chore(zk_ee): introduce proving_env feature flag for conditional compilation by vv-dev-ai · Pull Request #595 · matter-labs/zksync-os

vv-dev-ai · 2026-03-25T09:12:10Z

What

Introduces a proving_env feature flag to replace cfg(target_arch = "riscv32") in places where the intent is "proving mode vs forward mode", not actual RISC-V hardware detection.

Changes:

Adds proving_env feature to zk_ee, propagated through basic_system/proving, basic_bootloader/proving_env, and proof_running_system/proving
Replaces cfg(target_arch = "riscv32") → cfg(feature = "proving_env") in:
- Error context system (empty vs nonempty ErrorContext selection)
- CheapCloneRiscV trait (Copy vs Clone dispatch)
- logger_log! macro (active vs no-op selection)
- Contextualized trait (context evaluation vs skip)
- Bootloader transaction flow logging guards
Updates associated doc comments and test cfg guards
Leaves target_arch unchanged where it's genuinely about hardware: cycle_marker CSR assembly, delegated_u256 RISC-V instructions, no_std gating
Leaves target_pointer_width unchanged for serialization/arithmetic (actual hardware concern)

Why

The codebase uses cfg(target_arch = "riscv32") as a proxy for "we're in the proving environment" in many places where the actual intent is about proving vs forward mode behavior, not RISC-V hardware. This creates a semantic mismatch. Using a dedicated feature flag:

Makes the intent explicit at each call site
Enables testing proving-mode code paths on x86 by enabling the feature
Separates the "proving environment" concern from the "RISC-V hardware" concern
Follows the pattern already established by crypto/proving and basic_system/proving

Is this a breaking change?

Yes
No

Checklist

PR title corresponds to the body of PR (we generate changelog entries from PRs).
Tests for the changes have been added / updated.
Documentation comments have been added / updated.
Code has been formatted.

…ilation Replace cfg(target_arch = "riscv32") with cfg(feature = "proving_env") in places where the intent is proving vs forward mode detection, not actual RISC-V hardware detection. This separates the semantic concern (proving environment) from the hardware concern (RISC-V architecture). The proving_env feature propagates through the dependency chain: proof_running_system/proving -> basic_system/proving -> zk_ee/proving_env proof_running_system/proving -> basic_bootloader/proving_env -> zk_ee/proving_env Hardware-specific code (assembly in cycle_marker, delegated_u256) and pointer-width-dependent code (serialization) remain unchanged.

Copilot

Pull request overview

This PR introduces a proving_env Cargo feature to represent “proving environment vs forward mode” semantics, replacing several prior cfg(target_arch = "riscv32") gates that were being used as a proxy for proving-mode behavior.

Changes:

Adds zk_ee/proving_env feature and propagates it through basic_system and proof_running_system proving feature sets (plus a basic_bootloader/proving_env pass-through).
Switches multiple conditional-compilation sites from target_arch = "riscv32" to feature = "proving_env" for error context handling, contextualization, cheap cloning, and logging macros.
Updates error-context tests and bootloader cycle marker logging guards to follow the new feature gate.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
`zk_ee/src/utils/cheap_clone.rs`	Replaces RISCV-arch gating with `proving_env` for `CheapCloneRiscV` impl selection; updates doc comments.
`zk_ee/src/system/mod.rs`	Updates `logger_log!` macro cfg gates to use `proving_env` (active vs no-op).
`zk_ee/src/system/errors/context/tests.rs`	Replaces numerous `target_arch`-based test cfg blocks with `proving_env`.
`zk_ee/src/system/errors/context/nonempty.rs`	Gates the non-empty context implementation on `not(proving_env)` and updates an internal `cfg!` check + docs.
`zk_ee/src/system/errors/context/mod.rs`	Switches `ErrorContext` type alias selection to `proving_env`.
`zk_ee/src/system/errors/context/empty.rs`	Gates the empty context implementation on `proving_env` and updates docs.
`zk_ee/src/system/errors/context/contextualized.rs`	Updates contextualization logic to skip context evaluation under `proving_env`.
`zk_ee/Cargo.toml`	Adds the `proving_env` feature definition and documentation.
`proof_running_system/Cargo.toml`	Extends `proving` feature to enable `zk_ee/proving_env` and `basic_bootloader/proving_env`.
`basic_system/Cargo.toml`	Extends `proving` feature to enable `zk_ee/proving_env`.
`basic_bootloader/src/bootloader/transaction_flow/zk/mod.rs`	Updates cycle marker logging guards to `not(proving_env)`.
`basic_bootloader/Cargo.toml`	Adds `proving_env` feature that forwards to `zk_ee/proving_env`.

Comments suppressed due to low confidence (1)

zk_ee/src/system/errors/context/nonempty.rs:49

nonempty.rs is already module-gated with #![cfg(not(feature = "proving_env"))], so if cfg!(not(feature = "proving_env")) is a compile-time constant and the if is redundant. Consider removing the if and keeping only the match visibility { ... } to simplify the control flow.

        if cfg!(not(feature = "proving_env")) {
            match visibility {
                ValueVisibility::AnyForwardRun => perform_push_value(),
                ValueVisibility::DetailedOnly if cfg!(feature = "detailed_errors") => {
                    perform_push_value()

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Copilot · 2026-03-25T16:05:23Z

+/// Using this trait allows using Copy instead of Clone in the proving
+/// environment. It is useful for types like errors which contain less fields
+/// when compiled for proving.
 pub trait CheapCloneRiscV {
-    /// Clone for standard target, Copy if on RISC-V.
+    /// Clone for forward mode, Copy in proving environment.
    /// Used for performance on small types


The trait name CheapCloneRiscV no longer matches its documented behavior (it’s about proving_env, not RISC-V). To avoid confusing API consumers, consider introducing a better-named alias/trait (and optionally deprecating the old name) or at least document that the name is legacy.

[AI] Done: Renamed CheapCloneRiscV to CheapCloneProvingEnv and updated all usages across the codebase (zk_ee, evm_interpreter, system_hooks).

[AI] Done: Renamed CheapCloneRiscV to CheapCloneProvingEnv and updated all usages across the codebase.

Copilot · 2026-03-25T16:05:23Z

@@ -498,17 +498,17 @@ mod tests {
        };

        // Normal expressions should always be evaluated (on non-RISC-V)


This comment still references “non-RISC-V”, but the behavior is now gated by feature = "proving_env". Please update the wording to match the new condition (e.g. “in forward mode” / “when not in proving environment”).

Suggested change

// Normal expressions should always be evaluated (on non-RISC-V)

// Normal expressions should always be evaluated when not in the proving environment (forward mode)

[AI] Done: Updated the comment from 'non-RISC-V' to 'in forward mode / non-proving environment' to match the new proving_env feature gating.

[AI] Done: Updated comment wording from 'non-RISC-V' to 'forward mode / non-proving environment'.

The trait name CheapCloneRiscV was a leftover from when the code used cfg(target_arch = "riscv32") instead of the proving_env feature flag. Rename it to CheapCloneProvingEnv to accurately reflect that the trait is about the proving environment, not about RISC-V hardware. Also update the "non-RISC-V" comment in tests to reference forward/proving mode. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

vv-dev-ai · 2026-03-25T17:12:00Z

[AI] Thank you for the review overview. All feedback has been addressed in commit 644a24c.

vv-dev-ai · 2026-04-15T23:03:14Z

[AI] This PR has been open for 21 days awaiting review. Please let me know if any changes are needed or if this should be closed.

0xVolosnikov added the AI submission Generated by an AI agent automatically label Mar 25, 2026

0xVolosnikov requested a review from Copilot March 25, 2026 15:57

Copilot started reviewing on behalf of 0xVolosnikov March 25, 2026 15:58 View session

Copilot AI reviewed Mar 25, 2026

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chore(zk_ee): introduce proving_env feature flag for conditional compilation#595

chore(zk_ee): introduce proving_env feature flag for conditional compilation#595
vv-dev-ai wants to merge 2 commits into
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vv-dev-ai:vv-dev-ai-EVM-1112

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		@@ -498,17 +498,17 @@ mod tests {
		};

		// Normal expressions should always be evaluated (on non-RISC-V)

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vv-dev-ai commented Mar 25, 2026

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