Make a variety of low-impact Clang tidy fixes in Impeller.

impeller/base/thread.h

@@ -53,7 +53,9 @@ class IPLR_CAPABILITY("mutex") RWMutex {
 
 class IPLR_SCOPED_CAPABILITY Lock {
  public:
-  Lock(Mutex& mutex) IPLR_ACQUIRE(mutex) : mutex_(mutex) { mutex_.Lock(); }
+  explicit Lock(Mutex& mutex) IPLR_ACQUIRE(mutex) : mutex_(mutex) {
+    mutex_.Lock();
+  }
 
   ~Lock() IPLR_RELEASE() { mutex_.Unlock(); }
 
@@ -65,7 +67,8 @@ class IPLR_SCOPED_CAPABILITY Lock {
 
 class IPLR_SCOPED_CAPABILITY ReaderLock {
  public:
-  ReaderLock(RWMutex& mutex) IPLR_ACQUIRE_SHARED(mutex) : mutex_(mutex) {
+  explicit ReaderLock(RWMutex& mutex) IPLR_ACQUIRE_SHARED(mutex)
+      : mutex_(mutex) {
     mutex_.LockReader();
   }
 
@@ -79,7 +82,7 @@ class IPLR_SCOPED_CAPABILITY ReaderLock {
 
 class IPLR_SCOPED_CAPABILITY WriterLock {
  public:
-  WriterLock(RWMutex& mutex) IPLR_ACQUIRE(mutex) : mutex_(mutex) {
+  explicit WriterLock(RWMutex& mutex) IPLR_ACQUIRE(mutex) : mutex_(mutex) {
     mutex_.LockWriter();
   }
 

impeller/base/version.h

@@ -18,7 +18,9 @@ struct Version {
   size_t minor_version;
   size_t patch_version;
 
-  constexpr Version(size_t p_major = 0, size_t p_minor = 0, size_t p_patch = 0)
+  constexpr explicit Version(size_t p_major = 0,
+                             size_t p_minor = 0,
+                             size_t p_patch = 0)
       : major_version(p_major),
         minor_version(p_minor),
         patch_version(p_patch) {}

impeller/geometry/color.h

@@ -144,7 +144,7 @@ struct Color {
 
   explicit Color(const ColorHSB& hsbColor);
 
-  Color(const Vector4& value);
+  explicit Color(const Vector4& value);
 
   constexpr Color(Scalar r, Scalar g, Scalar b, Scalar a)
       : red(r), green(g), blue(b), alpha(a) {}

impeller/geometry/matrix.h

@@ -62,7 +62,7 @@ struct Matrix {
             Vector4(m12, m13, m14, m15)} {}
   // clang-format on
 
-  Matrix(const MatrixDecomposition& decomposition);
+  explicit Matrix(const MatrixDecomposition& decomposition);
 
   // clang-format off
   static constexpr Matrix MakeColumn(

impeller/golden_tests/metal_screenshot.h

@@ -30,9 +30,9 @@ class MetalScreenshot {
 
  private:
   friend class MetalScreenshoter;
-  MetalScreenshot(CGImageRef cgImage);
+  explicit MetalScreenshot(CGImageRef cgImage);
   FML_DISALLOW_COPY_AND_ASSIGN(MetalScreenshot);
-  CGImageRef cgImage_;
+  CGImageRef cg_image_;
   CFDataRef pixel_data_;
 };
 }  // namespace testing

impeller/golden_tests/metal_screenshot.mm

@@ -7,26 +7,26 @@
 namespace impeller {
 namespace testing {
 
-MetalScreenshot::MetalScreenshot(CGImageRef cgImage) : cgImage_(cgImage) {
+MetalScreenshot::MetalScreenshot(CGImageRef cgImage) : cg_image_(cgImage) {
   CGDataProviderRef data_provider = CGImageGetDataProvider(cgImage);
   pixel_data_ = CGDataProviderCopyData(data_provider);
 }
 
 MetalScreenshot::~MetalScreenshot() {
   CFRelease(pixel_data_);
-  CGImageRelease(cgImage_);
+  CGImageRelease(cg_image_);
 }
 
 const UInt8* MetalScreenshot::GetBytes() const {
   return CFDataGetBytePtr(pixel_data_);
 }
 
 size_t MetalScreenshot::GetHeight() const {
-  return CGImageGetHeight(cgImage_);
+  return CGImageGetHeight(cg_image_);
 }
 
 size_t MetalScreenshot::GetWidth() const {
-  return CGImageGetWidth(cgImage_);
+  return CGImageGetWidth(cg_image_);
 }
 
 bool MetalScreenshot::WriteToPNG(const std::string& path) const {
@@ -36,7 +36,7 @@
   CGImageDestinationRef destination = CGImageDestinationCreateWithURL(
       (__bridge CFURLRef)output_url, kUTTypePNG, 1, nullptr);
   if (destination != nullptr) {
-    CGImageDestinationAddImage(destination, cgImage_,
+    CGImageDestinationAddImage(destination, cg_image_,
                                (__bridge CFDictionaryRef) @{});
 
     if (CGImageDestinationFinalize(destination)) {

impeller/renderer/pool.h

@@ -14,7 +14,7 @@ namespace impeller {
 template <typename T>
 class Pool {
  public:
-  Pool(uint32_t limit_bytes) : limit_bytes_(limit_bytes), size_(0) {}
+  explicit Pool(uint32_t limit_bytes) : limit_bytes_(limit_bytes) {}
 
   std::shared_ptr<T> Grab() {
     std::scoped_lock lock(mutex_);
@@ -46,7 +46,7 @@ class Pool {
  private:
   std::vector<std::shared_ptr<T>> pool_;
   const uint32_t limit_bytes_;
-  uint32_t size_;
+  uint32_t size_ = 0;
   // Note: This would perform better as a lockless ring buffer.
   mutable std::mutex mutex_;
 };

impeller/scene/importer/importer_unittests.cc

@@ -102,10 +102,10 @@ TEST(ImporterTest, CanParseSkinnedGLTF) {
   ASSERT_COLOR_NEAR(color, Color(1, 1, 1, 1));
 
   Vector4 joints = ToVector4(vertex.joints());
-  ASSERT_COLOR_NEAR(joints, Vector4(0, 0, 0, 0));
+  ASSERT_VECTOR4_NEAR(joints, Vector4(0, 0, 0, 0));
 
   Vector4 weights = ToVector4(vertex.weights());
-  ASSERT_COLOR_NEAR(weights, Vector4(1, 0, 0, 0));
+  ASSERT_VECTOR4_NEAR(weights, Vector4(1, 0, 0, 0));
 
   ASSERT_EQ(scene.animations.size(), 2u);
   ASSERT_EQ(scene.animations[0]->name, "Idle");