Bug 1791961 - layout: Fix C++20 -Wambiguous-reversed-operator warnings. r=dholbert

clang is warning that C++20 expects comparison operators to be commutative: `a == b` and `b == a` should resolve to the same comparison operator function. Warnings about the comparison of const and non-const objects can be fixed by making the comparison operator function const.

layout/base/DisplayPortUtils.cpp:120:30 [-Wambiguous-reversed-operator] ISO C++20 considers use of overloaded operator '==' (with operand types 'const mozilla::CSSPoint' (aka 'const PointTyped<mozilla::CSSPixel>') and 'mozilla::CSSPoint' (aka 'PointTyped<mozilla::CSSPixel>')) to be ambiguous despite there being a unique best viable function
...

Depends on D179021

Differential Revision: https://phabricator.services.mozilla.com/D179022

layout/generic/ReflowOutput.h

@@ -129,11 +129,11 @@ struct nsCollapsingMargin {
 
   nsCollapsingMargin(const nsCollapsingMargin& aOther) = default;
 
-  bool operator==(const nsCollapsingMargin& aOther) {
+  bool operator==(const nsCollapsingMargin& aOther) const {
     return mMostPos == aOther.mMostPos && mMostNeg == aOther.mMostNeg;
   }
 
-  bool operator!=(const nsCollapsingMargin& aOther) {
+  bool operator!=(const nsCollapsingMargin& aOther) const {
     return !(*this == aOther);
   }
 

layout/generic/nsLineBox.h

@@ -710,27 +710,13 @@ class nsLineList_iterator {
     return --copy;
   }
 
-  // Passing by value rather than by reference and reference to const
-  // to keep AIX happy.
-  bool operator==(const iterator_self_type aOther) const {
+  bool operator==(const iterator_self_type& aOther) const {
     MOZ_ASSERT(mListLink);
     MOZ_ASSERT(mListLink == aOther.mListLink,
                "comparing iterators over different lists");
     return mCurrent == aOther.mCurrent;
   }
-  bool operator!=(const iterator_self_type aOther) const {
-    MOZ_ASSERT(mListLink);
-    MOZ_ASSERT(mListLink == aOther.mListLink,
-               "comparing iterators over different lists");
-    return mCurrent != aOther.mCurrent;
-  }
-  bool operator==(const iterator_self_type aOther) {
-    MOZ_ASSERT(mListLink);
-    MOZ_ASSERT(mListLink == aOther.mListLink,
-               "comparing iterators over different lists");
-    return mCurrent == aOther.mCurrent;
-  }
-  bool operator!=(const iterator_self_type aOther) {
+  bool operator!=(const iterator_self_type& aOther) const {
     MOZ_ASSERT(mListLink);
     MOZ_ASSERT(mListLink == aOther.mListLink,
                "comparing iterators over different lists");
@@ -738,7 +724,7 @@ class nsLineList_iterator {
   }
 
 #ifdef DEBUG
-  bool IsInSameList(const iterator_self_type aOther) const {
+  bool IsInSameList(const iterator_self_type& aOther) const {
     return mListLink == aOther.mListLink;
   }
 #endif
@@ -849,27 +835,13 @@ class nsLineList_reverse_iterator {
   }
 #endif /* !__MWERKS__ */
 
-  // Passing by value rather than by reference and reference to const
-  // to keep AIX happy.
-  bool operator==(const iterator_self_type aOther) const {
+  bool operator==(const iterator_self_type& aOther) const {
     MOZ_ASSERT(mListLink);
     NS_ASSERTION(mListLink == aOther.mListLink,
                  "comparing iterators over different lists");
     return mCurrent == aOther.mCurrent;
   }
-  bool operator!=(const iterator_self_type aOther) const {
-    MOZ_ASSERT(mListLink);
-    NS_ASSERTION(mListLink == aOther.mListLink,
-                 "comparing iterators over different lists");
-    return mCurrent != aOther.mCurrent;
-  }
-  bool operator==(const iterator_self_type aOther) {
-    MOZ_ASSERT(mListLink);
-    NS_ASSERTION(mListLink == aOther.mListLink,
-                 "comparing iterators over different lists");
-    return mCurrent == aOther.mCurrent;
-  }
-  bool operator!=(const iterator_self_type aOther) {
+  bool operator!=(const iterator_self_type& aOther) const {
     MOZ_ASSERT(mListLink);
     NS_ASSERTION(mListLink == aOther.mListLink,
                  "comparing iterators over different lists");
@@ -877,7 +849,7 @@ class nsLineList_reverse_iterator {
   }
 
 #ifdef DEBUG
-  bool IsInSameList(const iterator_self_type aOther) const {
+  bool IsInSameList(const iterator_self_type& aOther) const {
     return mListLink == aOther.mListLink;
   }
 #endif
@@ -985,27 +957,13 @@ class nsLineList_const_iterator {
     return --copy;
   }
 
-  // Passing by value rather than by reference and reference to const
-  // to keep AIX happy.
-  bool operator==(const iterator_self_type aOther) const {
+  bool operator==(const iterator_self_type& aOther) const {
     MOZ_ASSERT(mListLink);
     NS_ASSERTION(mListLink == aOther.mListLink,
                  "comparing iterators over different lists");
     return mCurrent == aOther.mCurrent;
   }
-  bool operator!=(const iterator_self_type aOther) const {
-    MOZ_ASSERT(mListLink);
-    NS_ASSERTION(mListLink == aOther.mListLink,
-                 "comparing iterators over different lists");
-    return mCurrent != aOther.mCurrent;
-  }
-  bool operator==(const iterator_self_type aOther) {
-    MOZ_ASSERT(mListLink);
-    NS_ASSERTION(mListLink == aOther.mListLink,
-                 "comparing iterators over different lists");
-    return mCurrent == aOther.mCurrent;
-  }
-  bool operator!=(const iterator_self_type aOther) {
+  bool operator!=(const iterator_self_type& aOther) const {
     MOZ_ASSERT(mListLink);
     NS_ASSERTION(mListLink == aOther.mListLink,
                  "comparing iterators over different lists");
@@ -1013,7 +971,7 @@ class nsLineList_const_iterator {
   }
 
 #ifdef DEBUG
-  bool IsInSameList(const iterator_self_type aOther) const {
+  bool IsInSameList(const iterator_self_type& aOther) const {
     return mListLink == aOther.mListLink;
   }
 #endif
@@ -1111,27 +1069,13 @@ class nsLineList_const_reverse_iterator {
   }
 #endif /* !__MWERKS__ */
 
-  // Passing by value rather than by reference and reference to const
-  // to keep AIX happy.
-  bool operator==(const iterator_self_type aOther) const {
+  bool operator==(const iterator_self_type& aOther) const {
     MOZ_ASSERT(mListLink);
     NS_ASSERTION(mListLink == aOther.mListLink,
                  "comparing iterators over different lists");
     return mCurrent == aOther.mCurrent;
   }
-  bool operator!=(const iterator_self_type aOther) const {
-    MOZ_ASSERT(mListLink);
-    NS_ASSERTION(mListLink == aOther.mListLink,
-                 "comparing iterators over different lists");
-    return mCurrent != aOther.mCurrent;
-  }
-  bool operator==(const iterator_self_type aOther) {
-    MOZ_ASSERT(mListLink);
-    NS_ASSERTION(mListLink == aOther.mListLink,
-                 "comparing iterators over different lists");
-    return mCurrent == aOther.mCurrent;
-  }
-  bool operator!=(const iterator_self_type aOther) {
+  bool operator!=(const iterator_self_type& aOther) const {
     MOZ_ASSERT(mListLink);
     NS_ASSERTION(mListLink == aOther.mListLink,
                  "comparing iterators over different lists");
@@ -1139,7 +1083,7 @@ class nsLineList_const_reverse_iterator {
   }
 
 #ifdef DEBUG
-  bool IsInSameList(const iterator_self_type aOther) const {
+  bool IsInSameList(const iterator_self_type& aOther) const {
     return mListLink == aOther.mListLink;
   }
 #endif