From fe09c79f4be25de0ab7917296fc50aa36e7de747 Mon Sep 17 00:00:00 2001
From: Pierre-Emmanuel Viel <p.emmanuel.viel@gmail.com>
Date: Tue, 16 Jun 2020 16:51:41 +0200
Subject: [PATCH 1/2] Fix the 'cvflann::anyimpl::bad_any_cast' error using Lsh

---
 .../flann/include/opencv2/flann/lsh_index.h   | 22 +++++++++----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/modules/flann/include/opencv2/flann/lsh_index.h b/modules/flann/include/opencv2/flann/lsh_index.h
index ee620dae3e..2a1f1dea20 100644
--- a/modules/flann/include/opencv2/flann/lsh_index.h
+++ b/modules/flann/include/opencv2/flann/lsh_index.h
@@ -60,13 +60,13 @@ struct LshIndexParams : public IndexParams
 {
     LshIndexParams(unsigned int table_number = 12, unsigned int key_size = 20, unsigned int multi_probe_level = 2)
     {
-        (* this)["algorithm"] = FLANN_INDEX_LSH;
+        (*this)["algorithm"] = FLANN_INDEX_LSH;
         // The number of hash tables to use
-        (*this)["table_number"] = table_number;
+        (*this)["table_number"] = static_cast<int>(table_number);
         // The length of the key in the hash tables
-        (*this)["key_size"] = key_size;
+        (*this)["key_size"] = static_cast<int>(key_size);
         // Number of levels to use in multi-probe (0 for standard LSH)
-        (*this)["multi_probe_level"] = multi_probe_level;
+        (*this)["multi_probe_level"] = static_cast<int>(multi_probe_level);
     }
 };
 
@@ -94,9 +94,9 @@ public:
     {
         // cv::flann::IndexParams sets integer params as 'int', so it is used with get_param
         // in place of 'unsigned int'
-        table_number_ = (unsigned int)get_param<int>(index_params_,"table_number",12);
-        key_size_ = (unsigned int)get_param<int>(index_params_,"key_size",20);
-        multi_probe_level_ = (unsigned int)get_param<int>(index_params_,"multi_probe_level",2);
+        table_number_ = get_param(index_params_,"table_number",12);
+        key_size_ = get_param(index_params_,"key_size",20);
+        multi_probe_level_ = get_param(index_params_,"multi_probe_level",2);
 
         feature_size_ = (unsigned)dataset_.cols;
         fill_xor_mask(0, key_size_, multi_probe_level_, xor_masks_);
@@ -112,7 +112,7 @@ public:
     void buildIndex() CV_OVERRIDE
     {
         tables_.resize(table_number_);
-        for (unsigned int i = 0; i < table_number_; ++i) {
+        for (int i = 0; i < table_number_; ++i) {
             lsh::LshTable<ElementType>& table = tables_[i];
             table = lsh::LshTable<ElementType>(feature_size_, key_size_);
 
@@ -378,11 +378,11 @@ private:
     IndexParams index_params_;
 
     /** table number */
-    unsigned int table_number_;
+    int table_number_;
     /** key size */
-    unsigned int key_size_;
+    int key_size_;
     /** How far should we look for neighbors in multi-probe LSH */
-    unsigned int multi_probe_level_;
+    int multi_probe_level_;
 
     /** The XOR masks to apply to a key to get the neighboring buckets */
     std::vector<lsh::BucketKey> xor_masks_;

From cdac7c7bec3d1983b3a635a49d1b69cf07d0bdb7 Mon Sep 17 00:00:00 2001
From: Pierre-Emmanuel Viel <p.emmanuel.viel@gmail.com>
Date: Sun, 28 Jun 2020 16:55:50 +0200
Subject: [PATCH 2/2] Add test checking we don't throw when creating
 GenericIndex with LshIndexParams()

---
 modules/flann/test/test_lshtable_badarg.cpp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/modules/flann/test/test_lshtable_badarg.cpp b/modules/flann/test/test_lshtable_badarg.cpp
index 8fb25b44cb..f75925f659 100644
--- a/modules/flann/test/test_lshtable_badarg.cpp
+++ b/modules/flann/test/test_lshtable_badarg.cpp
@@ -90,4 +90,10 @@ void CV_LshTableBadArgTest::run( int /* start_from */ )
 
 TEST(Flann_LshTable, badarg) { CV_LshTableBadArgTest test; test.safe_run(); }
 
+TEST(Flann_LshTable, bad_any_cast) {
+    Mat features = Mat::ones(1, 64, CV_8U);
+    EXPECT_NO_THROW(flann::GenericIndex<cvflann::Hamming2<unsigned char> >(
+                                            features, cvflann::LshIndexParams()));
+}
+
 }} // namespace