Merge pull request #24028 from VadimLevin:dev/vlevin/fix-flann-python-bindings

Fix FLANN python bindings #24028

As a side-effect this patch improves reporting errors by FLANN `get_param`.

resolves #21642

### Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [x] There is a reference to the original bug report and related work
- [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [x] The feature is well documented and sample code can be built with the project CMake

modules/flann/include/opencv2/flann/any.h

@@ -19,16 +19,39 @@
 #include <ostream>
 #include <typeinfo>
 
+#include "opencv2/core/cvdef.h"
+#include "opencv2/core/utility.hpp"
+
 namespace cvflann
 {
 
 namespace anyimpl
 {
 
-struct bad_any_cast
+struct bad_any_cast : public std::exception
 {
+    bad_any_cast() = default;
+
+    bad_any_cast(const char* src, const char* dst)
+        : message_(cv::format("cvflann::bad_any_cast(from %s to %s)", src, dst)) {}
+
+
+    const char* what() const noexcept override
+    {
+        return message_.c_str();
+    }
+
+private:
+    std::string message_{"cvflann::bad_any_cast"};
 };
 
+#ifndef CV_THROW_IF_TYPE_MISMATCH
+#define CV_THROW_IF_TYPE_MISMATCH(src_type_info, dst_type_info) \
+    if ((src_type_info) != (dst_type_info)) \
+        throw cvflann::anyimpl::bad_any_cast((src_type_info).name(), \
+                                             (dst_type_info).name())
+#endif
+
 struct empty_any
 {
 };
@@ -271,7 +294,7 @@ public:
     template<typename T>
     T& cast()
     {
-        if (policy->type() != typeid(T)) throw anyimpl::bad_any_cast();
+        CV_THROW_IF_TYPE_MISMATCH(policy->type(), typeid(T));
         T* r = reinterpret_cast<T*>(policy->get_value(&object));
         return *r;
     }
@@ -280,7 +303,7 @@ public:
     template<typename T>
     const T& cast() const
     {
-        if (policy->type() != typeid(T)) throw anyimpl::bad_any_cast();
+        CV_THROW_IF_TYPE_MISMATCH(policy->type(), typeid(T));
         const T* r = reinterpret_cast<const T*>(policy->get_value(&object));
         return *r;
     }

modules/flann/include/opencv2/flann/general.h

@@ -31,6 +31,8 @@
 #ifndef OPENCV_FLANN_GENERAL_H_
 #define OPENCV_FLANN_GENERAL_H_
 
+#include "opencv2/core/version.hpp"
+
 #if CV_VERSION_MAJOR <= 4
 
 //! @cond IGNORED

modules/flann/include/opencv2/flann/matrix.h

@@ -35,6 +35,9 @@
 
 #include <stdio.h>
 
+#include "opencv2/core/cvdef.h"
+#include "opencv2/flann/defines.h"
+
 namespace cvflann
 {
 

modules/flann/include/opencv2/flann/params.h

@@ -72,11 +72,16 @@ struct SearchParams : public IndexParams
 
 
 template<typename T>
-T get_param(const IndexParams& params, cv::String name, const T& default_value)
+T get_param(const IndexParams& params, const cv::String& name, const T& default_value)
 {
     IndexParams::const_iterator it = params.find(name);
     if (it != params.end()) {
-        return it->second.cast<T>();
+        try {
+            return it->second.cast<T>();
+        } catch (const std::exception& e) {
+            CV_Error_(cv::Error::StsBadArg,
+                      ("FLANN '%s' param type mismatch: %s", name.c_str(), e.what()));
+        }
     }
     else {
         return default_value;
@@ -84,11 +89,16 @@ T get_param(const IndexParams& params, cv::String name, const T& default_value)
 }
 
 template<typename T>
-T get_param(const IndexParams& params, cv::String name)
+T get_param(const IndexParams& params, const cv::String& name)
 {
     IndexParams::const_iterator it = params.find(name);
     if (it != params.end()) {
-        return it->second.cast<T>();
+        try {
+            return it->second.cast<T>();
+        } catch (const std::exception& e) {
+            CV_Error_(cv::Error::StsBadArg,
+                      ("FLANN '%s' param type mismatch: %s", name.c_str(), e.what()));
+        }
     }
     else {
         FLANN_THROW(cv::Error::StsBadArg, cv::String("Missing parameter '")+name+cv::String("' in the parameters given"));

modules/flann/include/opencv2/flann/result_set.h

@@ -40,6 +40,9 @@
 #include <set>
 #include <vector>
 
+#include "opencv2/core/base.hpp"
+#include "opencv2/core/cvdef.h"
+
 namespace cvflann
 {