[rust-compiler] Return the compiled AST by value instead of JSON (#36729)
`compile_program` serialized the transformed `File` to a JSON string and every in-process consumer immediately deserialized it back, so each oxc/swc compile paid a full serialize/parse round-trip of the entire program for nothing. `CompileResult::Success.ast` is now `Option<react_compiler_ast::File>`; the napi bridge keeps its JSON boundary by serializing at the edge, while the oxc and swc frontends consume the typed AST directly. This ports the typed-AST patch the Oxc team carries on their fork (co-authored with Boshen), which also makes their integration patch-free going forward. Verified: cargo workspace tests, both snap channels 1804/1804, e2e comparison harness at parity baseline (1802 byte-identical, fbt local-require the one known divergence). First of a stack of three with #36730 and #36731. Co-authored-by: Boshen <1430279+Boshen@users.noreply.github.com>
lauren committed
Jun 10, 2026 at 20:19 UTC
ae6fe8a3e1d6806d4ed7c0f3930ad4de2f24ef2c
4 files changed
+13
-39
compiler/crates/react_compiler/src/entrypoint/compile_result.rs
+6
-3
@@ -1,6 +1,7 @@
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use react_compiler_ast::expressions::Identifier as AstIdentifier;
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use react_compiler_ast::patterns::PatternLike;
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use react_compiler_ast::statements::BlockStatement;
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+use react_compiler_ast::File;
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use react_compiler_diagnostics::SourceLocation;
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use react_compiler_hir::ReactFunctionType;
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use serde::Serialize;
@@ -81,10 +82,12 @@ pub struct BindingRenameInfo {
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pub enum CompileResult {
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/// Compilation succeeded (or no functions needed compilation).
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/// `ast` is None if no changes were made to the program.
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- /// The AST is stored as a pre-serialized JSON string (RawValue) to avoid
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- /// double-serialization: File→Value→String becomes File→String directly.
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+ /// The compiled Babel AST is returned by value so in-process Rust consumers
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+ /// (the oxc/swc frontends) use it directly instead of round-tripping through
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+ /// JSON. CompileResult still derives Serialize, so the napi consumer
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+ /// serializes the whole result (inlining the File) as before.
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Success {
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- ast: Option<Box<serde_json::value::RawValue>>,
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+ ast: Option<File>,
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events: Vec<LoggerEvent>,
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/// Unified ordered log interleaving events and debug entries.
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/// Items appear in the order they were emitted during compilation.
compiler/crates/react_compiler/src/entrypoint/program.rs
+3
-18
@@ -4020,27 +4020,12 @@ pub fn compile_program(mut file: File, scope: ScopeInfo, options: PluginOptions)
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// Now we can mutate file.program
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apply_compiled_functions(&replacements, &mut file.program, &mut context);
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- // Serialize the modified File AST directly to a JSON string and wrap as RawValue.
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- // This avoids double-serialization (File→Value→String) by going File→String directly.
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- // The RawValue is embedded verbatim when the CompileResult is serialized.
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- let ast = match serde_json::to_string(&file) {
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- Ok(s) => match serde_json::value::RawValue::from_string(s) {
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- Ok(raw) => Some(raw),
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- Err(e) => {
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- eprintln!("RUST COMPILER: Failed to create RawValue: {}", e);
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- None
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- }
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- },
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- Err(e) => {
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- eprintln!("RUST COMPILER: Failed to serialize AST: {}", e);
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- None
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- }
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- };
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-
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let timing_entries = context.timing.into_entries();
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+ // Return the compiled File by value; in-process Rust consumers use it
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+ // directly, and the napi consumer serializes the whole result as before.
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CompileResult::Success {
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- ast,
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+ ast: Some(file),
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events: context.events,
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ordered_log: context.ordered_log,
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renames: convert_renames(&context.renames),
compiler/crates/react_compiler_oxc/src/lib.rs
+1
-9
@@ -77,16 +77,8 @@ pub fn transform(
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// This maps source positions to new identifier names for uncompiled code.
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let rename_plan = build_rename_plan(&scope_info, &renames);
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- let compiled_file = program_ast.and_then(|raw_json| {
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- // First parse to serde_json::Value which deduplicates "type" fields
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- // (the compiler output can produce duplicate "type" keys due to
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- // BaseNode.node_type + #[serde(tag = "type")] enum tagging)
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- let value: serde_json::Value = serde_json::from_str(raw_json.get()).ok()?;
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- serde_json::from_value(value).ok()
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- });
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-
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TransformResult {
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- file: compiled_file,
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+ file: program_ast,
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diagnostics,
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events,
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rename_plan,
compiler/crates/react_compiler_swc/src/lib.rs
+3
-9
@@ -91,7 +91,7 @@ pub fn transform(
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react_compiler::entrypoint::program::compile_program(file, scope_info, options);
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let diagnostics = compile_result_to_diagnostics(&result);
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- let (program_json, events, renames) = match result {
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+ let (program_ast, events, renames) = match result {
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react_compiler::entrypoint::compile_result::CompileResult::Success {
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ast,
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events,
@@ -103,14 +103,8 @@ pub fn transform(
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} => (None, events, Vec::new()),
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};
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- let conversion_result = program_json.and_then(|raw_json| {
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- // First parse to serde_json::Value which deduplicates "type" fields
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- // (the compiler output can produce duplicate "type" keys due to
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- // BaseNode.node_type + #[serde(tag = "type")] enum tagging)
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- let value: serde_json::Value = serde_json::from_str(raw_json.get()).ok()?;
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- let file: react_compiler_ast::File = serde_json::from_value(value).ok()?;
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- let result = convert_program_to_swc_with_source(&file, Some(source_text));
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- Some(result)
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+ let conversion_result = program_ast.map(|file| {
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+ convert_program_to_swc_with_source(&file, Some(source_text))
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});
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let (mut swc_module, mut comments) = match conversion_result {