Use constexpr to avoid a static initializer

webrtc/modules/audio_processing/vad/vad_audio_proc.cc

Index: webrtc/modules/audio_processing/vad/vad_audio_proc.cc
diff --git a/webrtc/modules/audio_processing/vad/vad_audio_proc.cc b/webrtc/modules/audio_processing/vad/vad_audio_proc.cc
index af1214b99a04ccce9835f364f2218bd6d57cde60..bd855a8d7a3a0295e3707aa422f76d88851331e1 100644
--- a/webrtc/modules/audio_processing/vad/vad_audio_proc.cc
+++ b/webrtc/modules/audio_processing/vad/vad_audio_proc.cc
@@ -33,7 +33,7 @@ namespace webrtc {
 struct VadAudioProc::PitchAnalysisStruct : public ::PitchAnalysisStruct {};
 struct VadAudioProc::PreFiltBankstr : public ::PreFiltBankstr {};
 
-static const float kFrequencyResolution =
+constexpr float kFrequencyResolution =

[kwiberg-webrtc, 2017/06/17 22:54:30]

That constexpr (and const) imply internal linkage is probably not well enough
known---consider e.g. that this declaration and that on the next line were both
"static const". Could you put it in an unnamed namespace to make the internal
linkage obvious?

(Also, to reduce eyesore, give the kSilenceRms declaration the same treatment if
you want.)

[hlundin-webrtc, 2017/06/19 07:45:23]

What kwiberg@ says.

[brucedawson, 2017/06/19 18:45:56]

I added constexpr to kSilenceRms, to make it appear more consistent.

I agree that removing static may cause some confusion so I put it back. I can't
convince myself to put the declarations in an anonymous namespace that I know is
unnecessary so I think restoring static is the right compromise.

     kSampleRateHz / static_cast<float>(VadAudioProc::kDftSize);
 static const int kSilenceRms = 5;