Joseph Savona

This commit **improves the React Compiler's diagnostic output** by **deduplicating error messages** related to `useMemo`/`useCallback` dependencies. It resolves an issue where `ValidatePreservedManualMemoization` would redundantly report errors already covered by the more informative `ValidateExhaustiveDependencies` pass. A new `hasInvalidDeps` flag is introduced to the **HIR**'s `StartMemoize` instruction, which `ValidateExhaustiveDependencies` sets when it finds invalid dependencies. This allows `ValidatePreservedManualMemoization` to skip validation for already-flagged blocks, providing **cleaner and more focused compiler diagnostics** for developers.

This commit **enhances the React Compiler's ref validation logic** by allowing non-mutating functions that freeze their inputs and capture refs to be safely ignored during render-time ref access checks. Specifically, the `ValidateNoRefAccessInRender` module now recognizes combined `Freeze` and `ImmutableCapture` effects, preventing false positives for patterns like **React Native's `PanResponder.create()`**. This **targeted feature improvement** ensures that valid, non-mutating interactions are not incorrectly flagged, thereby **improving compiler accuracy** for specific use cases. The compiler's shared runtime type provider was updated to include `PanResponder` definitions to support this.

This commit significantly **updates the documentation** for the **React Compiler**, providing a comprehensive summary of its **fault tolerance mechanisms**. It enhances `compiler/CLAUDE.md` with details on error handling, accumulation, and different error categories, while adding a new 'Fault Tolerance' section to `compiler/packages/babel-plugin-react-compiler/docs/passes/README.md` that explains how compiler passes manage errors using `env.tryRecord()` and `lower()`. This **documentation update** clarifies the distinction between validation and infrastructure passes, improving developer understanding of the compiler's robustness. Concurrently, an outdated planning document is removed, performing a **cleanup** now that the related work is complete.

This commit primarily **fixes a bug** in the **React Compiler's pipeline** by adjusting the early-exit logic within the `transformFire` pass in `Pipeline.ts`. The previous `env.hasErrors()` check was too broad, causing the compiler to prematurely exit on pre-existing errors; it now correctly triggers only on new errors generated by `transformFire` itself. Additionally, this commit includes minor **style and formatting improvements** across the compiler, such as adding a blank line in `CodegenReactiveFunction.ts` and fixing formatting in `ValidateMemoizedEffectDependencies.ts`. This ensures more robust error handling and improves code readability within the compiler's core logic.

This commit performs an internal **refactoring** within the **React Compiler's validation phase** to improve code clarity and consistency. It renames several variable identifiers to align with recent type changes, specifically updating `state` to `env` in `ValidateMemoizedEffectDependencies` visitor methods. Additionally, the `errorState` parameter in the `validateInferredDep` function within `ValidatePreservedManualMemoization` is renamed to `env`. This **compiler maintenance** change has no impact on generated code or runtime behavior, focusing solely on enhancing the internal readability and maintainability of the compiler's validation logic.

This commit **refactors** the **React Compiler's error reporting mechanism** by eliminating local `CompilerError` accumulators in most compiler passes, instead **emitting errors directly** to `env.recordError()` as they are discovered. This change impacts **17 different compiler passes**, including core **HIR building** (`BuildHIR.ts`, `HIRBuilder.ts`), various **inference stages** like `InferMutationAliasingRanges`, and numerous **validation checks** such as `ValidateExhaustiveDependencies` and `ValidateHooksUsage`. The **refactoring streamlines error propagation**, reducing indirection and improving the immediacy and consistency of diagnostic reporting within the compiler. For specific recursive validation passes, internal accumulators are retained but flushed via individual `recordError()` calls, maintaining necessary logic while aligning with the new direct emission pattern.

This commit **refactors the React Compiler's error handling mechanism** by removing the `env.tryRecord()` wrapper and introducing a centralized, catch-all `try/catch` block in `Program.ts`. It **standardizes error reporting** across various compiler passes, such as `HIRBuilder` and `CodegenReactiveFunction`, ensuring they record diagnostics via `env.recordError()` or use `invariant` instead of throwing exceptions. This change significantly **improves compiler robustness** by preventing unexpected crashes and introduces a new `CompileUnexpectedThrow` event. This event is now used to **fail snap tests**, enforcing correct error handling discipline during development. The overall impact is a more predictable and stable compilation pipeline with clearer error diagnostics.

This commit performs a significant **refactoring** and **cleanup** of the **React Compiler's error handling and recording infrastructure**. It introduces **consistent error recording** by wrapping various validation and analysis steps in `env.tryRecord` within the `Entrypoint/Pipeline` module. Furthermore, several **validation modules**, including `ValidateNoDerivedComputationsInEffects` and `ValidatePreservedManualMemoization`, are updated to use batch calls to `env.recordErrors`, streamlining the reporting of multiple issues. This work primarily enhances the **internal robustness and maintainability** of the compiler's diagnostic capabilities, ensuring more uniform and efficient error capture.

This commit **adds new test fixtures** to the **React Compiler's Babel plugin** to improve its **fault tolerance** validation. These tests cover various error scenarios, including prop mutations and ref access within `try/finally` blocks and `var` declarations. By introducing these specific test cases, the commit ensures the compiler correctly identifies and reports problematic code patterns, enhancing the robustness and diagnostic capabilities of the compiler. This is a **test enhancement** that helps maintain the quality and reliability of the compiler's error handling.

This commit introduces a significant **refactoring** to the **React Compiler's High-Level Intermediate Representation (HIR) generation**, specifically within the `lower()` function. Previously, `lower()` could throw errors, but it now **always produces an `HIRFunction`** object, even if errors are encountered during the lowering process. This **improves fault tolerance** by accumulating errors in the environment rather than halting execution, allowing for partial HIR generation and more robust error reporting. The change primarily affects the **`BuildHIR` module** (`BuildHIR.ts`), the **compiler pipeline** (`Pipeline.ts`), and updates **documentation** (`fault-tolerance-overview.md`) and **test fixtures** to reflect the new error handling paradigm.

This commit **enhances the React Compiler's fault tolerance** by enabling it to report multiple independent errors within a single function, such as both mutation and ref access errors, rather than bailing out after the first detected issue. A **new test fixture** (`error.fault-tolerance-reports-multiple-errors.js`) is added to demonstrate this improved diagnostic capability, ensuring the compiler provides more comprehensive feedback. This **new capability** significantly improves the developer experience by offering a complete picture of issues in a single compilation pass. Additionally, the `compiler/fault-tolerance-overview.md` **documentation is updated** to mark all phases of this fault tolerance work as complete.

This commit continues the **React Compiler's fault-tolerance refactoring**, updating numerous **validation, inference, and codegen passes** to record errors directly on the environment instead of throwing or using `Result` types. Specifically, passes like `validateSourceLocations`, `inferMutationAliasingRanges`, and `codegenFunction` now return their direct results or `void`, propagating errors via the environment. This **refactoring** simplifies the `Pipeline.ts` orchestration by removing `tryRecord/unwrap` calls, establishing a more consistent and robust **error handling mechanism** across the compiler. This is a significant internal architectural change to how the **React Compiler** handles and reports errors, improving its overall resilience.

This commit introduces a significant **refactoring** to the **React Compiler's error handling mechanism**, specifically for nine key validation and inference passes. Instead of returning `Result` types, passes like `validateHooksUsage` and `validateExhaustiveDependencies` now directly record errors onto the function's environment using `fn.env.recordErrors()`. This change simplifies the **compiler pipeline** in `Pipeline.ts` by eliminating `tryRecord()` wrappers and `.unwrap()` calls, streamlining error propagation. The work enhances the **internal architecture** and **fault tolerance** of the `babel-plugin-react-compiler`, accompanied by **documentation updates** in `fault-tolerance-overview.md` and new test cases for `NoCapitalizedCallsRule`.

This commit introduces a significant **fault tolerance enhancement** to the **React Compiler pipeline**, allowing it to continue processing and accumulate errors rather than halting on the first issue. It **refactors** the compiler's internal `run`, `runWithEnvironment`, and `compileFn` functions to return a `Result` type, explicitly handling success or `CompilerError` outcomes. All pipeline passes are now wrapped in `env.tryRecord()` to catch and record errors, providing a more comprehensive error reporting experience by allowing the compiler to discover multiple issues in a single run. This change primarily impacts the core **compilation flow** within `babel-plugin-react-compiler` and required updating 52 test fixture expectations to reflect the newly reported additional errors.

This commit introduces a **new capability** for the **React Compiler's HIR (High-level Intermediate Representation) `Environment`** by adding **error accumulation infrastructure**. It implements methods such as `recordError()`, `hasErrors()`, and `aggregateErrors()` to collect and manage multiple diagnostics during compilation, rather than stopping on the first error. This foundational change enhances the compiler's **fault tolerance** and improves the developer experience by enabling comprehensive error reporting in a single pass. The `compiler/packages/babel-plugin-react-compiler/src/HIR/Environment.ts` file is updated with these new error handling mechanisms, and the `fault-tolerance-overview.md` **documentation** is also updated to reflect this progress.

This commit **adds a new documentation file**, `compiler/fault-tolerance-overview.md`, outlining a detailed plan for enhancing the **React Compiler**. This **design document** describes how the compiler will be made **fault-tolerant** by accumulating errors across all compilation passes instead of stopping at the first one. The primary goal is to enable the compiler to report **multiple compilation errors at once**, providing more comprehensive feedback. This **preparatory work** lays the groundwork for a significant improvement in the compiler's robustness and developer experience.

This commit performs significant **dead code removal** within the **React Compiler's Babel plugin**, specifically targeting remnants of a deprecated fallback compilation pipeline. It **refactors** the internal **compiler infrastructure** by deleting unused types like `CompileProgramMetadata`, removing the `retryErrors` property from `ProgramContext`, and changing the `compileProgram` function's return type to `void`. Additionally, the `'client-no-memo'` output mode is eliminated from the compiler's environment configuration. This **maintenance** task simplifies the **compilation pipeline** and reduces the overall codebase complexity by removing features no longer in use.

This commit introduces **source location tracking** for reactive scope dependencies and their paths within the **React Compiler's High-level Intermediate Representation (HIR)**. This **enhancement** modifies several core compiler passes, including dependency collection, propagation, and scope merging, to consistently store and pass location information. Files such as `HIR.ts` (for type definitions), `CollectHoistablePropertyLoads.ts`, and `PropagateScopeDependenciesHIR.ts` are updated to handle these new location details. The primary purpose is to support an **experimental type-directed compilation** feature, ensuring that expression types can be accurately looked up by their source location, which is critical for future compiler optimizations.

This commit introduces **enhancements to the `snap` compiler's minimization process** by adding new strategies within `minimize.ts`. Specifically, it enables the removal of **function parameters**, **array pattern elements**, and **object pattern properties** to further reduce code size. Additionally, the commit refines the **error handling logic** to ensure errors are preserved based on their description, category, and reason, leading to more precise error matching. This work improves the overall effectiveness and reliability of the **`snap` package's code minimization capabilities**, aiming for more efficient code reduction while maintaining error integrity.

This commit introduces a **new `compile` command** to the **`snap` tool** within the **`compiler`** project, enabling users to compile any file via `yarn snap compile <path>`. It also **enhances the existing `minimize` command** to accept a positional path argument for improved consistency. Crucially, this update **fixes relative path resolution** for both `compile` and `minimize` commands, ensuring they correctly handle paths when executed from the `compiler/` directory. This **improves the developer experience** by making the `snap` commands more robust and user-friendly, supported by refactored path constants in `src/constants.ts` and comprehensive documentation updates across various guides.