From 25d9936df8ab920519e0f44f01c7a7bf457b7601 Mon Sep 17 00:00:00 2001
From: Mathieu Pellerin <nirvn.asia@gmail.com>
Date: Thu, 6 Apr 2017 16:04:48 +0700
Subject: [PATCH] [OGR] fix feature count issue for OSM datasets (fixes #16402)
 (#4322)

---
 python/core/qgsvectordataprovider.sip | 11 +++++++++++
 src/core/qgsvectordataprovider.h      | 11 +++++++++++
 src/providers/ogr/qgsogrprovider.cpp  | 10 +++++++---
 3 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/python/core/qgsvectordataprovider.sip b/python/core/qgsvectordataprovider.sip
index 3c43a1e6f05..a7f6c2d7f32 100644
--- a/python/core/qgsvectordataprovider.sip
+++ b/python/core/qgsvectordataprovider.sip
@@ -57,6 +57,17 @@ class QgsVectorDataProvider : QgsDataProvider
     /** Bitmask of all provider's editing capabilities */
     static const int EditingCapabilities;
 
+    /**
+     * Enumeration of feature count states
+     */
+    enum FeatureCountState
+    {
+      //! Feature count not yet computed
+      Uncounted = -2,
+      //! Provider returned an unknown feature count
+      UnknownCount = -1,
+    };
+
     /**
      * Constructor of the vector provider
      * @param uri  uniform resource locator (URI) for a dataset
diff --git a/src/core/qgsvectordataprovider.h b/src/core/qgsvectordataprovider.h
index 492c9be12e4..acc99a84686 100644
--- a/src/core/qgsvectordataprovider.h
+++ b/src/core/qgsvectordataprovider.h
@@ -112,6 +112,17 @@ class CORE_EXPORT QgsVectorDataProvider : public QgsDataProvider
                                            ChangeAttributeValues | ChangeGeometries | AddAttributes | DeleteAttributes |
                                            RenameAttributes;
 
+    /**
+     * Enumeration of feature count states
+     */
+    enum FeatureCountState
+    {
+      //! Feature count not yet computed
+      Uncounted = -2,
+      //! Provider returned an unknown feature count
+      UnknownCount = -1,
+    };
+
     /**
      * Constructor of the vector provider
      * \param uri  uniform resource locator (URI) for a dataset
diff --git a/src/providers/ogr/qgsogrprovider.cpp b/src/providers/ogr/qgsogrprovider.cpp
index 0398301ebef..16d9226a1d5 100644
--- a/src/providers/ogr/qgsogrprovider.cpp
+++ b/src/providers/ogr/qgsogrprovider.cpp
@@ -378,7 +378,7 @@ QgsOgrProvider::QgsOgrProvider( QString const &uri )
   , ogrDriver( nullptr )
   , mValid( false )
   , mOGRGeomType( wkbUnknown )
-  , mFeaturesCounted( -1 )
+  , mFeaturesCounted( QgsVectorDataProvider::Uncounted )
   , mWriteAccess( false )
   , mWriteAccessPossible( false )
   , mDynamicWriteAccess( false )
@@ -450,7 +450,7 @@ bool QgsOgrProvider::setSubsetString( const QString &theSQL, bool updateFeatureC
   if ( !ogrDataSource )
     return false;
 
-  if ( theSQL == mSubsetString && mFeaturesCounted >= 0 )
+  if ( theSQL == mSubsetString && mFeaturesCounted != QgsVectorDataProvider::Uncounted )
     return true;
 
   OGRLayerH prevLayer = ogrLayer;
@@ -3300,7 +3300,7 @@ void QgsOgrProvider::recalculateFeatureCount()
 {
   if ( !ogrLayer )
   {
-    mFeaturesCounted = 0;
+    mFeaturesCounted = QgsVectorDataProvider::Uncounted;
     return;
   }
 
@@ -3316,6 +3316,10 @@ void QgsOgrProvider::recalculateFeatureCount()
   if ( mOgrGeometryTypeFilter == wkbUnknown )
   {
     mFeaturesCounted = OGR_L_GetFeatureCount( ogrLayer, true );
+    if ( mFeaturesCounted == -1 )
+    {
+      mFeaturesCounted = QgsVectorDataProvider::UnknownCount;
+    }
   }
   else
   {