalue2 = cms.double(101),
+            iswitch = cms.int32(1),
+            ivalue1 = cms.double(101),
+            ivalue2 = cms.untracked.double(101),
+            sswitch = cms.string('1'),
+            svalue1 = cms.double(101),
+            svalue2 = cms.double(101),
+            testint = cms.int32(1000)
+        ),
+        uDrinks = cms.untracked.uint32(5)
     )
   ),
   subpset = cms.PSet(
@@ -369,6 +413,13 @@
     cms.PSet(
       type = cms.string('edmtestAnotherMakerWithRecursivePlugin'),
       value = cms.int32(11)
+    ), 
+    template = cms.PSetTemplate(
+        pluginRecursive = cms.PSet(
+
+        ),
+        type = cms.string('edmtestAnotherMakerWithRecursivePlugin'),
+        value = cms.int32(5)
     )
   ),
   mightGet = cms.optional.untracked.vstring

FWCore/ParameterSet/interface/ParameterSetDescription.h

@@ -296,6 +296,7 @@ namespace edm {
 
     const_iterator end() const { return entries_.end(); }
 
+    bool empty() const noexcept { return entries_.empty(); }
     // Better performance if space is reserved for the number of
     // top level parameters before any are added.
     void reserve(SetDescriptionEntries::size_type n) { entries_.reserve(n); }

FWCore/ParameterSet/src/ParameterDescription.cc

@@ -365,14 +365,23 @@ namespace edm {
                                                                    int indentation,
                                                                    CfiOptions& options) const {
     bool nextOneStartsWithAComma = false;
-    for_all(vPset_,
-            std::bind(&writeOneElementToCfi,
-                      std::placeholders::_1,
-                      std::ref(os),
-                      indentation,
-                      options,
-                      std::ref(nextOneStartsWithAComma)));
-    os << "\n";
+    for (auto const& p : vPset_) {
+      writeOneElementToCfi(p, os, indentation, options, nextOneStartsWithAComma);
+    }
+    if (cfi::shouldWriteUntyped(options) or psetDesc_->empty() or psetDesc_->anythingAllowed() or
+        psetDesc_->isUnknown()) {
+      os << "\n";
+    } else {
+      if (not vPset_.empty()) {
+        os << ",";
+      }
+      os << "\n";
+      printSpaces(os, indentation + 2);
+      CfiOptions fullOp = cfi::Typed{};
+      os << "template = cms.PSetTemplate(";
+      psetDesc_->writeCfi(os, false, indentation + 4, fullOp);
+      os << ")\n";
+    }
     printSpaces(os, indentation);
   }
 

FWCore/ParameterSet/test/test_catch_ParameterSetDescription.cc

@@ -1398,6 +1398,36 @@ vp = cms.VPSet(
     p = cms.PSet(),
     vp = cms.VPSet(
     )
+  ),
+  template = cms.PSetTemplate(
+    i = cms.required.int32,
+    vi = cms.required.vint32,
+    ui = cms.required.uint32,
+    vui = cms.required.vuint32,
+    l = cms.required.int64,
+    vl = cms.required.vint64,
+    ul = cms.required.uint64,
+    vul = cms.required.vuint64,
+    b = cms.required.bool,
+    d = cms.required.double,
+    vd = cms.required.vdouble,
+    s = cms.required.string,
+    vs = cms.required.vstring,
+    t = cms.required.InputTag,
+    vt = cms.required.VInputTag,
+    et = cms.required.ESInputTag,
+    vet = cms.required.VESInputTag,
+    f = cms.required.FileInPath,
+    e = cms.required.EventID,
+    ve = cms.required.VEventID,
+    L = cms.required.LuminosityBlockID,
+    vL = cms.required.VLuminosityBlockID,
+    er = cms.required.EventRange,
+    ver = cms.required.VEventRange,
+    Lr = cms.required.LuminosityBlockRange,
+    vLr = cms.required.VLuminosityBlockRange,
+    p = cms.PSet(),
+    vp = cms.required.VPSet
   )
 )
 )-";