Plum Hall Compiler and Library Validation Suites

The Plum Hall suites are compiler and library validation test suites with a long history: Plum Hall was founded in 1979 and released its first validation suite in 1986. Solid Sands acquired the Plum Hall test suite portfolio in 2025, announced on 20 November 2025, and the two catalogues now sit side by side. Their job is narrow and technical: prove that a C or C++ implementation, the compiler and the library that ship with it, behaves the way the ISO language specification says it must.

The Three Suites and How They Differ

There are three Plum Hall suites, and they stack rather than overlap. Plum Hall C Base is the C compiler and library validation suite, with positive and negative tests for the preprocessor, language behaviour, the Standard Library, undefined behaviour, implementation limits, and the optional bounds-checking library (Annex K), plus generated permutation tests. Plum Hall C++ is the C++ compiler validation suite for verifying the implementation of the C++ language; it builds on C Base and adds C++ language conformance tests. Plum Hall Lib++ is the C++ standard library implementation validation suite, validating C++ Standard Library conformance to the ISO specifications. A team validating a C-only toolchain needs C Base. A team shipping C++ needs C Base plus the C++ suite, since the C++ suite builds on it, and Lib++ as well if it owns or ports the library.

Standard-Version Reach, and Why the Audience Matters More

Per Plum Hall, the suites cover C up to C23 and C++ up to C++26, tracking the WG14 and WG21 committee standards. SuperTest publishes coverage of C90, C99, C11, and C18 (ISO/IEC 9899), Embedded C (ISO/IEC TR 18037:2008), and C++03 through C++20 (ISO/IEC 14882).

That picture changed in September 2026, though less neatly than a headline would suggest. Solid Sands’ SuperTest Van Gogh 6.0 announcement, dated 23 September 2026, states that the release adds 480 tests for C23 and 440 for C++23. Read the two claims separately, because the announcement words them differently: for C++23 it says SuperTest “now supports all language features” covered by some 45 committee papers, while for C23 it says only that the new coverage “supports more than 40 standard committee papers”, which is not a claim of complete C23. Plum Hall’s own claim remains C up to C23 and C++ up to C++26. So the reach difference narrowed; it did not vanish, and C++26 is the part of it that is unambiguous. The SuperTest product page has not been updated to list C23 or C++23 at all, so before either suite goes into a plan on the strength of a standard version, confirm the scope against the release you are licensed for. See the Van Gogh 6.0 write-up for what the announcement does and does not say.

The durable distinction between the two is not the standard version anyway, it is the audience. If you need qualification evidence for a safety case, SuperTest and the SuperTest Qualification Suite are the tools. If you are implementing or porting a toolchain and need conformance tests, including for C++26 as it lands, Plum Hall is where those live.

Marianne Damstra, CEO of Solid Sands, framed what the addition does for the combined catalogue rather than for the Plum Hall suites on their own: “We welcome the Plum Hall community of customers and partners to Solid Sands. By adding the renowned and upgraded Plum Hall suites to our product portfolio, we can now deliver broader test coverage and improved qualification capabilities, which are always a must for software developers.”

Who These Suites Are Actually For

Plum Hall is aimed at the people building the toolchain, not the people using it. That means compiler and library implementers validating their own implementation against the ISO C and C++ specifications, silicon and toolchain teams bringing up a language front end or standard library for a new part, and backend teams working on RISC-V or custom-ISA targets who need a conformance yardstick once the code generator is producing real code. If your team maintains a downstream GCC or LLVM tree, ports a libc or libc++ to a new environment, or ships a proprietary compiler to customers, this is the test set that tells you where the implementation diverges from the standard. The suites are described as optimized for any environment and requiring only a minimal execution environment, which is what makes them usable on the constrained bring-up targets those teams typically have in front of them.

For a team that is still earlier than that, before the backend handles real C constructs reliably, the Code Generator Trainer is the graduated bootstrapping path, and Plum Hall is what you run once the backend is standing up.

How Plum Hall Sits Alongside SuperTest, SuperGuard, and the Qualification Suite

These are different jobs, and it is worth being precise about which is which. Plum Hall is conformance validation for people building or porting a toolchain: does this implementation match the ISO specification. The Plum Hall material makes no functional-safety claims, and the suites are not positioned as tool-qualification or functional-safety tooling.

The safety side of the portfolio is separate. SuperTest validates a compiler against the ISO language standards with requirements-based, negative, and stress tests; the SuperTest Qualification Suite packages that work into the compiler tool-confidence demonstration standards such as ISO 26262 require; and SuperGuard qualifies the C and C++ standard library with requirements traceability and MC/DC coverage. If your deliverable is a safety case, those are the products. If your deliverable is a conforming compiler or library, Plum Hall is the one. A toolchain vendor that also ships into a regulated product needs both, in that order: get the implementation conforming, then produce the qualification evidence for the customers who ship it into a regulated product.

Solid Sands notes that the Plum Hall suites are a product of Plum Hall B.V., with commercial inquiries, maintenance, and support services managed by Solid Sands B.V., and says customers can expect continued support for the Plum Hall suite from the Solid Sands engineering team.

Why Buy from GSAS

GSAS Micro Systems is the authorized Solid Sands engineering partner for India, UAE, and Sri Lanka, and handles Plum Hall inquiries, onboarding, and toolchain engineering support locally. Our compiler and functional-safety engineers in Bengaluru, Hyderabad, Chennai, Pune, Mumbai, and Delhi NCR work with semiconductor, RISC-V, and embedded toolchain teams who are building or porting a C/C++ implementation and need a conformance test set that reaches the current language revisions, plus a clear view of where SuperTest, SuperGuard, and the Qualification Suite take over when the same toolchain later has to carry a safety argument. See the full Solid Sands portfolio for how the suites fit together.