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For decades, C and C++ have been the default languages for embedded systems development—entrenched in legacy codebases, toolchains, and developer expertise. Yet as safety and security requirements intensify in aerospace, automotive, and medical devices, their memory vulnerabilities and weak typing increasingly appear as existential risks. AdaCore’s latest analysis, spearheaded by Chief Product Officer Quentin Ochem, challenges teams to reconsider their toolchains in an era where "default" might mean "dangerous."

The C/C++ Safety Debt

C/C++’s dominance stems from familiarity and deterministic development costs, but evidence mounts that these languages make safe, secure software unnecessarily difficult. Despite decades of research, no cost-effective solution has fully mitigated their vulnerabilities. "Teams are realizing that technical debt in language choice compounds into safety debt," notes Ochem. The search for alternatives now centers on two contenders: Ada and Rust—with SPARK offering a radical leap through formal methods.

The Ada vs. Rust Showdown

Ecosystem Maturity vs. Community Momentum

  • Ada/SPARK: Mature embedded toolchains, off-the-shelf certification (DO-178C, ISO 26262), and battle-tested long-term support. Library coverage is limited but supplemented by C bindings.
  • Rust: Explosive community growth and rich libraries via Cargo, but fragmented commercial tooling and nascent certification evidence. Long-term support remains uncertain.

Safety Architectures

  • Rust enforces memory safety via its borrow checker, eliminating entire vulnerability classes.
  • Ada counters with unparalleled strong typing and hardware/software consistency checks (e.g., enforcing unit constraints like miles vs. percentages).
  • SPARK (Ada’s superset) adds mathematical proof of correctness for run-time error absence and custom contracts.
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Quentin Ochem, AdaCore CPRO, emphasizes SPARK’s paradigm shift: "You’re not just changing syntax—you’re shifting left on verification."

The SPARK Revolution

SPARK transcends traditional programming by statically proving properties at compile time:
- No run-time checks: Array bounds, null dereferences, and overflow are mathematically eliminated.
- Provable contracts: Pre/post-conditions and invariants replace unit tests for critical logic.
- Cost tradeoff: Requires rigorous upfront specification but slashes testing overhead and defect rates in high-integrity contexts.

-- SPARK example: Statically proven array bounds
Type Safe_Array is array (Positive range <>) of Integer;
Procedure Process_Data (Data : in out Safe_Array) with
  Pre => Data'First = 1 and Data'Last <= 100; -- Compile-time proof

The Strategic Choice

Dimension Ada Rust SPARK
Cost Language shift Language shift Methodology shift
Memory Safety Run-time checks Borrow checker Borrow checker + proofs
Certification Off-the-shelf Emerging Off-the-shelf
Key Benefit Constraint enforcement Memory safety Proof of absence

For teams prioritizing immediate certification or hardware-bound constraints, Ada’s maturity is compelling. Rust appeals when memory safety dominates requirements and community support accelerates development. SPARK, however, delivers the highest assurance—at the cost of rethinking development workflows. As Ochem concludes: "This isn’t just about avoiding crashes. It’s about guaranteeing that embedded systems behave exactly as intended—from pacemakers to avionics—when failure isn’t an option."

Source: Should I choose Ada/SPARK or Rust over C/C++? by Quentin Ochem (AdaCore)