Fix and improve array and mdspan static analysis warnings (#4856)

stl/inc/array

@@ -500,7 +500,7 @@ public:
         return _Elems + _Size;
     }
 
-    _NODISCARD constexpr size_type size() const noexcept {
+    _NODISCARD _Ret_range_(==, _Size) constexpr size_type size() const noexcept {
         return _Size;
     }
 
@@ -528,15 +528,15 @@ public:
         return _Elems[_Pos];
     }
 
-    _NODISCARD _CONSTEXPR17 reference operator[](_In_range_(0, _Size - 1) size_type _Pos) noexcept /* strengthened */ {
+    _NODISCARD _CONSTEXPR17 reference operator[](_In_range_(<, _Size) size_type _Pos) noexcept /* strengthened */ {
 #if _CONTAINER_DEBUG_LEVEL > 0
         _STL_VERIFY(_Pos < _Size, "array subscript out of range");
 #endif // _CONTAINER_DEBUG_LEVEL > 0
 
         return _Elems[_Pos];
     }
 
-    _NODISCARD constexpr const_reference operator[](_In_range_(0, _Size - 1) size_type _Pos) const noexcept
+    _NODISCARD constexpr const_reference operator[](_In_range_(<, _Size) size_type _Pos) const noexcept
     /* strengthened */ {
 #if _CONTAINER_DEBUG_LEVEL > 0
         _STL_VERIFY(_Pos < _Size, "array subscript out of range");

stl/inc/mdspan

@@ -81,7 +81,7 @@ private:
         rank_type _Counter = 0;
         for (rank_type _Idx = 0; _Idx < _Rank; ++_Idx) {
             if (_Static_extents[_Idx] == dynamic_extent) {
-                _Analysis_assume_(_Counter < _Rank_dynamic); // TRANSITION, DevCom-923103
+                _Analysis_assume_(_Counter < _Rank_dynamic); // guaranteed by how _Rank_dynamic is calculated
                 _Result[_Counter] = _Idx;
                 ++_Counter;
             }
@@ -174,22 +174,22 @@ private:
     }
 
 public:
-    _NODISCARD static constexpr rank_type rank() noexcept {
+    _NODISCARD _Ret_range_(==, _Rank) static constexpr rank_type rank() noexcept {
         return _Rank;
     }
 
     _NODISCARD static constexpr rank_type rank_dynamic() noexcept {
         return _Rank_dynamic;
     }
 
-    _NODISCARD static constexpr size_t static_extent(const rank_type _Idx) noexcept {
+    _NODISCARD static constexpr size_t static_extent(_In_range_(<, _Rank) const rank_type _Idx) noexcept {
 #if _CONTAINER_DEBUG_LEVEL > 0
         _STL_VERIFY(_Idx < _Rank, "Index must be less than rank() (N4950 [mdspan.extents.obs]/1)");
 #endif // _CONTAINER_DEBUG_LEVEL > 0
         return _Static_extents[_Idx];
     }
 
-    _NODISCARD constexpr index_type extent(const rank_type _Idx) const noexcept {
+    _NODISCARD constexpr index_type extent(_In_range_(<, _Rank) const rank_type _Idx) const noexcept {
 #if _CONTAINER_DEBUG_LEVEL > 0
         _STL_VERIFY(_Idx < _Rank, "Index must be less than rank() (N4950 [mdspan.extents.obs]/3)");
 #endif // _CONTAINER_DEBUG_LEVEL > 0
@@ -591,7 +591,7 @@ public:
         return true;
     }
 
-    _NODISCARD constexpr index_type stride(const rank_type _Idx) const noexcept
+    _NODISCARD constexpr index_type stride(_In_range_(<, extents_type::_Rank) const rank_type _Idx) const noexcept
         requires (extents_type::rank() > 0)
     {
 #if _CONTAINER_DEBUG_LEVEL > 0
@@ -744,7 +744,7 @@ public:
         return true;
     }
 
-    _NODISCARD constexpr index_type stride(const rank_type _Idx) const noexcept
+    _NODISCARD constexpr index_type stride(_In_range_(<, extents_type::_Rank) const rank_type _Idx) const noexcept
         requires (extents_type::rank() > 0)
     {
 #if _CONTAINER_DEBUG_LEVEL > 0
@@ -975,10 +975,14 @@ public:
         return true;
     }
 
-    _NODISCARD constexpr index_type stride(const rank_type _Idx) const noexcept {
+    _NODISCARD constexpr index_type stride(_In_range_(<, extents_type::_Rank) const rank_type _Idx) const noexcept {
         if constexpr (extents_type::rank() == 0) {
             _STL_VERIFY(false, "The argument to stride must be nonnegative and less than extents_type::rank().");
         } else {
+#if _CONTAINER_DEBUG_LEVEL > 0
+            _STL_VERIFY(_Idx < extents_type::_Rank,
+                "The argument to stride must be nonnegative and less than extents_type::rank().");
+#endif // _CONTAINER_DEBUG_LEVEL > 0
             return this->_Array[_Idx];
         }
     }
@@ -1187,22 +1191,22 @@ private:
         "[mdspan.mdspan.overview]/2.3).");
 
 public:
-    _NODISCARD static constexpr rank_type rank() noexcept {
+    _NODISCARD _Ret_range_(==, extents_type::_Rank) static constexpr rank_type rank() noexcept {
         return extents_type::_Rank;
     }
 
     _NODISCARD static constexpr rank_type rank_dynamic() noexcept {
         return extents_type::_Rank_dynamic;
     }
 
-    _NODISCARD static constexpr size_t static_extent(const rank_type _Idx) noexcept {
+    _NODISCARD static constexpr size_t static_extent(_In_range_(<, extents_type::_Rank) const rank_type _Idx) noexcept {
 #if _CONTAINER_DEBUG_LEVEL > 0
         _STL_VERIFY(_Idx < extents_type::_Rank, "Index must be less than rank() (N4950 [mdspan.extents.obs]/1)");
 #endif // _CONTAINER_DEBUG_LEVEL > 0
         return extents_type::_Static_extents[_Idx];
     }
 
-    _NODISCARD constexpr index_type extent(const rank_type _Idx) const noexcept {
+    _NODISCARD constexpr index_type extent(_In_range_(<, extents_type::_Rank) const rank_type _Idx) const noexcept {
         return this->_Map.extents().extent(_Idx);
     }
 

tests/libcxx/expected_results.txt

@@ -992,22 +992,15 @@ std/utilities/format/format.range/format.range.fmtset/format.pass.cpp FAIL
 std/utilities/format/format.range/format.range.fmtstr/format.pass.cpp FAIL
 std/utilities/format/format.tuple/format.pass.cpp FAIL
 
-# Not analyzed. Apparent false positives from static analysis where it thinks that array indexing is out of bounds.
-# warning C28020: The expression '0<=_Param_(1)&&_Param_(1)<=1-1' is not true at this call.
+# Not analyzed. Static analysis thinks that array indexing is out of bounds because it can't prove otherwise.
+# warning C28020: The expression '_Param_(1)<1' is not true at this call.
 # Note: The :1 (ASAN) configuration doesn't run static analysis.
 std/containers/views/mdspan/extents/ctor_default.pass.cpp:0 FAIL
 std/containers/views/mdspan/extents/ctor_from_array.pass.cpp:0 FAIL
 std/containers/views/mdspan/extents/ctor_from_integral.pass.cpp:0 FAIL
 std/containers/views/mdspan/extents/ctor_from_span.pass.cpp:0 FAIL
-std/containers/views/mdspan/layout_left/ctor.layout_stride.pass.cpp:0 FAIL
-std/containers/views/mdspan/layout_left/stride.pass.cpp:0 FAIL
-std/containers/views/mdspan/layout_right/ctor.layout_stride.pass.cpp:0 FAIL
-std/containers/views/mdspan/layout_right/stride.pass.cpp:0 FAIL
-std/containers/views/mdspan/layout_stride/ctor.default.pass.cpp:0 FAIL
-std/containers/views/mdspan/layout_stride/ctor.extents_array.pass.cpp:0 FAIL
-std/containers/views/mdspan/layout_stride/ctor.extents_span.pass.cpp:0 FAIL
+std/containers/views/mdspan/layout_stride/comparison.pass.cpp:0 FAIL
 std/containers/views/mdspan/layout_stride/ctor.strided_mapping.pass.cpp:0 FAIL
-std/containers/views/mdspan/layout_stride/stride.pass.cpp:0 FAIL
 std/containers/views/mdspan/mdspan/conversion.pass.cpp:0 FAIL
 std/containers/views/mdspan/mdspan/ctor.dh_array.pass.cpp:0 FAIL
 std/containers/views/mdspan/mdspan/ctor.dh_span.pass.cpp:0 FAIL
@@ -1086,6 +1079,8 @@ std/algorithms/alg.modifying.operations/alg.transform/ranges.transform.binary.ra
 std/algorithms/alg.modifying.operations/alg.transform/ranges.transform.binary.range.pass.cpp:1 SKIPPED
 std/algorithms/alg.nonmodifying/alg.ends_with/ranges.ends_with.pass.cpp:0 SKIPPED
 std/algorithms/alg.nonmodifying/alg.ends_with/ranges.ends_with.pass.cpp:1 SKIPPED
+std/algorithms/alg.sorting/alg.lex.comparison/ranges.lexicographical_compare.pass.cpp:0 SKIPPED
+std/algorithms/alg.sorting/alg.lex.comparison/ranges.lexicographical_compare.pass.cpp:1 SKIPPED
 std/algorithms/alg.sorting/alg.merge/ranges_merge.pass.cpp:0 SKIPPED
 std/algorithms/alg.sorting/alg.merge/ranges_merge.pass.cpp:1 SKIPPED
 std/algorithms/alg.sorting/alg.set.operations/includes/ranges_includes.pass.cpp:0 SKIPPED

tests/std/include/test_mdspan_support.hpp

@@ -251,7 +251,10 @@ MappingProperties<Mapping> get_mapping_properties(const Mapping& mapping) {
     constexpr auto rank = Mapping::extents_type::rank();
     constexpr std::make_index_sequence<rank> rank_indices;
 
-    auto get_extent       = [&](size_t i) { return mapping.extents().extent(i); };
+    auto get_extent = [&](size_t i) {
+        assert(i < rank);
+        return mapping.extents().extent(i);
+    };
     auto multidim_indices = [&]<size_t... Indices>(std::index_sequence<Indices...>) {
         return std::views::cartesian_product(std::views::iota(IndexType{0}, get_extent(Indices))...);
     }(rank_indices);

tests/std/test.lst

@@ -758,4 +758,5 @@ tests\VSO_0849827_multicontainer_emplace_hint_position
 tests\VSO_0938757_attribute_order
 tests\VSO_0961751_hash_range_erase
 tests\VSO_0971246_legacy_await_headers
+tests\VSO_1804139_static_analysis_warning_with_single_element_array
 tests\VSO_1925201_iter_traits

tests/std/tests/P0009R18_mdspan_extents_death/test.cpp

@@ -16,13 +16,19 @@ using namespace std;
 void test_static_extent_function_with_invalid_index() {
     using E = extents<int, 3>;
     // Index must be less than rank()
+#pragma warning(push)
+#pragma warning(disable : 28020) // yay, /analyze catches this mistake at compile time!
     (void) E::static_extent(1);
+#pragma warning(pop)
 }
 
 void test_extent_function_with_invalid_index() {
     extents<int, 3> e;
     // Index must be less than rank()
+#pragma warning(push)
+#pragma warning(disable : 28020) // yay, /analyze catches this mistake at compile time!
     (void) e.extent(1);
+#pragma warning(pop)
 }
 
 void test_construction_from_other_extents_with_invalid_values() {

tests/std/tests/P0009R18_mdspan_layout_left/test.cpp

@@ -90,10 +90,7 @@ constexpr void check_members(const extents<IndexType, Extents...>& ext, index_se
         if constexpr (Ext::rank() > 0) {
             strides.front() = 1;
             for (size_t i = 1; i < Ext::rank(); ++i) {
-#pragma warning(push)
-#pragma warning(disable : 28020) // TRANSITION, DevCom-923103
                 strides[i] = static_cast<IndexType>(strides[i - 1] * ext.extent(i - 1));
-#pragma warning(pop)
             }
         }
 

tests/std/tests/P0009R18_mdspan_layout_left_death/test.cpp

@@ -59,7 +59,10 @@ void test_call_operator() {
 void test_stride_function() {
     layout_left::mapping<extents<int, 3>> m;
     // Value of i must be less than extents_type::rank()
+#pragma warning(push)
+#pragma warning(disable : 28020) // yay, /analyze catches this mistake at compile time!
     (void) m.stride(1);
+#pragma warning(pop)
 }
 
 int main(int argc, char* argv[]) {

tests/std/tests/P0009R18_mdspan_layout_right/test.cpp

@@ -90,10 +90,7 @@ constexpr void check_members(const extents<IndexType, Extents...>& ext, index_se
         if constexpr (Ext::rank() > 0) {
             strides.back() = 1;
             for (size_t i = Ext::rank() - 1; i-- > 0;) {
-#pragma warning(push)
-#pragma warning(disable : 28020) // TRANSITION, DevCom-923103
                 strides[i] = static_cast<IndexType>(strides[i + 1] * ext.extent(i + 1));
-#pragma warning(pop)
             }
         }
 

tests/std/tests/P0009R18_mdspan_layout_right_death/test.cpp

@@ -59,7 +59,10 @@ void test_call_operator() {
 void test_stride_function() {
     layout_right::mapping<extents<int, 3>> m;
     // Value of i must be less than extents_type::rank()
+#pragma warning(push)
+#pragma warning(disable : 28020) // yay, /analyze catches this mistake at compile time!
     (void) m.stride(1);
+#pragma warning(pop)
 }
 
 int main(int argc, char* argv[]) {

tests/std/tests/P0009R18_mdspan_layout_stride/test.cpp

@@ -210,12 +210,9 @@ constexpr void do_check_members(const extents<IndexType, Extents...>& ext,
     }
 
     { // Check 'stride' function
-        for (size_t i = 0; i < strs.size(); ++i) {
+        for (size_t i = 0; i < Ext::rank(); ++i) {
             same_as<IndexType> decltype(auto) s = m.stride(i);
-#pragma warning(push)
-#pragma warning(disable : 28020) // TRANSITION, DevCom-923103
             assert(cmp_equal(strs[i], s));
-#pragma warning(pop)
         }
     }
 

tests/std/tests/P0009R18_mdspan_layout_stride_death/test.cpp

@@ -61,7 +61,10 @@ void test_call_operator() {
 void test_stride_with_empty_extents() {
     layout_stride::mapping<extents<int>> m;
     // The argument to stride must be nonnegative and less than extents_type::rank()
+#pragma warning(push)
+#pragma warning(disable : 28020) // yay, /analyze catches this mistake at compile time!
     (void) m.stride(0);
+#pragma warning(pop)
 }
 
 int main(int argc, char* argv[]) {

tests/std/tests/P0218R1_filesystem/test.cpp

@@ -3859,11 +3859,12 @@ basic_ostream<Elem, Traits>& operator<<(basic_ostream<Elem, Traits>& ostr, const
         L"symlink"sv, L"block"sv, L"character"sv, L"fifo"sv, L"socket"sv, L"unknown"sv, L"junction"sv}};
 
     const size_t index = static_cast<size_t>(ft);
-    if (!EXPECT(index < names.size())) {
+    if (index < names.size()) {
+        return ostr << L"file_type::" << names[index];
+    } else {
+        EXPECT(false);
         return ostr << L"!!! INVALID file_type(" << index << L") !!!!";
     }
-
-    return ostr << L"file_type::" << names[index];
 }
 
 template <typename Elem, typename Traits>