Merge pull request #23736 from seanm:c++11-simplifications

Removed all pre-C++11 code, workarounds, and branches #23736

This removes a bunch of pre-C++11 workrarounds that are no longer necessary as C++11 is now required.
It is a nice clean up and simplification.

* No longer unconditionally #include <array> in cvdef.h, include explicitly where needed
* Removed deprecated CV_NODISCARD, already unused in the codebase
* Removed some pre-C++11 workarounds, and simplified some backwards compat defines
* Removed CV_CXX_STD_ARRAY
* Removed CV_CXX_MOVE_SEMANTICS and CV_CXX_MOVE
* Removed all tests of CV_CXX11, now assume it's always true. This allowed removing a lot of dead code.
* Updated some documentation consequently.
* Removed all tests of CV_CXX11, now assume it's always true
* Fixed links.

---------

Co-authored-by: Maksim Shabunin <maksim.shabunin@gmail.com>
Co-authored-by: Alexander Smorkalov <alexander.smorkalov@xperience.ai>

doc/tutorials/core/how_to_use_OpenCV_parallel_for_/how_to_use_OpenCV_parallel_for_.markdown

@@ -9,6 +9,9 @@ How to use the OpenCV parallel_for_ to parallelize your code {#tutorial_how_to_u
 | -: | :- |
 | Compatibility | OpenCV >= 3.0 |
 
+
+@note See also C++ lambda usage with parallel for in [tuturial](@ref tutorial_how_to_use_OpenCV_parallel_for_new).
+
 Goal
 ----
 
@@ -20,7 +23,7 @@ If you want more information about multithreading, you will have to refer to a r
 to remain simple.
 
 Precondition
-----
+------------
 
 The first precondition is to have OpenCV built with a parallel framework.
 In OpenCV 3.2, the following parallel frameworks are available in that order:
@@ -50,7 +53,7 @@ We will use the example of drawing a Mandelbrot set to show how from a regular s
 the code to parallelize the computation.
 
 Theory
------------
+------
 
 The Mandelbrot set definition has been named in tribute to the mathematician Benoit Mandelbrot by the mathematician
 Adrien Douady. It has been famous outside of the mathematics field as the image representation is an example of a
@@ -69,7 +72,7 @@ Here, we will just introduce the formula to draw the Mandelbrot set (from the me
 > \f[\limsup_{n\to\infty}|z_{n+1}|\leqslant2\f]
 
 Pseudocode
------------
+----------
 
 A simple algorithm to generate a representation of the Mandelbrot set is called the
 ["escape time algorithm"](https://en.wikipedia.org/wiki/Mandelbrot_set#Escape_time_algorithm).
@@ -110,10 +113,10 @@ On this figure, we recall that the real part of a complex number is on the x-axi
 You can see that the whole shape can be repeatedly visible if we zoom at particular locations.
 
 Implementation
------------
+--------------
 
 Escape time algorithm implementation
---------------------------
+------------------------------------
 
 @snippet how_to_use_OpenCV_parallel_for_.cpp mandelbrot-escape-time-algorithm
 
@@ -121,7 +124,7 @@ Here, we used the [`std::complex`](http://en.cppreference.com/w/cpp/numeric/comp
 complex number. This function performs the test to check if the pixel is in set or not and returns the "escaped" iteration.
 
 Sequential Mandelbrot implementation
---------------------------
+------------------------------------
 
 @snippet how_to_use_OpenCV_parallel_for_.cpp mandelbrot-sequential
 
@@ -149,7 +152,7 @@ The green curve corresponds to a simple linear scale transformation, the blue on
 and you can observe how the lowest values will be boosted when looking at the slope at these positions.
 
 Parallel Mandelbrot implementation
---------------------------
+----------------------------------
 
 When looking at the sequential implementation, we can notice that each pixel is computed independently. To optimize the
 computation, we can perform multiple pixel calculations in parallel, by exploiting the multi-core architecture of modern
@@ -181,7 +184,7 @@ C++ 11 standard allows to simplify the parallel implementation by get rid of the
 @snippet how_to_use_OpenCV_parallel_for_.cpp mandelbrot-parallel-call-cxx11
 
 Results
------------
+-------
 
 You can find the full tutorial code [here](https://github.com/opencv/opencv/blob/4.x/samples/cpp/tutorial_code/core/how_to_use_OpenCV_parallel_for_/how_to_use_OpenCV_parallel_for_.cpp).
 The performance of the parallel implementation depends of the type of CPU you have. For instance, on 4 cores / 8 threads

modules/core/include/opencv2/core/async.hpp

@@ -7,10 +7,8 @@
 
 #include <opencv2/core/mat.hpp>
 
-#ifdef CV_CXX11
 //#include <future>
 #include <chrono>
-#endif
 
 namespace cv {
 
@@ -69,7 +67,6 @@ public:
 
     CV_WRAP bool valid() const CV_NOEXCEPT;
 
-#ifdef CV_CXX11
     inline AsyncArray(AsyncArray&& o) { p = o.p; o.p = NULL; }
     inline AsyncArray& operator=(AsyncArray&& o) CV_NOEXCEPT { std::swap(p, o.p); return *this; }
 
@@ -89,7 +86,6 @@ public:
     std::future<Mat> getFutureMat() const;
     std::future<UMat> getFutureUMat() const;
 #endif
-#endif
 
 
     // PImpl

modules/core/include/opencv2/core/cvdef.h

@@ -752,89 +752,44 @@ __CV_ENUM_FLAGS_BITWISE_XOR_EQ   (EnumType, EnumType)
 #endif
 
 
-/****************************************************************************************\
-*                      CV_NODISCARD attribute (deprecated, GCC only)                     *
-* DONT USE: use instead the standard CV_NODISCARD_STD macro above                        *
-*           this legacy method silently fails to issue warning until some version        *
-*           after gcc 6.3.0. Yet with gcc 7+ you can use the above standard method       *
-*           which makes this method useless. Don't use it.                               *
-* @deprecated use instead CV_NODISCARD_STD                                               *
-\****************************************************************************************/
-#ifndef CV_NODISCARD
-#  if defined(__GNUC__)
-#    define CV_NODISCARD __attribute__((__warn_unused_result__))
-#  elif defined(__clang__) && defined(__has_attribute)
-#    if __has_attribute(__warn_unused_result__)
-#      define CV_NODISCARD __attribute__((__warn_unused_result__))
-#    endif
-#  endif
-#endif
-#ifndef CV_NODISCARD
-#  define CV_NODISCARD /* nothing by default */
-#endif
-
-
 /****************************************************************************************\
 *                                    C++ 11                                              *
 \****************************************************************************************/
-#ifndef CV_CXX11
+#ifdef __cplusplus
-#  if __cplusplus >= 201103L || (defined(_MSC_VER) && _MSC_VER >= 1800)
+// MSVC was stuck at __cplusplus == 199711L for a long time, even where it supports C++11,
-#    define CV_CXX11 1
+// so check _MSC_VER instead. See:
-#  endif
+// <https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus>
-#else
+#  if defined(_MSC_VER)
-#  if CV_CXX11 == 0
+#    if _MSC_VER < 1800
-#    undef CV_CXX11
-#  endif
-#endif
-#ifndef CV_CXX11
 #      error "OpenCV 4.x+ requires enabled C++11 support"
 #    endif
+#  elif __cplusplus < 201103L
+#    error "OpenCV 4.x+ requires enabled C++11 support"
+#  endif
+#endif
+
+#ifndef CV_CXX11
+#  define CV_CXX11 1
+#endif
 
-#define CV_CXX_MOVE_SEMANTICS 1
-#define CV_CXX_MOVE(x) std::move(x)
-#define CV_CXX_STD_ARRAY 1
-#include <array>
 #ifndef CV_OVERRIDE
 #  define CV_OVERRIDE override
 #endif
+
 #ifndef CV_FINAL
 #  define CV_FINAL final
 #endif
 
 #ifndef CV_NOEXCEPT
-#  if __cplusplus >= 201103L || (defined(_MSC_VER) && _MSC_VER >= 1900/*MSVS 2015*/)
 #  define CV_NOEXCEPT noexcept
 #endif
-#endif
-#ifndef CV_NOEXCEPT
-#  define CV_NOEXCEPT
-#endif
 
 #ifndef CV_CONSTEXPR
-#  if __cplusplus >= 201103L || (defined(_MSC_VER) && _MSC_VER >= 1900/*MSVS 2015*/)
 #  define CV_CONSTEXPR constexpr
 #endif
-#endif
-#ifndef CV_CONSTEXPR
-#  define CV_CONSTEXPR
-#endif
 
 // Integer types portability
-#ifdef OPENCV_STDINT_HEADER
+#ifdef __cplusplus
-#include OPENCV_STDINT_HEADER
-#elif defined(__cplusplus)
-#if defined(_MSC_VER) && _MSC_VER < 1600 /* MSVS 2010 */
-namespace cv {
-typedef signed char int8_t;
-typedef unsigned char uint8_t;
-typedef signed short int16_t;
-typedef unsigned short uint16_t;
-typedef signed int int32_t;
-typedef unsigned int uint32_t;
-typedef signed __int64 int64_t;
-typedef unsigned __int64 uint64_t;
-}
-#elif defined(_MSC_VER) || __cplusplus >= 201103L
 #include <cstdint>
 namespace cv {
 using std::int8_t;
@@ -846,19 +801,6 @@ using std::uint32_t;
 using std::int64_t;
 using std::uint64_t;
 }
-#else
-#include <stdint.h>
-namespace cv {
-typedef ::int8_t int8_t;
-typedef ::uint8_t uint8_t;
-typedef ::int16_t int16_t;
-typedef ::uint16_t uint16_t;
-typedef ::int32_t int32_t;
-typedef ::uint32_t uint32_t;
-typedef ::int64_t int64_t;
-typedef ::uint64_t uint64_t;
-}
-#endif
 #else // pure C
 #include <stdint.h>
 #endif

modules/core/include/opencv2/core/detail/async_promise.hpp

@@ -52,10 +52,8 @@ public:
     */
     void setException(const cv::Exception& exception);
 
-#ifdef CV_CXX11
     explicit AsyncPromise(AsyncPromise&& o) { p = o.p; o.p = NULL; }
     AsyncPromise& operator=(AsyncPromise&& o) CV_NOEXCEPT { std::swap(p, o.p); return *this; }
-#endif
 
 
     // PImpl

modules/core/include/opencv2/core/detail/exception_ptr.hpp

@@ -8,14 +8,8 @@
 #ifndef CV__EXCEPTION_PTR
 #  if defined(__ANDROID__) && defined(ATOMIC_INT_LOCK_FREE) && ATOMIC_INT_LOCK_FREE < 2
 #    define CV__EXCEPTION_PTR 0  // Not supported, details: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58938
-#  elif defined(CV_CXX11)
+#  else
 #    define CV__EXCEPTION_PTR 1
-#  elif defined(_MSC_VER)
-#    define CV__EXCEPTION_PTR (_MSC_VER >= 1600)
-#  elif defined(__clang__)
-#    define CV__EXCEPTION_PTR 0  // C++11 only (see above)
-#  elif defined(__GNUC__) && defined(__GXX_EXPERIMENTAL_CXX0X__)
-#    define CV__EXCEPTION_PTR (__GXX_EXPERIMENTAL_CXX0X__ > 0)
 #  endif
 #endif
 #ifndef CV__EXCEPTION_PTR

modules/core/include/opencv2/core/eigen.hpp

@@ -61,8 +61,7 @@
 #endif
 
 #if !defined(OPENCV_DISABLE_EIGEN_TENSOR_SUPPORT)
-#if EIGEN_WORLD_VERSION == 3 && EIGEN_MAJOR_VERSION >= 3 \
+#if EIGEN_WORLD_VERSION == 3 && EIGEN_MAJOR_VERSION >= 3
-    && defined(CV_CXX11) && defined(CV_CXX_STD_ARRAY)
 #include <unsupported/Eigen/CXX11/Tensor>
 #define OPENCV_EIGEN_TENSOR_SUPPORT 1
 #endif  // EIGEN_WORLD_VERSION == 3 && EIGEN_MAJOR_VERSION >= 3

modules/core/include/opencv2/core/mat.hpp

@@ -53,6 +53,7 @@
 
 #include "opencv2/core/bufferpool.hpp"
 
+#include <array>
 #include <type_traits>
 
 namespace cv

modules/core/include/opencv2/core/matx.hpp

@@ -376,10 +376,8 @@ public:
     static Vec randn(_Tp a, _Tp b);
     static Vec randu(_Tp a, _Tp b);
     static Vec zeros();
-#ifdef CV_CXX11
     static Vec diag(_Tp alpha) = delete;
     static Vec eye() = delete;
-#endif
 
     //! per-element multiplication
     Vec mul(const Vec<_Tp, cn>& v) const;
@@ -402,9 +400,7 @@ public:
     const _Tp& operator ()(int i) const;
     _Tp& operator ()(int i);
 
-#ifdef CV_CXX11
     Vec<_Tp, cn>& operator=(const Vec<_Tp, cn>& rhs) = default;
-#endif
 
     Vec(const Matx<_Tp, cn, 1>& a, const Matx<_Tp, cn, 1>& b, Matx_AddOp);
     Vec(const Matx<_Tp, cn, 1>& a, const Matx<_Tp, cn, 1>& b, Matx_SubOp);

modules/core/include/opencv2/core/utils/allocator_stats.impl.hpp

@@ -9,8 +9,6 @@
 
 //#define OPENCV_DISABLE_ALLOCATOR_STATS
 
-#ifdef CV_CXX11
-
 #include <atomic>
 
 #ifndef OPENCV_ALLOCATOR_STATS_COUNTER_TYPE
@@ -26,14 +24,6 @@
 #define OPENCV_ALLOCATOR_STATS_COUNTER_TYPE long long
 #endif
 
-#else  // CV_CXX11
-
-#ifndef OPENCV_ALLOCATOR_STATS_COUNTER_TYPE
-#define OPENCV_ALLOCATOR_STATS_COUNTER_TYPE int  // CV_XADD supports int only
-#endif
-
-#endif  // CV_CXX11
-
 namespace cv { namespace utils {
 
 #ifdef CV__ALLOCATOR_STATS_LOG
@@ -59,7 +49,7 @@ public:
     void onAllocate(size_t /*sz*/) {}
     void onFree(size_t /*sz*/) {}
 
-#elif defined(CV_CXX11)
+#else
 
 protected:
     typedef OPENCV_ALLOCATOR_STATS_COUNTER_TYPE counter_t;
@@ -104,49 +94,7 @@ public:
 #endif
         curr -= (counter_t)sz;
     }
-
+#endif // OPENCV_DISABLE_ALLOCATOR_STATS
-#else  // non C++11
-
-protected:
-    typedef OPENCV_ALLOCATOR_STATS_COUNTER_TYPE counter_t;
-    volatile counter_t curr, total, total_allocs, peak;  // overflow is possible, CV_XADD operates with 'int' only
-public:
-    AllocatorStatistics()
-        : curr(0), total(0), total_allocs(0), peak(0)
-    {}
-    ~AllocatorStatistics() CV_OVERRIDE {}
-
-    uint64_t getCurrentUsage() const CV_OVERRIDE { return (uint64_t)curr; }
-    uint64_t getTotalUsage() const CV_OVERRIDE { return (uint64_t)total; }
-    uint64_t getNumberOfAllocations() const CV_OVERRIDE { return (uint64_t)total_allocs; }
-    uint64_t getPeakUsage() const CV_OVERRIDE { return (uint64_t)peak; }
-
-    void resetPeakUsage() CV_OVERRIDE { peak = curr; }
-
-    // Controller interface
-    void onAllocate(size_t sz)
-    {
-#ifdef CV__ALLOCATOR_STATS_LOG
-        CV__ALLOCATOR_STATS_LOG(cv::format("allocate: %lld (curr=%lld)", (long long int)sz, (long long int)curr));
-#endif
-
-        counter_t new_curr = (counter_t)CV_XADD(&curr, (counter_t)sz) + (counter_t)sz;
-
-        peak = std::max((counter_t)peak, new_curr);  // non-thread safe
-
-        //CV_XADD(&total, (uint64_t)sz);  // overflow with int, non-reliable...
-        total += sz;
-
-        CV_XADD(&total_allocs, (counter_t)1);
-    }
-    void onFree(size_t sz)
-    {
-#ifdef CV__ALLOCATOR_STATS_LOG
-        CV__ALLOCATOR_STATS_LOG(cv::format("free: %lld (curr=%lld)", (long long int)sz, (long long int)curr));
-#endif
-        CV_XADD(&curr, (counter_t)-sz);
-    }
-#endif
 };
 
 #ifdef CV__ALLOCATOR_STATS_LOG

modules/core/src/async.cpp

@@ -3,7 +3,6 @@
 // of this distribution and at http://opencv.org/license.html.
 
 #include "precomp.hpp"
-//#undef CV_CXX11  // debug non C++11 mode
 #include "opencv2/core/async.hpp"
 #include "opencv2/core/detail/async_promise.hpp"
 
@@ -16,11 +15,9 @@
 
 #ifndef OPENCV_DISABLE_THREAD_SUPPORT
 
-#ifdef CV_CXX11
 #include <mutex>
 #include <condition_variable>
 #include <chrono>
-#endif
 
 namespace cv {
 
@@ -37,12 +34,8 @@ struct AsyncArray::Impl
     void releasePromise() CV_NOEXCEPT { CV_XADD(&refcount_promise, -1); if(1 == CV_XADD(&refcount, -1)) delete this; } \
     int refcount_promise;
 
-#ifdef CV_CXX11
     mutable std::mutex mtx;
     mutable std::condition_variable cond_var;
-#else
-    mutable cv::Mutex mtx;
-#endif
 
     mutable bool has_result; // Mat, UMat or exception
 
@@ -88,11 +81,7 @@ struct AsyncArray::Impl
             if (!wait_for(timeoutNs))
                 return false;
         }
-#ifdef CV_CXX11
         std::unique_lock<std::mutex> lock(mtx);
-#else
-        cv::AutoLock lock(mtx);
-#endif
         if (has_result)
         {
             if (!result_mat.empty())
@@ -145,7 +134,6 @@ struct AsyncArray::Impl
         if (timeoutNs == 0)
             return has_result;
         CV_LOG_INFO(NULL, "Waiting for async result ...");
-#ifdef CV_CXX11
         std::unique_lock<std::mutex> lock(mtx);
         const auto cond_pred = [&]{ return has_result == true; };
         if (timeoutNs > 0)
@@ -156,9 +144,6 @@ struct AsyncArray::Impl
             CV_Assert(has_result);
             return true;
         }
-#else
-        CV_Error(Error::StsNotImplemented, "OpenCV has been built without async waiting support (C++11 is required)");
-#endif
     }
 
     AsyncArray getArrayResult()
@@ -175,11 +160,7 @@ struct AsyncArray::Impl
     {
         if (future_is_returned && refcount_future == 0)
             CV_Error(Error::StsError, "Associated AsyncArray has been destroyed");
-#ifdef CV_CXX11
         std::unique_lock<std::mutex> lock(mtx);
-#else
-        cv::AutoLock lock(mtx);
-#endif
         CV_Assert(!has_result);
         int k = value.kind();
         if (k == _InputArray::UMAT)
@@ -193,9 +174,7 @@ struct AsyncArray::Impl
             value.copyTo(*result_mat.get());
         }
         has_result = true;
-#ifdef CV_CXX11
         cond_var.notify_all();
-#endif
     }
 
 #if CV__EXCEPTION_PTR
@@ -203,18 +182,12 @@ struct AsyncArray::Impl
     {
         if (future_is_returned && refcount_future == 0)
             CV_Error(Error::StsError, "Associated AsyncArray has been destroyed");
-#ifdef CV_CXX11
         std::unique_lock<std::mutex> lock(mtx);
-#else
-        cv::AutoLock lock(mtx);
-#endif
         CV_Assert(!has_result);
         has_exception = true;
         exception = e;
         has_result = true;
-#ifdef CV_CXX11
         cond_var.notify_all();
-#endif
     }
 #endif
 
@@ -222,18 +195,12 @@ struct AsyncArray::Impl
     {
         if (future_is_returned && refcount_future == 0)
             CV_Error(Error::StsError, "Associated AsyncArray has been destroyed");
-#ifdef CV_CXX11
         std::unique_lock<std::mutex> lock(mtx);
-#else
-        cv::AutoLock lock(mtx);
-#endif
         CV_Assert(!has_result);
         has_exception = true;
         cv_exception = e;
         has_result = true;
-#ifdef CV_CXX11
         cond_var.notify_all();
-#endif
     }
 };
 

modules/core/src/matrix_wrap.cpp

@@ -1919,12 +1919,7 @@ void _OutputArray::move(UMat& u) const
     int k = kind();
     if (k == UMAT)
     {
-#ifdef CV_CXX11
         *(UMat*)obj = std::move(u);
-#else
-        *(UMat*)obj = u;
-        u.release();
-#endif
     }
     else if (k == MAT)
     {
@@ -1959,12 +1954,7 @@ void _OutputArray::move(Mat& m) const
     }
     else if (k == MAT)
     {
-#ifdef CV_CXX11
         *(Mat*)obj = std::move(m);
-#else
-        *(Mat*)obj = m;
-        m.release();
-#endif
     }
     else if (k == MATX)
     {

modules/core/src/parallel.cpp

@@ -912,8 +912,7 @@ int getNumberOfCPUs_()
      * the minimum most value as it has high probablity of being right and safe.
      * Return 1 if we get 0 or not found on all methods.
     */
-#if defined CV_CXX11 \
+#if !defined(__MINGW32__) /* not implemented (2020-03) */
-    && !defined(__MINGW32__) /* not implemented (2020-03) */ \
 
     /*
      * Check for this standard C++11 way, we do not return directly because

modules/core/src/system.cpp

@@ -305,9 +305,7 @@ DECLARE_CV_CPUID_X86
   #endif
 #endif
 
-#if defined CV_CXX11
 #include <chrono>
-#endif
 
 namespace cv
 {
@@ -909,50 +907,15 @@ bool useOptimized(void)
 
 int64 getTickCount(void)
 {
-#if defined CV_CXX11
     std::chrono::steady_clock::time_point now = std::chrono::steady_clock::now();
     return (int64)now.time_since_epoch().count();
-#elif defined _WIN32 || defined WINCE
-    LARGE_INTEGER counter;
-    QueryPerformanceCounter( &counter );
-    return (int64)counter.QuadPart;
-#elif defined __MACH__ && defined __APPLE__
-    return (int64)mach_absolute_time();
-#elif defined __unix__
-    struct timespec tp;
-    clock_gettime(CLOCK_MONOTONIC, &tp);
-    return (int64)tp.tv_sec*1000000000 + tp.tv_nsec;
-#else
-    struct timeval tv;
-    gettimeofday(&tv, NULL);
-    return (int64)tv.tv_sec*1000000 + tv.tv_usec;
-#endif
 }
 
 double getTickFrequency(void)
 {
-#if defined CV_CXX11
     using clock_period_t = std::chrono::steady_clock::duration::period;
     double clock_freq = clock_period_t::den / clock_period_t::num;
     return clock_freq;
-#elif defined _WIN32 || defined WINCE
-    LARGE_INTEGER freq;
-    QueryPerformanceFrequency(&freq);
-    return (double)freq.QuadPart;
-#elif defined __MACH__ && defined __APPLE__
-    static double freq = 0;
-    if( freq == 0 )
-    {
-        mach_timebase_info_data_t sTimebaseInfo;
-        mach_timebase_info(&sTimebaseInfo);
-        freq = sTimebaseInfo.denom*1e9/sTimebaseInfo.numer;
-    }
-    return freq;
-#elif defined __unix__
-    return 1e9;
-#else
-    return 1e6;
-#endif
 }
 
 #if defined __GNUC__ && (defined __i386__ || defined __x86_64__ || defined __ppc__)

modules/core/test/test_async.cpp

@@ -7,7 +7,7 @@
 
 #include <opencv2/core/bindings_utils.hpp>
 
-#if defined(CV_CXX11) && !defined(OPENCV_DISABLE_THREAD_SUPPORT)
+#if !defined(OPENCV_DISABLE_THREAD_SUPPORT)
 #include <thread>
 #include <chrono>
 #endif
@@ -85,7 +85,7 @@ TEST(Core_Async, LikePythonTest)
 }
 
 
-#if defined(CV_CXX11) && !defined(OPENCV_DISABLE_THREAD_SUPPORT)
+#if !defined(OPENCV_DISABLE_THREAD_SUPPORT)
 
 TEST(Core_Async, AsyncThread_Simple)
 {

modules/core/test/test_misc.cpp

@@ -8,10 +8,8 @@
 
 #include <opencv2/core/utils/fp_control_utils.hpp>
 
-#ifdef CV_CXX11
 #include <chrono>
 #include <thread>
-#endif
 
 namespace opencv_test { namespace {
 
@@ -282,9 +280,7 @@ public:
             // FP state is not supported
             // no checks
         }
-#ifdef CV_CXX11
         std::this_thread::sleep_for(std::chrono::milliseconds(100));
-#endif
     }
 
     cv::details::FPDenormalsModeState base_state;

modules/core/test/test_precomp.hpp

@@ -4,6 +4,8 @@
 #ifndef __OPENCV_TEST_PRECOMP_HPP__
 #define __OPENCV_TEST_PRECOMP_HPP__
 
+#include <array>
+
 #include "opencv2/ts.hpp"
 #include "opencv2/ts/ocl_test.hpp"
 #include "opencv2/core/private.hpp"

modules/core/test/test_utils_tls.impl.hpp

@@ -4,9 +4,7 @@
 
 // This is .hpp file included from test_utils.cpp
 
-#ifdef CV_CXX11
 #include <thread>  // std::thread
-#endif
 
 #include "opencv2/core/utils/tls.hpp"
 
@@ -34,8 +32,6 @@ public:
 int TLSReporter::g_last_id = 0;
 int TLSReporter::g_allocated = 0;
 
-#ifdef CV_CXX11
-
 template<typename T>
 static void callNThreadsWithTLS(int N, TLSData<T>& tls)
 {
@@ -129,6 +125,4 @@ static void testTLSAccumulator(bool detachFirst)
 TEST(Core_TLS, AccumulatorHoldData_detachData) { testTLSAccumulator(true); }
 TEST(Core_TLS, AccumulatorHoldData_gather) { testTLSAccumulator(false); }
 
-#endif
-
 }}  // namespace

modules/dnn/src/net_impl.cpp

@@ -918,7 +918,6 @@ AsyncArray Net::Impl::forwardAsync(const String& outputName)
     CV_Assert(!empty());
     FPDenormalsIgnoreHintScope fp_denormals_ignore_scope;
 
-#ifdef CV_CXX11
     String layerName = outputName;
 
     if (layerName.empty())
@@ -939,9 +938,6 @@ AsyncArray Net::Impl::forwardAsync(const String& outputName)
     isAsync = false;
 
     return getBlobAsync(layerName);
-#else
-    CV_Error(Error::StsNotImplemented, "DNN: Asynchronous forward requires build with enabled C++11");
-#endif  // CV_CXX11
 }
 
 

modules/dnn/src/net_impl.hpp

@@ -273,11 +273,9 @@ struct Net::Impl : public detail::NetImplBase
 
     Mat getBlob(String outputName) const;
 
-#ifdef CV_CXX11
     virtual AsyncArray getBlobAsync(const LayerPin& pin);
 
     AsyncArray getBlobAsync(String outputName);
-#endif  // CV_CXX11
 
     string dump(bool forceAllocation = false) const;
 

modules/dnn/src/onnx/onnx_importer.cpp

@@ -22,6 +22,7 @@
 
 #ifdef HAVE_PROTOBUF
 
+#include <array>
 #include <iostream>
 #include <fstream>
 #include <string>

modules/dnn/test/test_misc.cpp

@@ -1035,14 +1035,10 @@ TEST_P(Test_two_inputs, basic)
     randu(firstInp, 0, 100);
     randu(secondInp, 0, 100);
 
-#ifndef CV_CXX11
     std::vector<String> input_names;
     input_names.push_back("data");
     input_names.push_back("second_input");
     net.setInputsNames(input_names);
-#else
-    net.setInputsNames({"data", "second_input"});
-#endif
     net.setInput(firstInp, "data", kScale);
     net.setInput(secondInp, "second_input", kScaleInv);
     net.setPreferableBackend(backendId);

modules/imgcodecs/src/loadsave.cpp

@@ -210,15 +210,8 @@ struct ImageCodecInitializer
 static
 ImageCodecInitializer& getCodecs()
 {
-#ifdef CV_CXX11
     static ImageCodecInitializer g_codecs;
     return g_codecs;
-#else
-    // C++98 doesn't guarantee correctness of multi-threaded initialization of static global variables
-    // (memory leak here is not critical, use C++11 to avoid that)
-    static ImageCodecInitializer* g_codecs = new ImageCodecInitializer();
-    return *g_codecs;
-#endif
 }
 
 /**

modules/objdetect/src/precomp.hpp

@@ -52,5 +52,7 @@
 #include "opencv2/core/private.hpp"
 
 #include <numeric>
+#include <array>
+#include <vector>
 
 #endif

modules/objdetect/src/qrcode.cpp

@@ -15,6 +15,7 @@
 #include "quirc.h"
 #endif
 
+#include <array>
 #include <limits>
 #include <cmath>
 #include <queue>

modules/objdetect/test/test_precomp.hpp

@@ -7,10 +7,6 @@
 #include "opencv2/ts.hpp"
 #include "opencv2/objdetect.hpp"
 
-#if defined CV_CXX11
 #include <random>
-#else
-  #include <cstdlib>
-#endif
 
 #endif

modules/objdetect/test/test_qrcode_encode.cpp

@@ -5,16 +5,6 @@
 #include "test_precomp.hpp"
 namespace opencv_test { namespace {
 
-#if !defined CV_CXX11
-// Wrapper for generating seeded random number via std::rand.
-template<unsigned Seed>
-class SeededRandFunctor {
-public:
-    SeededRandFunctor() { std::srand(Seed); }
-    int operator()(int i) { return std::rand() % (i + 1); }
-};
-#endif
-
 std::string encode_qrcode_images_name[] = {
         "version1_mode1.png", "version1_mode2.png", "version1_mode4.png",
         "version2_mode1.png", "version2_mode2.png", "version2_mode4.png",

modules/python/src2/cv2_util.cpp

@@ -128,11 +128,7 @@ void pyPopulateArgumentConversionErrors()
         PySafeObject exception_message(PyObject_Str(exception_value));
         std::string message;
         getUnicodeString(exception_message, message);
-#ifdef CV_CXX11
         conversionErrorsTLS.getRef().push_back(std::move(message));
-#else
-        conversionErrorsTLS.getRef().push_back(message);
-#endif
     }
 }
 

modules/python/src2/hdr_parser.py

@@ -455,8 +455,7 @@ class CppHeaderParser(object):
                                                  ("CV_INLINE", ""),
                                                  ("CV_DEPRECATED", ""),
                                                  ("CV_DEPRECATED_EXTERNAL", ""),
-                                                 ("CV_NODISCARD_STD", ""),
+                                                 ("CV_NODISCARD_STD", "")]).strip()
-                                                 ("CV_NODISCARD", "")]).strip()
 
         if decl_str.strip().startswith('virtual'):
             virtual_method = True

modules/stitching/src/precomp.hpp

@@ -45,6 +45,7 @@
 
 #include "opencv2/opencv_modules.hpp"
 
+#include <array>
 #include <vector>
 #include <algorithm>
 #include <utility>

modules/ts/include/opencv2/ts.hpp

@@ -941,13 +941,9 @@ namespace opencv_test {
 using namespace cvtest;
 using namespace cv;
 
-#ifdef CV_CXX11
 #define CVTEST_GUARD_SYMBOL(name) \
     class required_namespace_specificatin_here_for_symbol_ ## name {}; \
     using name = required_namespace_specificatin_here_for_symbol_ ## name;
-#else
-#define CVTEST_GUARD_SYMBOL(name) /* nothing */
-#endif
 
 CVTEST_GUARD_SYMBOL(norm)
 CVTEST_GUARD_SYMBOL(add)

modules/videoio/src/cap_mfx_common.hpp

@@ -334,26 +334,11 @@ protected:
 
 
 // TODO: move to core::util?
-#ifdef CV_CXX11
 #include <thread>
 static void sleep_ms(int64 ms)
 {
     std::this_thread::sleep_for(std::chrono::milliseconds(ms));
 }
-#elif defined(__linux__)
-#include <time.h>
-static void sleep_ms(int64 ms)
-{
-    nanosleep(ms * 1000 * 1000);
-}
-#elif defined _WIN32
-static void sleep_ms(int64 ms)
-{
-    Sleep(ms);
-}
-#else
-#error "Can not detect sleep_ms() implementation"
-#endif
 
 
 // Linux specific

modules/videoio/src/cap_msmf.cpp

@@ -39,6 +39,7 @@
 #include <string>
 #include <algorithm>
 #include <deque>
+#include <iterator>
 #include <stdio.h>
 #include <stdarg.h>
 #include <string.h>

samples/cpp/tutorial_code/core/how_to_use_OpenCV_parallel_for_/how_to_use_OpenCV_parallel_for_.cpp

@@ -2,6 +2,8 @@
 #include <opencv2/core.hpp>
 #include <opencv2/imgcodecs.hpp>
 
+#define PARALLEL_FOR_LAMBDA
+
 using namespace std;
 using namespace cv;
 
@@ -33,6 +35,8 @@ int mandelbrotFormula(const complex<float> &z0, const int maxIter=500) {
 }
 //! [mandelbrot-grayscale-value]
 
+#ifndef PARALLEL_FOR_LAMBDA
+
 //! [mandelbrot-parallel]
 class ParallelMandelbrot : public ParallelLoopBody
 {
@@ -71,6 +75,8 @@ private:
 };
 //! [mandelbrot-parallel]
 
+#endif // !PARALLEL_FOR_LAMBDA
+
 //! [mandelbrot-sequential]
 void sequentialMandelbrot(Mat &img, const float x1, const float y1, const float scaleX, const float scaleY)
 {
@@ -102,7 +108,7 @@ int main()
 
     double t1 = (double) getTickCount();
 
-    #ifdef CV_CXX11
+#ifdef PARALLEL_FOR_LAMBDA
 
     //! [mandelbrot-parallel-call-cxx11]
     parallel_for_(Range(0, mandelbrotImg.rows*mandelbrotImg.cols), [&](const Range& range){
@@ -121,14 +127,14 @@ int main()
     });
     //! [mandelbrot-parallel-call-cxx11]
 
-    #else
+#else // PARALLEL_FOR_LAMBDA
 
     //! [mandelbrot-parallel-call]
     ParallelMandelbrot parallelMandelbrot(mandelbrotImg, x1, y1, scaleX, scaleY);
     parallel_for_(Range(0, mandelbrotImg.rows*mandelbrotImg.cols), parallelMandelbrot);
     //! [mandelbrot-parallel-call]
 
-    #endif
+#endif // PARALLEL_FOR_LAMBDA
 
     t1 = ((double) getTickCount() - t1) / getTickFrequency();
     cout << "Parallel Mandelbrot: " << t1 << " s" << endl;

samples/cpp/tutorial_code/core/how_to_use_OpenCV_parallel_for_/how_to_use_OpenCV_parallel_for_new.cpp

@@ -4,6 +4,8 @@
 #include <opencv2/imgproc.hpp>
 #include <opencv2/highgui.hpp>
 
+#define PARALLEL_FOR_LAMBDA
+
 using namespace std;
 using namespace cv;
 
@@ -47,7 +49,8 @@ void conv_seq(Mat src, Mat &dst, Mat kernel)
 }
 //! [convolution-sequential]
 
-#ifdef CV_CXX11
+#ifdef PARALLEL_FOR_LAMBDA
+
 void conv_parallel(Mat src, Mat &dst, Mat kernel)
 {
     int rows = src.rows, cols = src.cols;
@@ -118,7 +121,8 @@ void conv_parallel_row_split(Mat src, Mat &dst, Mat kernel)
                     });
     //! [convolution-parallel-cxx11-row-split]
 }
-#else
+
+#else // PARALLEL_FOR_LAMBDA
 
 //! [convolution-parallel]
 class parallelConvolution : public ParallelLoopBody
@@ -235,7 +239,7 @@ void conv_parallel_row_split(Mat src, Mat &dst, Mat kernel)
     //! [convolution-parallel-function-row]
 }
 
-#endif
+#endif // PARALLEL_FOR_LAMBDA
 
 static void help(char *progName)
 {

samples/cpp/tutorial_code/core/mat_the_basic_image_container/mat_the_basic_image_container.cpp

@@ -59,12 +59,12 @@ int main(int,char**)
     cout << "C = " << endl << " " << C << endl << endl;
     //! [comma]
     // do the same with initializer_list
-#ifdef CV_CXX11
+
     //! [list]
     C = (Mat_<double>({0, -1, 0, -1, 5, -1, 0, -1, 0})).reshape(3);
     cout << "C = " << endl << " " << C << endl << endl;
     //! [list]
-#endif
+
     //! [clone]
     Mat RowClone = C.row(1).clone();
     cout << "RowClone = " << endl << " " << RowClone << endl << endl;

samples/dnn/object_detection.cpp

@@ -5,7 +5,7 @@
 #include <opencv2/imgproc.hpp>
 #include <opencv2/highgui.hpp>
 
-#if defined(CV_CXX11) && defined(HAVE_THREADS)
+#if defined(HAVE_THREADS)
 #define USE_THREADS 1
 #endif