More transparent code and other fixes according to @asfernandes.

Author: sim1984

src/jrd/RecordSourceNodes.cpp

@@ -4429,13 +4429,12 @@ dsql_fld* GenSeriesFunctionSourceNode::makeField(DsqlCompilerScratch* dsqlScratc
 
 	if (!field)
 	{
-		const auto newField = FB_NEW_POOL(dsqlScratch->getPool()) dsql_fld(dsqlScratch->getPool());
-		field = newField;
+		field = FB_NEW_POOL(dsqlScratch->getPool()) dsql_fld(dsqlScratch->getPool());
 
 		dsc desc;
 		desc.makeInt64(scale);
-		MAKE_field(newField, &desc);
-		newField->fld_id = 0;
+		MAKE_field(field, &desc);
+		field->fld_id = 0;
 	}
 
 	if (dsqlNameColumns.hasData())

src/jrd/RecordSourceNodes.h

@@ -1081,19 +1081,20 @@ class UnlistFunctionSourceNode : public TableValueFunctionSourceNode
 	}
 };
 
-class GenSeriesFunctionSourceNode : public TableValueFunctionSourceNode
+class GenSeriesFunctionSourceNode final : public TableValueFunctionSourceNode
 {
 public:
-	explicit GenSeriesFunctionSourceNode(MemoryPool& pool) : TableValueFunctionSourceNode(pool)
+	explicit GenSeriesFunctionSourceNode(MemoryPool& pool) 
+		: TableValueFunctionSourceNode(pool)
 	{
 	}
 
-	RecordSource* compile(thread_db* tdbb, Optimizer* opt, bool innerSubStream) final;
-	dsql_fld* makeField(DsqlCompilerScratch* dsqlScratch) final;
+	RecordSource* compile(thread_db* tdbb, Optimizer* opt, bool innerSubStream) override;
+	dsql_fld* makeField(DsqlCompilerScratch* dsqlScratch) override;
 
 	static constexpr char const* FUNC_NAME = "GENERATE_SERIES";
 
-	const char* getName() const final
+	const char* getName() const override
 	{
 		return FUNC_NAME;
 	}

src/jrd/recsrc/RecordSource.h

@@ -1617,7 +1617,7 @@ namespace Jrd
 
 	class GenSeriesFunctionScan final : public TableValueFunctionScan
 	{
-		enum GenSeriesTypeItemIndex : unsigned
+		enum GenSeriesTypeItemIndex : UCHAR
 		{
 			GEN_SERIES_INDEX_START = 0,
 			GEN_SERIES_INDEX_FINISH = 1,
@@ -1632,21 +1632,20 @@ namespace Jrd
 			SINT64 m_step;
 			SINT64 m_result;
 			SCHAR m_scale;
-			bool m_recordExists;
 		};
 
 	public:
 		GenSeriesFunctionScan(CompilerScratch* csb, StreamType stream, const Firebird::string& alias,
 						   ValueListNode* list);
 
 	protected:
-		void close(thread_db* tdbb) const final;
-		void internalOpen(thread_db* tdbb) const final;
+		void close(thread_db* tdbb) const override;
+		void internalOpen(thread_db* tdbb) const override;
 		void internalGetPlan(thread_db* tdbb, PlanEntry& planEntry, unsigned level,
-							 bool recurse) const final;
-		bool internalGetRecord(thread_db* tdbb) const final;
+							 bool recurse) const override;
+		bool internalGetRecord(thread_db* tdbb) const override;
 
-		bool nextBuffer(thread_db* tdbb) const final;
+		bool nextBuffer(thread_db* tdbb) const override;
 
 	private:
 		NestConst<ValueListNode> m_inputList;

src/jrd/recsrc/TableValueFunctionScan.cpp

@@ -431,16 +431,8 @@ void GenSeriesFunctionScan::internalOpen(thread_db* tdbb) const
 	impure->m_step = step;
     impure->m_result = start;
 	impure->m_scale = scale;
-	impure->m_recordExists = true;
 
-    Record* const record = VIO_record(tdbb, rpb, m_format, &pool);
-
-	auto toDesc = m_format->fmt_desc.begin();
-
-	dsc fromDesc;
-	fromDesc.makeInt64(scale, &impure->m_result);
-
-	assignParameter(tdbb, &fromDesc, toDesc, 0, record);
+	VIO_record(tdbb, rpb, m_format, &pool);
 }
 
 void GenSeriesFunctionScan::internalGetPlan(thread_db* tdbb, PlanEntry& planEntry, unsigned /*level*/,
@@ -473,15 +465,10 @@ bool GenSeriesFunctionScan::internalGetRecord(thread_db* tdbb) const
 
 	rpb->rpb_number.increment();
 
-	do
-	{
-		if (impure->m_recordExists)
-		{
-			impure->m_recordExists = false;
-			rpb->rpb_number.setValid(true);
-			return true;
-		}
-	} while (nextBuffer(tdbb));
+	if (nextBuffer(tdbb)) {
+		rpb->rpb_number.setValid(true);
+		return true;
+	}
 
 	rpb->rpb_number.setValid(false);
 	return false;
@@ -492,8 +479,6 @@ bool GenSeriesFunctionScan::nextBuffer(thread_db* tdbb) const
 	const auto request = tdbb->getRequest();
 	const auto impure = request->getImpure<Impure>(m_impure);
 
-	impure->m_result += impure->m_step;
-
 	if (((impure->m_step > 0) && (impure->m_result <= impure->m_finish)) ||
         ((impure->m_step < 0) && (impure->m_result >= impure->m_finish)))
 	{
@@ -504,7 +489,8 @@ bool GenSeriesFunctionScan::nextBuffer(thread_db* tdbb) const
 		dsc fromDesc;
 		fromDesc.makeInt64(impure->m_scale, &impure->m_result);
 		assignParameter(tdbb, &fromDesc, toDesc, 0, record);
-		impure->m_recordExists = true;
+
+		impure->m_result += impure->m_step;
 
 		return true;
 	}