feat(transformer/react): read comment pragma @jsxRuntime classic / automatic (#1133)

closes #1120

crates/oxc_ast/src/trivia.rs

@@ -74,10 +74,7 @@ impl TriviasMap {
         self.comments.insert(span.start, comment);
     }
 
-    pub fn comments_spans(&self) -> Vec<(Comment, Span)> {
-        self.comments()
-            .iter()
-            .map(|(start, comment)| (*comment, Span::new(*start, comment.end)))
-            .collect()
+    pub fn comments_spans(&self) -> impl Iterator<Item = (Comment, Span)> + '_ {
+        self.comments().iter().map(|(start, comment)| (*comment, Span::new(*start, comment.end)))
     }
 }

crates/oxc_semantic/src/jsdoc/builder.rs

@@ -35,7 +35,7 @@ impl<'a> JSDocBuilder<'a> {
         comment_text.is_some()
     }
 
-    /// Find the jsdoc doc in frontend this span, a.k.a leading comment
+    /// Find the jsdoc doc in front of this span, a.k.a leading comment
     fn find_jsdoc_comment(&self, span: Span) -> Option<&'a str> {
         let (start, comment) = self.trivias.comments().range(..span.start).next()?;
 

crates/oxc_transformer/examples/transformer.rs

@@ -35,7 +35,10 @@ fn main() {
     println!("Original:\n");
     println!("{printed}\n");
 
-    let semantic = SemanticBuilder::new(&source_text, source_type).build(&ret.program).semantic;
+    let semantic = SemanticBuilder::new(&source_text, source_type)
+        .with_trivias(ret.trivias)
+        .build(&ret.program)
+        .semantic;
 
     let program = allocator.alloc(ret.program);
     let transform_options = TransformOptions {

crates/oxc_transformer/src/context.rs

@@ -18,6 +18,10 @@ impl<'a> TransformerCtx<'a> {
         Self { ast, semantic }
     }
 
+    pub fn semantic(&self) -> Ref<'_, Semantic<'a>> {
+        self.semantic.borrow()
+    }
+
     pub fn symbols(&self) -> Ref<'_, SymbolTable> {
         Ref::map(self.semantic.borrow(), |semantic| semantic.symbols())
     }

crates/oxc_transformer/src/lib.rs

@@ -77,7 +77,7 @@ impl<'a> Transformer<'a> {
         Self {
             // TODO: pass verbatim_module_syntax from user config
             typescript: source_type.is_typescript().then(|| TypeScript::new(Rc::clone(&ast), ctx.clone(), false)),
-            react_jsx: options.react_jsx.map(|options| ReactJsx::new(Rc::clone(&ast), options)),
+            react_jsx: options.react_jsx.map(|options| ReactJsx::new(Rc::clone(&ast), &ctx, options)),
             regexp_flags: RegexpFlags::new(Rc::clone(&ast), &options),
             es2022_class_static_block: es2022::ClassStaticBlock::new(Rc::clone(&ast), &options),
             es2021_logical_assignment_operators: LogicalAssignmentOperators::new(Rc::clone(&ast), ctx.clone(), &options),

crates/oxc_transformer/src/react_jsx/mod.rs

@@ -11,6 +11,7 @@ use oxc_syntax::{
 };
 
 pub use self::options::{ReactJsxOptions, ReactJsxRuntime};
+use crate::context::TransformerCtx;
 
 /// Transform React JSX
 ///
@@ -67,8 +68,13 @@ impl<'a, 'b> JSXElementOrFragment<'a, 'b> {
 }
 
 impl<'a> ReactJsx<'a> {
-    pub fn new(ast: Rc<AstBuilder<'a>>, options: ReactJsxOptions) -> Self {
+    pub fn new(
+        ast: Rc<AstBuilder<'a>>,
+        ctx: &TransformerCtx<'a>,
+        options: ReactJsxOptions,
+    ) -> Self {
         let imports = ast.new_vec();
+        let options = options.with_comments(&ctx.semantic());
         Self {
             ast,
             options,

crates/oxc_transformer/src/react_jsx/options.rs

@@ -1,5 +1,7 @@
 use serde::Deserialize;
 
+use oxc_semantic::Semantic;
+
 #[derive(Debug, Default, Clone, Copy, Deserialize)]
 pub struct ReactJsxOptions {
     /// Decides which runtime to use.
@@ -28,3 +30,30 @@ impl ReactJsxRuntime {
         matches!(self, Self::Automatic)
     }
 }
+
+impl ReactJsxOptions {
+    /// Scan through all comments and find the following pragmas
+    ///
+    /// * @jsxRuntime classic / automatic
+    ///
+    /// The comment does not need to be a jsdoc,
+    /// otherwise `JSDoc` could be used instead.
+    ///
+    /// This behavior is aligned with babel.
+    pub(crate) fn with_comments(mut self, semantic: &Semantic) -> Self {
+        for (_, span) in semantic.trivias().comments_spans() {
+            let comment = span.source_text(semantic.source_text());
+            // strip leading jsdoc comment `*` and then whitespaces
+            let comment = comment.strip_prefix('*').unwrap_or(comment).trim_start();
+            // strip leading `@`
+            let Some(comment) = comment.strip_prefix('@') else { continue };
+            // read jsxRuntime
+            match comment.strip_prefix("jsxRuntime").map(str::trim) {
+                Some("classic") => self.runtime = ReactJsxRuntime::Classic,
+                Some("automatic") => self.runtime = ReactJsxRuntime::Automatic,
+                _ => {}
+            }
+        }
+        self
+    }
+}

tasks/transform_conformance/babel.snap.md

@@ -1,4 +1,4 @@
-Passed: 241/1080
+Passed: 242/1080
 
 # All Passed:
 * babel-plugin-transform-numeric-separator
@@ -803,7 +803,7 @@ Passed: 241/1080
 * regression/11061/input.mjs
 * variable-declaration/non-null-in-optional-chain/input.ts
 
-# babel-plugin-transform-react-jsx (92/170)
+# babel-plugin-transform-react-jsx (93/170)
 * autoImport/after-polyfills-compiled-to-cjs/input.mjs
 * autoImport/after-polyfills-script-not-supported/input.js
 * autoImport/auto-import-react-source-type-module/input.js
@@ -878,7 +878,6 @@ Passed: 241/1080
 * removed-options/invalid-use-spread-true/input.js
 * runtime/defaults-to-automatic/input.js
 * runtime/invalid-runtime/input.js
-* runtime/pragma-runtime-classsic/input.js
 * runtime/runtime-automatic/input.js
 * spread-transform/transform-to-babel-extend/input.js
 * spread-transform/transform-to-object-assign/input.js

tasks/transform_conformance/src/test_case.rs

@@ -137,12 +137,13 @@ pub trait TestCase {
         let allocator = Allocator::default();
         let source_text = fs::read_to_string(path).unwrap();
         let source_type = SourceType::from_path(path).unwrap();
-        let transformed_program =
-            Parser::new(&allocator, &source_text, source_type).parse().program;
+        let ret = Parser::new(&allocator, &source_text, source_type).parse();
 
-        let semantic =
-            SemanticBuilder::new(&source_text, source_type).build(&transformed_program).semantic;
-        let transformed_program = allocator.alloc(transformed_program);
+        let semantic = SemanticBuilder::new(&source_text, source_type)
+            .with_trivias(ret.trivias)
+            .build(&ret.program)
+            .semantic;
+        let transformed_program = allocator.alloc(ret.program);
 
         Transformer::new(&allocator, source_type, semantic, self.transform_options())
             .build(transformed_program);
@@ -190,9 +191,12 @@ impl TestCase for ConformanceTestCase {
         }
 
         // Transform input.js
-        let program = Parser::new(&allocator, &input, source_type).parse().program;
-        let semantic = SemanticBuilder::new(&input, source_type).build(&program).semantic;
-        let program = allocator.alloc(program);
+        let ret = Parser::new(&allocator, &input, source_type).parse();
+        let semantic = SemanticBuilder::new(&input, source_type)
+            .with_trivias(ret.trivias)
+            .build(&ret.program)
+            .semantic;
+        let program = allocator.alloc(ret.program);
         Transformer::new(&allocator, source_type, semantic, self.transform_options())
             .build(program);
         let transformed_code = Codegen::<false>::new(input.len(), CodegenOptions).build(program);