From 1fadb7fa2f6e5e8e5b5905dedf7597dba19dee3b Mon Sep 17 00:00:00 2001
From: Jeremy Andrews <athenian200@outlook.com>
Date: Wed, 6 Jul 2022 09:04:40 -0500
Subject: Issue #1956 - Use preprocessor to work around strange template
 behavior with 32-bit MSVC2022.

---
 dom/media/webrtc/MediaTrackConstraints.cpp | 50 ++++++++++++++++++++++++++++++
 dom/media/webrtc/MediaTrackConstraints.h   | 10 ++++++
 2 files changed, 60 insertions(+)

diff --git a/dom/media/webrtc/MediaTrackConstraints.cpp b/dom/media/webrtc/MediaTrackConstraints.cpp
index 08bb513955..63dab1492f 100644
--- a/dom/media/webrtc/MediaTrackConstraints.cpp
+++ b/dom/media/webrtc/MediaTrackConstraints.cpp
@@ -34,6 +34,56 @@ NormalizedConstraintSet::Range<ValueType>::SetFrom(const ConstrainRange& aOther)
   }
 }
 
+// FIXME(Issue #1956): 32-bit MSVC 2022 does not like these functions being
+// defined here. The 64-bit version accepts my workaround for the 32-bit
+// version as valid code, but every other compiler dislikes them being defined
+// elsewhere. 
+
+#if _MSC_VER <= 1900 || !defined(_MSC_VER)
+// The Range code works surprisingly well for bool, except when averaging ideals.
+template<>
+bool
+NormalizedConstraintSet::Range<bool>::Merge(const Range& aOther) {
+  if (!Intersects(aOther)) {
+    return false;
+  }
+  Intersect(aOther);
+
+  // To avoid "unsafe use of type 'bool'", we keep counter in mMergeDenominator
+  uint32_t counter = mMergeDenominator >> 16;
+  uint32_t denominator = mMergeDenominator & 0xffff;
+
+  if (aOther.mIdeal.isSome()) {
+    if (mIdeal.isNothing()) {
+      mIdeal.emplace(aOther.Get(false));
+      counter = aOther.Get(false);
+      denominator = 1;
+    } else {
+      if (!denominator) {
+        counter = Get(false);
+        denominator = 1;
+      }
+      counter += aOther.Get(false);
+      denominator++;
+    }
+  }
+  mMergeDenominator = ((counter & 0xffff) << 16) + (denominator & 0xffff);
+  return true;
+}
+
+template<>
+void
+NormalizedConstraintSet::Range<bool>::FinalizeMerge()
+{
+  if (mMergeDenominator) {
+    uint32_t counter = mMergeDenominator >> 16;
+    uint32_t denominator = mMergeDenominator & 0xffff;
+
+    *mIdeal = !!(counter / denominator);
+    mMergeDenominator = 0;
+  }
+}
+#endif
 
 NormalizedConstraintSet::LongRange::LongRange(
     LongPtrType aMemberPtr,
diff --git a/dom/media/webrtc/MediaTrackConstraints.h b/dom/media/webrtc/MediaTrackConstraints.h
index 693c905d5f..0746fc245f 100644
--- a/dom/media/webrtc/MediaTrackConstraints.h
+++ b/dom/media/webrtc/MediaTrackConstraints.h
@@ -261,6 +261,11 @@ public:
                         aOther.mMozAutoGainControl, advanced, aList) {}
 };
 
+// FIXME (Issue #1956): 32-bit MSVC 2022 needed this code to be moved here,
+// and the 64-bit version seems fine with it as well. But other compilers
+// are not.
+
+#if _MSC_VER > 1900
 // The Range code works surprisingly well for bool, except when averaging ideals.
 template<>
 bool
@@ -304,7 +309,12 @@ NormalizedConstraintSet::Range<bool>::FinalizeMerge()
     mMergeDenominator = 0;
   }
 }
+#endif
 
+#if _MSC_VER <= 1900 || !defined(_MSC_VER)
+template<> bool NormalizedConstraintSet::Range<bool>::Merge(const Range& aOther);
+template<> void NormalizedConstraintSet::Range<bool>::FinalizeMerge();
+#endif
 
 // Used instead of MediaTrackConstraints in lower-level code.
 struct NormalizedConstraints : public NormalizedConstraintSet
-- 
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