BDE 4.38.0 Release

Schedule

The BDE team announces that the BDE 4.38.0 production release was completed on Monday, June 1, 2026.

BDE 4.38.0 Release Highlights

C++23 Compatibility Changes

BDE 4.38.0 delivers a large set of C++23 compatibility enhancements to the bsl library. A full description of all changes is available in the BSL Support for C++23 article. The highlights are summarised below.

Ranges-Aware Construction and Insertion for `bsl` Containers

All bsl sequence and associative containers now support the C++23 bsl::from_range tag constructor and range-insertion methods such as append_range and insert_range, backported to C++03:

// Before: named variable required to keep the tokenizer alive
bdlb::Tokenizer tokenizer(text, " ");
bsl::vector<bsl::string_view> tokens(tokenizer.begin(), tokenizer.end());

// Now: pass directly using the from_range constructor
bsl::vector<bsl::string_view> tokens(bsl::from_range,
                                     bdlb::Tokenizer(text, " "));

Container adaptors (bsl::stack, bsl::queue, bsl::priority_queue) likewise gain from_range constructors and push_range.

Heterogeneous Erasure for Associative Containers

When a container’s comparator or hash is tagged as transparent, erase(key) now accepts any type comparable to the stored key type, eliminating unnecessary temporary constructions. For example, erasing from a bsl::set<bsl::string, bdlb::TransparentLess> supplied with a bsl::string_view no longer requires constructing a temporary bsl::string.

`bsl::print` and `bsl::println`: Backported C++23 Print Facility

<bsl_print.h> provides bsl::print and bsl::println available in all language modes back to C++03. On platforms with a C++23 standard library these delegate to the native implementation; elsewhere they are backed by BDE’s bslfmt formatter. See the <bsl_print_ostream.h> header for the separate output-stream overloads.

`bsl::optional` Monadic Interface

and_then, or_else, and transform enable functional-style chaining over optional values without explicit engagement checks (requires C++17 or later).

`bsl::string` / `bsl::string_view` Construction from `nullptr` Prohibited

Constructing a bsl::string or bsl::string_view from a null pointer literal is now a compile-time error (requires C++11), as required by C++23 (P2166). Previously such construction compiled silently but produced undefined behavior at runtime.

Because the deleted constructor takes bsl::nullptr_t, overload resolution selects it for any null pointer constant — defined by the C++ standard as an integer literal with value zero or a prvalue of type std::nullptr_t. This covers nullptr, 0, and NULL. A const char* variable is not a null pointer constant, even if its runtime value is null, and therefore does not select the deleted constructor:

bsl::string s(nullptr);    // now: compile-time error
bsl::string t(0);          // now: compile-time error
bsl::string u(NULL);       // now: compile-time error

const char* p = nullptr;
bsl::string v(p);          // unchanged: undefined behavior

New Standard Library Headers

The following headers were added to alias new C++23 standard library types:

<bsl_print.h> / <bsl_print_ostream.h> — bsl::print, bsl::println, and vprint_* variants
<bsl_mdspan.h> — bsl::mdspan, bsl::extents, bsl::dextents, layout policies, and bsl::default_accessor
<bsl_spanstream.h> — bsl::spanbuf, bsl::ispanstream, bsl::ospanstream, bsl::spanstream (and w-prefixed wide variants)
<bsl_generator.h> — bsl::generator (C++23 coroutine generator)
<bsl_stacktrace.h> — bsl::stacktrace, bsl::stacktrace_entry, bsl::basic_stacktrace
<bsl_stdfloat.h> — bsl::float16_t, bsl::float32_t, bsl::float64_t, bsl::float128_t, bsl::bfloat16_t

C++23 Aliases Added to Existing Headers

<bsl_algorithm.h>, <bsl_bit.h>, <bsl_functional.h>, <bsl_iosfwd.h>, <bsl_iterator.h>, <bsl_memory.h>, <bsl_numeric.h>, <bsl_ranges.h>, <bsl_type_traits.h>, and <bsl_utility.h>. These include the new ranges algorithms (fold_left, fold_right, contains, find_last, starts_with, ends_with, iota, shift_left, shift_right), ranges views (zip, adjacent, chunk, slide, stride, enumerate, join_with, cartesian_product, as_const), and utility types (bsl::out_ptr, bsl::inout_ptr, bsl::allocation_result, bsl::start_lifetime_as, bsl::bind_back, bsl::forward_like).

Other C++23 Additions

bsl::string::contains() / bsl::string_view::contains() — tests whether a string contains a given substring, character, or string view (backported to C++03).
bsl::basic_string::substr() && — rvalue overload that can move storage rather than copy (requires C++11).
bsl::visit() extended to accept arguments whose static type is a class publicly derived from bsl::variant, as required by C++23 (requires C++11).

`bdlb::PairUtil::adaptForRanges` Pipe Operator

bdlb::PairUtil::adaptForRanges now supports operator|, enabling it to be used directly as a range pipeline adaptor. Previously, the range had to be passed as an argument to adaptForRanges; it can now be piped:

bsl::map<int, int> myMap = {{1, 2}, {3, 4}};

const bsl::vector<int> expectedValues = {2, 4};

// Before (4.27+):
assert(bsl::ranges::equal(expectedValues,
                          bdlb::PairUtil::adaptForRanges(myMap) | bsl::views::values));

// Now also possible:
assert(bsl::ranges::equal(expectedValues,
                          myMap | bdlb::PairUtil::adaptForRanges | bsl::views::values));

`bslma::TestAllocator` Configurable Fill for Newly Allocated Memory

bslma::TestAllocator has been enhanced with the ability to fill freshly allocated memory with a user-configurable byte value. This aids in detecting use-of-uninitialized-memory bugs during testing.

Fixed Tickets

Summary
C++23 Support In BSL
C++23: Add aliases to `<bsl_algorithm.h>`
C++23: Add aliases to `<bsl_bit.h>`
C++23: Add `BSLS_LIBRARYFEATURES_HAS_CPP23_BASELINE_LIBRARY` macro
C++23: Add aliases to `<bsl_functional.h>`
C++23: Add aliases to `<bsl_ranges.h>`
C++23: Add aliases to `<bsl_type_traits.h>`
C++23: Add aliases to `<bsl_utility.h>`
C++23: Add aliases to `<bsl_numeric.h>`
C++23: Add `<bsl_generator.h>` header
C++23: Add `<bsl_spanstream.h>` header
C++23: Add `<bsl_mdspan.h>` header
C++23: Add `<bsl_stacktrace.h>` header
C++23: Add `<bsl_stdfloat.h>` header
C++23: Add aliases to `<bsl_iosfwd.h>`
C++23: Add aliases to `<bsl_iterator.h>`
C++23: Add aliases to `<bsl_memory.h>`
C++23: Avoid deprecated UDL operator suffix syntax
C++23: BDE allocator testing in `bslim_bslstandardheadertest.t.cpp`
C++23: Prohibit `bsl::basic_string` and `bsl::basic_string_view` construction from `nullptr`
C++23: Add `bsl::string::contains()` and `bsl::string_view::contains()`
C++23: `bsl::basic_string::substr() &&`
C++23: Monadic operations for `bsl::optional`
C++23: Iterator-pair constructors for `bsl::stack` and `bsl::queue`
C++23: `bsl::string` ranges-aware construction and insertion
C++23: Ranges-aware construction for container adaptors
C++23: Ranges-aware construction and insertion for sequence containers
C++23: Make concepts and ranges available in `bslstl`
C++23: Ordered containers: Add ranges-aware construction and insertion
C++23: Unordered containers: Add ranges-aware construction and insertion
C++23: Fix in `bslstl_priorityqueue.t.cpp`
C++23: `bsl::visit()` for classes derived from `bsl::variant`
C++23: `bsl::string` range operations follow-ups
C++23: Add `<bsl_print.h>` header
C++23: `bsl::string`: enhance for ‘’sized’’ ranges
C++23: Heterogeneous erasure overloads for associative containers
C++23: `std::views::zip` in `bslstl_ranges.h`
`std::ranges::iota`: aliases are not found
`bsl::stop_token` – add callback alias template
C++23: Port additional ranges views (`slide`, `stride`, `adjacent`, `chunk`, `enumerate`, `join_with`, `cartesian_product`, and more)
Simplify `bcec` test drivers to verify aliasing
Fix use-after-free bug in `bdxa_simpletask.t`
Remove `std` type aliases from wrong BDE header
`bdex_testinstreamformatter`: fix bad indentation
`bdlmt::EventScheduler` thread safety has been weakened
TSAN race fix in `bdlcc::TimeQueue`
Ability to set freshly allocated memory in `bslma::TestAllocator` to a configurable value
Remove BOMs from BDE repo
`bdlb::PairUtil::adaptForRanges` – add `operator\|` adaptor
Improve `bdlt` format article and `bdlt_formatdoc`
Fix `bdld::Datum` nightly build failure on clang
Correct `bslalg_numericformatterutil.t.cpp` failures
Correct `bdlt_localtimeoffset.t.cpp` compile warnings
Correct UBSan issues in `bdl`
Correct BDE test driver compile warnings
Assorted minor drive-by fixes
Remove `bslfmt` include from `bsl_ostream.h`
C++23: Add `bsl_print_ostream.h`