Replace a DCHECK with static_assert

webrtc/modules/audio_processing/audio_processing_impl.cc

Index: webrtc/modules/audio_processing/audio_processing_impl.cc
diff --git a/webrtc/modules/audio_processing/audio_processing_impl.cc b/webrtc/modules/audio_processing/audio_processing_impl.cc
index bd311ad6b1615c75762f85061a8da5b7f73b03d2..3f26356d4b5842289313dc24f4309565da48454f 100644
--- a/webrtc/modules/audio_processing/audio_processing_impl.cc
+++ b/webrtc/modules/audio_processing/audio_processing_impl.cc
@@ -70,15 +70,7 @@
 
 namespace webrtc {
 
-const int AudioProcessing::kNativeSampleRatesHz[] = {
-    AudioProcessing::kSampleRate8kHz,
-    AudioProcessing::kSampleRate16kHz,
-    AudioProcessing::kSampleRate32kHz,
-    AudioProcessing::kSampleRate48kHz};
-const size_t AudioProcessing::kNumNativeSampleRates =
-    arraysize(AudioProcessing::kNativeSampleRatesHz);
-const int AudioProcessing::kMaxNativeSampleRateHz = AudioProcessing::
-    kNativeSampleRatesHz[AudioProcessing::kNumNativeSampleRates - 1];
+constexpr int AudioProcessing::kNativeSampleRatesHz[];
 
 namespace {
 
@@ -103,12 +95,15 @@ bool SampleRateSupportsMultiBand(int sample_rate_hz) {
 
 int FindNativeProcessRateToUse(int minimum_rate, bool band_splitting_required) {
 #ifdef WEBRTC_ARCH_ARM_FAMILY
-  const int kMaxSplittingNativeProcessRate = AudioProcessing::kSampleRate32kHz;
+  constexpr int kMaxSplittingNativeProcessRate =
+      AudioProcessing::kSampleRate32kHz;
 #else
-  const int kMaxSplittingNativeProcessRate = AudioProcessing::kSampleRate48kHz;
+  constexpr int kMaxSplittingNativeProcessRate =
+      AudioProcessing::kSampleRate48kHz;
 #endif
-  RTC_DCHECK_LE(kMaxSplittingNativeProcessRate,
-                AudioProcessing::kMaxNativeSampleRateHz);
+  static_assert(
+      kMaxSplittingNativeProcessRate <= AudioProcessing::kMaxNativeSampleRateHz,
+      "");

[peah-webrtc, 2016/09/13 12:50:12]

Don't we want a message for the assert?

[kwiberg-webrtc, 2016/09/13 13:11:17]

No. If the assert fails, there'll be a compilation error that points to this
source line---that's enough. The second argument to static_assert is almost
never useful. (And indeed, in C++17 you're allowed to omit it.)

   const int uppermost_native_rate = band_splitting_required
                                         ? kMaxSplittingNativeProcessRate
                                         : AudioProcessing::kSampleRate48kHz;