From d59d3bb117544f2d4efe9f27d199f440a1da6cb8 Mon Sep 17 00:00:00 2001
From: kwiberg <kwiberg@webrtc.org>
Date: Tue, 13 Sep 2016 07:49:33 -0700
Subject: [PATCH] Replace a DCHECK with static_assert

This requires marking a bunch of compile-time constants "constexpr"
instead of just "const".

Review-Url: https://codereview.webrtc.org/2335483003
Cr-Commit-Position: refs/heads/master@{#14199}
---
 .../audio_processing/audio_processing_impl.cc | 21 +++++++------------
 .../include/audio_processing.h                | 12 ++++++++---
 2 files changed, 17 insertions(+), 16 deletions(-)

diff --git a/webrtc/modules/audio_processing/audio_processing_impl.cc b/webrtc/modules/audio_processing/audio_processing_impl.cc
index 72f154a66d..5478456cdb 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,
+      "");
   const int uppermost_native_rate = band_splitting_required
                                         ? kMaxSplittingNativeProcessRate
                                         : AudioProcessing::kSampleRate48kHz;
diff --git a/webrtc/modules/audio_processing/include/audio_processing.h b/webrtc/modules/audio_processing/include/audio_processing.h
index 035fa32c7a..172da0891f 100644
--- a/webrtc/modules/audio_processing/include/audio_processing.h
+++ b/webrtc/modules/audio_processing/include/audio_processing.h
@@ -513,9 +513,15 @@ class AudioProcessing {
     kSampleRate48kHz = 48000
   };
 
-  static const int kNativeSampleRatesHz[];
-  static const size_t kNumNativeSampleRates;
-  static const int kMaxNativeSampleRateHz;
+  // TODO(kwiberg): We currently need to support a compiler (Visual C++) that
+  // complains if we don't explicitly state the size of the array here. Remove
+  // the size when that's no longer the case.
+  static constexpr int kNativeSampleRatesHz[4] = {
+      kSampleRate8kHz, kSampleRate16kHz, kSampleRate32kHz, kSampleRate48kHz};
+  static constexpr size_t kNumNativeSampleRates =
+      arraysize(kNativeSampleRatesHz);
+  static constexpr int kMaxNativeSampleRateHz =
+      kNativeSampleRatesHz[kNumNativeSampleRates - 1];
 
   static const int kChunkSizeMs = 10;
 };