<format>: Detect some invalid contiguous ranges in range_formatter

stl/inc/format

@@ -3288,9 +3288,11 @@ void _Range_formatter_format_as_string(_Range&& _Rng, _FormatContext& _Ctx, cons
     if constexpr (_RANGES contiguous_range<_Range>) {
         const auto _Size = _STD _To_unsigned_like(_RANGES distance(_Rng));
 
-        if (!_STD in_range<size_t>(_Size)) [[unlikely]] {
-            _Throw_format_error("Formatted range is too long.");
+#ifdef _DEBUG
+        if constexpr (sizeof(_Size) > sizeof(size_t)) {
+            _STL_VERIFY(_Size <= size_t{PTRDIFF_MAX}, "contiguous range has impossible size.");
         }
+#endif // defined(_DEBUG)
 
         formatter<basic_string_view<_CharT>, _CharT> _String_view_formatter;
         if (_Debug) {

tests/std/test.lst

@@ -638,6 +638,7 @@ tests\P2286R8_text_formatting_range_map
 tests\P2286R8_text_formatting_range_sequence
 tests\P2286R8_text_formatting_range_set
 tests\P2286R8_text_formatting_range_string
+tests\P2286R8_text_formatting_range_string_death
 tests\P2286R8_text_formatting_tuple
 tests\P2286R8_text_formatting_tuple_disambiguation
 tests\P2286R8_text_formatting_vector_bool_reference

tests/std/tests/P2286R8_text_formatting_range_string_death/env.lst

@@ -0,0 +1,4 @@
+# Copyright (c) Microsoft Corporation.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+RUNALL_INCLUDE ..\usual_latest_matrix.lst

tests/std/tests/P2286R8_text_formatting_range_string_death/test.cpp

@@ -0,0 +1,113 @@
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#include <cassert>
+#include <cstddef>
+#include <cstdint>
+#include <format>
+#include <ranges>
+
+#include <range_algorithm_support.hpp>
+#include <test_death.hpp>
+
+using namespace std;
+
+struct based_huge_iterator {
+    const char* base_;
+    _Signed128 offset_;
+
+    using iterator_category = contiguous_iterator_tag;
+    using difference_type   = _Signed128;
+    using value_type        = char;
+
+    const char& operator*() const noexcept {
+        return base_[static_cast<ptrdiff_t>(offset_)];
+    }
+
+    based_huge_iterator& operator++() noexcept {
+        ++offset_;
+        return *this;
+    }
+    based_huge_iterator operator++(int) noexcept {
+        auto old = *this;
+        ++*this;
+        return old;
+    }
+
+    based_huge_iterator& operator--() noexcept {
+        --offset_;
+        return *this;
+    }
+    based_huge_iterator operator--(int) noexcept {
+        auto old = *this;
+        --*this;
+        return old;
+    }
+
+    based_huge_iterator& operator+=(difference_type n) noexcept {
+        offset_ += n;
+        return *this;
+    }
+
+    based_huge_iterator& operator-=(difference_type n) noexcept {
+        offset_ -= n;
+        return *this;
+    }
+
+    const char* operator->() const noexcept {
+        return base_ + static_cast<ptrdiff_t>(offset_);
+    }
+
+    const char& operator[](difference_type n) const noexcept {
+        return base_[static_cast<ptrdiff_t>(offset_ + n)];
+    }
+
+    friend based_huge_iterator operator+(based_huge_iterator i, difference_type n) noexcept {
+        return {i.base_, i.offset_ + n};
+    }
+    friend based_huge_iterator operator+(difference_type n, based_huge_iterator i) noexcept {
+        return {i.base_, i.offset_ + n};
+    }
+
+    friend based_huge_iterator operator-(based_huge_iterator i, difference_type n) noexcept {
+        return {i.base_, i.offset_ - n};
+    }
+    friend difference_type operator-(based_huge_iterator i, based_huge_iterator j) noexcept {
+        assert(i.base_ == j.base_);
+        return i.offset_ - j.offset_;
+    }
+
+    friend auto operator<=>(const based_huge_iterator&, const based_huge_iterator&) = default;
+};
+
+struct based_huge_view : ranges::view_interface<based_huge_view> {
+    const char* base_;
+    _Signed128 size_;
+
+    based_huge_iterator begin() const noexcept {
+        return {base_, 0};
+    }
+
+    based_huge_iterator end() const noexcept {
+        return {base_, size_};
+    }
+};
+
+static_assert(ranges::contiguous_range<based_huge_view>);
+
+void test_case_invalid_range_size() {
+    based_huge_view v{.base_ = "", .size_ = static_cast<size_t>(PTRDIFF_MAX) + 1};
+    (void) format("{:s}", v);
+}
+
+int main(int argc, char** argv) {
+    std_testing::death_test_executive exec;
+
+#ifdef _DEBUG
+    exec.add_death_tests({
+        test_case_invalid_range_size,
+    });
+#endif // defined(_DEBUG)
+
+    return exec.run(argc, argv);
+}