[NFC] Rewrite PossibleContents::combine to be static (#5192)

This makes the logic symmetric and easier to read.

Measuring speed, this seems identical to before, so that concern seems fine.

1 files changed, 8 insertions, 3 deletions

diff --git a/src/ir/possible-contents.h b/src/ir/possible-contents.h
index cf92a578a..b7c9bfafd 100644
--- a/src/ir/possible-contents.h
+++ b/src/ir/possible-contents.h
@@ -103,12 +103,12 @@ class PossibleContents {
   // full cone of all subtypes for that type.
   static ConeType FullConeType(Type type) { return ConeType{type, FullDepth}; }
 
+  template<typename T> PossibleContents(T value) : value(value) {}
+
 public:
   PossibleContents() : value(None()) {}
   PossibleContents(const PossibleContents& other) = default;
 
-  template<typename T> explicit PossibleContents(T val) : value(val) {}
-
   // Most users will use one of the following static functions to construct a
   // new instance:
 
@@ -163,7 +163,12 @@ public:
 
   // Combine the information in a given PossibleContents to this one. The
   // contents here will then include whatever content was possible in |other|.
-  void combine(const PossibleContents& other);
+  [[nodiscard]] static PossibleContents combine(const PossibleContents& a,
+                                                const PossibleContents& b);
+
+  void combine(const PossibleContents& other) {
+    *this = PossibleContents::combine(*this, other);
+  }
 
   // Removes anything not in |other| from this object, so that it ends up with
   // only their intersection. Currently this only handles an intersection with a