few simple fixes to work around strict-aliasing and one-definition-rules issues
that cause problems with LTO compilation.

most issues are actual problems withoverlapping file-local variable names which
leak into other contexts. most are easily fixed with couple of anonymous
namespaces to satisfy the compiler (none cause issues in practice, but generate
errors when standard Gentoo LTO flags are used)

NOTE: these fixes don't cover lib-ffmpeg-support module, which generate an
enormous number of ODR violations

diff --git a/src/prefs/SpectrumPrefs.cpp b/src/prefs/SpectrumPrefs.cpp
index e9034ff83..b775475ab 100644
--- a/src/prefs/SpectrumPrefs.cpp
+++ b/src/prefs/SpectrumPrefs.cpp
@@ -228,9 +228,11 @@ void SpectrumPrefs::PopulateOrExchange(ShuttleGui & S)
                8);
 
             // i18n-hint Scheme refers to a color scheme for spectrogram colors
+            int _selection = static_cast<int>(mTempSettings.colorScheme);
             S.Id(ID_COLOR_SCHEME).TieChoice(XC("Sche&me", "spectrum prefs"),
-               (int&)mTempSettings.colorScheme,
+               _selection,
                Msgids( SpectrogramSettings::GetColorSchemeNames() ) );
+            mTempSettings.colorScheme = static_cast<SpectrogramSettings::ColorScheme>(_selection);
          }
          S.EndMultiColumn();
       }
diff --git a/src/effects/Equalization.cpp b/src/effects/Equalization.cpp
index 0cdf94500..3496658d0 100644
--- a/src/effects/Equalization.cpp
+++ b/src/effects/Equalization.cpp
@@ -148,13 +148,15 @@ enum
    ID_Slider,   // needs to come last
 };
 
-enum kInterpolations
-{
-   kBspline,
-   kCosine,
-   kCubic,
-   nInterpolations
-};
+namespace {
+    enum kInterpolations
+    {
+       kBspline,
+       kCosine,
+       kCubic,
+       nInterpolations
+    };
+}
 
 // Increment whenever EQCurves.xml is updated
 #define EQCURVES_VERSION   1
diff --git a/src/effects/Noise.cpp b/src/effects/Noise.cpp
index e075b79ae..aa72bf792 100644
--- a/src/effects/Noise.cpp
+++ b/src/effects/Noise.cpp
@@ -32,13 +32,15 @@
 #include "../widgets/valnum.h"
 #include "../widgets/NumericTextCtrl.h"
 
-enum kTypes
-{
-   kWhite,
-   kPink,
-   kBrownian,
-   nTypes
-};
+namespace {
+	enum kTypes
+	{
+	   kWhite,
+	   kPink,
+	   kBrownian,
+	   nTypes
+	};
+}
 
 static const EnumValueSymbol kTypeStrings[nTypes] =
 {
diff --git a/src/effects/ScienFilter.cpp b/src/effects/ScienFilter.cpp
index 2c3b9b786..6ce5ecf2e 100644
--- a/src/effects/ScienFilter.cpp
+++ b/src/effects/ScienFilter.cpp
@@ -88,13 +88,15 @@ enum
    ID_StopbandRipple
 };
 
-enum kTypes
-{
-   kButterworth,
-   kChebyshevTypeI,
-   kChebyshevTypeII,
-   nTypes
-};
+namespace {
+    enum kTypes
+    {
+       kButterworth,
+       kChebyshevTypeI,
+       kChebyshevTypeII,
+       nTypes
+    };
+}
 
 static const EnumValueSymbol kTypeStrings[nTypes] =
 {
diff --git a/src/effects/ToneGen.cpp b/src/effects/ToneGen.cpp
index 8225421b9..3ff5081ae 100644
--- a/src/effects/ToneGen.cpp
+++ b/src/effects/ToneGen.cpp
@@ -38,12 +38,14 @@ frequency changes smoothly during the tone.
 #include "../widgets/valnum.h"
 #include "../widgets/NumericTextCtrl.h"
 
-enum kInterpolations
-{
-   kLinear,
-   kLogarithmic,
-   nInterpolations
-};
+namespace {
+	enum kInterpolations
+	{
+	   kLinear,
+	   kLogarithmic,
+	   nInterpolations
+	};
+}
 
 static const EnumValueSymbol kInterStrings[nInterpolations] =
 {