Various warning fix

ScriptableRenderPipeline/Core/CoreRP/ShaderLibrary/Color.hlsl

 // Gamma22
 real Gamma22ToLinear(real c)
 {
-    return pow(c, 2.2);
+    return PositivePow(c, 2.2);
-    return pow(c.rgb, real3(2.2, 2.2, 2.2));
+    return PositivePow(c.rgb, real3(2.2, 2.2, 2.2));
 }
 
 real4 Gamma22ToLinear(real4 c)
 
 real LinearToGamma22(real c)
 {
-    return pow(c, 0.454545454545455);
+    return PositivePow(c, 0.454545454545455);
-    return pow(c.rgb, real3(0.454545454545455, 0.454545454545455, 0.454545454545455));
+    return PositivePow(c.rgb, real3(0.454545454545455, 0.454545454545455, 0.454545454545455));
 }
 
 real4 LinearToGamma22(real4 c)
 real3 SRGBToLinear(real3 c)
 {
     real3 linearRGBLo  = c / 12.92;
-    real3 linearRGBHi  = pow((c + 0.055) / 1.055, real3(2.4, 2.4, 2.4));
+    real3 linearRGBHi  = PositivePow((c + 0.055) / 1.055, real3(2.4, 2.4, 2.4));
     real3 linearRGB    = (c <= 0.04045) ? linearRGBLo : linearRGBHi;
     return linearRGB;
 }
 real3 LinearToSRGB(real3 c)
 {
     real3 sRGBLo = c * 12.92;
-    real3 sRGBHi = (pow(c, real3(1.0/2.4, 1.0/2.4, 1.0/2.4)) * 1.055) - 0.055;
+    real3 sRGBHi = (PositivePow(c, real3(1.0/2.4, 1.0/2.4, 1.0/2.4)) * 1.055) - 0.055;
     real3 sRGB   = (c <= 0.0031308) ? sRGBLo : sRGBHi;
     return sRGB;
 }
 
 real3 FastLinearToSRGB(real3 c)
 {
-    return saturate(1.055 * pow(abs(c), 0.416666667) - 0.055);
+    return saturate(1.055 * PositivePow(c, 0.416666667) - 0.055);
 }
 
 real4 FastLinearToSRGB(real4 c)

ScriptableRenderPipeline/Core/CoreRP/ShaderLibrary/Common.hlsl

 
 // Using pow often result to a warning like this
 // "pow(f, e) will not work for negative f, use abs(f) or conditionally handle negative values if you expect them"
-// PositivePow remove this warning when you know the value is positive and avoid inf/NAN.
-TEMPLATE_2_REAL(PositivePow, base, power, return pow(max(abs(base), FLT_EPS), power))
+// PositivePow remove this warning when you know the value is positive or 0 and avoid inf/NAN.
+// Note: https://msdn.microsoft.com/en-us/library/windows/desktop/bb509636(v=vs.85).aspx pow(0, >0) == 0
+TEMPLATE_2_REAL(PositivePow, base, power, return pow(abs(base), power))
 
 // Composes a floating point value with the magnitude of 'x' and the sign of 's'.
 // See the comment about FastSign() below.

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Editor/HDAssetFactory.cs

 
                 // Load default renderPipelineResources / Material / Shader
                 string HDRenderPipelinePath = HDEditorUtils.GetHDRenderPipelinePath();
-                string PostProcessingPath = HDEditorUtils.GetPostProcessingPath();
                 string CorePath = HDEditorUtils.GetCorePath();
 
                 newAsset.defaultDiffuseMaterial = Load<Material>(HDRenderPipelinePath + "RenderPipelineResources/DefaultHDMaterial.mat");

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Editor/Lighting/Reflection/PlanarReflectionProbeUI.Handles.cs

 {
     partial class PlanarReflectionProbeUI
     {
+#if false
+#endif
         static readonly Color k_GizmoMirrorPlaneCamera = new Color(128f / 255f, 128f / 255f, 233f / 255f, 128f / 255f);
 
         public static void DrawHandles(PlanarReflectionProbeUI s, PlanarReflectionProbe d, Editor o)
             {
                 case EditBaseShape:
                     InfluenceVolumeUI.DrawGizmos(
-                        s.influenceVolume, 
-                        d.influenceVolume, 
-                        mat, 
-                        InfluenceVolumeUI.HandleType.Base, 
+                        s.influenceVolume,
+                        d.influenceVolume,
+                        mat,
+                        InfluenceVolumeUI.HandleType.Base,
-                        s.influenceVolume, 
-                        d.influenceVolume, 
+                        s.influenceVolume,
+                        d.influenceVolume,
-                        InfluenceVolumeUI.HandleType.Influence, 
+                        InfluenceVolumeUI.HandleType.Influence,
-                        s.influenceVolume, 
+                        s.influenceVolume,
-                        InfluenceVolumeUI.HandleType.InfluenceNormal, 
+                        InfluenceVolumeUI.HandleType.InfluenceNormal,
                         InfluenceVolumeUI.HandleType.All);
                     break;
                 default:

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Lighting/DeferredDirectionalShadow.compute

 float   _DirectionalShadowIndex;
 float3  _LightDirection;
 float4  _ScreenSpaceShadowsParameters;
-uint	_SampleCount;
+int     _SampleCount;
 CBUFFER_END
 
 #define _ContactShadowLength                _ScreenSpaceShadowsParameters.x