suppress build error in gtest w/ clangcl

For more info: https://github.com/actions/runner-images/issues/13345

.github/workflows/compilers.yml

@@ -61,7 +61,7 @@ jobs:
   xcode:
     strategy:
       matrix:
-        xcode_version: [ '16.4' ]
+        xcode_version: [ '26.6' ]
         build_type: [ Debug, Release ]
         cxx_version: [ 14, 17, 20, 23 ]
     runs-on: macos-latest
@@ -88,9 +88,13 @@ jobs:
           # Regular MSVC builds use Ninja (from preset)
           - toolset: 'msvc'
             generator_override: ''
-          # ClangCL builds require Visual Studio generator
-          - toolset: 'ClangCL'
+          # ClangCL builds require Visual Studio generator; version depends on image
+          - image: windows-2022
+            toolset: 'ClangCL'
             generator_override: '-G "Visual Studio 17 2022" -T ClangCL'
+          - image: windows-2025
+            toolset: 'ClangCL'
+            generator_override: '-G "Visual Studio 18 2026" -T ClangCL'
     runs-on: ${{ matrix.image }}
     steps:
       - uses: actions/checkout@v6

docs/headers.md

@@ -158,7 +158,7 @@ Convert the given value `I` to a `byte`. The template requires `I` to be in the
 
 ## <a name="H-dyn_array" />`<dyn_array>`
 
-This header contains an owning dynamically allocated array type whose size is fixed at construction.
+This header contains an owning dynamically allocated array type whose size is fixed between assignments.
 
 - [`gsl::dyn_array`](#user-content-H-dyn_array-dyn_array)
 
@@ -170,7 +170,7 @@ class dyn_array;
 ```
 
 `gsl::dyn_array` owns a contiguous sequence of `T` objects allocated with `Allocator`.
-The number of elements is established when the object is constructed and remains unchanged.
+The number of elements is established when the object is constructed and remains unchanged until the object is copy-assigned.
 It provides bounds-checked element access and checked random-access iterators.
 
 `gsl::dyn_array` is useful when the number of elements is known only at runtime, but the array should not grow or shrink through container operations.
@@ -242,7 +242,8 @@ constexpr dyn_array(dyn_array&&) = delete;
 dyn_array& operator=(dyn_array&&) = delete;
 ```
 
-Copy assignment, move assignment, and move construction are explicitly deleted.
+Copy assignment replaces the contents with copies of the elements in `other`.
+Move construction and move assignment are explicitly deleted.
 
 ##### Observers
 
@@ -299,7 +300,7 @@ constexpr auto crend() const;
 
 Returns a reverse iterator to the first element of the reversed range or to one past the last element of the reversed range.
 
-The iterators are random-access iterators and perform bounds checking; they can never be invalidated.
+The iterators are random-access iterators and perform bounds checking.
 Dereferencing `end()`, moving before `begin()` or past `end()`, or comparing iterators from different arrays violates preconditions.
 
 ##### Comparisons

include/gsl/assert

@@ -31,6 +31,9 @@
 #if defined(__clang__)
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Winvalid-noreturn"
+#if __clang_major__ >= 22
+#pragma clang diagnostic ignored "-Wunique-object-duplication"
+#endif // __clang_major >= 22
 #endif // defined(__clang__)
 
 #else // defined(_MSC_VER) && (defined(_KERNEL_MODE) || (defined(_HAS_EXCEPTIONS) &&

include/gsl/dyn_array

@@ -216,9 +216,8 @@ namespace details
 
         constexpr auto operator++(int)
         {
-            auto rv = *this;
             ++(*this);
-            return rv;
+            return dyn_array_iterator{_ptr, _pos - 1, _end_pos};
         }
 
         constexpr auto operator--() -> dyn_array_iterator&
@@ -230,9 +229,8 @@ namespace details
 
         constexpr auto operator--(int)
         {
-            auto rv = *this;
             --(*this);
-            return rv;
+            return dyn_array_iterator{_ptr, _pos + 1, _end_pos};
         }
 
         constexpr auto operator+=(difference_type diff) -> dyn_array_iterator&

include/gsl/util

@@ -133,6 +133,12 @@ namespace details
 } // namespace details
 
 // final_action allows you to ensure something gets run at the end of a scope
+// The bool member causes trailing padding when F has alignment > 1; suppress
+// -Wpadded since the padding is unavoidable for a generic callable wrapper.
+#if defined(__clang__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wpadded"
+#endif // defined(__clang__)
 template <class F>
 class final_action
 {
@@ -157,6 +163,9 @@ private:
     F f;
     bool invoke = true;
 };
+#if defined(__clang__)
+#pragma clang diagnostic pop
+#endif // defined(__clang__)
 
 // finally() - convenience function to generate a final_action
 template <class F>

tests/CMakeLists.txt

@@ -54,6 +54,14 @@ if (NOT GTestMain_FOUND)
         ${CMAKE_CURRENT_BINARY_DIR}/googletest-build
         EXCLUDE_FROM_ALL
     )
+
+    # googletest is built as its own target, so apply this workaround there.
+    if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang"
+      AND CMAKE_CXX_SIMULATE_ID STREQUAL "MSVC"
+      AND CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 22)
+      target_compile_options(gtest PRIVATE -Wno-character-conversion)
+      target_compile_options(gtest_main PRIVATE -Wno-character-conversion)
+    endif()
 endif()
 
 if (CMAKE_CURRENT_SOURCE_DIR STREQUAL CMAKE_SOURCE_DIR)
@@ -111,7 +119,7 @@ if(MSVC) # MSVC or simulating MSVC
           -Wno-undef # GTest
           -Wno-used-but-marked-unused # GTest EXPECT_DEATH
           -Wno-switch-default # GTest EXPECT_DEATH
-          $<$<EQUAL:${GSL_CXX_STANDARD},14>: # no support for [[maybe_unused]]
+           $<$<EQUAL:${GSL_CXX_STANDARD},14>: # no support for [[maybe_unused]]
             -Wno-unused-member-function
             -Wno-unused-variable
             $<$<VERSION_EQUAL:$<CXX_COMPILER_VERSION>,15.0.1>:

tests/dyn_array_tests.cpp

@@ -189,6 +189,10 @@ TEST(dyn_array_tests, ranges)
 #endif /* __cpp_lib_ranges >= 201911L */
 
 #if defined(__cpp_lib_constexpr_dynamic_alloc) && (__cpp_lib_constexpr_dynamic_alloc >= 201907L)
+#if defined(__clang__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wpadded"
+#endif // defined(__clang__)
 template <typename T, unsigned N>
 struct ConstexprAllocator
 {
@@ -218,6 +222,9 @@ struct ConstexprAllocator
 
     constexpr void deallocate(value_type*, std::size_t) noexcept {}
 };
+#if defined(__clang__)
+#pragma clang diagnostic pop
+#endif // defined(__clang__)
 
 template <typename T1, unsigned N1, typename T2, unsigned N2>
 constexpr auto operator==(const ConstexprAllocator<T1, N1>& lhs,