Update Xcode 26.4 support

features_cpp17.yaml

@@ -446,7 +446,7 @@ features:
       - GCC 6
       - Clang 3.7
       - MSVC 14.0
-      - Xcode 15
+      - Xcode 26.4
     ftm:
       - name: __cpp_lib_allocator_traits_is_always_equal
         value: 201411L

features_cpp20.yaml

@@ -1466,7 +1466,7 @@ features:
       - GCC 13
       - Clang 21
       - MSVC 14.29
-      - Xcode 26
+      - Xcode 26.4
 
   - desc: "Mathematical constants"
     paper: P0631

features_cpp23.yaml

@@ -498,7 +498,7 @@ features:
       - GCC 13
       - Clang 21
       - MSVC 14.31
-      - Xcode 16.1
+      - Xcode 26.4
 
   - desc: "What is a view?"
     paper: P2415
@@ -726,16 +726,18 @@ features:
     paper: P2255
     lib: true
     support:
-      - GCC 13 (partial)
       - GCC 14
+      - GCC 13 (partial)
       - Clang 21 (partial)
       - MSVC 14.51
-      - Xcode 16.3
+      - Xcode 26.4 (partial)
     hints:
       - target: GCC 13
         msg: "Missing changes to `std::tuple`."
       - target: Clang 21
         msg: "Only type traits are implemented."
+      - target: Xcode 16.3
+        msg: "Only type traits are implemented."
     ftm:
       - name: __cpp_lib_reference_from_temporary
         value: 202202L
@@ -796,6 +798,7 @@ features:
       - GCC 13
       - Clang 21
       - MSVC 14.34
+      - Xcode 26.4
     ftm:
       - name: __cpp_lib_ranges_join_with
         value: 202202L
@@ -1035,6 +1038,7 @@ features:
       - GCC 15
       - Clang 21
       - MSVC 14.51
+      - Xcode 26.4
     ftm:
       - name: __cpp_lib_flat_set
         value: 202207L
@@ -1499,6 +1503,7 @@ features:
       - GCC 14
       - Clang 21
       - MSVC 14.37
+      - Xcode 26.4
 
   - desc: "`views::enumerate()`"
     paper: P2164
@@ -1596,6 +1601,7 @@ features:
       - GCC 16
       - Clang 21 (hint)
       - MSVC 14.37
+      - Xcode 26.4
     hints:
       - target: Clang 21
         msg: "The feature is implemented as a defect report to C++20."

features_cpp26.yaml

@@ -104,7 +104,7 @@ features:
   - desc: "`constexpr` stable sorting"
     paper: P2562
     lib: true
-    support: [GCC 15, Clang 21]
+    support: [GCC 15, Clang 21, Xcode 26.4]
     ftm:
       - name: __cpp_lib_constexpr_algorithms
         value: 202306L
@@ -637,7 +637,7 @@ features:
   - desc: "Variadic friends"
     paper: P2893
     summary: "Class templates can now declare all types in a parameter pack as friends."
-    support: [GCC 15, Clang 20]
+    support: [GCC 15, Clang 20, Xcode 26.4]
     ftm:
       - name: __cpp_variadic_friend
         value: 202403L
@@ -766,7 +766,7 @@ features:
     support:
       - GCC 15
       - Clang 20
-      - Xcode 26
+      - Xcode 26.4
     ftm:
       - name: __cpp_constexpr
         value: 202406L
@@ -794,13 +794,14 @@ features:
       - GCC 15
       - Clang 6 (partial)
       - Clang 21
+      - Xcode 26.4
     hints:
       - target: Clang 6
         msg: "Supported as an extension, not fully conforming to standardized version."
     ftm:
       - name: __cpp_structured_bindings
         value: 202406L
-    keywords: ["decompose"]
+    keywords: [decompose]
 
   - desc: "Removing the common reference requirement from the indirectly invocable concepts"
     paper: P2997
@@ -895,7 +896,7 @@ features:
   - desc: "Deprecate the notion of trivial types (`std::is_trivial` and `std::is_trivial_v`)"
     paper: P3247
     lib: true
-    support: [GCC 15, Clang 21]
+    support: [GCC 15, Clang 21, Xcode 26.4]
 
   - desc: "Remove deprecated array comparisons from C++26"
     paper: P2865
@@ -908,14 +909,14 @@ features:
   - desc: "[Structured bindings](https://en.cppreference.com/w/cpp/language/structured_binding.html) can introduce a pack"
     paper: P1061
     summary: "Structured bindings can now capture remaining elements into a parameter pack."
-    support: [GCC 16, Clang 21]
+    support: [GCC 16, Clang 21, Xcode 16.4]
     ftm:
       - name: __cpp_structured_bindings
         value: 202411L
 
   - desc: "The Oxford variadic comma"
     paper: P3176
-    support: [GCC 15, Clang 20]
+    support: [GCC 15, Clang 20, Xcode 26.4]
     summary: "Variadic ellipsis parameters (`...`) without a separating comma are deprecated, such as `int...`."
     content: oxford-variadic-comma.md
 
@@ -948,7 +949,7 @@ features:
   - desc: "`std::aligned_accessor`: An `std::mdspan` accessor expressing pointer over-alignment (and `std::is_sufficiently_aligned()`)"
     paper: P2897
     lib: true
-    support: [GCC 16, Clang 21]
+    support: [GCC 16, Clang 21, Xcode 26.4]
     ftm:
       - name: __cpp_lib_aligned_accessor
         value: 202411L
@@ -1099,6 +1100,7 @@ features:
       - GCC 15
       - Clang 21
       - MSVC 14.50
+      - Xcode 26.4
 
   - desc: "Converting contiguous iterators to pointers"
     paper: P3349
@@ -1144,6 +1146,11 @@ features:
       - name: __cpp_lib_constexpr_unordered_set
         value: 202502L
         desc: "`constexpr` `std::unordered_set`"
+    support:
+      - Xcode 26.4 (partial)
+    hints:
+      - target: Xcode 26.4
+        msg: "`std::forward_list`, `std::list`, `std::priority_queue`, `std::flat_map`, and `std::flat_set` are implemented."
 
   - desc: "`constexpr` exception types"
     paper: P3378