Issue #2342: Use [[nodiscard]] in /gfx and /layout

10 files changed, 48 insertions, 48 deletions

diff --git a/gfx/2d/BaseRect.h b/gfx/2d/BaseRect.h
index a4e5e4c1d0..7f1590060d 100644
--- a/gfx/2d/BaseRect.h
+++ b/gfx/2d/BaseRect.h
@@ -111,7 +111,7 @@ struct BaseRect {
   // Intersection with an empty Rect may not produce an empty Rect if overflow
   // occurs. e.g. {INT_MIN, 0, 0, 20} Intersect { 5000, 0, 500, 20 } gives:
   // the non-emtpy {5000, 0, 500, 20 } instead of {5000, 0, 0, 0}
-  MOZ_MUST_USE Sub Intersect(const Sub& aRect) const
+  [[nodiscard]] Sub Intersect(const Sub& aRect) const
   {
     Sub result;
     result.x = std::max<T>(x, aRect.x);
@@ -127,7 +127,7 @@ struct BaseRect {
   // better. This comes at a tiny cost in performance.
   // e.g. {INT_MIN, 0, 0, 20} Intersect { 5000, 0, 500, 20 } gives:
   // {5000, 0, 0, 0}
-  MOZ_MUST_USE Sub SafeIntersect(const Sub& aRect) const
+  [[nodiscard]] Sub SafeIntersect(const Sub& aRect) const
   {
     Sub result;
     result.x = std::max<T>(x, aRect.x);
@@ -161,7 +161,7 @@ struct BaseRect {
   // If both rectangles are empty, returns this.
   // WARNING! This is not safe against overflow, prefer using SafeUnion instead
   // when dealing with int-based rects.
-  MOZ_MUST_USE Sub Union(const Sub& aRect) const
+  [[nodiscard]] Sub Union(const Sub& aRect) const
   {
     if (IsEmpty()) {
       return aRect;
@@ -176,7 +176,7 @@ struct BaseRect {
   // Thus, empty input rectangles are allowed to affect the result.
   // WARNING! This is not safe against overflow, prefer using SafeUnionEdges
   // instead when dealing with int-based rects.
-  MOZ_MUST_USE Sub UnionEdges(const Sub& aRect) const
+  [[nodiscard]] Sub UnionEdges(const Sub& aRect) const
   {
     Sub result;
     result.x = std::min(x, aRect.x);
@@ -588,7 +588,7 @@ struct BaseRect {
    * Clamp aPoint to this rectangle. It is allowed to end up on any
    * edge of the rectangle.
    */
-  MOZ_MUST_USE Point ClampPoint(const Point& aPoint) const
+  [[nodiscard]] Point ClampPoint(const Point& aPoint) const
   {
     return Point(std::max(x, std::min(XMost(), aPoint.x)),
                  std::max(y, std::min(YMost(), aPoint.y)));
@@ -599,7 +599,7 @@ struct BaseRect {
    * aRect then the dimensions that don't fit will be shrunk so that they
    * do fit. The resulting rect is returned.
    */
-  MOZ_MUST_USE Sub MoveInsideAndClamp(const Sub& aRect) const
+  [[nodiscard]] Sub MoveInsideAndClamp(const Sub& aRect) const
   {
     Sub rect(std::max(aRect.x, x),
              std::max(aRect.y, y),
diff --git a/gfx/2d/Rect.h b/gfx/2d/Rect.h
index 942cb200db..d17b802434 100644
--- a/gfx/2d/Rect.h
+++ b/gfx/2d/Rect.h
@@ -166,7 +166,7 @@ struct IntRectTyped :
     // Same as Union(), but in the cases where aRect is non-empty, the union is
     // done while guarding against overflow. If an overflow is detected, Nothing
     // is returned.
-    MOZ_MUST_USE Maybe<Self> SafeUnion(const Self& aRect) const
+    [[nodiscard]] Maybe<Self> SafeUnion(const Self& aRect) const
     {
       if (this->IsEmpty()) {
         return aRect.Overflows() ? Nothing() : Some(aRect);
@@ -179,7 +179,7 @@ struct IntRectTyped :
 
     // Same as UnionEdges, but guards against overflow. If an overflow is detected,
     // Nothing is returned.
-    MOZ_MUST_USE Maybe<Self> SafeUnionEdges(const Self& aRect) const
+    [[nodiscard]] Maybe<Self> SafeUnionEdges(const Self& aRect) const
     {
       if (this->Overflows() || aRect.Overflows()) {
         return Nothing();
diff --git a/gfx/src/nsPoint.h b/gfx/src/nsPoint.h
index b377eb5a56..3c406e5a61 100644
--- a/gfx/src/nsPoint.h
+++ b/gfx/src/nsPoint.h
@@ -35,12 +35,12 @@ struct nsPoint : public mozilla::gfx::BasePoint<nscoord, nsPoint> {
    * @param aFromAPP the APP to scale from
    * @param aToAPP the APP to scale to
    */
-  MOZ_MUST_USE inline nsPoint
+  [[nodiscard]] inline nsPoint
     ScaleToOtherAppUnits(int32_t aFromAPP, int32_t aToAPP) const;
 
-  MOZ_MUST_USE inline nsPoint
+  [[nodiscard]] inline nsPoint
     RemoveResolution(const float resolution) const;
-  MOZ_MUST_USE inline nsPoint
+  [[nodiscard]] inline nsPoint
     ApplyResolution(const float resolution) const;
 };
 
diff --git a/gfx/src/nsRect.h b/gfx/src/nsRect.h
index 267f5849cb..403d3c06b2 100644
--- a/gfx/src/nsRect.h
+++ b/gfx/src/nsRect.h
@@ -56,7 +56,7 @@ struct nsRect :
   // overflowing nscoord values in the 'width' and 'height' fields by
   // clamping the width and height values to nscoord_MAX if necessary.
 
-  MOZ_MUST_USE nsRect SaturatingUnion(const nsRect& aRect) const
+  [[nodiscard]] nsRect SaturatingUnion(const nsRect& aRect) const
   {
     if (IsEmpty()) {
       return aRect;
@@ -67,7 +67,7 @@ struct nsRect :
     }
   }
 
-  MOZ_MUST_USE nsRect SaturatingUnionEdges(const nsRect& aRect) const
+  [[nodiscard]] nsRect SaturatingUnionEdges(const nsRect& aRect) const
   {
 #ifdef NS_COORD_IS_FLOAT
     return UnionEdges(aRect);
@@ -102,7 +102,7 @@ struct nsRect :
 
 #ifndef NS_COORD_IS_FLOAT
   // Make all nsRect Union methods be saturating.
-  MOZ_MUST_USE nsRect UnionEdges(const nsRect& aRect) const
+  [[nodiscard]] nsRect UnionEdges(const nsRect& aRect) const
   {
     return SaturatingUnionEdges(aRect);
   }
@@ -110,7 +110,7 @@ struct nsRect :
   {
     *this = aRect1.UnionEdges(aRect2);
   }
-  MOZ_MUST_USE nsRect Union(const nsRect& aRect) const
+  [[nodiscard]] nsRect Union(const nsRect& aRect) const
   {
     return SaturatingUnion(aRect);
   }
@@ -141,32 +141,32 @@ struct nsRect :
    * @param aToAPP the APP to scale to
    * @note this can turn an empty rectangle into a non-empty rectangle
    */
-  MOZ_MUST_USE inline nsRect
+  [[nodiscard]] inline nsRect
     ScaleToOtherAppUnitsRoundOut(int32_t aFromAPP, int32_t aToAPP) const;
-  MOZ_MUST_USE inline nsRect
+  [[nodiscard]] inline nsRect
     ScaleToOtherAppUnitsRoundIn(int32_t aFromAPP, int32_t aToAPP) const;
 
-  MOZ_MUST_USE inline mozilla::gfx::IntRect
+  [[nodiscard]] inline mozilla::gfx::IntRect
   ScaleToNearestPixels(float aXScale, float aYScale,
                        nscoord aAppUnitsPerPixel) const;
 
-  MOZ_MUST_USE inline mozilla::gfx::IntRect
+  [[nodiscard]] inline mozilla::gfx::IntRect
   ToNearestPixels(nscoord aAppUnitsPerPixel) const;
 
   // Note: this can turn an empty rectangle into a non-empty rectangle
-  MOZ_MUST_USE inline mozilla::gfx::IntRect
+  [[nodiscard]] inline mozilla::gfx::IntRect
   ScaleToOutsidePixels(float aXScale, float aYScale,
                        nscoord aAppUnitsPerPixel) const;
 
   // Note: this can turn an empty rectangle into a non-empty rectangle
-  MOZ_MUST_USE inline mozilla::gfx::IntRect
+  [[nodiscard]] inline mozilla::gfx::IntRect
   ToOutsidePixels(nscoord aAppUnitsPerPixel) const;
 
-  MOZ_MUST_USE inline mozilla::gfx::IntRect
+  [[nodiscard]] inline mozilla::gfx::IntRect
   ScaleToInsidePixels(float aXScale, float aYScale,
                       nscoord aAppUnitsPerPixel) const;
 
-  MOZ_MUST_USE inline mozilla::gfx::IntRect
+  [[nodiscard]] inline mozilla::gfx::IntRect
   ToInsidePixels(nscoord aAppUnitsPerPixel) const;
 
   // This is here only to keep IPDL-generated code happy. DO NOT USE.
@@ -175,7 +175,7 @@ struct nsRect :
     return IsEqualEdges(aRect);
   }
 
-  MOZ_MUST_USE inline nsRect RemoveResolution(const float aResolution) const;
+  [[nodiscard]] inline nsRect RemoveResolution(const float aResolution) const;
 };
 
 /*
diff --git a/gfx/src/nsRegion.h b/gfx/src/nsRegion.h
index e4ad5fc8a0..143be356e6 100644
--- a/gfx/src/nsRegion.h
+++ b/gfx/src/nsRegion.h
@@ -296,9 +296,9 @@ public:
    * @param aToAPP the APP to scale to
    * @note this can turn an empty region into a non-empty region
    */
-  MOZ_MUST_USE nsRegion
+  [[nodiscard]] nsRegion
     ScaleToOtherAppUnitsRoundOut (int32_t aFromAPP, int32_t aToAPP) const;
-  MOZ_MUST_USE nsRegion
+  [[nodiscard]] nsRegion
     ScaleToOtherAppUnitsRoundIn (int32_t aFromAPP, int32_t aToAPP) const;
   nsRegion& ScaleRoundOut(float aXScale, float aYScale);
   nsRegion& ScaleInverseRoundOut(float aXScale, float aYScale);
diff --git a/gfx/src/nsSize.h b/gfx/src/nsSize.h
index f27c478f96..bb1505a2c2 100644
--- a/gfx/src/nsSize.h
+++ b/gfx/src/nsSize.h
@@ -30,7 +30,7 @@ struct nsSize : public mozilla::gfx::BaseSize<nscoord, nsSize> {
    * @param aFromAPP the APP to scale from
    * @param aToAPP the APP to scale to
    */
-  MOZ_MUST_USE inline nsSize
+  [[nodiscard]] inline nsSize
     ScaleToOtherAppUnits(int32_t aFromAPP, int32_t aToAPP) const;
 };
 
diff --git a/layout/generic/AspectRatio.h b/layout/generic/AspectRatio.h
index 5cb281c804..b940376257 100644
--- a/layout/generic/AspectRatio.h
+++ b/layout/generic/AspectRatio.h
@@ -47,7 +47,7 @@ struct AspectRatio {
   }
 
   // Inverts the ratio, in order to get the height / width ratio.
-  MOZ_MUST_USE AspectRatio Inverted() const {
+  [[nodiscard]] AspectRatio Inverted() const {
     if (!*this) {
       return AspectRatio();
     }
diff --git a/layout/style/ServoStyleSheet.h b/layout/style/ServoStyleSheet.h
index d32d576746..8c3b888c4d 100644
--- a/layout/style/ServoStyleSheet.h
+++ b/layout/style/ServoStyleSheet.h
@@ -34,11 +34,11 @@ public:
   ServoStyleSheet* GetParentSheet() const;
   void AppendStyleSheet(ServoStyleSheet* aSheet);
 
-  MOZ_MUST_USE nsresult ParseSheet(const nsAString& aInput,
-                                   nsIURI* aSheetURI,
-                                   nsIURI* aBaseURI,
-                                   nsIPrincipal* aSheetPrincipal,
-                                   uint32_t aLineNumber);
+  [[nodiscard]] nsresult ParseSheet(const nsAString& aInput,
+                                    nsIURI* aSheetURI,
+                                    nsIURI* aBaseURI,
+                                    nsIPrincipal* aSheetPrincipal,
+                                    uint32_t aLineNumber);
 
   /**
    * Called instead of ParseSheet to initialize the Servo stylesheet object
diff --git a/layout/style/StyleAnimationValue.h b/layout/style/StyleAnimationValue.h
index e318cecb6b..af58daac13 100644
--- a/layout/style/StyleAnimationValue.h
+++ b/layout/style/StyleAnimationValue.h
@@ -55,7 +55,7 @@ public:
    * @param aCount      The number of times to add aValueToAdd.
    * @return true on success, false on failure.
    */
-  static MOZ_MUST_USE bool
+  [[nodiscard]] static bool
   Add(nsCSSPropertyID aProperty, StyleAnimationValue& aDest,
       const StyleAnimationValue& aValueToAdd, uint32_t aCount) {
     return AddWeighted(aProperty, 1.0, aDest, aCount, aValueToAdd, aDest);
@@ -93,7 +93,7 @@ public:
    * @param aDistance   The result of the calculation.
    * @return true on success, false on failure.
    */
-  static MOZ_MUST_USE bool
+  [[nodiscard]] static bool
   ComputeDistance(nsCSSPropertyID aProperty,
                   const StyleAnimationValue& aStartValue,
                   const StyleAnimationValue& aEndValue,
@@ -116,7 +116,7 @@ public:
    * @param [out] aResultValue The resulting interpolated value.
    * @return true on success, false on failure.
    */
-  static MOZ_MUST_USE bool
+  [[nodiscard]] static bool
   Interpolate(nsCSSPropertyID aProperty,
               const StyleAnimationValue& aStartValue,
               const StyleAnimationValue& aEndValue,
@@ -140,7 +140,7 @@ public:
    * difficulty, we might change this to restrict them to being
    * positive.
    */
-  static MOZ_MUST_USE bool
+  [[nodiscard]] static bool
   AddWeighted(nsCSSPropertyID aProperty,
               double aCoeff1, const StyleAnimationValue& aValue1,
               double aCoeff2, const StyleAnimationValue& aValue2,
@@ -162,7 +162,7 @@ public:
    * has a value which is outside the range [0, 1] so that we can calculate
    * plausible values as interpolation with the return value.
    */
-  static MOZ_MUST_USE bool
+  [[nodiscard]] static bool
   Accumulate(nsCSSPropertyID aProperty, StyleAnimationValue& aDest,
              const StyleAnimationValue& aValueToAccumulate,
              uint64_t aCount);
@@ -199,7 +199,7 @@ public:
    *                        nullptr.
    * @return true on success, false on failure.
    */
-  static MOZ_MUST_USE bool
+  [[nodiscard]] static bool
   ComputeValue(nsCSSPropertyID aProperty,
                mozilla::dom::Element* aTargetElement,
                nsStyleContext* aStyleContext,
@@ -218,7 +218,7 @@ public:
    * to aResult.  On failure, aResult might still have partial results
    * in it.
    */
-  static MOZ_MUST_USE bool
+  [[nodiscard]] static bool
   ComputeValues(nsCSSPropertyID aProperty,
                 mozilla::CSSEnabledState aEnabledState,
                 mozilla::dom::Element* aTargetElement,
@@ -231,7 +231,7 @@ public:
    * A variant on ComputeValues that takes an nsCSSValue as the specified
    * value. Only longhand properties are supported.
    */
-  static MOZ_MUST_USE bool
+  [[nodiscard]] static bool
   ComputeValues(nsCSSPropertyID aProperty,
                 mozilla::CSSEnabledState aEnabledState,
                 mozilla::dom::Element* aTargetElement,
@@ -244,7 +244,7 @@ public:
    * A variant of ComputeValues that takes a RawServoDeclarationBlock
    * as the specified value.
    */
-  static MOZ_MUST_USE bool
+  [[nodiscard]] static bool
   ComputeValues(nsCSSPropertyID aProperty,
                 mozilla::CSSEnabledState aEnabledState,
                 nsStyleContext* aStyleContext,
@@ -268,18 +268,18 @@ public:
    * @param [out] aSpecifiedValue The resulting specified value.
    * @return true on success, false on failure.
    *
-   * These functions are not MOZ_MUST_USE because failing to check the return
+   * These functions are not [[nodiscard]] because failing to check the return
    * value is common and reasonable.
    */
-  static MOZ_MUST_USE bool
+  static bool
   UncomputeValue(nsCSSPropertyID aProperty,
                  const StyleAnimationValue& aComputedValue,
                  nsCSSValue& aSpecifiedValue);
-  static MOZ_MUST_USE bool
+  static bool
   UncomputeValue(nsCSSPropertyID aProperty,
                  StyleAnimationValue&& aComputedValue,
                  nsCSSValue& aSpecifiedValue);
-  static MOZ_MUST_USE bool
+  static bool
   UncomputeValue(nsCSSPropertyID aProperty,
                  const StyleAnimationValue& aComputedValue,
                  nsAString& aSpecifiedValue);
@@ -298,7 +298,7 @@ public:
    * @param [out] aComputedValue The resulting computed value.
    * @return true on success, false on failure.
    */
-  static MOZ_MUST_USE bool ExtractComputedValue(
+  [[nodiscard]] static bool ExtractComputedValue(
     nsCSSPropertyID aProperty,
     nsStyleContext* aStyleContext,
     StyleAnimationValue& aComputedValue);
diff --git a/layout/svg/AutoReferenceLimiter.h b/layout/svg/AutoReferenceLimiter.h
index 5f822ba135..268f84539a 100644
--- a/layout/svg/AutoReferenceLimiter.h
+++ b/layout/svg/AutoReferenceLimiter.h
@@ -96,7 +96,7 @@ public:
    * within the specified limits), else returns false on failure (there is a
    * reference loop/the reference chain has exceeded the specified limits).
    */
-  MOZ_MUST_USE bool Reference() {
+  [[nodiscard]] bool Reference() {
     // If we fail this assertion then either a consumer failed to break a
     // reference loop/chain, or else they called Reference() more than once
     MOZ_ASSERT(*mRefCounter >= 0);