RisingWave Rust Analyzer

Overview

Use rust-analyzer to get semantic feedback faster than a full workspace build. In RisingWave, always resolve the crate root and feature set first: rust-analyzer feature settings are workspace-level per linked project, so per-crate feature differences usually require separate roots or editor workspaces.

Workflow

1. Confirm the analysis root.
2. Resolve the target crate and its features.
3. Run the narrowest rust-analyzer CLI command that answers the question.
4. Escalate to editor/LSP configuration only when CLI scope or features are insufficient.

Step 1: Confirm the Analysis Root

Default to the repository root so rust-analyzer sees the pinned toolchain and Cargo flags:

• rust-toolchain pins nightly-2025-10-10.
• .cargo/config.toml sets important rustflags, including +avx2, tokio_unstable, and linker flags.

Use a crate directory or crate Cargo.toml only when you intentionally want narrower analysis and can tolerate missing cross-workspace context.

Step 2: Resolve the Crate and Features

List workspace packages and features before tuning rust-analyzer:

• Run scripts/list-crate-features.sh with no arguments to list package names.
• Run scripts/list-crate-features.sh <package> to print the manifest path and feature map.
• Use exact Cargo package names such as risingwave_meta, risingwave_stream, or risingwave_connector.

Important limitation: rust-analyzer does not expose a first-class per-crate feature matrix inside one linked project. The relevant settings are:

• rust-analyzer.cargo.features
• rust-analyzer.cargo.noDefaultFeatures
• rust-analyzer.check.features
• rust-analyzer.check.noDefaultFeatures
• rust-analyzer.check.overrideCommand
• rust-analyzer.linkedProjects

These settings apply per linked project or workspace, not per package within one workspace root. When different RisingWave crates need different feature sets:

• Prefer a narrower root such as src/meta or that crate's Cargo.toml.
• Or open separate editor workspaces / linked projects for each crate variant.
• Or use rust-analyzer.check.overrideCommand to force diagnostics to run cargo check -p <package> ... --message-format=json.

For command examples and config snippets, read references/rust-analyzer-cli.md.

Step 3: Use rust-analyzer CLI

Use the lightest command that answers the question:

• rust-analyzer diagnostics . for workspace diagnostics.
• rust-analyzer unresolved-references . for missing symbols/imports.
• rust-analyzer analysis-stats . --parallel for batch semantic analysis.
• rust-analyzer analysis-stats . -o path/to/file.rs to narrow to one file or subtree.
• rust-analyzer prime-caches . before a long editor session on a cold workspace.
• rust-analyzer search '$a.foo($b)' for structural search.
• rust-analyzer ssr '$a.foo($b) ==>> bar($a, $b)' for structural replacement.
• cat file.rs | rust-analyzer parse and cat file.rs | rust-analyzer symbols for syntax-level inspection.

Prefer CLI for quick analysis and refactor planning. Prefer the editor when you need hover, jump-to-definition, rename, recursive macro expansion, or interactive diagnostics.

Step 4: Configure LSP Carefully

For RisingWave, keep both of these enabled unless you have a measured reason to disable them:

• rust-analyzer.cargo.buildScripts.enable = true
• rust-analyzer.procMacro.enable = true

The workspace is macro-heavy, and disabling either option causes misleading unresolved references or incomplete types.

For the lints crate, remember that lints/Cargo.toml sets package.metadata.rust-analyzer.rustc_private = true.

RisingWave-Specific Heuristics

• Start from the repository root unless the request is explicitly crate-local.
• If diagnostics look wrong, compare rust-analyzer output with cargo check -p <package> using the same features.
• For crates with many optional integrations, such as risingwave_connector, resolve features before trusting diagnostics.
• For macro-heavy paths, pair rust-analyzer with cargo expand when the user asks how generated code really looks.
• Avoid claiming feature-specific correctness unless you have matched the target crate and features explicitly.

Resources

• scripts/list-crate-features.sh lists package names, manifest paths, features, and suggested Cargo / rust-analyzer commands.
• references/rust-analyzer-cli.md captures the command cookbook and feature-flag caveats for this repository.