Avoid different kinds of compiler warnings (#2481)

* Avoid different kinds of compiler warnings that started to appear when upgrading my build environment

* Avoid more compiler warnings

* Revert the overly verbose static_cast changes

* Make resize_bilinear and resize_bilinear_gradient take long long (previously just long)

* Circumvent what appears to be a bug in Visual Studio 2019's optimizer
(see: https://forum.juce.com/t/warning-in-the-lastest-vs2019/38267)

dlib/cuda/cpu_dlib.cpp

@@ -2000,11 +2000,11 @@ namespace dlib
 
         void resize_bilinear (
             tensor& dest,
-            long dest_row_stride,
-            long dest_channel_stride,
+            long long dest_row_stride,
+            long long dest_channel_stride,
             const tensor& src,
-            long src_row_stride,
-            long src_channel_stride
+            long long src_row_stride,
+            long long src_channel_stride
         )
         {
             DLIB_CASSERT(is_same_object(dest, src)==false);
@@ -2028,11 +2028,11 @@ namespace dlib
 
         void resize_bilinear_gradient (
             tensor& grad,
-            long grad_row_stride,
-            long grad_channel_stride,
+            long long grad_row_stride,
+            long long grad_channel_stride,
             const tensor& gradient_input,
-            long gradient_input_row_stride,
-            long gradient_input_channel_stride
+            long long gradient_input_row_stride,
+            long long gradient_input_channel_stride
         )
         {
             DLIB_CASSERT(is_same_object(grad, gradient_input)==false);

dlib/cuda/cpu_dlib.h

@@ -423,20 +423,20 @@ namespace dlib
 
         void resize_bilinear (
             tensor& dest,
-            long dest_row_stride,
-            long dest_channel_stride,
+            long long dest_row_stride,
+            long long dest_channel_stride,
             const tensor& src,
-            long src_row_stride,
-            long src_channel_stride
+            long long src_row_stride,
+            long long src_channel_stride
         );
 
         void resize_bilinear_gradient (
             tensor& grad,
-            long grad_row_stride,
-            long grad_channel_stride,
+            long long grad_row_stride,
+            long long grad_channel_stride,
             const tensor& gradient_input,
-            long gradient_input_row_stride,
-            long gradient_input_channel_stride
+            long long gradient_input_row_stride,
+            long long gradient_input_channel_stride
         );
 
         inline void resize_bilinear (

dlib/cuda/cuda_dlib.cu

@@ -1732,11 +1732,11 @@ namespace dlib
 
         void resize_bilinear (
             tensor& dest,
-            long dest_row_stride,
-            long dest_channel_stride,
+            long long dest_row_stride,
+            long long dest_channel_stride,
             const tensor& src,
-            long src_row_stride,
-            long src_channel_stride
+            long long src_row_stride,
+            long long src_channel_stride
         )
         {
             DLIB_CASSERT(is_same_object(dest, src)==false);
@@ -1838,11 +1838,11 @@ namespace dlib
 
         void resize_bilinear_gradient (
             tensor& grad,
-            long grad_row_stride,
-            long grad_channel_stride,
+            long long grad_row_stride,
+            long long grad_channel_stride,
             const tensor& gradient_input,
-            long gradient_input_row_stride,
-            long gradient_input_channel_stride
+            long long gradient_input_row_stride,
+            long long gradient_input_channel_stride
         )
         {
             DLIB_CASSERT(is_same_object(grad, gradient_input)==false);

dlib/cuda/cuda_dlib.h

@@ -467,20 +467,20 @@ namespace dlib
 
         void resize_bilinear (
             tensor& dest,
-            long dest_row_stride,
-            long dest_channel_stride,
+            long long dest_row_stride,
+            long long dest_channel_stride,
             const tensor& src,
-            long src_row_stride,
-            long src_channel_stride
+            long long src_row_stride,
+            long long src_channel_stride
         );
 
         void resize_bilinear_gradient (
             tensor& grad,
-            long grad_row_stride,
-            long grad_channel_stride,
+            long long grad_row_stride,
+            long long grad_channel_stride,
             const tensor& gradient_input,
-            long gradient_input_row_stride,
-            long gradient_input_channel_stride
+            long long gradient_input_row_stride,
+            long long gradient_input_channel_stride
         );
 
         inline void resize_bilinear (

dlib/cuda/tensor.h

@@ -110,7 +110,7 @@ namespace dlib
         
         tensor& operator/= (float val)
         {
-            *this *= 1.0/val;
+            *this *= 1.f/val;
             return *this;
         }
 

dlib/cuda/tensor_tools.h

@@ -1868,7 +1868,7 @@ namespace dlib { namespace tt
             if (items.size() < 1)
                 return;
 
-            scale = 1.0/items.size();
+            scale = 1.f/items.size();
 
             // split item into groups of accessible devices
             std::vector<tensor*> group, unused;

dlib/dnn/input.h

@@ -40,9 +40,9 @@ namespace dlib
 
         input_rgb_image (
         ) : 
-            avg_red(122.782), 
-            avg_green(117.001),
-            avg_blue(104.298) 
+            avg_red(122.782f),
+            avg_green(117.001f),
+            avg_blue(104.298f)
         {
         }
 

dlib/dnn/loss.h

@@ -745,7 +745,7 @@ namespace dlib
         unsigned long total_num_labels = 0;
 
         // We make it true that: possible_labels[classifier][label_idx_lookup[classifier][label]] == label
-        std::map<std::string, std::map<std::string,long>> label_idx_lookup;
+        std::map<std::string, std::map<std::string, size_t>> label_idx_lookup;
 
 
         // Scratch doesn't logically contribute to the state of this object.  It's just
@@ -2188,8 +2188,8 @@ namespace dlib
             {
                 // These values used to be hard coded, so for this version of the metric
                 // learning loss we just use these values.
-                item.margin = 0.1;
-                item.dist_thresh = 0.75;
+                item.margin = 0.1f;
+                item.dist_thresh = 0.75f;
                 return;
             }
             else if (version == "loss_metric_2")
@@ -2215,8 +2215,8 @@ namespace dlib
         }
 
     private:
-        float margin = 0.04;
-        float dist_thresh = 0.6;
+        float margin = 0.04f;
+        float dist_thresh = 0.6f;
 
 
         // These variables are only here to avoid being reallocated over and over in

dlib/dnn/solvers.h

@@ -24,7 +24,7 @@ namespace dlib
         }
 
         sgd(
-        ) : sgd(0.0005, 0.9) 
+        ) : sgd(0.0005f, 0.9f)
         { 
         }
 
@@ -209,7 +209,7 @@ namespace dlib
         }
 
         adam(
-        ) : adam(0.0005, 0.9, 0.999) 
+        ) : adam(0.0005f, 0.9f, 0.999f)
         {}
 
         float get_momentum1 (

dlib/geometry/rectangle.h

@@ -748,6 +748,10 @@ namespace dlib
 
 // ----------------------------------------------------------------------------------------
 
+    // Circumvent what appears to be a bug in Visual Studio 2019's optimizer
+    // (see: https://forum.juce.com/t/warning-in-the-lastest-vs2019/38267)
+#pragma warning ( push )
+#pragma warning ( disable: 4723 )
     inline rectangle set_rect_area (
         const rectangle& rect,
         unsigned long area
@@ -768,6 +772,7 @@ namespace dlib
             return centered_rect(rect, (long)std::round(rect.width()*scale), (long)std::round(rect.height()*scale));
         }
     }
+#pragma warning ( pop )
 
 // ----------------------------------------------------------------------------------------
 

dlib/statistics/lda.h

@@ -22,7 +22,7 @@ namespace dlib
         )
         {
             std::map<unsigned long,unsigned long> class_labels;
-            for (unsigned long i = 0; i < row_labels.size(); ++i)
+            for (size_t i = 0; i < row_labels.size(); ++i)
             {
                 const unsigned long next = class_labels.size();
                 if (class_labels.count(row_labels[i]) == 0)

dlib/vectorstream/vectorstream.h

@@ -111,7 +111,7 @@ namespace dlib
             {  
                 // if they are trying to push back a character that they didn't read last
                 // that is an error
-                const unsigned long prev = read_pos-1;
+                const auto prev = read_pos-1;
                 if (c != EOF && prev < buffer.size() && 
                     c != static_cast<unsigned char>(buffer[prev]))
                 {